| Author | Message | ||
     Mark Taxis New User Username: mark_taxis Post Number: 10 Registered: 4-2007 |
Last leave I noticed that the front tyres are starting to wear on the outer edges also the steering seems very heavy with a slight pull to the left I took the car to the local tyre shop and asked them to do a wheel alignment. The manager looked at the car and told me that this was too difficult and that it would take them ages to do, basically they were not interested. Is this job really that hard to do ? also what settings would you recommend for a Mk 6 special. I know very little about steering geometry and what causes tyre scrub etc, any advice or info gratefully received Thanks Mark | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1021 Registered: 4-2003 |
Mark/ The suspension on those cars whilst very robust was fairly simple. There are four principal angles in a wheel alignment. Toe in. As the term suggests this is how much the wheels point in forwards described originally by the distance between the wheels at the back of the front wheels minus the same dimension taken at the front of the wheel. It is a very small amount (say 1/16") but has a considerable bearing on directional stability and tyre wear. Camber. The front wheels are seldom vertical they lean in or out at the top and that is expressed in degrees. Again a small angle. Caster. This is the angle of the pin that the wheel swivels on. It always leans towards the rear of the car and is the geometry that more or less keeps the car tracking in a straight line and certainly the setup that self centres the wheels after you have gone around a corner! Ackerman Angle. This is a bit esoteric but is the angular difference between the two front wheels when the car goes around a bend. If you think about it the inner wheel on the car has a shorter distance to travel that the outer one. If the wheels remained parallel the front would crab on a bend - form of skidding. Turning the inner wheel to a sharper angle means it goes a shorter distance and overcomes the problem. So that's the good news. The bad news is that of all those angle only the toe in is adjustable on your car and that is quite simple by varying the length of the track rod at the back of the suspension. Why your man should baulk at that I cannot imagine. If the caster is out that can be adjusted by fitting wedges between the radius arms at the back of the king pins which will slew the latter and increase the caster. Camber. This is the most interesting one. You see despite the spin merchants climaxing over the brilliant cruciform chassis it is not unusual for the front 'axle' to sag or bow upwards. I have experienced both. The only way to fix this that I am aware of is to trot the old girl to a body aligner shop take a lien on the manager's gonads and trust him to literally bend the thing back to where it should be. If you think about it the object is to move the shock absorber towards the centre of the car or away from it which will lean the top of the wheel inwards or outwards. | ||
| Paul Yorke Prolific User Username: paul_yorke Post Number: 229 Registered: 6-2006 |
Hi Mark, I think Bill has covered it all. But I'd like to add a couple of things: 1. That the toe-in is the setting that usually changes with use. Pot holes, mounting curbs etc. Luckily it is also the easiest to adjust. Find a shop with a non computerised tracking machine / tool. Because both your tyres are wearing equally, it is probably the toe in that's the problem. (Look down at your feet, imagine they are wheels - toe-in or toe-out  ) 2. Check that oil is getting to all the front suspension and that there is NO play / rust evident in any of them. I assume you press the self lube every time you go out? (Was the garage you went to using a computerised tracking machine? Often I've found that unless the machine has the car details programmed in and it tells them step by step what to do, the operators have no idea what each reading is and what to adjust.) | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1022 Registered: 4-2003 |
Paul/As always the practical man. Why I assume in these cases that all the mechanism is perfectly oiled etc I know not. I have just witnesed a beautiful S series that the owner thought there seemed to be a looseness 'underneath'. Every bearing in the suspension had to be replaced - the parts alone cost $40,000! Someone had replaced the drip valves with grease nipples, thrown away most of the piping but then forgot to grease the thing. Mind you the owner had spent a fortune on the wood work leather paint etc etc! Talk about wearing dirty underpants with a new suit! Anyway I was intrigued with your remarks about electronic wheel aligners. I have no experience or training in this side of the business. I can tell when something is wrong and can replace all the worn bits but of course I have no equipment to adjust or even measure suspension settings. I try to have my cars aligned (at least checked) once a year unless a little do-it-yourself aligning has been done with the aid of a kerb and half a bottle of Glen Livet. A new wheel for a Spirit I found out recently is $900! Wheel balances every 10,000K. I have a highly experienced operator who uses the latest singing and dancing machines. I asked him one day did he have all the different models of RR and B and he said he seldom uses them on any car. What he does do is adjust the suspension after he has driven the car and checked the tyre wear. So much for all the readout etc. He always gives me a print out which I must confess I have never checked against the Factory specs. The proof however is in the eating(??)the cars always steer and handle perfectly after his treatment and occasionally he gets me in after a month to check - no charge. I have always believed that a wheel alignment was a compromise between quite a few factors. | ||
| Paul Yorke Prolific User Username: paul_yorke Post Number: 230 Registered: 6-2006 |
Bill . . . I've obviously come across too many horror stories with these cars! If only all customers were as diligent as you! Hmmmm or maybe not ;) I can imagine the owner of that S type you mentioned phoning up and asking - "can I pop by and have my tracking checked" " yes sure, it'll be about $40 " "Opps - did I say 40? " Bill you are quite correct about the compromise on the alignment. If the car drives properly and the tyres don't scrub, it's spot on! Use the factory settings as a starting point, then adjust as necessary | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 43 Registered: 6-2004 |
Mark Before you change anything make sure that the various bearings in the front suspension are in good order. If they are not then the toe in, camber etc. of the front wheels will be upset and will change as you drive. In the early days with B420EY attention was needed from time to time to the needle bearings at the bottom of the yokes. They can get to the stage, with water getting in, where the needles have been virtually ground away and there is a lot of play ( more than 1/16" ! ). But this is not possible to check unless you take the load off the bearings. Any play in the bottom yoke bearings, king pins etc. will result in the position of the front wheels changing from where they should be as you hit bumps and go round corners. Toe in, camber and caster angle are all affected. With everything as it should be the top of each yoke should be about central between the shock absorber arms. Then as wear develops in the needle bearings the rear needle bearIng usually deteriorates faster than the front which causes the top of the yoke to move forward and it can get to the point where the top of the yoke actually touches the shock absorber arm. If the top of the yoke is not in the middle of the shock absorber arms then the needle bearings need to be attended to and you can see this easily on a MK VI special. Unfortunately the converse is not true since the yoke top will still be central if both front and rear needle bearings have worn to the same extent. Best to undo the top bearing, move the shock absorber arms out of the way and test for movement in the needle bearings. You can do this without disturbing the front brake hoses if you are careful not to let the top of the yoke move too far laterally. Uneven tyre wear across the tyre is usually caused by the toe in errors, particularly if the tyre pressure is wrong. Uneven wear round the tyre is often a sign of the shock absorber not working properly. Caster and camber don't usually affect the tyres but do affect the way the car handles. Your car has the early steering geometry (prior to the G series) like mine. If you ever have to fit a replacement front shock absorber then check that the travel of the arm is OK for the early geometry. The later geometry uses the same shock absorber parts but the shock absorber arm is assembled in a different position. Regards Laurie | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 44 Registered: 6-2004 |
Mark Correction. I think your car is a J series so it will have the later steering geometry. But the point about the shock absorber differences still applies. Regards Laurie | ||
| Mark Taxis Experienced User Username: mark_taxis Post Number: 11 Registered: 4-2007 |
Thank you everyone for your input. It would seem to me that the way forward is to first check for wear in the bearings, kingpins etc. Assuming this is ok then I should take the car to a different tyre centre and get them to measure what the toe in , camber etc actually is. From those readings I will be able to narrow down the area that needs adjustment. Regards Mark | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1023 Registered: 4-2003 |
Something I have not seen mentioned for quite a while is checking the drippers. Unless you are trying to preserve your garage floor for the archiologists, visit your local newspaper office and buy a residual roll of newsprint. You can roll the sheet flat on the floor then drive your dripper car over it. Give the old pedal several pumps and leave it overnight. Next morning check the evidence. The usual constipation occurs at the rear (pun not intended)meaning your rear spring shackels are gorging themselves on a very expensive diet of threaded pins and bushes! First step is to disconnect the supply line to the dripper and pump. If oil flows remove the dripper connect it to the line and pump, if oil flows the blockage is in the bearing - very unusual but it has happened. The drippers are repairable but are now available again. They are cheaper than suspension bits. I have an old butane cylinder for which I have had made a valve to replace the usual tap. This allows me to fill the cylinder with fluid and to then pressurise the thing. Originally built to test oil flow from engine bearings galleries etc I have used it for flushing crappy Shadow brake lines and yes, replacing the drippers with open unions and pumping kero through the whole system. Drastic but worked on a chassis that had not moved for 22 years. Oh and I did tie off the dripper to the clutch bearing! | ||
| Martin Cutler Frequent User Username: martin_cutler Post Number: 88 Registered: 7-2007 |
Hi guys, What is the actual toe-in measurement? I think it is 1/8th of an inch, but I am not sure. Have not done it myself, but have had my car checked not with any fancy wheel alignment machine, but a length of steel with a "pin" at each end. This is slid under the front wheels at the front, set on the centre of the tyres, then moved to the back of the wheels, and the difference checked. If someone can confirm what the actual adjustment is, then Mark (and the rest of us) could actually check this ourselves. Cheers Marty | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1489 Registered: 4-2003 |
Martin, The original toe-in setting is 1/16“ to 1/8“ (see the manual at http://rrtechnical.info/mkvi/wshoplate/8.pdf ). Yes, you can set it fairly accurately the way you describe, Martin. That means an outcome of probably 1/16” +/- 100%. That assumes that you have suspension in perfect condition and that there is no chassis sag at all. However, 1/8” is a reasonable starting point. Also, note that the setting is only valid after the vehicle has been moved only forwards and for at least 50 M, and the wheels are still on the ground (ie not jacked up in the meantime). However, the ideal setting depends on the camber and type of tyres you are using. If the camber is still 0 to 1 degrees positive (ie the tyres are closer to eachother at the bottom than the top), then the toe-in is best 1/16” to 1/8” respectively with crossply tyres. As a guide, with radials, best is 1/16” less toe-in in each case, ie 0” to 1/16” respectively. Ultimately, only the tyre wear pattern will tell you what is optimum to allow for any wear in the suspension: scrubbing on the inside edges means you need more toe- in, scrubbing on the outside edges means you need less. If the camber is negative, as with worn suspension and a sagged chassis, you may actually need toe-out to compensate. Roughly, each degree less of camber equates to 1/16” less toe-in required. As the camber is not normally adjustable without a chassis bender or repositioning the shock damper on the chassis, normally a trade-off between camber and toe-in is the best you can achieve on an early postwar car. You may make a camber reading +/- 50% accurate using a perpendicular device on a perfectly flat garage floor, reading the distance from the device to the top and bottom of the wheel rim, again loaded and only moved forwards for 50 M. Of course it is best to do these measurements as a good enough effort to allow you to drive to the wheel alignment shop armed with the setting you really want. If the tyres are almost worn out, you may choose to wait to do the final alignment as a package deal with new tyres. I haven’t bought tyres in Sydney for a while, but a proper wheel alignment was usually thrown in free with new tyres. In any case, a proper wheel alignment is done rather cheaply on a modern machine, especially when you put the cost in the context of the price of replacement tyres. RT. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 795 Registered: 9-2004 |
Reading the postings and not seeing the text clearly etc of the link of the technical discription.[old computer] I would maybe point to the first check with the steering "slight pull to the left". First I would ask if the car suffers from any bump steer. This can be common with cars that have incorrect settings when doing a toe-out on turns check. Check the track rods making sure they are both the same length and also not bent. Heavy steering can be caused by many causes. The fitting of radials and low pressures within can make a tough time with low speed parking. Castor and KPI with camber variations between sides can effect the tyre wear even if the tracking is set correctly in the straight ahead position,parallel to 1/8" toe-in IMO. Carry out the tracking checks twice. do the first check and note the reading, then move the car forward 180% of the road wheel, check again and the diferental of the two readings is the true figure. This takes into any account of slight buckles of the road wheels or slight suspension movement. Hope this may help. | ||
| Martin Cutler Frequent User Username: martin_cutler Post Number: 89 Registered: 7-2007 |
Hi Richard, Why 50 metres? I can understand only moving it forward, and having a level floor. Hi Patrick, moving it forward half a wheel rotation may account for a buckled rim, good tip. Here's another question for you guru's. The Freestone & Webb has very nice steering, but the suspension "bottoms out" on bigger bumps. There is 1/2 an inch clearance between the bump stop rubber and the suspension arm. On the SSRB, the gap between the bump stop rubber and the suspension arm is 1 1/4 inches. The Standard Steel is export, so stiffer springs, whereas the Freestone & Webb is home market. What do you think? Marty | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 796 Registered: 9-2004 |
Marty,do a check on the cars trim height and check with the data suppied if it is there[home market?]. Also check that the car is running the correct aspect ratio tyres and pressures for this check. If the coil springs are found to be sagging[the cause maybe] the camber and KPI can be affected. Even when the tracking is correct. | ||
| Martin Cutler Frequent User Username: martin_cutler Post Number: 90 Registered: 7-2007 |
Hi Patrick, By home market, I mean the car was delivered in England, so no stiffer springs, bigger bumper bars for kangaroos, etc. As for trim height, not sure. The car looks OK, the whels fill the wheel arches, if it was 3/4 of an inch higher, it would probably look wrong. The question is more about bump stop clearance, so tyre size doesn't really come into it. Unless, of course, you over tyre the car, and the bump stop clearance enables the tyre to borrow into the underside of the guards. Cheers Marty | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 797 Registered: 9-2004 |
Marty, I was thinking if incorrect tyre sizes were fitted then the info for the trim hieght if stated would be different! | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1494 Registered: 4-2003 |
There were a few fundamental issues raised above, ones which would be answered very quickly by any suspension or steering shop. These apply to practically any motor vehicle ever built, but my opinions relating to their application to early postwar cars may be of interest. 1. Castor. The castor settings mainly affect steering feel. Especially at lower speeds, too much castor leads to heavy steering and increased tendency of the steering to fight the driver. At higher speeds, excessive castor often leads to very unpleasant steering quirks and horrible bump-steer. Too little castor leads to light but vague and sometimes erratic steering with inadequate self centring. A difference in castor left to right of the vehicle in itself leads to slight instability, and if the difference is excessive it leads to pulling to one side. Castor does not markedly affect tyre wear patterns except in cases of extreme deviation from the design settings. Application: as the castor is relatively easily adjusted on these cars by varying the shims, poor castor settings may be corrected readily. 2. Toe-in. Toe-in mainly affects steering feel. Inappropriate toe-in leads to similar but milder effects to those of inappropriate castor. Toe-in does-however, have a dramatic effect on tyre scrubbing when poorly set. 3. Camber. Camber has most to do with cornering stability. Generally, negative camber improves cornering stability. However, if the camber is not too far out (maybe 1 1/2 degrees is an upper limit of deviation from the design setting provided it is equal within ½ degree left to right), then toe-in and camber must be adjusted to suit eachother otherwise tyres will scrub-out rapidly. Naturally, a negative camber requires a reduced toe-in or even toe-out, leading to steering vagueness and loss of self-centring as the main downside. A difference in camber left-to-right leads to tyre scrubbing, usually far more pronounced on one tyre , and the vehicle will pull to one side. Application. Camber is not normally adjustable on early postwar cars. However, a camber differential left to right needs urgent correction, and is most commonly due to bent suspension or chassis components. Chassis bending or relocating the upper levers/dampers may be the only solutions in bad cases. This is a nasty and sometimes expensive operation. 4. Standing height. Apart from the obvious appearance, ground clearance and suspension travel issues, the standing height has some effect on all the steering geometry settings depending on the design. Naturally, sagged springs will bottom-out far earlier than they should. This is exacerbated if the shock dampers are ineffective. Generally, the original standing heights should be observed for all vehicles to preserve suspension settings as well as keeping driveline components aligned avoiding tendencies to vibrate and drivetrain wear. Inappropriate standing heights either at the front or rear have large effects, mainly negative, on vehicle balance and dynamic stability. Component wear is especially acute with independent suspension on the drive axle. Vehicles lowered for style, bling, racing or rallying behave poorly without stiffer suspension and dampers, and the steering geometries required are a whole new ball game as well. Application: The standing height at the front is highly critical on these cars. The design figures in the manuals are rather lenient in their wide tolerances specified my opinion. The type of coachwork fitted does not have any bearing on the required standing height A-B measurements stated in the manuals, as the spring preloads should be adjusted to compensate for the vehicle weight in the first place. The A-B method of measurement gives a figure for the difference between the chassis-to-ground height (ground clearance) relative to the axle height. This measurement is not dependent on the wheel or tyre size, as chassis height and axle height are equally affected by the tyre diameter. Note that with standard springs, the cars from B1GT/SCA1 are set to a lower height by ¾” compared to those with Colonial springs. This is a double-whammy for rough roads, with Colonial-sprung cars having a greater standing height and stiffer springs front and rear at the same time. Colonial-sprung cars also have different and stiffer damper settings. Generally, low front standing heights may be adjusted by shimming the front coils in mild cases, or by fitting new or reset springs in most cases. Many of these cars have been driven for decades with broken front coils. Rear standing height - Application: Driveline wear is not critical on early postwar cars as the rear propeller shaft half is already steeply angled. However, the effect of rear end standing height on vehicle behaviour is rather pronounced. 9/10 of all early postwar cars I have seen have broken rear spring leaves, but owners are oblivious as they are neatly wrapped up in leather gaitors. 5, Damping – Application. Poor suspension damping is usually due simply to oil loss in the dampers. If leakage is not too rapid, regular topping up is generally preferable to a rebuild. In my opinion, a 20-grade straight mineral oil is a useful weight to use in the shock dampers of these cars as it gives a slight increase in damping. . My two bob’s worth. RT. | ||
| Laurie Fox Experienced User Username: laurie_fox Post Number: 45 Registered: 6-2004 |
My MK VI is B420EY and thus has the steering geometry of the cars before the G series. I don't drive fast round corners and have no significant experience of the handling of cars from the G series onwards. How do the different geometries compare from the handling point of view? I see that the king pin pivot angle was changed (increased by 1 deg) which means increased changes in both camber and castor as the front wheels are turned from straight ahead. All of these handling matters ultimately depend on what forces are being applied to the stub axles under various conditions. In the case of a car moving straight ahead on a level road there will be no net lateral force on the car as a whole although, due to toe in, etc., there may be equal and opposite lateral forces on the front stub axles. When going round a bend things are different. The lateral force involved comes from both the front wheels and the back wheels, all of which take up an angle to the direction in which they are actually moving. They do this because of the way in which a tyre generates a lateral force. It is somewhat similar to the way in which an aerofoil generates lift. With no angle of incidence there is no lift (please forgive the simplification) and the lift increases with angle of incidence up to the point of stalling. Tyres behave in much the same way. The footprint changes and in the early stages there is no slip at the point of contact. The rubber distorts, transmits the lateral force to the tyre casing and recovers its original shape as the wheel goes round. As the "angle of incidence" increases some parts of the footprint will start to slip, other parts will have more lateral load to bear and eventually the whole footprint will be slipping with an angle of incidence of (probably) about 12 or 15 deg. This applies to the back wheels as well as to the front because they have to provide lateral force too and they do this because the whole car turns, relative to the direction of motion, so as to provide the necessary angle of incidence to the back wheels. This has an effect on the steering lock needed to go round the curve. All of this determines whether the front or the back wheels ultimately break away first and what happens next. Different tread patterns have their own characteristics regarding where the slip starts and the distribution of the lateral load over the footprint as a whole even when there is no slip. The outward leaning of the car as it corners will also have an effect and I am sure that the racing people know all about these things. But for an ordinary driver like myself it does not seem to matter too much. I am now on my twelfth set of tyres and have some records as to how they have performed - all crossply of various makes. Toe in has never been adjusted in nearly 50 years. Some tread patterns have worn slightly unevenly across the width of the tyre and some have not. Average mileage per tyre has been about 26000 with enormous variations even between several from the same manufacturer and batch bought at the same time. Rate of wear on the front seems to be about the same as on the back. Regards Laurie | ||
| Martin Cutler Frequent User Username: martin_cutler Post Number: 91 Registered: 7-2007 |
Thanks Richard, that is very informative, and explains the 3/4 inch difference in my 2 cars. Must remember to slow down for speed humps.... Cheers Marty | ||
| Bill Vatter Frequent User Username: bill_vatter Post Number: 48 Registered: 9-2004 |
Richard, I believe the most common cause of incorrect camber is worn out silentbloc bushings on the inner end of the lower suspension arm. These are located in the center of the car and are hidden from view by a heavy skid plate. Normally the camber is about 1 1/2 degrees positive (top of wheel tilted outwards) and as the bushing expires, the effective length of the lower arm will increase, causing the camber to become less positive and eventually negative. Repair is not terribly difficult nor are the parts terribly expensive in a relative sense. (All RR parts seem to cost more than they should.) The key point in such deficiency is the springs must be removed, a task that can be very dangerous if not done correctly. Some special tools are needed to compress the spring properly and safely so that they can be safely removed to allow the lower arms to be removed and the bushings replaced. This is not a job for someone who is unsure about what he is doing. The spring can literally kill you if it slips out due to incorrect disassembly. I don't think camber has that much effect on straight tracking. In my experience it is incorrect caster on one or the other side that has the greatest effect on the steering pulling to one side or the other. This is especially so with these cars where the lower yoke bearings and upper silentbloc bushings are typically in terrible condition, causing the caster to be negative on one or the other wheel. Negative caster will cause the steering to pull towards the side with the less-positive caster. Often those yoke parts are the only repairs needed to make the suspension right on an EPW car, and those can be easily addressed without removing the spring. However, one does need to have his wits about him taking the yoke out or the spring can get away possibly giving someone a fatal knock on the head. The yoke bushings and bearings are the weakest part of a pretty good design, but it is the weakest part that gives out first. Incidentally, in the American dictionary, it is caster, not castor, the latter being oil or the bean from which such infamous oil is squeezed. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1569 Registered: 4-2003 |
Thank you, Bill V. Quite correct, and all good stuff. Definitive values for camber and castor are set out in the full article. Note the inference that incorrect camber may be compensated to a certain extent by setting the toe-in to suit. The note is that left-to-right differences are probably more important than the camber readings themselves within limits. Important is that the steering tracks and does not pull to one side for whatever reason, and that the tyres wear evenly and never scrub. Scrubbed tyres only seem to make poor steering worse than ever. You mention the Silentbloc bushes, noting those obscured lower inner lever bushes in particular. The assumption is that all are in good shape, as are all the bushes and bearings in the suspension and steering. Especially, the top yoke bushes on the damper levers have often collapsed, but they are easy to see and to replace. When one is shot, it causes suspension noise and wobble, and the castor will be suddenly way out on one side as one yoke top slips backwards by maybe ¼”. With care and the right tools, the lower lever inner Silentbloc bushes may be replaced in-situ without removing the road springs. Although I have replaced all the bushes on my R-Type over the years on a needs-basis, only one road spring has ever been out purely for suspension work: that was in 1970 to replace a broken coil. Our annual roadworthiness tests in the ACT were very stringent on all these bushes, but the tests are largely waived as the cars become so ancient. The assumption is that old-car enthusiasts have too much pride to own a car with worn suspension. No longer are we failed for rear hydraulic brake leaks, when it is only the Bijur doing its job on the shackles. Nor are we failed for having no front brakes when only the front wheels are spun on the brake tester. Sure, spring removal needs a really solid and robust spring compressor, but it’s nothing so exotic as on a Silver Shadow: take pity on those guys. At least the early postwar cars springs may be compressed with a good conventional spring compressor. It’s still a rather disquieting operation with all that stored energy in the compressed road spring for sure. Suspension parts are not dirt cheap, but then they are not as punitive as they were by the late 1970s. Actually, the components have come down in price dramatically in real terms since then. For example, a yoke pin (king pin) in 1976 cost me A$275, about US$300 at the time in dollars of the day. Today they cost just US$100. Most other suspension parts have enjoyed similarly favourable huge declines in real prices. We can thank the UK parts suppliers for that, and that’s one reason why I support them. If I pay a bit more for small items like a thermostat or a head gasket than I would like, they are there loyally supplying the more esoteric parts at very reasonable prices. Unklike owners of many old cars, we have no need to waste time and money scrounging the generic parts bins and begging for inferior alternatives. With luck, no longer are people skimping by fitting bronze bushes to replace the needle rollers on the king pin and lower yoke shafts of early Crewe cars. Worthy of note are the front suspension lower yoke shafts and bearings, items all too often dry and shot to bits. The yoke castings, the ones which carry the king pins, the Silentbloc bushes and the lower bearing shafts/bearings, are hollow. They each hold about 50ml of Bijur oil, acting as reservoirs. Until those reservoirs overflow, there is no feed down the tube to the lower yoke shafts and bearings whatsoever. Unless the Bijur is pumped adequately, the king pins may show lubrication at their bases while the upper king pin bearings, and especially the lower yoke shaft bearings, are dry. Many assume that oil at the king pin bases is a sign of enough. Hence, the Bijur needs pumping such that the lower pins shows signs of oil. Balancing the one-shot on my R-Type took a decade of fine-tuning before it was working really properly. Oh, yes, watch out for our quaint old-fashioned spelling. No Webster’s here: agreed it is the US standard, but we still use the old Concise Oxford. Downunder, US aluminum is aluminium, centers are centres, colors are colours. Then, to us, caster has a box of sand to pour liquid metal or plastic into. Tire is what happens when we stay up too late. Tyre is not just a hapless place in Lebanon bombed to hell by you-know who. Cheers, Richard. | ||
| Bill Vatter Frequent User Username: bill_vatter Post Number: 49 Registered: 9-2004 |
Richard, Thanks for your detailed response, and entertaining comments on spelling differences. Shame on me. I shall no longer think of my British and Aussie brethren as poor spellers. I think we are in about 99% agreement, possibly 100%. I am most interested in your comment: "With care and the right tools, the lower lever inner Silentbloc bushes may be replaced in-situ without removing the road springs." Can you elaborate please? I have been procrastinating replacing the inner silentbloc bushings of my Silver Wraith WGC66 (early-style suspension). While the camber is about equal on both sides, it is about zero, less than specified, and I really want to make that right. I have not felt urgency since the tires are wearing quite well and the car runs very straight with hands off. However, I doubt very much these bushings have ever been replaced, and nothing lasts forever. I had often wondered if it might be possible to bind everything up to hold the spring, then take down the center fixing, and and finally make a task-specific threaded press to extract and replace the bushings in-situ. I know this type press is workable because it is described for the yoke bushings in the service instructions, but I have heretofore just removed the yoke and pressed the bushing with my shop press. I have replaced springs on a Cloud, but I did not enjoy that task. It is too much like work, and I don't expect that task on the earlier cars is any easier. Last comment, possibly the 1% disagreement, I fully expect correcting the camber will require an adjustment of the toe-in when I am finished. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 1571 Registered: 4-2003 |
Bill V, I do agree entirely on the toe-in: it is best checked after any suspension joint work. I would suggest a camber measurement first in every case, then to set the toe-in to suit. The toe-in is always the last adjustment to be made. Lower levers’ inner Silentbloc bushes: To replace the inner Silentbloc bushes on the lower levers is not as bad as to remove the springs in my opinion, and that’s why I have done it that way. As they say, the first is the worst. It is a much more pleasant job than to remove the steering box ! I am unsure as to whether the early centre steering arrangement needs releasing, but at worst it may need simply to be unbolted from the chassis first as a unit. On later cars it is not necessary, but is no drama in any case. I don’t think that it needs releasing, and the rest is certainly the same as on later cars. First, place the front suspension on stands or blocks about 1½" outwards from the centres of the road springs bearing the full weight of the front of the vehicle. Support the so-called jacking plate at the centre of the chassis with a jack and place a pair of blocks, each maybe 4” below each lower lever close to the jacking plate. Do not remove the flat fore-aft positioning bracket attached to the centres of the lower suspension levers. Undo the jacking plate bolts which hold the assembly to the chassis: there are four bolts: two 5/16” BSF bolts fore and two aft. Note that there are two central 3/8 “ BSF bolts which should not be removed at this stage. Lower the jacking plate slowly 4” so that the lower levers rest on the blocks. There will be not much load on the levers at the centre, so it is a safe operation. Should the jacking plate not lower, rebolt it loosely with two bolts, then reposition the stands or blocks under the springs a little further outwards and try again. Mark the Silentbloc securing bracket position with a scriber and felt pen for reassembly. Now you may release the Silentbloc mounting bracket for inspection and release the bolts through the Silentblocs. Take the jacking plate away for a good clean-up, making sure not to lose the scribing marks. Just before releasing the first Silentbloc, rock the levers from side to side to check that there is negligible lateral force so that reassembly is straightforward. Secure the lower levers in the unlikely event that they are under excessive lateral load. Now the Silentblocs will be exposed sufficiently to work on them. Use a sturdy puller and a suitable socket to press the old Silentblocs out from the levers, and fit the new ones in reverse. Your idea of a portable press may be a good one if the bushes are extremely tight, but usually a professional-grade puller is fine. As they say, assembly is the reverse, taking care to refit the centre Silentbloc bracket to the markings you have scribed. I have always replaced the Silentblocs on the upper yokes on a press as I have always taken the king pins and yokes apart at the same time. However, I am sure that they can be done readily in-situ too. I’ll elaborate if you wish. See page 31 (H28) of http://rrtechnical.info/mkvi/wshoplate/8.pdf (I'm sure that you have it already of course) for the layout and a description of how to do it all when the springs are removed. RT. (Message edited by Richard Treacy on 12 January 2009) | ||
| Bill Vatter Frequent User Username: bill_vatter Post Number: 50 Registered: 9-2004 |
Richard, Excellent and many thanks. Now all I need is the bushings, which I will order from the UK. I don't think the center pivot for the steering needs to be disturbed, but as you indicated, it will not be much to do if it needs to come away. It will in any event be an opportunity to inspect that for possible wear. It is the place where the biggest Bijur mess occurs on my 2 cars (both the early single pivot steering design). |
