Post Number: 6
|Posted on Thursday, 30 November, 2006 - 08:38: |
B72DA is at present having its winter service and brakes restored. I have also renewed the gaskets and oil seal on my leaking gearbox.
I have looked at previous postings but not found any mention of what types of oils to use when replacing fluids. Would someone be able to suggest the right modern type for the following?
2. Steering Box
3. Shock absorbers
I looked in the manual and saw SAE20? was listed for the gearbox but my local motor factors say that grade of gearbox oil is unavailable. He also said the oil SAEs in the nineteen forties and fifties have now been superseded by modern grades.
I just don't want to put the wrong oils in.
There is also no mention in the manual of how much oil to add to the shock absorbers, what is the correct way of filling them and how do you know when they are full? Same applies to the steering box.
Any help would be greatly appreciated.
Posted From: c211-30-202-33.carlnfd3.nsw.optusnet.com.au
|Posted on Friday, 01 December, 2006 - 20:02: |
Having just done the diff, I know you need a 90 weight hypoid diff oil, but mild ep, so it doesn't affect the bronze bushes. I used Penrite Shocker Oil # 2 in the rear shocks, but I was talking to a guy the other day who runs STP oil treatment in his rear shocks, (really thick gooey stuff) and he reckons it works great for stiffening up the ride. I am thinking about trying it.
Gearbox oil that John Vawser put in mine was just a 90 weight gear oil, works fine. Remember, engine oil grades don't mean the same thing for gear oil, so a 75 weight gear oil is very light, probably like a 20 weight engine oil.
As for the steering box, no idea. Sorry. Penrite make a semi fluid grease for steering boxes, but I don't know if it's suitable for our cars.
(Message approved by david_gore)
Post Number: 631
|Posted on Saturday, 02 December, 2006 - 21:37: |
Careful with shocks with the wrong oil viscosity,
can be the cause of rear leaf spring failure!
Post Number: 37
|Posted on Sunday, 03 December, 2006 - 03:35: |
I second Patrick's warning about the shock dampers but for possibly a slightly different reason. If the dampers even work at all with STP in them, there is something wrong inside. If you had ever seen the insides of the damper, you would know that to use a semi-solid oil is most likely a death sentence for the damper. Something is going to break because of excessive pressure resulting from that extreme viscosity oil being forced through a small orifice. Most likely that has already occurred in the car belonging to Marty's friend. When things don't work correctly, the answer is to make a proper repair, not put some band-aid in place that masks the problem or in this case probably causes further damage.
Marty you have really rung my bell with this one. Lots of early postwar cars have been buggered up by people doing foolish things to save a little money. That is one very large reason why it is difficult to find an EPW car for sale that does not have serious mechanical problems. EPW cars are not yet very expensive to buy, and they attract impoverished enthusiasts who can't afford to fix them correctly or properly maintain them. Please don't follow the fools down the path of car destruction. Fix your car the proper way.
As an aside, here, I do not agree the best oil for the gearbox is Hypoid 90. I believe the company had that recommendation for awhile to help cushion first gear, but the latest recommendation is SAE20W-50 engine oil. The way to protect first gear is by shifting correctly and carefully.
(Message edited by Bill Vatter on December 03, 2006)
Post Number: 38
|Posted on Sunday, 03 December, 2006 - 04:26: |
My opinion on the correct oil for the damper is SAE 10W-30. I think the factory recommended straight SAE 20, a commonly available oil in those days but now more difficult to find. I think 10W-30 is a reasonable substitute. I don't know about Penrite Shocker oil, but the name sounds like it would be OK. You know, you cannot really change the oil in the damper. You need to disassemble it to get the old oil out, or at the least turn it upside down with the top cover removed an pump it to clear the old oil from the chanbers.
If you try taking the damper off to get whatever oil out, please heed this warning: The damper incorporates the rebound stop of the rear suspension. If you take the damper off with the wheel off the ground, or raise it when the damper is removed, the rear spring shackle will probably fall over center, creating a mess. Likely rip off the bijur line or worse jolt the car off the jack stands, and whatever the immediate consequence, require spring removal to get it straightened out. If you remove the damper, the axle must be supported. Best way to do that is to have the wheel on the ground when you take the damper off.
Mark, we have covered everything in your question except the steering box. EP 90 is acceptable there or engine oil is also OK. Do not put in STP or some other semi-solid goo.
Really STP has no place in one of these cars. STP is a mixture of oil and a solid petrolium substance that never goes liquid in the temperatures cars experience. I think it is mostly solid. I don't personally think having a lot of that stuff running around inside in place of oil is the best thing for lubrication. The viscosity of of any mixed substance is an average of sorts of the its constituents, in the case of STP a solid and a liquid, and since the solid doesn't change with temperature, the temperature-related viscosity change of this mixture (viscosity index) is less than for oil. Incidentally this is how viscosity improver additives in engine oil work, one reason why a very broad viscosity range, like SAE 10W-40, isn't such a good thing as it appears to be. Please note this viscosity index comment applies mostly to conventional mineral-based oil. Synthetic oil has a naturally higher viscosity index, and uses less of the viscosity index improver additive to get the multi-viscosity numbers quoted.
I guess I have ranted enough. Please beam me up, Scotty.
Post Number: 49
|Posted on Sunday, 03 December, 2006 - 11:03: |
The wall-chart RR produced that shows recommended lubricants indicates - for all Mark VI chassis - SAE 20 for engine, shock dampers, carburetter air valve damper and hand oiling points.
For the steering box it indicates SAE 30 (also for the chassis oil tank and starter motor gears).
Gearbox is Hypoid SAE 80 and rear axle Hypoid SAE 90.
(Message edited by chrisg on December 03, 2006)
Post Number: 7
|Posted on Sunday, 03 December, 2006 - 23:24: |
My problem is I do not have a local oil supplier that can give me advice. My only place of purchasing oils is at a local motor factors. Unfortunately the assistant behind the counter did not fill me with confidence...especially as he looked for ten minutes in his catalogue wondering why the Bentley was not listed.
With regards the shock absorbers, would the rear not just use the oils from the gearbox? I see there is a pump that sends oil there. Does this go to a separate part of the shocks to harden the ride or does it fill them?
I still don't know about the correct method of filling the shocks and the steering box. Do I just pour the oil in through the top oil plug hole with the wheels on the ground? Where are the fill levels on both?
I need to get the car on the road ASAP, especially as I have a wedding at the end of this month. I also need to run the car up the road to check the braking system is OK after its major overhaul. I am currently having problems with the linkage settings and need to know how well the car is braking first.
This site in the UK might help for oils. I have emailed him to see what he recommends for the Bentley. I will report back his findings. I was just hoping someone could give me a recomendation for an off the shelf modern equivilant.
Thank you all for your advice so far.
(Message edited by Mark Anson on December 04, 2006)
Posted From: c211-30-231-163.carlnfd3.nsw.optusnet.com.au
|Posted on Monday, 04 December, 2006 - 08:23: |
Thanks for the info on the shocks. I was a little wary of this guy's use of STP in them, glad I mentioned it before trying it on my car!
(Message approved by david_gore)
Post Number: 49
|Posted on Tuesday, 05 December, 2006 - 15:00: |
SAE 20 oil for use in the shock absorbers can be bought from most motorcycle shops.
Post Number: 45
|Posted on Tuesday, 05 December, 2006 - 23:13: |
Contact: - www.morrislubricants.co.uk
Their products are widely used in the motor trade, especially by the old car maintenance/ restoration companies. They are based in Shrewsbury, will offer any technical advice you need and also put you in touch with their local agents.
I have used their oils for years and found them to be first class.
Post Number: 632
|Posted on Tuesday, 05 December, 2006 - 23:41: |
I second that.
Do not be afraid to move with the times with regard to useing modern oil if it is recomended by them.
Why pay over the odds for old oils that will not do a good job in the first place.
Post Number: 46
|Posted on Wednesday, 06 December, 2006 - 09:45: |
What news on that old 20/25 banger you were working on?