Post Number: 2098
|Posted on Tuesday, 30 March, 2010 - 04:40 pm: |
I am considering having a batch of antiroll bars made up in 30, 32 and 34mm if SY and SZ owners are interested. I already have a source for the solid-type ball joint antiroll bar links as shown in the picture below. The type I have had made may be set to suit handed or parallel use, eliminating the need to but two or three different types.
If you have ever wondered why your Silver Shadow or Rolls-Royce SZ leans a little too much in corners, and wallows and corkscrews over twists in the road camber, just have a look at its front antiroll bar. It is too small for the job, a compromise to suit certain markets. Road testers always complained bitterly of the suspension behaviour when the cars were released.
Below is a picture two antiroll bars for comparison: the skinny standard type and a 32mm Turbo R type. The skinny one is of all SYs and SZ Rolls-Royce cars, and to Bentleys until SZ Chassis 13833. That bar is part number UR15403, a 24.5mm bar. Turbo Rs and later Bentleys have the UR27110 32mm bar, except for the Continental T Mulliner which has the UR96450 34mm bar.
Incidentally, the stiff coils on an Australian car leave them skittish at the rear despite Crewe having deleted the rear antiroll bar as part of the AUS package. If you have ever inadvertently done a 180° on a wet road in your AUS SY you will know what I mean. Those cars are crying out for increased front suspension antiroll.
Many cars have already been upgraded, and some have the Harvey-Bailey kits of course. The improvement is astonishing. Cornering is almost roll-free and the ride is far more pleasant. Gone is that sickening lurch into corners, and the vehicle feels far more relaxed to travel in at all times. If I drive our upgraded SBH13247 then another SY, the difference is very marked indeed. I do not think that the ride is any harsher, rather simply more comfortable.
The heart of the Harvey-Bailey kits to fit revised coil springs and antiroll bars. Those kits are mainly centred upon Export-specification SY coils as fitted to Australian-specification cars from new, and an uprated antiroll bar up front. New dampers (shock absorbers) complete the kit, but those are standard-fare Bilsteins or Boges as designed for the cars.
To complete the upgrade, not usually part of the H-B kits or others, solid ball joint linkages between the antiroll bars and the suspension control arms are fitted. These are standard on Turbo R and late Bentley cars. For SYs and early SZs (until chassis 2550), the unhanded linkage from the rear antiroll bar of a Turbo R are best fitted to the front replacing the rubber-injected originals. For later cars, the handed Turbo R linkages are preferred. These linkages all bolt straight on to replace the squishy rubber-injected ones.
Turbo R cars all have the solid-type links, and they are handed: the links are attached at 90°, whereas the SY and early SZ cars have parallel attachments. See the picture below.
My message: there is a relatively inexpensive upgrade to achieve almost all that the expensive conversions offer.
As Australian-spec SY cars have no rear antiroll bar, a 30mm front bar and solid links make a good compromise, although I am very happy with the 32mm bar on ours. For UK-spec cars, a 32mm bar is ideal along with the linkages front and rear. Even then, a UK car ends up softer than an Australian car despite the UKs antiroll bar. For my Turbo R, I may opt for a 34mm bar shortly.
Bar thickness...........Roll Stiffness Increase..........Recommended for
24.5mm...........................Normal...................Standard uneasy ride
30mm..............................50% stiffer.............All SY and SY cars, Medium: ideal for Australian-spec SY cars (no rear antiroll bar, stiff coils). May be preferred by Rolls-Royce owners for softness.
32mm.............................70% stiffer..............All SY and SZ cars, sporty on Australian-spec cars
34mm..............................96% stiffer.............sporty for Bentley, especially Turbos
Also required: four solid ball joint antiroll links, except on AUS-spec SYs (two). Note that these links increase the stiffness a little over the figures quoted above.
SY-SZ standard bar compared to a Turbo R bar
Standard Turbo R ball joint antiroll linkage - note that it has a 90° offset. Left and right hand units differ as they skew in opposite directions (UR27358,9).
Brand-newly-made ball joint antiroll bar linkage on T-Series SBH13247. These may be set locked to parallel as shown (functionally identical to UR27357 standard Turbo R rear antiroll bar link, replacing original UR13778 rubber unit), or to +/-90° (functionally identical to standard Turbo R UR27358 or UR27359) for SZ cars from chassis 2550.
Omar M. Shams
Post Number: 125
|Posted on Wednesday, 31 March, 2010 - 02:14 am: |
If I lived in Oz i would opt for the upgrade for my Wraith IIs...........
Incidentally, how much do you think they will cost?
Post Number: 2099
|Posted on Wednesday, 31 March, 2010 - 07:18 am: |
The links are about A$150 each ready to bolt on, and an antiroll bar probably $250, all including GST Value Added Tax. I bought the last 32mm bar new for less than $200 to pattern as a guide. When I arrive back in Oz in two weeks, I'll price them all up. We have no problem having leaf springs, coil springs and antiroll bars made to pattern in Oz.
Also, almost all of the rubber antiroll bar links I have seen are at least partially shot after a few years. They look and seem OK until they are tested on the bench. That explains the slightly wiggly ride of most cars. Just fitting the upgraded links alone makes a marked improvement.
For those concerned about ball joints and bush stresses, I must point out that all SYs and SZs share the same ball joints, and that includes Continental T Mulliners. The other bushes are the same dimensions from 1972 onwards with compliant suspension, are interchangeable, and all are supplied with the slightly stiffer Turbo R bushes by Crewe as replacements these days. In any case, the suspensions are exceptionally strong and long-lived, but simply let down by the standard antiroll settings and tuning. Due to improved tyres over the years, I certainly find that the pre-compliant SYs win hands down on front suspension.
You may well think of an upgrade where you live. It transforms the cars in the city on roundabouts especially in Canberra, and tight city corners are so much more negotiable. On the highway, you wonder why Crewe took until 1985 to wake up, even though that was only for the Bentleys until the Silver Seraph came along.
As to wheel alignment, the standard SY/SZ specs are:
Front wheel toe-in 0° 12 +/- 5 (this equates to a half toe-in of 0.10 +/-0.04; 2.5mm +/-1mm double the numbers to measure the difference tyre centre to tyre centre, called the total toe-in)
Camber Angle 0° 30 Negative +/- 15
Caster Angle 3° 0 +/- 30
This is acceptable, but does not take into account road cambers and turn directions. It is also not ideal for tyre wear, especially on the edges, nor for steering response. The cars respond particularly well to increased negative camber. In practice over the years, we have found that the settings are better set on all SY and SZ cars, regardless of steel-belted radial tyre type and roll stiffness tuning, to:
Front wheel toe-in half toe-in of 2.9mm +/-1mm, or a total toe-in of 5.8mm +/- 2mm
Camber Angle - Drive on Left cars (UK, Australia, Japan, Hong Kong etc):
1° 30 Negative +/- 15 left hand side
1° 0 Negative +/- 15 right hand side
Camber Angle - Drive on Right cars (USA, Continental Europe etc):
1° 0 Negative +/- 15 left hand side
1° 30 Negative +/- 15 right hand side
Caster Angle 2°20 +/- 30
Rear Wheel Alignment:
Toe-in 5 +/- 2 (Total toe-in 2.6mm +/- 1mm)
Camber -30 +/- 15
Thrust angle 0.00° +/- 10
Set back 0.00° +/- 10
Post Number: 23
|Posted on Wednesday, 31 March, 2010 - 08:56 am: |
I too would be interested for my 75 Shadow SRH 19305 as I will be having some mods done in the near future, so would appreciate costs at some stage
Post Number: 2107
|Posted on Wednesday, 31 March, 2010 - 09:21 am: |
Sure, Kevin, I'll let you know mid-end April.
To convince yourself, I do recommend that you badger a drive in an uprated car !
I had our T-Series nearby you in Beecroft and Dural two weeks ago. If I drive it to Sydney again soon I'll give you a demo.
Post Number: 138
|Posted on Wednesday, 31 March, 2010 - 11:25 am: |
I too would be interested to see the $$ for my SZ 86 Spirit. While its fairly good re handling its nowhere near as firm and secure as my Turbo.
Let me know if you are seeing Kevin, I live very close to Beecroft, and I wouldn't mind, if its ok with you blokes, coming along too.
Post Number: 2146
|Posted on Sunday, 20 June, 2010 - 06:49 pm: |
I shall be in Sydney with the T this week. There is a story to write on why the mainshaft of the Turbo R's new transmission snapped after 2'000km.
Anyhow, if there is interst, I may come by for a demo.
Post Number: 26
|Posted on Tuesday, 22 June, 2010 - 09:45 am: |
Unfortunately I am in Noosa until next week, perhaps another time.