| Author | Message | ||
     Chris Miller Experienced User Username: cjm51213 Post Number: 20 Registered: 5-2013 |
Hi Folks, I have a '71 and a '72, neither of which has front height control. I also have a '66 which I am dismantling for parts, but I have only worked on external parts (trim, lights, bumpers, grill, &c) and interior (dashboard, seats, &c) meaning I have not yet gotten into the meat of the mechanical components. Are the front control valves from the '66 the same parts as the rear control valves? Now, speaking of suspension,... I drive the '71 every day and the suspension is "squishy". Some of this is probably due to malfunctioning height control, which I have no reason to believe is functioning correctly, but as my everyday Rolls, not something that I will fix until I have the '72 operating sufficiently to become my every day Rolls and I can put the '71 in the shop. But malfunctioning height control probably doesn't explain a "squishy" front suspension, which was deleted from the front before '71 (SRX10792) and '72 (SRH13161) How do I diagnose this? Do springs go bad? How can I test them -- remember, I have a '66 with springs of unknown condition which might serve or might be worse. Assuming I should replace the springs, is there an industry standard specification I can use to source some springs here in the Good Ole USA without importing heavy metal from U.K sources? Thanks for the help, Chris. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 618 Registered: 6-2009 |
Chris, Here's my two-cents: I have never, ever heard of the front springs in these cars going bad, though the back ones are a chronic issue. Take a look at section M3 of the spare parts manual (front height control) and you'll see that there are not many shared parts between front and rear systems. Rear height control parts for LHD cars are in section M9 and RHD cars in M8. Shocks/dampers, though, do eventually wear out. Based on the last service bulletin I saw from Crewe the "officially recommended" replacement parts for shocks are: Front: Bilstein B46-1429 Rear: Bilstein B46-1430 [Note: These give a firmer ride than the original Boge, but not terribly so.] I've got this documented, along with the "go to" company in the U.S. for replacement springs, in the RR & Bentley Parts, Repair, Restoration & Other Resources Compilation I maintain. Download that and search on "Coil Spring" to save me some typing. Brian | ||
| Chris Miller Experienced User Username: cjm51213 Post Number: 22 Registered: 5-2013 |
Hi Brian, This is helpful. I wasn't aware of your compilation, but I horked a copy! Thanks for that effort... I believe you that the springs are likely to fail with vanishingly small probability. Maybe I should have described the symptom -- the front will ride low enough that it will sometimes scrape during normal driving, like driving into my driveway or over speed bumps even at quite slow speeds. I'm pretty sure something is wrong in the front, in addition to any number of observable deficiencies in the rear. Can rear suspension problems manifest as front problems? Springs and shocks are pretty much the only suspects. This sounded to me like a spring because the shocks are responsible for oscillation damping, not load, and I don't see any excessive oscillation indicating worn shocks, but I would be happy to be wrong, if the shocks are easier to procure and replace. So, now I have the problem to determine if either the shocks or the springs need to be replaced and which. Does anybody know of a test to determine this? Thanks for the help, Chris. | ||
| David Gore Moderator Username: david_gore Post Number: 1332 Registered: 4-2003 |
Hi Chris, The standard "soft" springs are prone to breakage over time - the most likely location is the second coil from the base. The spring bases are VERY prone to corrosion and are often non-functional. As detailed elsewhere in this forum, the best solution to the handling problem is to fit the "colonial" specification springs, new shock absorbers and the Turbo R anti-roll bar as recommended by Richard Treacy. The original Shadow suspension settings were specifically intended to provide the soft "boulevarde" ride preferred by US buyers in that era - after all, the US was the key market for the Shadow. We mere colonials in the Antipodes had to make do with the more robust "colonial" suspension. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2887 Registered: 4-2003 |
A few points here. The standing height is adjustable without even removing the springs. Best check the front bump stops first: there should be at least 2cm between the rubber stop and the bump plate. Also, the springs are stocked here in Australia in case they have sagged too much, and there are options available for stiffness. The preferred option seems to be to fit Azure springs to all SYs and SZs. RT. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2888 Registered: 4-2003 |
A small selection of the springs available in Zetland, Sydney for SY and SZ cars. Shock absorbers etc etc too of course.  | ||
| Chris Miller Experienced User Username: cjm51213 Post Number: 23 Registered: 5-2013 |
Hi David and Richard, I have contacted a few spring manfacturers and asked about a Rolls Royce spring and I get blank stares... Apparently I need to know three things: 1) Uncompressed length 2) Diameter 3) Spring force constant (compression caused by specific weight Kg/cm or lb/in) Does anybody know these measurements for either the "boulevard" or the "colonial" spring? I assume they may differ bow to stern, so that means there are four sets of measurements "boulevard" bow and stern, and "colonial" bow and stern. How are shocks specified? Do the shocks differ between "boulevard" and "colonial"? Earlier, Brian suggested: "Front: Bilstein B46-1429" and "Rear: Bilstein B46-1430" which I find available. Are these "boulevard" or "colonial"? Thanks for the help, Chris. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2889 Registered: 4-2003 |
The spring free-lengths and spring rates are quite varied, but bear in mind that brand new springs are not at all expensive. A typical front spring costs no more than $200 new. That saves a lot of guesswork and iterations setting them up. It makes sense to fit new springs rather than having old ones reset if the spacers required to restore the standing height exceed 25mm. Bilstein shock absorbers are on the firm side as most prefer, but not strictly the Colonial variety. They are made especially for these vehicles as a development from first the Rolls-Royce then Boge units. They are a gas-charged oil monotube device with the floating piston like the R-R and Boge variants, and are bought most economically from the local Australian Crewe specialists. For example, in Australia Bilsteins cost roughly three times the price direct from Bilstein Australia compared to our specialists. RT.  | ||
| Chris Miller Experienced User Username: cjm51213 Post Number: 24 Registered: 5-2013 |
Hi Richard, "A typical front spring costs no more than $200 new." -- where? I would happily buy new springs, if I had a source. This is why I thought the spring length and constant would help -- this is the currency of a manufacturer to match their product to my project. Thanks for the help, Chris. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 623 Registered: 6-2009 |
Chris, Coil Spring Specialties is the aftermarket company that Bentley Zionsville (AKA Albers) and anyone else I've ever known of uses in the USA for springs for our cars. They already have the data on file to make the springs you want. For the rear springs, at least, they've already modified the design to add an extra coil and extra strength to avoid the sagging spring problem endemic to the originals. Their prices are quite reasonable, too. I have no interest in this company, financial or otherwise, other than knowing that they're pretty much the "go to" place in the USA if you want springs for virtually any vehicle, particularly low-production-number varieties. Brian | ||
| Chris Miller Experienced User Username: cjm51213 Post Number: 25 Registered: 5-2013 |
Hi Folks, I called Coil Spring Specialties and spoke with an helpful associate. I learned this: Silver Shadow Front: 186 lb/in 23 1/2" free length Silver Shadow Rear: 200 lb/in 21 1/2" free length So, how to tell if a spring is no longer within spec.? There are apparently two failure modes -- loss of length and loss of force. Each is identified by an incorrect spring lenth for an empty car on level ground. However, I don't know this value and Coil Spring Specialties did not know it either. If anybody knows this values, I'd be grateful. If the height is correct, then the spring can still be out of spec., but it requires measuring the force constant to make that determination. For this measurement, put the same amount of weight, say 100 lbs, on EACH of the four suspension points, measure the change is spring length and divide the weight by the change in spring length. In this case, it would be 100 lb/<spring> in. You can't load just one spring because the two adjacent suspension points become a fulcrum with the opposite suspension point becoming a counter-weight. Chris. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 312 Registered: 5-2012 |
Chris Did they give you current prices for the rear springs? I still haven't got round to replacing mine and it's earmarked as one of this winter's projects. Geoff | ||
| Chris Miller Experienced User Username: cjm51213 Post Number: 26 Registered: 5-2013 |
Hi Geoff, 1971 Rolls Royce Silver Shadow: Front – coil springs – replacement: Pricing: $ 348.40 pair Rear – coil springs – replacement: Pricing: $ 338.60 pair Chris. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2890 Registered: 4-2003 |
At those prices it's just not worth messing around with specially-manufactured one-offs. One-offs may or may not do the job and will not carry the customary 2-year warranty including consequentials offered by the two UK spares majors and presumably by Albers which buys their spares from them in any case. RT. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 313 Registered: 5-2012 |
Chris Thanks for the info. Incidentally, I found that our local Rolls Royce dealership was selling RR363 at $28 per litre, which is the going rate for it here in the US. Being an authorised dealership, I'd assumed they would have at least doubled the price. Encouraged by this matching of after-market prices I enquired as to the price of rear springs - $1300 the pair. Geoff. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2891 Registered: 4-2003 |
To put this all in perspective, why not just buy stock springs ? The way to go is SZ Azure springs for SY and SZ cars. As mentioned earlier, they sell for around just $200 each. By comparison, Continental GT springs, air springs admittedly, sell for around $5,000 each. Plus fitting and GST. Try $14,000 for an Arnage front suspension overhaul kit including ball joints but excluding dampers. A set of roller tappets for an Arnage will set you back over $12,500 at the full retail price. Spares for all R-R/B cars before 1999 are very reasonably priced by any benchmark. RT, | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2892 Registered: 4-2003 |
ps: SY rear springs are a little more expensive here at about A$290+GST, maybe US$260 these days. Those are stock items in Sydney. They are from the same source as Crewe and all the known major parts outlets, so the $1,300 looks rather silly. RT. | ||
| Chris Miller Experienced User Username: cjm51213 Post Number: 27 Registered: 5-2013 |
> To put this all in perspective, why not just buy stock springs? This would be my prefrence. Buy them where? Cbris. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 317 Registered: 5-2012 |
Richard >Buy them where? Yes - I'd be interested as well - or the name of the company that supplies Crewe and all the major parts outlets. With that information I may be able to track down a supplier of stock items here in the US that are not at silly prices. Geoff | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1113 Registered: 6-2006 |
Richard, have you fitted Azure springs to a Shadow? I have only tried once and even with no shims at all, it rode ridiculously high at the front. I had to remove them and fit alternatives. Harvey Bailey springs are a vast improvement handling wise over RR / Bentley ones. The Bilstein shocks were designed and specified by HBE and built by Bilstein for them and were only available through them for the first number of years. Boge are a poor and more expensive runner up - in both ride and quietness of operation imho. |
