| Author | Message | ||
     Gabriël Viljoen Frequent User Username: gabriel Post Number: 12 Registered: 3-2004 |
Good day. I bought a Silver Shadow about three year ago and it is almost complete. I had the car resprayed, the leather and woodwork redone. I bought a workshop manual and opened all the parts of the brakes and height control to replace all the rubber o-rings and rubber hoses. I think I have covered all the leaks now. I have driven it a lot of times, but only for short runs and not very fast - since I was still busy cleaning the brakes, and wanted to be sure everything is in good order before I stepped a bit on the gas. I took if for a good run yesterday. It drives and handles very well. But over a speed of about 130km/h (aprox 80m/h) one can feel vibration in the car. When I take my foot off the gas, there are no vibration. When I step an the gas again, one can feel the vibration again. Could anyone give me an indication as to where I can start looking for the fault. It is engine mountings, is if something with the diff, of is it anything else? | ||
| Glynn Experienced User Username: glynn Post Number: 9 Registered: 5-2004 |
I have had similar problems on Jags and sometimes it has been a crack in the flexiplate, sometimes an actual gearbox /converter problem. Regards Glynn | ||
| whunter Prolific User Username: whunter Post Number: 77 Registered: 10-2003 |
If the car has not been driven very much or has been idle for months, the first thing that I would suspect it tyre flat spots. If you must store these cars, put it on four jack stands to get the tyres off th ground. A bad flex disk, universal joint or engine mount are possible. | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 235 Registered: 4-2003 |
If it only happens at those higher road speeds on load, and is not just engine load and engine speed related (ie on load in first or second gear with a lower road speed), I would not expect a cracked or bent flexplate. Cracked flexplates are usually noisy rather than vibrational, but anything is possible. Also, bent or cracked flexplates usually introduce bands of harmonic vibrations at 1100, 2200, 2750, 3300 RPM etc. I learned this one the hard way. Bent flexplates are usually smoother on load than in neutral at a given engine load also. Tyre problems are usually not load related. If you look through the archives you will see that this topic has been covered many times. Possibly the first thing to do with a load-dependebt vibration is to swap the axle half shaft assemblies left to right. It is generally good practice to do this at some time anhow, so any efforts would never be wasted. This trick is as old as the hills. Explanation: The axle Detroit Joints wear on the load side, and if never swapped before the chances are that the overrun sides are unworn. The wear causes a ridge which the trunions run up and down each revolution on load, leading to vibrations which usually increase steadily with road speed. By swapping the shafts you will have a fresh load side on the Detroit joints, and cure the vibration. The ultimate fix is to fit CV joints as fitted to Spirits from around 1982: they are a different length but the correct ones are available for your car. Early Shadows had a propellor shaft Detroit joint too. If that is worn only a replacement will rid the vibrations. | ||
| John Aravanis Unregistered guest Posted From: 213.5.61.131 |
Had the same vibration on my S.S.1. Above 70 miles while accelerating, there it was. Assuming that you cars' rear height is correct ( is the vibration worse when you have a rear passenger load?), I would swap the rear halshafts AND the housings. Remember it is the housings that wear. Also check your main driveshaft u-joints ( in case they are frozen or worn loose ), and the engine mounts. My car's vibration dissapeared after switching the housing/halfshaft assemblies albeit a destroyed front engine mount that was discovered later. | ||
| KC Unregistered guest Posted From: 168.210.90.232 |
Thanks for raising this topic Gabriel. My Shadow has the same vibration, although very slight. It happens under load, regardless of the speed. However, it only happens when I accelerate hard. As I am a docile driver, I seldom feel the vibration. Should I also consider swapping the axle half-shaft assemblies, or is my vibration not severe enough? Should a Shadow be totally smooth under hard acceleration? Regards KC | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 236 Registered: 4-2003 |
KC, It sounds as if a half shaft swap left to right would be a good idea sometime. A Rolls-Royce especially should unquestionably be smooth at all times, including on hard acceleration, as should any motor car. | ||
| Gabriël Viljoen Frequent User Username: gabriel Post Number: 13 Registered: 3-2004 |
Thank you all. I cleaned the height control solenoids and this resulted in the car not being level. With this fixed, the vibration is much better, but not cured yet. I suppose my next task is to swop the half-shafts! Gabriël Viljoen | ||
| Dwayne Kennemore Frequent User Username: dkennemo Post Number: 18 Registered: 12-2003 |
How do you swap the halfshafts on a '76 Shadow? | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 375 Registered: 4-2003 |
It's a do-able job. One side at a time: Undo the halfshaft universal joint clamps at the wheel hub. That end of the halfshaft is now free. Move that end of the halfshaft clear of the hub. Undo the six setscrews on the small cover housing on the side of the main final drive housing. This is where the Detroit joint splined drive shaft goes into the differential carrier. Pull the halfshaft and small housing out from the final drive (ie differential) housing (by hand). The halfshaft is now removed. On a bench, remove the circlip on the splined Detroit joint shaft behind the housing and remove the shaft from the housing, bearing race and oil seal assembly. Repeat for the other side. It is advisable to fit new oil seals in the small housings. These seals are cheap and opportune to replace at this point. They should be available at your local industrial bearing supplier to pattern. Swap the drive shafts from the left to the right small housings and vice-vera. Refit the retaining circlips. Reinstall the two assemblies accordingly onto the car. Note that the small side housings are different between the left and right hand sides, hence they must not themselves be swapped. The left side has its bearing race retained by a large circlip, whilst the right hand side one needs and has none. The bearing races themselves are very rarely in need of changing. It is ideally all done with the chassis raised and the tear wheels hanging down as it gives you more room to remove the hub universal joints very easily. Beforehand, check the Detroit joint rubber boots for deterioration or splits. They are expensive, but if they need replacing then now is the time to order them in advance and do it. Don't forget to fill the Detroit joints with EP90 gear oil. |
