Rear End Noises

Non-Rotoflex Suspension Only - Herald, Vitesse 6 and Mk I, Spitfire, GT6 I and III (late)

Does the car knock or rattle when slowing down?

Yes - Not the differential but Universal Joints - See Note 1 below.

No - Go to next question.

Is there continuous bearing noise. No change during acceleration or slowing down?

Yes - Wheel bearings - Will be louder on one side - See Note 2 below.

No - Go to next question.

Is there a continuous whining noise, loudest under acceleration?

Yes - Differential - See Note 3 below.

No - Call us for advice!

Note 1

A rythmic knocking when slowing down is caused by a Universal Joint (UJ) problem, either due to:- worn UJs, worn yoke or flange or end float in UJ. Wear in the UJs is cured by replacement, but read on...

Wear in the yoke or flange is evident from the circlip rubbing against the UJ and causing a shiny ring, and the only permanent cure is replacing the flange or halfshaft and yoke assembly.

If all the above has been done and still there is this tapping noise, end float in the UJs is the answer and this is cured by fitting oversized circlips to give preload (tightness) in both planes.

Note 2

When the needle roller starts to wear it eats it's way into the shaft causing a graunching grinding noise of munched metal from one side of the rear of the car. Often the noise is worse with light cornering. This is an expensive noise as it invariably means the halfshaft is scrap and must be replaced. Putting the job off until the noise is excruciatingly loud can result in damage to the bearing housing. To do any work on the shaft will require removal of the hub - a job which must be done with the proper equipment to avoid scrapping the hub. A three legged puller will rarely do the job - in our experience, the original Churchill designed tool is the only one to have a 100% record.

Note 3

The differential gets blamed on all too many occasions when experience has shown that in general, differentials do not cause knocking, vibration, or rattling. Whining is usually a sign that the hardening on the crown wheel has worn through and the noise will be loudest on acceleration either disappearing entirely or becoming very low on overrun/deceleration. The pinion bearings can be a problem, but the noise is from the centre of the car (not on one side) and is very short term, i.e. the bearing collapses, the oil leaks out and the differential seizes.

Rotoflex Suspension Only Vitesse II, GT6 II and III (early)

Does it make continuous bearing noise with no change under acceleration or deceleration?

Yes - Wheel Bearings - See Note 4 below.

No - Go to next question.

Does it make continuous noise, but differing under acceleration/deceleration?

Yes - Differential, but some units can be noisy - See Note 3 above.

No - Go to next question.

Do you get knocks or rattles on poor road surfaces?

Yes - Where to start?? Loose Top Shock Mounting, Loose Shock Absorber, Incorrect Shocks, Worn Trunnions, Worn/Broken Spring.

Rotoflex suspension has problems all of it's own and each one is expensive. Unlike the simpler non-rotoflex setup, the Universal Joints do not knock to give warning of wear, they are silent but deadly, when they go, they explode, often destroying the flange or/and inner axle shaft. The trunnion bushes seize onto the 7.5" long lower bolt which often needs drilling out. Rotoflex couplings will wear out with monotonous regularity if the suspension isn't correctly set up and maintained or if cheap alternative couplings are used. If the threads on the outer axle shaft get damaged and cannot be reclaimed a new outer shaft will be needed. The hubs do not require a special tool to pull, but the bearing surface must be carefully inspected before re-use.

Note 4

Replacement wheel bearings should be re-shimmed to give the correct end float/preload. In most cases replacing the equivalent shims and spacers from the old unit will give an acceptable result but if the hub has been replaced or the unit assembled from parts, then the following procedure should be followed. Fit bearing cups into vertical link. Fit outer race and outer shell into vertical link. Fit hub making sure it is fully down. Fit inner race. Put spacer and shims in place - measure across bearing inner race with straight edge and feeler gauge such that the hub and shims are 0.001 - 0.002 higher than an inner bearing race. Fit outer axle shaft fully home and tighten nut to 90ft/lb. You should feel VERY slight play - if you can feel end float, reduce shims - if preload, increase shims. When correct, take apart, grease and fit inner seal.

One final word of warning, don't assume that every garage (even classic car specialists) is capable of rebuilding roto wheel bearings. We have seen some shocking bodges over the years carried out on customers stuff brought into us after recent work by 'professionals'.  You need to assertain that who ever  you trust your rotoflex with has a proven track record with the stuff, is regularly practised in the art, and has a ready stock of shims/spacers, etc before he attacks it.

You have been warned!