Annoying Noise

[Dolly-Nut]

I was driving along normally the other night on my way back from Jim's house with some nice Alleycats when my Toledo started making a noise from the back end. Initially I thought it was a flat tyre because it's that kind of thudding sound. It's once every wheel rotation and it's clear to hear and damn annoying. I've checked tyres for buldgeing and debris, had the drums off to see if anything has dislodged and even taken the backplate off the LSD. Everything looks normal but it won't shutup. Bare in mind it's fully poly-bushed so all drivetrain noises are amplified.
I hope it's going to be okay for its dyno date on Saturday!
Any other possibilities/ideas? A bit vague I know but I'm puzzled. The diff is still locking and usually they hum when there's an issue.

[Henk]

Lift the rear from the car on the diff housing, suspension stays in 'normal' position. Then rotate the wheels to locate the point of noise?

[Dolly-Nut]

I'll try it and let it idle in gear. it's not very audible below 20mph and what's weird is it almost goes away turning right!

[Henk]

The load on the right rear wheel is reduced when turning right, so possibly the right wheel to investigate?

[djw113uk]

Disappearing whilst turning in one direction usually means wheel bearing. I was blaming my 2000 diff, but that turned out to be wheel bearing. both felt fine when spun by hand too. At least on the big salon you can quickly swap a whole shaft to check. on the dolly its a but more involved

Perhaps prop centre bearing gone slack, or exhaust rubbing if you are lucky?

[Jon Tilson]

Incorrect wheel nuts...?

Jonners

[xvivalve]

Last time I had a noise like that I lost a wheel on the M3 through 3/8" studs shearing shortly after; they 'neck' at their base first, which allows play in the wheel.

[Dolly-Nut]

Had another look last night and tried different wheels and running on a jack etc. After all that I gave everything a good wobbling and it seems I have laternal play in thr rear bearings. Both sides were like this when I first got the car and replacement shafts sorted that for a while. Now here's the thing, those adjusting shims, are they what this is for? There is 5mm+ of in/out play. I assume this is the cause of the noise (I hope!). I have a dyno booked Saturday so really need this sorted.
Planning to have a play with shims tomorrow now we have some more daylight.

[djw113uk]

5mm!! That's a LOT of movement! Sorry I dont know how to adjust them. 'Richard the old one', has done a few 1500 rear bearings he might be able to assist.

[djw113uk]

Mikew also does things right and tackled his sprint rear bearings before RBRR. Maybe another one worth asking?

Take a look at his blog - around May 14. Does explain what endfloat it sets but does mention the shims!

[Jon Tilson]

Mike W fitted a new bearing carrier to his axle IIRC.
I've never had a Sprint rear wheel bearing apart, so a read of his blog on the subject is well worthwhile.

I was going to suggest exactly that before djw did.... Great minds...

Jonners

[sprint95m]

Planning to have a play with shims tomorrow now we have some more daylight.

I am uncomfortable with this idea because by simply removing the lateral play you won't have found out why said play has occurred.




Ian.

[Dolly-Nut]

Update. With my spare shaft fitted in one side I've managed to get roughly the book figure of 0.1 - 0.15mm endfloat. Adding shims increases endfloat, different thickness shims are available. I kept adding the thinnest shims until I had the smallest bit of detectable play.

I then stripped the other side to find no shims at all and a lot of play so therefore something has obviously worn (possibly because I didn't know anything about this shimming procedure last time I swapped the shafts). It looks like part of the bearing backing/race has worn, because its been rubbing on the axle tube??

I'm going to see if I can split the knackered shafts tomorrow at work but we only have a 15 tonne press which wouldn't budge them last time I tried. It took at least 30 on my friend's press and then everything flew across the room. I will put a wanted ad out there expecting to have to change the shafts again, anyone got some spare?!

It's always nice to learn new things about these cars but not this a week or so before a track day!

[gmsclassics]

Many years ago my race Sprint suffered what sounds like exactly the same damage as you describe. I had just acquired an LSD and gave the axle to a firm specialising in diffs to fit this. I didn't check the end float (I used to have this natural assumption that professionals know what they are doing) and ended up with loud clonking that turned out to be huge play in the end float. They couldn't get it right second time either so my friend and I did it ourselves. We were able to re-use the 'damaged' axle and with the end float set at the lower end of the range it worked perfectly for years afterwards, in fact until the LSD broke.

As you say you need a 50 tonne press to change the bearings and outer seals, but set up properly it should last a long time.

Good luck!

Geoff

[mikew]

You don't need a press if you get the churchill tool - its similar to the aftermarket hub pullers you see on ebay for spitfires / heralds, but be aware if you try one of these, they are not deep enough once bolted to the hub (in fact they won't actually bolt to the hub) - they are a copy of the original tool, but I think made shallower to reduce costs.

if you use a press you can significantly reduce the tonnage required, by getting a nice heavy steel drift and a lump hammer. Apply 5-7 tons of force, then give the hub / taper area (hard to describe) a very heavy thump using the drift and lump hammer - the shock helps release the taper - much like splitting ball joints with 2 large hammers