Lotus Elan

Rear wheel bearing - "Knocking from suspension over bumps"

PostPost by: JonB » Tue Jan 02, 2018 3:30 pm

Hi

There seems to be a lot of knocking coming from the suspension when I go over bumps in the road (of which there are many round here.. potholes too). Especially at the rear. I wonder if some bushes are worn out. See lotus-suspension-f42/front-suspension-bushing-turret-t40996.html#p287337 also.

Just wondering if it is supposed to be knocky. I'm guessing not, but jacking up the n/s rear of the car and moving the wheel didn't show any free play.

I'm not sure how to test the rear turret rubbers - any ideas?
Last edited by JonB on Mon Jan 08, 2018 4:36 pm, edited 1 time in total.
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PostPost by: Concrete-crusher » Tue Jan 02, 2018 6:46 pm

Hi Jon , your picture on the other post does not look quite right. I have just done my suspension front turrets and it used a large rubber bush on the lower section and a smaller rubber bush on the upper section , the smaller bush has a recess that fits into the chassis turret. There,s an upper washer on the top bush and a large washer below the bottom bush.

Regars Steve
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PostPost by: Concrete-crusher » Tue Jan 02, 2018 6:52 pm

Ps. Here's a picture of mine before I renewed the bushes ,
img_0362.jpg and


The new bushes came from Sue Miller , and are much firmer.

Steve
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PostPost by: MarkDa » Tue Jan 02, 2018 7:43 pm

Jon
Your other post provably shows where some of the knocking is coming from.
You can access the top of the lotocones from the inside.
They should be tight and unworn.
You can of remove them of course for a better look.
However there's an imminent danger that you'll end up doing a rear end rebuild if you even start looking!
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PostPost by: JonB » Tue Jan 02, 2018 7:45 pm

So be it, Mark. I'm not having that knocking sound. Besides, I have to remove the diff to fit new seals. Maybe I should man up and take the body off the chassis.

What a hobby! :roll:
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PostPost by: Bud English » Tue Jan 02, 2018 8:26 pm

JonB wrote:... Maybe I should man up and take the body off the chassis.


Beware the slippery slope!

It's a great hobby if you don't weaken. :D
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PostPost by: JonB » Tue Jan 02, 2018 9:21 pm

Oh, god....
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PostPost by: richardcox_lotus » Wed Jan 03, 2018 7:23 am

Rear knocking sounds could be movement of the diff. Check the top diff mounts and the side trailing arms.
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PostPost by: JonB » Wed Jan 03, 2018 7:47 am

Could be, but it happens going over bumps with the clutch held in (that is, no power going through the diff). I thought it was stuff jumping about in the boot, especially the battery (which was loose at the time), so I sorted that out.

My money is on the turret bushes (Lotocones?).
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PostPost by: rgh0 » Wed Jan 03, 2018 9:22 am

It could be the shock bodies not properly clamped in the struts

cheers
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PostPost by: UAB807F » Wed Jan 03, 2018 9:25 am

Does it come predominantly from one side or centrally ?

My first thought wasn't so much the lotocones or bushes but the dampers, either having failed or somehow becoming loose. Whenever I've had a damper fail I could imagine someone hitting the underneath with a hammer over the slightest bump.

Brian

edit - ^^ wot he said :D
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PostPost by: alan.barker » Wed Jan 03, 2018 10:32 am

rgh0 wrote:It could be the shock bodies not properly clamped in the struts

cheers
Rohan

That was the knock on my +2 where the Shock Insert was moving in the Strut. The special round nut needed tightening and centre punched to lock it. With the car lifted and the rear wheel off the ground it was possible to move the Insert Piston Rod in the Strut :shock:
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PostPost by: JonB » Wed Jan 03, 2018 2:33 pm

Well, I had a look at the off side top shock absorber nut. It's tight (and that cotter pin took me an hour to get out!).

As I was having a spot of lunch I thought I'd try something else for the nearside wheel. I jacked the car up and using a spring compressor I took up some slack in the Chapman strut. Then tried to lift the wheel and there it was, lots of play but not where I expected it. The hub bearings are shot, and I can rock the wheel in / out along the camber line by about 5mm at the tyre edge! I can even see the disk wobbling.

So, this is the first proper problem I have found that could cause the noise. The bearing on the other side seems to be OK.

Obviously not well pleased. I've read the workshop manual and it appears you can change the bearings without dismantling the whole back end. The outer Rotoflex joint needs to be disconnected from the hub spider, then the hub nut is undone and the hub drawn out using a puller (which I probably don't have). Then, remove the circlip on the inside of the inner bearing, push the shaft out and drive the bearing off the shaft. This does not look like too much bother to me... famous last words!
Last edited by JonB on Wed Jan 03, 2018 2:42 pm, edited 1 time in total.
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PostPost by: john.p.clegg » Wed Jan 03, 2018 2:40 pm

Jon
Don't be tempted to replace the split pin with a R clip , I did and regretted it.....big time....

John :wink:
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PostPost by: JonB » Wed Jan 03, 2018 2:44 pm

john.p.clegg wrote:Jon
Don't be tempted to replace the split pin with a R clip , I did and regretted it.....big time....

John :wink:


You mean on the nut at the top of the shock absorber? I torqued it up and didn't bother with a pin for now, as I expect to be doing not many miles before undoing it again.
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