The Lotus Grand Tourers

Afternoon guys. Hoping you might be able to provide some thoughts on what may be causing this issue I'm having.

Context: This is a 1979 Lotus Eclat with inboard drum brakes. A few weeks ago a wheel bearing failed in spectacular fashion, taking out the hub carrier in the process. New hub carrier and bearing has now been fitted.

Took the car for a test drive yesterday and almost straight away noticed a kind of clanging noise on rotation from the corner where the new bearing and hub carrier were fitted (passenger rear side). Turned back very quickly and got home. Lifted the car up and rotated the wheel and no sound at all. Strange, so I decided to get creative and jacked the hub carrier up too to simulate the car being at ride height. Rotating the wheel now gave me the sound you can hear in this video from the diff area, with a louder noise as I spin faster; also louder when I push the hub inwards and rotate. 1 clang per rotation both forwards and back, but occurring at different points in the rotation

https://youtu.be/84wD7ixico8

Only happening on that side and only happening when under load. The clang almost sounds like something hitting the brake drum so I took the brake drum off but no signs of any contact between bolts and shoes or inside mechanism. Decided to take the drum out of the equation and just snug up the outboard to inboard driveshafts. Rotating the hub then gives me the video below; you can see some movement of the hub carrier - looks to be getting pushed out where the clang would happen.

https://youtube.com/shorts/p1gBt3JbEOY

Now to reiterate, this only happens on the passenger rear corner, and only happens when that corner is at ride height. once per rotation. I tried disconnecting the inboard driveshaft and rotating it 180 degrees to see if the problem also rotated by 180 (maybe signifying that it's not the inboard driveshaft) or anything actually in the diff, as my thinking is that rotating the inboard driveshaft would have rotated the area where the noise occurs.

But what could be causing this? I thought maybe when the bearing died the UJs were damaged, and it might explain the hub carrier movement but I can't explain why that is translating to a clanging noise that sunds like it's coming from the diff area.

Any ideas what this could be, as I'm not many more ideas?

soldave wrote: Sun Aug 14, 2022 16:38 Afternoon guys. Hoping you might be able to provide some thoughts on what may be causing this issue I'm having.

next step in my book: try to find where the noise is coming from.
1) touch all the static bits in the drivetrain while recreating the knock: you can often feel where it is coming from
2) jam a screwdriver between your ear and the various static bits while recreating the noise, and see of you can locate it this way

Quite possible that a drive shaft yoke has twisted, given spectacular wheel bearing failure (more info on the detail of the failure event might shed more light).

The clanging could be induced by the pulling and shortening of the (twisted yoke on the) drive shaft as it's rotated.

Possibly, the clanging is exacerbated by damaged diff bushes during the spectacular event also. But to me, it does look like the drive shaft is pushing and pulling in the videos, pointing to a twisted yoke (probably at the hub end).

Lotus-e-Clan wrote: Mon Aug 15, 2022 08:04 Quite possible that a drive shaft yoke has twisted, given spectacular wheel bearing failure (more info on the detail of the failure event might shed more light).

The clanging could be induced by the pulling and shortening of the (twisted yoke on the) drive shaft as it's rotated.

Possibly, the clanging is exacerbated by damaged diff bushes during the spectacular event also. But to me, it does look like the drive shaft is pushing and pulling in the videos, pointing to a twisted yoke (probably at the hub end).

So here are a couple of pics of the aftermath, showing the inward facing part of the hub carrier:



Needless to say the hub carrier was replaced too. A little grazing on the outer shaft (the one that goes through the bearing and hub) but it didn't look like it had much damage so was reused. I guess as you say it may have warped or took some damage though and may need replacing, along with the UK on that side as a minimum.

Thanks for the thoughts - should really have considered that but hadn't yet.

More thoughts.
The hub carrier appears to move inwards suggesting play along the driveshaft and UJ´s.
The UJ´s take quite a pounding in normal uase and are a common failure so well worth very close inspection.
While out it is well worth changeing for new. I believe there are available heavy duty UJ´s.
Also check the hub carrier lower bushes and locating bolt, also known to shear off, plus the trailing arm bolt holes after the carrier failure.

Dave the cog.

Looks like mystery may be solved. That clanging coming from the diff area... outer UJ had gone. Three ends looked good, the other had no grease in. Am assuming linked to the bearing failure. Took all circlips off the UJs but ended up just replacing the outer UJ and replacing the clips on the inner one as it sorted it straight away

To tell the truth, I'm so nervous now about whether the circlips are in the UJs securely. It all looks good but it did with the wheel bearing circlip and I just don't trust myself! Might have to do some very gentle drives then come back and check them to build up my confidence. Or I just take the shaft to my local garage and ask them to sense check it for me.

soldave wrote: Thu Aug 18, 2022 18:19 Looks like mystery may be solved. That clanging coming from the diff area... outer UJ had gone. Three ends looked good, the other had no grease in. Am assuming linked to the bearing failure. Took all circlips off the UJs but ended up just replacing the outer UJ and replacing the clips on the inner one as it sorted it straight away

To tell the truth, I'm so nervous now about whether the circlips are in the UJs securely. It all looks good but it did with the wheel bearing circlip and I just don't trust myself! Might have to do some very gentle drives then come back and check them to build up my confidence. Or I just take the shaft to my local garage and ask them to sense check it for me.

Check the space between the ends of the circlip with a drill shank or similar. They should all be fairly similar without an odd one out