Lotus Elan

Sounds like a tyre rubbing (but its not)

PostPost by: aussieelan » Sun Feb 15, 2009 12:33 am

Hi Guys,

I seem to have developed a strange noise coming from the passenger side rear. It's a rotational noise (i.e. gets faster and slower), most noticeable at low speed and sounds like a tyre rubbing (but its not) ... kinda like a chhhhh ... chhhhh ... chhhhh. Seems to be worse on left handers, sometimes disappears on right handers, and is intermittent in a straight line (sometimes but not always depending on previous corner).

I can't reproduce it in the garage, and I am fairly sure its not wheel bearings (more of a rumble noise) or CV's (more of a clack clack).

I first noticed it about 30 mins into a Sat AM drive a couple weeks ago. Upon inspection I noticed that the hub drive pegs on this side have been replaced at some stage with a tapped and threaded version. These were about 5mm longer than those on the other side (originals). I could also get a high tech feeler gauge (the thin end of a cable tie) inbetween the hub and the inside of the rim.

Thinking this was most likely the issue (although no idea why it just started to make itself apparent) I shortened these to the same size as the originals, and went for a test drive this morning. Initially the noise was gone, but after about 30 mins of driving it re-appeared. Very annoying.

Upon checking with my feeler gauge I couldn't get any gap between hub and rim on 3 of 5 pegs .... and a very small gap on the other 2. I ~think~ this is caused by a small shoulder on the pegs between the threaded end and the smooth peg end.

Removing the pegs and turning them down is a PITA, but can be done if this is the issue. Recently I have rebuild the diff and had the entire rear drive line apart, repacked the CV's, re-torqued all the nuts and bolts etc, and have had 700 trouble free miles since.

Very open to any other ideas/suggestions or confirmations that I am on the right track.

Thanks

Andrew
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PostPost by: rgh0 » Sun Feb 15, 2009 1:01 am

The wheel needs to sit flat on the hub with no gap. If it is hanging up on the pegs you need to modify your non standard pegs so they fit properly.

The noise could be the wheel moving on the hub as it rotates if it is not seated properly.

But also could be something rubbing

Common places for contact are

1. Side wall of tyre with spring seat
2. Wheel rim with bolt heads in lower wishbone
3. Brake hose on tyre or wheel
4. Wheel on body depending on what tyres fitted
5. If the bearings are on the way out it could be a bearing seal or the dust shield rubbing on the shaft or the brake disk rubbing on the pads or caliper.

Does the noise go away when applying the brakes ?

cheers
Rohan
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PostPost by: neilsjuke » Sun Feb 15, 2009 12:08 pm

You could rub chalk on the tire and go for a run.
neil
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PostPost by: JOHNKENNER » Sun Feb 15, 2009 9:44 pm

I think I had the same problem and it took me about 2 years unitl i finally found it. My transmission rubber mount was completely worn and the drive shaft was rubbing against the tunnel at times. Check out your tranny mount.

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PostPost by: aussieelan » Mon Feb 16, 2009 3:19 am

Thanks guys,

Its definitely not a tyre rubbing on anything ... lots of clearance everywhere, and brake hoses are well secured out of the way, and it still continues under braking ... so its not a warped disc or a pad rubbing.

I will continue on the most obvious issue of the wheel not sitting square on the pegs. Being as they are screw in, I managed to get half a turn more on one of the offending pegs and moved the "shoulder" out of the way. I will try a bit of heat on the other tonite and see if I can get the same there.

If that doesn't work, I will investigate the tranny mount option ... though all mounts were renewed less than 3000 miles ago, so they should be OK.

The thing that really baffles me is a) why it has only become apparent now and b) why it takes about 30mins of driving to show up .... almost like it something that needs to "warm up" first. Which makes me think wheel bearings, but its not a bearing rumble, and there is no movement in that area.

More investigation required.

Andrew
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PostPost by: iain.hamilton » Mon Feb 16, 2009 2:58 pm

Something similar happened to me and drove me mad until I found it.

I had stick-on balance-weights on the inside of the back wheels. On the left hand side thes just touched the a-frame where it is bolted to the hub-carrier.

good luck, iain
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