Lotus Elan

Slight knock from front wheels

PostPost by: Rich135 » Wed Apr 18, 2018 2:47 pm

Hi All

I have just had all four tyres replaced before Goodwood on Saturday. I jacked the car up and took the wheels to the tyre shop.

On the test drive I noticed a bit of knocking from the front end whicj I don't think was there before. If I grab the top of the wheel and pull out in and out I hear and feel a small knock on both sides.

I have cleaned up the faces of the hubs and wheels and made sure the knock offs are right but it's still there.

Can you recommend the next things to check? My anti roll bar bushes are not the culprit as I did them six months ago and they still look fine.

Can I tighten the front wheel bearing on a +2? I am not familiar with the front hubs yet!

Many thanks

Rich
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PostPost by: Rich135 » Wed Apr 18, 2018 3:44 pm

I think I have answered my own question. Looks like the hub nut needing tightening one flat, so there must have been a slight bit of play in the bearings.

All seems fine now.

Rich
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PostPost by: JonB » Wed Apr 18, 2018 3:48 pm

Rich, did you replace the split pin with a new one?
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PostPost by: Rich135 » Wed Apr 18, 2018 4:50 pm

No I didn't Jon, I reused the old one. Bad idea?
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PostPost by: oldelanman » Wed Apr 18, 2018 5:10 pm

Don't overtighten the hub nut ... there is supposed to be a small amount of end float when it's correctly adjusted. Check out the workshop manual if you have one, the adjustment procedure is described in detail .... at least it is in the 2 seater manual, I assume the Plus 2 has it too.
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PostPost by: Rich135 » Wed Apr 18, 2018 7:44 pm

oldelanman wrote:Don't overtighten the hub nut ... there is supposed to be a small amount of end float when it's correctly adjusted. Check out the workshop manual if you have one, the adjustment procedure is described in detail .... at least it is in the 2 seater manual, I assume the Plus 2 has it too.

Thanks. I do have the manual so will go through it and check.
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PostPost by: JonB » Wed Apr 18, 2018 8:58 pm

Supposed to use a new split pin Rich.. I'm personally not too precious about reusing things I shouldn't, but it's the front wheels we are talking about here. Safety critical and all that.

If you don't get round to replacing them by Saturday I'll bring some with me. I've got loads of them.

Speaking of which, I tightened mine today as there was some play. Now my wheels no longer vibrate at 70mph. I expect I'll have them apart again to check the end float at the weekend (now I have a dial gauge).

See you Saturday...
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PostPost by: 69S4 » Thu Apr 19, 2018 6:46 am

JonB wrote: I tightened mine today as there was some play. Now my wheels no longer vibrate at 70mph. I expect I'll have them apart again to check the end float at the weekend (now I have a dial gauge).


It's supposed to be between .002" and .004" according to my workshop manual but measuring it without a dial gauge is a little tricky. It's even worse when the bearings are packed full of grease as pulling the hub in and out to feel the play gets damped out.

My rule of thumb has been to tighten to the point where I can't feel any play by wiggling the hub but can just feel some clearance by wiggling the wheel when it's back on and still jacked up. Exactly how much clearance that is is anybody's guess but it hasn't burnt out any bearings over the years. If you get it set up with the dial gauge maybe you could try and translate that into wheel movement or something as a guide for those of us without measuring equipment (can't believe many garages would have had dial gauges back in the 60's anyway).
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PostPost by: denicholls2 » Thu Apr 19, 2018 1:27 pm

A finer thread on the axle would have made getting this right a whole lot easier. The available pitch usually gives you the options of too loose or too tight relative to the specification, though you can get lucky and have a flat that's spot-on.

Inspectors tend to be very picky about front-end play, but too tight is more dangerous if you drive long enough distances to cook the grease out of the bearings. I tighten them up for inspections and back off a flat after them. The inspection is supposed to keep you from driving with worn-out parts but sometimes the methods favor creating them.

For a track day, I would favor loose over tight because everything is going to get hotter at speed and braking tends to be much more aggressive than street use. As noted, the actual adjustment process is simple, determining which of the typically two pin placements to use is the judgement call.
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PostPost by: Rich135 » Thu Apr 19, 2018 2:52 pm

Thanks very much for your replies, they are really helpful.

I will do a bit more adjusting tomorrow before I head to the track.
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PostPost by: alan.barker » Fri Apr 20, 2018 7:07 am

I thought the threaded part of the stub axle has 2 holes at right angles. So you can adjust the nut to a half flat which is a small adjustment 30?.
I think when you take the Lotus for the MOT it's a good idea to put the Workshop Manuel in the car opened at the page for adjusting front wheel bearings :wink: :wink:
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