Lotus Elan

Wishbone Rim Clearance

PostPost by: phil1800 » Thu May 19, 2022 3:20 pm

I have noticed that the LH rear wishbone outer ,eye‘ has a clearance against the rim/ wheel of only 0,15 mm, whereas the other outer eyes have a clearance of 3 to 3,3 mm. The distance between the eyes is as it should at 144, 2 mm. The measured distance between the rims and the rear disks is identical on both sides, so the position of the stub axle and bearing should be ok. Changing wheels over doesn’t change the clearance. It seems that I don‘t have the intellectual capacity to where the issue could be. I first thought that the wishbone bushes might be pressed in incorrectly, but the measurement speaks against it. If the wishbone is bend in any direction, but the distance between the eyes is correct, it can‘t be the problem. If the chassis is bend, the position of the wheel would change, but not the eye position against the wheel. Please help me to understand………

Philipp
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PostPost by: mbell » Thu May 19, 2022 6:08 pm

It is normal for them to be very close. Maybe not that close.

What washers do you have between the arm and carrier? My memory is there are meant to be special thin washers used. IF that is wrong it would move the wheel relative to the arm.
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PostPost by: phil1800 » Thu May 19, 2022 6:25 pm

Thank you for that hint. But the clearance issue is between the ‚eye‘ and rim. Both the washer and the bolt have much more clearance. If the washer would be too thick, it would move the bolt head outwards, not the eye, wouldn‘t it? Am I thinking wrong here?

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PostPost by: NTG999 » Thu May 19, 2022 6:54 pm

The position of the outer bushes in the wishbones would change that clearance, likewise if there are washers between the aluminium strut and bush
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PostPost by: mbell » Thu May 19, 2022 6:56 pm

There should be a washer between the arm and the wheel carrier (can just about make it out in your third picture). That washer effects the relative position of the arm and the hub/wheel carrier. As the wheel and hub carrier are fixed relative, it also effects the arm to wheel clearance. I am not talking about the washer under the bolt head.

If that washer is too fat, it will push the arm away from the carrier and towards the wheel. These should be special thin washer I believe. So the first thing a would do is check that washer thickness out. As if it a standard thickness changing it for a thinner washer might get you more clearance.
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PostPost by: NTG999 » Thu May 19, 2022 7:00 pm

Thinking some more, your accurate measurements rely on the aluminium hubs being identical (but mirrored) left to right
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PostPost by: phil1800 » Thu May 19, 2022 7:34 pm

Aaahhh, a washer between the wheel carrier and the wishbone. I‘ll check tomorrow and will remove the bolts to measure the washers. This didn‘t came to my mind (for reasons mentioned earlier). The manual didn‘t show no freakn‘ washer.

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PostPost by: mbell » Thu May 19, 2022 7:42 pm

phil1800 wrote:The manual didn‘t show no freakn‘ washer.


Yup, the parts manual does list them (A07W0000) but there not shown on the diagram:
http://rdent.com/manuals/plus2/rear_suspension/da.htm

Just part of the fun of Lotus ownership :lol:
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PostPost by: 661 » Fri May 20, 2022 1:26 pm

mbell wrote:It is normal for them to be very close. Maybe not that close.

What washers do you have between the arm and carrier? My memory is there are meant to be special thin washers used. IF that is wrong it would move the wheel relative to the arm.

^^This.
Usually the width of the hub carrier is slightly less than the distance between the two 'eyes' of the outer wishbone bearing carriers. It is packed with a washer or two ( or 3).
Therefore the hub ( and wheel) centre can be moved slightly forwards or backwards depending on where the washers are packed.
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PostPost by: phil1800 » Fri May 20, 2022 2:42 pm

Thank you! I will remove the bolts and will try to shim the hub towards the back. What is the recommendation for loading the suspension to free the bolts? A jack or spring compressors (dunno if mine would fit at all) ?

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PostPost by: ericbushby » Fri May 20, 2022 3:48 pm

Hi Philipp
I used small spring compressors. Even then when I tried them the end of the threaded rod would have touched the body when compressed. I made some tubular spacers to fit under the hexagon head to shorten them.
Now two conflicting statements.
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They were excellent and I have used them several times.
Best of luck
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PostPost by: Andy8421 » Sat May 21, 2022 10:59 am

Phillip,

At full droop, the lower wishbone bolts are unloaded, you don't need to compress the spring. The shock absorber acts as a stop.

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PostPost by: ericbushby » Sat May 21, 2022 11:31 am

Hi Andy,
You are right, I forgot that.
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PostPost by: Hawksfield » Tue May 24, 2022 1:02 pm

Hi Phillip

I was thinking about your problem and some of the advice given you did not seem correct. My thoughts on this are that the bolts should be thin head with washer, nuts on the inner. the problem I think you have is that either you have the bushes not positioned correctly or the wrong type. the bushes should but up to the carrier (no washers) this should centralise the wishbone leaving a small gap at the wheel.
The suggestion that there should be washers between the carrier and bush is in my opinion not correct, the manual states two washers per outer wishbone but does not say in which position.
I have done a quick insitu check of mine the dimensions are Inner eye 143.72 and the carrier width 136.63 mm. the gaps between the eye and the carrier are rear 3mm front 4mm, this means my carrier is offset by approx 1mm. These bushes were fitted in 1987 and its just now that I have noticed, but there is running clearance at the wheel.
The critical thing then is to fit the bushes correctly into the eye but must but up to to the carrier equally.

Did you fit these bushes, are they standard and do the have washers next to the carrier.

See images of my suspension to help I don't know how accurate my dimensions but I think good enough for insitu.

Hope you get it sorted


rear.jpg and
rear

front.jpg and
front
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PostPost by: smo17003 » Tue May 24, 2022 2:21 pm

Hi John,

The Wiki Parts Manual does not show the washers but it does list them (A07W1405) as additional to each outer bolt (29 and 30 on the drawing). Both described as "Washer - Wishbone to Bearing Housing". There are no washers listed against the inner bolts however. I have a spare housing that has evidently been run without the washers because the bush has worn a circular groove into the housing.

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