Lotus Elan

Setting steering rack height

PostPost by: ericbushby » Sun May 18, 2014 12:34 pm

lotus insurance 2014.jpg and
As I am getting used to driving my Elan I have slowly realised that the steering and roadholding are not as good as others have described how it should be. I have not driven another.
During investigation I find that there are no shims fitted under the steering rack clamps.!!
I have moved the clamps and there are no dimensions engraved on the replacement galvanised chassis.
There is a lot to read in the archives here and I will work my way through all that and learn as much as i can.
It seems I may have to work from first principles to set it.
I have ordered a new steering rack in order to remove some variables.
As I do not trust anything any more, can anyone help me by measuring the distance from the bottom of the radius to the underside on an aluminium rack clamp as shown. The clamps look like that on page 420 of Brian Bucklands book but are lacking the stamped marks. This is actually the top part of the clamp as I cannot release the bottom half until I remove the rack but it shows the dimension I want. This measurement on this piece is 0.370" by the way.
Any guidance from anyone who has done this will be welcomed, but I am going to read through the archives, and no doubt will be back soon even more confused.
Eric in Burnley
1967 S3SE DHC ( Up on stands again and the suns out!)
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PostPost by: john.p.clegg » Sun May 18, 2014 4:14 pm

Eric
I'd bin the solid mounts if I was you,there was too much vibration coming through them for my taste...as for rack height..looks like you'll be reading the joys of "bump-steer"....just remember,as you set one side it will alter the other side so it's a game of back and forth,back and forth until it's right.

John :wink:
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PostPost by: Elanman99 » Sun May 18, 2014 6:35 pm

Eric

The lack of shims means nothing. As John Clegg mentioned you need to read up on bump steer (search this sites archives). There is no real shortcut if you want to get it right.

New rack? is this a brand new unit, or a rebuilt one. In the past there have been problems getting parts for rebuilding, resulting in some less than perfect 'fully reconditioned' racks. Also there are small variations between Elan models so you need to be sure that your new rack is correct for your car.

I bought a genuine Lotus replacement chassis in the 1980s, it had shim thicknesses marked on in felt tip pen but when I assembled the front suspension I checked the steering geometry and found I needed different shims than what was marked up.

Ian
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PostPost by: ericbushby » Sun May 18, 2014 8:12 pm

John,
Thankyou for the advice as always.

Ian,
It will be a rebuilt rack from Paul Matty. I don`t think there are any `new` ones.

I`m reading! I`m reading!.There is a lot there.

I understood that the chassis were built to take shims because the makers could not manufacture them to sufficiently close tolerances. On that basis, no shims at all must be wrong.
Of course the clamp bottom half could have been made to suit. Hence my question about the thickness. Unlikely, I know, but as I said, I do not trust anything on this car until proved.
New clamps as suggested by John would mean that I do not need to know, and at the moment looks like the way to go.
Thanks,
Eric in Burnley
1967 S3SE DHC
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PostPost by: englishmaninwales » Mon May 19, 2014 11:42 am

Good article on bumpsteer on this website. While applicable for a Caterham or Lotus 7, the principles are the same and I guess much of the measuring technique is probably transferable to the Elan.
http://www.myothercarsa2cv.co.uk/howto/buildacaterham.htm

Malcolm
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PostPost by: Elanman99 » Mon May 19, 2014 1:50 pm

englishmaninwales wrote:Good article on bumpsteer on this website. While applicable for a Caterham or Lotus 7, the principles are the same and I guess much of the measuring technique is probably transferable to the Elan.
http://www.myothercarsa2cv.co.uk/howto/buildacaterham.htm

Malcolm



Malcolm

I cant make head nor tail of the links you have given, one seems to be an advert for brake pads and the other has introduced me to a whole new terminology. 'Carbon light blocks, MOPG etc.

Oops! just found the bump steer article but my browser wont open it without me saving it first so I've not bothered.

Ian
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PostPost by: ericbushby » Mon May 19, 2014 3:27 pm

Malcolm,
Thats brilliant, thankyou. I have printed it off.
Eric
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