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Caster shims/washers 88-92 - Suspension/Brakes/Wheels/Hubs/Steering/Geo - The Lotus Forums #ForTheOwners Jump to content


Caster shims/washers 88-92


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Hey guys,

While rebuilding my front suspension I observed that the quantity and placement of caster shims on my 91 SE really don't match the service book, in any respect.

The good book says that, nominally, there should be a total of 6 mm of shims distributed between the chassis and top wishbones, with a minimum of 1,5 mm at the front to prevent fouling of the chassis under "extreme conditions" (I'm guessing this doesn't involve the daily trip to the supermarket for milk). 

Should that not suffice, additional shim washers may be placed at the wishbone/chassis while simultaneously placing the same thickness of shim at the opposite wishbone half, sandwiched between the wishbone and the upper ball joint. 

What I found, when pulling apart my suspension, was 
a) no shim washers at the front wishbone, RHS (minimum: 1,5 mm)
b) no total of 6 mm on the RHS
c) shims sandwiched on either side of the upper ball joint, both sides, despite the above (sum not exceeding 6 mm at either side of the car, so theoretically these shouldn't even be there).

Now ironically, a couple of years ago when I had the geometry checked on a Hunter machine, everything was ok with the exception of Caster which was out of whack on the LHS but in spec on the RHS. I also had a setback of 11 mm between left and right (left side wheelbase was 11 mm shorter).

To those of you who have made this trip (setting up geo) - is it normal to shim way out of spec in order to achieve the right geometry, or has some monkey tried to set the geometry at some point in the past without access to the workshop manual?

I should add that it didn't look like the suspension had been taken apart since the car left the factory.... 

Here's some links to my Flickr since pictures tell a thousand words.
LHS:
https://www.flickr.com/photos/[email protected]/albums/72157682525141336/with/33892931122/
RHS:
https://www.flickr.com/photos/[email protected]/albums/72157681294057605/with/33361298176/

Advice? 

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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My advice would be start afresh, sort out a set of shims (at least matching pairs of, one for the ball joint and one for the 1/2" pin), put them in the default position and measure the castor then adjust the positions to achieve the target.

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My Europa had received a front end corner bump during it's earlier life which had put the chassis out of alignment necessitating the opposite corner rear radius arm to require extra shims in order to correct the rear toe.  

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Cheers,

John W

http://jonwatkins.co.uk

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Cheers guys. 

@ian29gte Thankfully the upper wishbones were stock. I'm having them re-plated this week, they seem to be true geometrically with no bending or warping. But the 93 upgrade with the additional adjustments is tempting.

@andydclements Ok. I've got some on order from SJ. Technically there should be no shims present at the ball joint from the get go. But they're inexpensive so I guess I can order 6 mm per side at those locations too. Will be cool to drive the car with all the geo setup correctly, at least in the front (ain't touching the back till I've bought an induction heater...those lower links you know...) 

@jonwat There's evidence on my SE that it's either hit something and/or driven over something up front. The car had a clear HPI report when I bought it but I was 24 and didn't know any better so didn't crawl under it prior to buying. I've got misaligned pivot sleeves on the left side front where the lower wishbone bolt goes through. Dunno how that happened with the bolt that was in there at the time. But does explain the fact we had to saw that bolt off to remove the wishbone. Anyhow I did the only chassis dimension check that was possible with the body on and that seemed ok so hopefully things can be rectified by shimming. 

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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