Rack Shimming

[William2]

I know this topic has been covered but...
I am about to remount the rack on my S4 which came without any shims and the chassis has been powder coated so any chassis markings are not visible. It would appear that if I follow Brian's Lotus manual and measure from the top of the upper wishbone pivot stud to the top of the rack to try and achieve a dimension of 158mm then I would need shims amounting to 0.210" which seems a lot.
I was talking to a well known Lotus gurus today who has been in the business for many years and he gave the opinion that accurate shimming is a bit of a myth and that it can only really be done with the car fully assembled and with the ride height adjusted before hand.

[john.p.clegg]

I'll second that as you are looking for movement up and down from ride height ( which varies with weight/spring loading etc etc.. )
Not as easy with the body etc installed but the only way to do it ( IMHO)

John

[lotocone]

Will try this again. My first post didn't appear on the forum.

I ended up with shims that were about 0.200" after checking for bump steer, so I don't think your number is too bad. The original shims were much thinner. This was back in the 90s before Brian Buckland's book.

We just tried to keep the toe-in change to a minimum as the suspension was moved up and down with the shock and spring removed. It did help a lot with bump steer which was not so good, as I remember. The body was off when we did this.

Bob

[pharriso]

I called Miles Wilkins on the issue of shimming as I had purchased a Lotus Replacement chassis that also had no required shim thickness markings on the rack mount (bare chassis no paint or galvanizing).

His comment was that his chassis are right & don't need any shims...