Lotus Elan

Rear Brake Caliper mounting shims

PostPost by: ivan.wood » Mon Aug 06, 2018 12:36 pm

It seems the simple jobs become the most confusing.

So having resolved the front bearing caliper issue by fitting shim washers to centralise the rotor I am now refitting the rebuilt rear calipers and heath robinson parking brake assembly but when I took them off 3 years ago there were a number of brass shim washers which fell out when I removed the caliper to lower strut mounting bolts. There were 5 shims on the LH side and 4 on the RT and they appear to be a mixture of .006" or .008" and 0.75" OD but unfortunately I did not see where they came from. I don't think the rear calipers had ever been removed and I have the original Lotus Workshop manual as well as other reference material but no mention of the shims or what/where to take any measurements.

Can anyone throw any light on this issue as I am sure Colin Chapman fitted them for a good reason?
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PostPost by: alan.barker » Mon Aug 06, 2018 2:09 pm

No shims should be there. Someone has added them :shock:
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PostPost by: USA64 » Mon Aug 06, 2018 2:19 pm

Just be sure the shoulder of the bolt doesn't protrude past the strut or it will break the caliper. Ask me how I know.
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PostPost by: alan.barker » Mon Aug 06, 2018 2:32 pm

I think you mean the plain part of the shank should be no longer than the thickness of strut lugs.
There should be plain washers under the bolt heads. The heads of the bolts should be drilled so locking wire is fitted between the 2 bolt heads. :wink:
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PostPost by: USA64 » Mon Aug 06, 2018 4:17 pm

Yes I meant that but the "plain part" was too long even with a washer. They were drilled and appeared original. Needs a thick washer or shims.
We are supposed to be having fun, are we not?
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PostPost by: alan.barker » Mon Aug 06, 2018 4:42 pm

I think i would buy new bolts with the plain part of the shank shorter. Imho to have shims is not a good idea.
Perhaps some thick hardened steel washers would be not so bad and protect the alloy lugs on the Struts.
The bolts heads can tend to recess the lugs and could crack them :shock:
Alan
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PostPost by: RotoFlexible » Mon Aug 06, 2018 4:43 pm

My S2 has thin brass shims between the caliper and strut. They don't show up in the S2 shop manual exploded diagrams, but I have no reason to believe they were added by the previous owner.
Andrew Bodge
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PostPost by: alan.barker » Mon Aug 06, 2018 4:45 pm

I've owned and worked on 4 different Elans and never seen shims :shock:
Alan

ps i have heard of people putting shims between the Driveshaft Lugs and Brake Disks to get them to run true.
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PostPost by: ivan.wood » Mon Aug 06, 2018 5:13 pm

This car only has 46,000 miles on the speedo and I suspect it is correct as the car was parked for 35 plus years before my friend bought it. Unfortunately it had had a serious front end impact and although they put a new fibre glass front section on the frame was fairly badly bent so it would have never driven straight which is probably why it was parked till the owner passed away. That makes me think the rear calipers have never been removed and why would someone go to all the trouble to fit 9 brass shims of two different thicknesses????
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PostPost by: bitsobrits » Mon Aug 06, 2018 5:29 pm

FWIW-I've had 5 Elans over 40 years, and the two most original ones I've owned, one S1 RHD and one S3 LHD both had thin brass shim washers on the rear calipers. Both of these cars had every indication of not having the rear suspensions disassembled in the past, though of course it's difficult to be sure as I was not the original owner.
Steve

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Formerly:
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Elan S4 1969 FHC
Europa S2 1970
Esprit S2 1979
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PostPost by: MarkDa » Tue Aug 07, 2018 1:00 pm

Having decried the need elsewbere to shim front calipers unless they foul the rotors I have a different experience at the rear.
Given the sensitivity of the hand brake adjustment I have shimmed my rear calipers to even up the mechanism and get balanced application.
Shim washers are a hell of a price aren't they?
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PostPost by: alan.barker » Wed Aug 08, 2018 5:28 am

I have known Rear Brake Disks to run out and people Shim between Drive Shaft Lugs and Disk to make them run true. I suppose they think it's easier than removing the Drive Shaft from the Chapman Strut and getting the Lugs trued up in a Lathe.
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