Lotus Elan

Rear caliper bolts

PostPost by: davidj » Sat Mar 28, 2020 1:03 pm

Good morning,

I am fitting my rear calipers and the new fixing bolts supplied by one of the major lotus parts suppliers are hitting the disks. The bolts (drilled for the locking wire) are 1 1/4" long. Should there be a washer? There is no mention of one in workshop manual and unfortunately I don't have the braking section of the elan parts list. I could fit spring washers, but they should not be needed if the bolts are wired.

Thanks in advance,

Cheers.
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PostPost by: SENC » Sat Mar 28, 2020 1:52 pm

My parts book shows them...

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20200328_095119.jpg and
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PostPost by: Donels » Sat Mar 28, 2020 1:53 pm

Mine are fitted with washers as well. See pic.

073F5B7F-5F05-4AA9-B12F-E9F31B70B6FD.jpeg and
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PostPost by: 2cams70 » Sat Mar 28, 2020 2:09 pm

It's actually been scientifically proven that spring washers mostly cause bolt looseness rather than prevent it! They may be of some help where there is something compressable being clamped (eg. a soft gasket) but not needed elsewhere. Key thing is to get the clamping load correct by tightening to the correct torque

Usually modern cars do not use spring washers anywhere!
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PostPost by: oldelanman » Sat Mar 28, 2020 2:20 pm

That parts diagram is the front caliper which does have lock washers, no washers shown on the rear caliper parts list. Front caliper mount is steel and rear is alloy, that may be why one has lock washers and the other is wired.
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PostPost by: SENC » Sat Mar 28, 2020 3:08 pm

oldelanman wrote:That parts diagram is the front caliper which does have lock washers, no washers shown on the rear caliper parts list. Front caliper mount is steel and rear is alloy, that may be why one has lock washers and the other is wired.

Indeed! Sorry, I was not paying close attention when grabbing the picture.
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PostPost by: davidj » Sat Mar 28, 2020 3:15 pm

Thanks for all the quick replies. Can I conclude therefore there are no lock or plain washers, and my bolts just are too long?
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PostPost by: SENC » Sat Mar 28, 2020 3:20 pm

When I replaced the ones on my Elan, a prior owner had used longer bolts and lock washers, so seems a reasonable conclusion.
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PostPost by: 661 » Sat Mar 28, 2020 4:50 pm

If the bolts will fit with a plain washer, then use those, tighten to the correct torque and lockwire.
If the bolts are too long, grind them down far enough.
It's all part of the 'nothing new fits' Lotus experience.
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PostPost by: Donels » Sat Mar 28, 2020 5:05 pm

Lock washers or plain washers in this application is good engineering practice. You are fastening a relatively high torque loaded bolt head against a relatively soft aluminium surface. A washer will prevent the bolt head digging into the aluminium.
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PostPost by: fattogatto » Sun Mar 29, 2020 9:34 pm

"A washer will prevent the bolt head digging into the aluminium."

Only if the washers used are hardened washers. Standard hardware store or AN washers are too soft.
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PostPost by: Quart Meg Miles » Sun Mar 29, 2020 9:38 pm

Donels wrote:Lock washers or plain washers in this application is good engineering practice. You are fastening a relatively high torque loaded bolt head against a relatively soft aluminium surface. A washer will prevent the bolt head digging into the aluminium.

Like the head bolts.
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PostPost by: USA64 » Sun Mar 29, 2020 10:21 pm

I used to often see hung up in workshops a cartoon which depicted a masculine bolt chasing a feminine nut that was shouting "not without a washer!". I used a lock washer on the caliper not for it's locking but because its smaller diameter fit the space; a standard washer being too large.
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PostPost by: jono » Mon Mar 30, 2020 9:12 am

I never used the lockwire on the Elan - Schnorr washer + a dab of thread lock and never had any issues.

Current Evora uses only threadlock on the caliper bolts - no washer of any sort
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PostPost by: patrics » Fri Apr 03, 2020 7:56 pm

Hi,
I use a thick flat washer on my car – as already stated you don’t want to damage the aluminium mounting face also with a washer you should get a higher clamp force.
Despite being the best / correct method I wouldn’t use any thread lock as it can bugger up threads especially in aluminium – our casting are expensive and rear calipers particularly so.
In the past I have always wire locked but whenever I have checked the torque they have always been good - don’t bother anymore, but I do check regularly.

@Donels have you got the right bolts on the lower arm to strut? – the heads look very big.

Regards
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