Lotus Elan

Brake callipers - just wondering

PostPost by: martinbrowning » Thu Jan 24, 2019 5:14 pm

Hi there, My Lotus and Jaguar factory workshop manuals all warn against splitting the brake calipers. I can understand such a warning in, say, Haynes manuals where the intended readers may be keen amateur. However, can't see the reason in workshop manuals which are aimed at professional workshops or those with more than a degree of mechanical empathy.

So, why am I not supposed to split them to refurb/overhaul?

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PostPost by: Bombay Racing Green » Thu Jan 24, 2019 5:37 pm

I’m probably wrong on this but here goes. Is it because you could potentially leave out the neoprene washer that goes in the caliper? I assume that it used to be difficult to obtain. However, Canley Classics sells them now I think. Also I don’t think the torque settings are published anywhere.

This might help:
https://youtu.be/UUJuW6Ho2LY

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PostPost by: Foxie » Thu Jan 24, 2019 5:39 pm

I spilt and reclosed the rear calipers on my +2S a long time ago.

Never had a problem. :)
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PostPost by: john.p.clegg » Thu Jan 24, 2019 5:57 pm

Ditto,no problem..

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PostPost by: UAB807F » Fri Jan 25, 2019 9:02 am

Another "splitter" here as well and now I do it as a routine if the caliper needs painting or it's been a long time since it was overhauled.

I once found some yellow/brown "gooey" stuff in the middle inside that sealing washer between the two halves. I've no idea what it was and I don't believe it was affecting operation but that reinforced the idea of splitting to make sure it's all clear.

There's no logic to "do not split". Someone has bolted them together in the past so with sufficient care someone can do it again. I suspect the caution may be down to the engineered faces being damaged while lying about a bench, the rubber seal not being correctly located or even not tightening the bolts properly on a safety critical item.

But common sense should get you past those.

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PostPost by: rgh0 » Fri Jan 25, 2019 9:50 am

I am a "non splitter" not because they say not to but because I don't believe its necessary.

In 1980 when doing the total rebuild of my Elan the last bolts on the entire care to remove were the caliper bolts. It was a "total nut and bolt rebuild" so I wanted these out also

After many attempts it became clear that I would shear of the bolt heads if I continued and then face the challenge of removing the broken bolts after than. By this stage I had cleaned up the calipers and their bores and it was clear they were in OK shape so I could not see the need to split them. Now almost 40 years later they are still the only bolts on the car i have never removed and the brakes work just fine :D

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PostPost by: Donels » Fri Jan 25, 2019 11:16 am

I agree with Rohan and try not to split the callipers as its usually not necessary. However, on my last rebuild I did have some professionally refurbished callipers one which had an internal blockage. Splitting was necessary and surprisingly easy and revealed 'crud' blocking a drilling. I split both callipers to make sure they were clean.

I don't see any reason why they should not be split if you're competent and check for leaks afterwards. Just a word of caution do not finally clean with paraffin, petrol or similar as it's not good for the seal material. I always finally clean with methylated spirit.
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PostPost by: Craven » Fri Jan 25, 2019 11:45 am

I suspect the calipers were not considered, in their time, to be a normally serviceable part, other than fitting available official spare parts, a replacement caliper would be the expected route by Lotus service agents. Going against manufactures ( Gerling ) guidance, may lead in case of failure, to possible litigation.
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PostPost by: nmauduit » Fri Jan 25, 2019 1:33 pm

I also split only in last resort (terrible looking caliper, possibly requiring splitting for better access to remove the pistons...), last time I needed some, urgently of course, the proper seals were not so easy to source : they are of square section, not O'rings, of precise thickness to be compressed just so, made of proper material... I have one set left in stock, had to pay more than I expected (about €6 each from a local outlet iirc) then but they should not be more than a buck (e.g. https://mossmotors.com/seal-between-caliper-halves no affiliation).
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PostPost by: pharriso » Fri Jan 25, 2019 2:47 pm

In the States Ray (RDent) stocks them, part #26J4908 $2.50 ea.
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PostPost by: john.p.clegg » Fri Jan 25, 2019 4:12 pm

I punched them out of sheet neoprene , can't remember the diameters or thickness at the moment...

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PostPost by: jk952 » Mon Jan 28, 2019 6:01 pm

Martin,
For what it’s worth, while not claiming to be an expert in any way, I have taken apart several, including one exceedingly rusty rear calliper. On that one after much liquid wrench soaking the fine thread bolts undid without breaking though I was half expecting the bolts to snap as took a lot of torque to break them free. The square edged seal was fine. Once apart a 1/8 dia or suitable drill fits nicely down the internal passageways to clear those out if clogged up with gunk. Also if not seen prior, a grease gun with a (homemade?) suitable adapter will get siezed pistons out when air pressure won’t do the job. (which also saves the brake fluid in the face problem when the rag you put them over blows out of position. :lol: )

So if you need to take them apart to clean properly should be fine, but otherwise likely not really necessary. I did not find a torque number for the caliper bolts, so went with std for fine thread and high grade bolts, (ie good and tight)!

cheers,
Jack
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PostPost by: mikealdren » Tue Jan 29, 2019 9:59 am

I've never failed to get stuck pistons out of old calipers (and master cylinders) by putting some water in and then sealing them shut and putting in the oven (say 140C) until the pistons pop out. The combination of heat and steam pressure seems infallible.

Always use something to stop the pistons flying too far (say a wood block between them) and cover to stop fluid or rubbish being sprayed around.
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PostPost by: john.p.clegg » Tue Jan 29, 2019 12:15 pm

Well,I'm not going to give the wife £50:00 and send her shopping for half an hour,I'll stick to the modified grease gun adaptor...

John :lol:
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PostPost by: mikealdren » Tue Jan 29, 2019 12:26 pm

£50 for 30 mins, you spoil her!
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