Lotus Elan

On to planning for the brakes!

PostPost by: tdskip » Tue Sep 03, 2019 12:56 pm

First of all I?d like to say thank you for all of the coaching and information so far. I very much appreciate everyone taking the time to answer my questions.

My ?69 DHC has sat since 1992 - to state the obvious the brake will need attention.

Rather than fuss around with unknown cores I was planning on just ordering a new brake MC.

Would it make sense to just order new front brake calipers as well?

Any common brake line upgrades recommended for a road car?

Anything special about the rear brakes to be aware of?

Thanks!
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PostPost by: MarkDa » Tue Sep 03, 2019 10:13 pm

Master cylinders and refurbed calipers readily available and a quick easy fix if you don't fancy doing them yourself - mc could easily be damaged anyway.
If you've got a workshop manual do read up on the handbrake mechanism that's attached to the rear calipers.
There will be threads on here.
They aren't actually difficult to refurb but are now obsolete.
You may want to consider braided hoses to the calipers.
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PostPost by: tdskip » Tue Sep 03, 2019 10:50 pm

Thanks (again) Mark, I don?t really feel like fooling around with it so I think I?ll just order ready to bolt on stuff.
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PostPost by: MarkDa » Tue Sep 03, 2019 11:11 pm

Front discs are the sa.e as other contemporary cars so are a reasonable price and definitely worth replacing while you've got the calipers off.
Rears are Lotus specials - available but volume reflected in the price.
Not an easy replacement as they are connected into the final drive - or are you planning to remove that anyway?
In which case unless yours are very good you may want to replace.
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PostPost by: steve.thomas » Wed Sep 04, 2019 11:08 am

Be aware that replacement master cylinders may be supplied with the wrong length actuating rod and you will need to replace it with the part from the old mc. So don?t bin the old one until you?ve compared with the new.
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PostPost by: tdskip » Wed Sep 04, 2019 11:54 am

Good tip Steve, thank you.

Mark, are you indicating I need to drop the rear axle to replace the rear brake calipers / rotor because they are inboard of the hub?
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PostPost by: MarkDa » Wed Sep 04, 2019 1:15 pm

Rear calipers come off easily enough but inboard disks are bolted to rotoflex.
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PostPost by: tdskip » Wed Sep 04, 2019 1:27 pm

MarkDa wrote:Rear calipers come off easily enough but inboard disks are bolted to rotoflex.


Ah - so change them for sure when I am putting in the CVs?

Thanks!
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PostPost by: 69S4 » Wed Sep 04, 2019 2:17 pm

And check the run-out when you do otherwise you'll be taking them all apart again.
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PostPost by: tdskip » Wed Sep 04, 2019 2:40 pm

69S4 wrote:And check the run-out when you do otherwise you'll be taking them all apart again.


Can I get a bit more info for a newbie on what I specifically need to check here please?

Thanks!
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PostPost by: 69S4 » Wed Sep 04, 2019 3:37 pm

The rear disc sits sandwiched between the 3 legs of the outer driveshaft and the outer rotoflex (or CV joint if you've converted). It doesn't need much error in the parts (or even grit in the joints) to have the disc run with a slight side to side wobble - and there's very little leeway in the specification (about .004"max iirc).

After spending ages chasing down brake judder when I changed my first set of rotoflex couplings it came down to excess runout. I now put a dial gauge on the disc to check it's either within spec or as good as I can get it (not necessarily the same thing :lol: ). Moving the disc and the other parts around on the three bolts to give different assembly arrangements can change the run out quite a bit, or you may have to resort to more drastic methods (file / lathe etc if it's really bad). I've only had to do that once and a few file strokes fixed it.

It's a pain to do but better than assembling without checking and finding you've got to take it all apart again because the juddering drives you nuts and the handbrake won't stay in adjustment (runout can wear the pads).

I always check the front discs as well but it's rare to get a problem with them if you keep everything clean.
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PostPost by: tdskip » Wed Sep 04, 2019 4:16 pm

Super helpful - thank you.
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PostPost by: alan.barker » Thu Oct 17, 2019 8:21 am

I think the 3 Lugs of the Driveshaft are sandwiched between the Disk and the Rotoflex :mrgreen: :mrgreen:
For the Front Disks you could fit +2 Calipers and +2 Disks and scrap the Servo.
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PostPost by: Tmac897 » Thu Oct 24, 2019 2:39 pm

At least somewhat on topic...

I've seen a few listings for front brake pads here in the US, but not much on rears. I still have my handbrake pads, which are in good shape; but I need new front and rear pads. I've seen some older threads mentioning EBC, but they are in the UK. I realize they ship, but it might be more economical to find some here in the States. Sources, anyone?
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PostPost by: joe7 » Thu Oct 24, 2019 2:49 pm

According to Whitepost restorations web site the do brake relining.
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