Lotus Elan

Question for you tandem brake guys....

PostPost by: dlbutler » Wed Sep 16, 2009 1:31 pm

Have you bled the Master Cylinder? Have someone pump & hold while you open a line (one at a time) on the M/C itself. Another potential problem are the "down hill" sections of the Brake Lines. If the bubble doesn't make it past the bottom it can float up again. Bleeding seems normal, but the peddle stays soft. A pressure bleeder can be a help. I use Ferodo DS2500 pads on the front and only a brick wall could stop the car faster. :) I would keep the lines per factory spec.

Don


As to my pedal, it's hard to describe. In and of itself, it's not bad. While not the most solid pedal I've felt, there's plenty of meat to it. Probably drops 1/4 before it comes on. If I threshold brake, i.e., full-on from 50mph, I probably get 3/4 of the way down, but never to the floor, for instance. Like I said, the stopping power is improved, and is probably even usable as is, but it just doesn't have that bite. The pads are called Classic Gold. I don't know if they make more than one type of pad. I got them from Ray at RD. I bled the master (i.e, cracking the 2 output bolts while pushing down on the pedal), and I had no problem bleeding all the lines.

I'm wondering if I should try to switch the lines, to feed the front brakes from the rear of the master.
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PostPost by: Chrisrich » Wed Sep 16, 2009 7:39 pm

Dan, maybe you're suggesting the shorter run to the front might give me a little more pressure? Or are you thinking that if I were to switch the fronts to the rear of the master, it'd be an easier run? Probably a good suggestion, either way.

You don't happen to have an infra-red thermometer, do ya? I wonder what kind of heat I should be getting in those discs.
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PostPost by: collins_dan » Wed Sep 16, 2009 9:11 pm

Chris, I was thinking of the way the line runs from the mc across to the right side, then back to the left front, instead of just directly from the mc to the left front right beneath it.

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PostPost by: patrics » Thu Sep 17, 2009 6:32 pm

Hi Chris,

What size is the master cylinder?

Regards
Steve
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PostPost by: Chrisrich » Thu Sep 17, 2009 7:07 pm

Don, yes, I bled the master as you described. It feels like there might be air in the lines, frankly, but I've passed so much fluid through all the pipes and I get such a steady stream of fluid, it's hard to believe there's still air in there.

Steve, I'm not sure what size it is, but here's a picture before it went back to WhitePost (it leaked the first time I got it back from them)

http://web.me.com/christopherrich/Cars_ ... tus_2.html

Thanks everyone-

Chris
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PostPost by: Galwaylotus » Thu Sep 17, 2009 7:27 pm

patrics wrote:Hi Chris,

What size is the master cylinder?

Regards
Steve

Not sure on a Federal tandem m/c but the Girling single circuit m/c is 0.7 inch. The size may well be cast into the body of the m/c. Check it out!
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PostPost by: patrics » Thu Sep 17, 2009 7:36 pm

Hi Chris,

This the original type TVCV fitted to federal cars - the correct one with out a servo is 0.70 but the +2 came with 0.875 so you need to be sure which one is fitted otherwise the pedal efforts would be very high.

Did your car originally have a servo or two?

cheers
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PostPost by: Chrisrich » Fri Sep 18, 2009 9:24 pm

Ok.
After swapping out front and rear on the master cylinder, and getting a set of speed bleeders (THANK YOU, Dan) I now have a car that stops. I'm thinking that my master is still faulty, however, as I'm quite certain that the factory setup is to feed the front brakes from the forward reservoir, and my deal only works when I've connected the front to the rear side. I think I've effectively just moved the problem to the rear, where it's less noticable.

Now I've got good heat in the front discs (150-175 or so) and very little in the rear (just under 100).
I'm going to have to reconcile this, at some point, but for now I've got with a nice stiff pedal that actually stops.

Thanks everyone for their time and input.

Chris
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PostPost by: Galwaylotus » Sat Sep 19, 2009 7:52 pm

Well,if it's a m/c problem, you know the answer! Get a seal kit, take it out, thoroughly clean and inspect it, and put in the new seals. 8)
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PostPost by: cabc26b » Wed Sep 23, 2009 10:17 pm

Not sure how much this applies to this thread but here are a couple of alternative tandem master cylinders i have had worked up for elan application. the nabco is a Datsun f10 application should be fine in a RHD car. I modified it for a LHD application. The Raybestos is a VW/datsun application again, modified for remote reservoirs and turned down a bit to fit the elan bulkhead. they have not been on the car - raybestos has bleeders on the cylinder. Nabco is pretty clearly marked for circuit and diameter ( it also has a residual valve for the rear circuit that was removed.)

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PostPost by: pharriso » Thu Oct 19, 2017 5:08 pm

I've read this topic with personal interest as I am running new brake lines on my new chassis. My conclusion is that whoever came up with the brake pipe layout for the Tandem system for LHD cars must have been doing drugs. I've documented the layout below:
Visio-FederalElanBrakeLines.pdf
(36.67 KiB) Downloaded 135 times


So as previously mentioned instead of placing a "T" on the LHS of the engine bay, Lotus decided to keep the original 3 way fitting position on the RHS & then run the line to the LH front caliper back again. Crazey... Add lightness Not! :roll:

Interesting enough when Rick Cranshaw re-piped 0262K he re-designed the brake pipes how they should have been done:
0262k_brakereroutecranshaw.jpg and


I assume the T was added for the rear line so Lotus could use the same brake pipe in the rear as on other market cars, with just a minor bend or two.

I also found that contrary to normal Girling practice, the primary piston (the one nearest the brake pedal) in the master cylinder is connected to the rear brake circuit & not per normal practice connected to the fronts.
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PostPost by: lotocone » Thu Oct 19, 2017 8:38 pm

pharriso wrote: ...

So as previously mentioned instead of placing a "T" on the LHS of the engine bay, Lotus decided to keep the original 3 way fitting position on the RHS & then run the line to the LH front caliper back again. Crazey... Add lightness Not!

Interesting enough when Rick Cranshaw re-piped 0262K he re-designed the brake pipes how they should have been done



I wish I was thinking about this a few years ago when I put in new lines from the MC to the front brakes. I just started following what Lotus had done and realized there was extra work with lines going left to right and left again. Plus the lines get crammed into those clips on the chassis so fewer lines would be better.

All of that tube bending in 3 dimensions just about made me crazy to make everything fit together.

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