Lotus Elan

Sizes of brake line components?

PostPost by: The Veg » Fri Nov 03, 2017 2:48 am

I'm soon going to be making a couple of new brake lines for the Plus 2, going straight from the master (.7" Girling dual) to the lines to the front and rear, eliminating the servos. What size fittings will I need to use, and is each end the same size or different size?
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PostPost by: alan.barker » Fri Nov 03, 2017 7:18 am

I think are the same and you only need to be careful with the pipes that screw into the front calipers( some imperial thread, some metric).
Be sure to put the correct flare or double flare on the ends. I only use "Kunifer" tube for brake lines, no rust problems after :wink:
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PostPost by: pharriso » Fri Nov 03, 2017 11:39 am

Pipes are 3/16 kunifer, fiitings are 3/8-24 (UNF).
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PostPost by: CBUEB1771 » Fri Nov 03, 2017 2:21 pm

The Veg wrote:going straight from the master (.7" Girling dual) to the lines to the front and rear, eliminating the servos.


Alan and Phil are both correct. It is later +2 versions that have M10 fittings in the front calipers. You won't necessarily be touching the front calipers to make this modification. Keep the servos handy, stopping a +2 without the 3:1 boost ratio servos requires an almighty shove on the brake pedal, even with a 5/8" bore master cylinder. I put my servos back in after a similar experiment. I become worried about how much the fiberglass at the base of the pedal box deformed when stopping without the servos.
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PostPost by: prezoom » Fri Nov 03, 2017 4:11 pm

When I replaced the front and rear brake lines on my August 72 Plus2, the lines from the balance block had two different sized fittings. The fronts had 7/16", while the rear had 3/8". The DPO had removed the servos and dumped them at some point, and the 1" original master needed both feet on the pedal to stop the car. I replaced the original master with an 11/16" Datsun dual master, which works without the servos and it provides a pedal feel similar to my S2.
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PostPost by: The Veg » Sat Nov 04, 2017 3:20 am

Thanks Gents.

Rob, that's good to know. If I'm not mistaken, .7" is the same as 11/16".
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PostPost by: CBUEB1771 » Sat Nov 04, 2017 12:31 pm

11/16" (0.688") and 0.7" are nominally the same. I have never measured the bore of a 0.7" cylinder, it would not surprise me if the are actually 11/16".
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PostPost by: prezoom » Sat Nov 04, 2017 7:44 pm

I found it difficult to find a .7"/11/16" dual master cylinder, as most dual masters are associated with a servo/vacuum assist, and their bores are much larger. Being familiar with the Datsun 1200/Sunny, I knew its diameter was 11/16", and it was used without a power assist. It does require some modification, as the bottom feed will hit the body on a Plus2. The bottom bosses were shortened and capped off with a shortened 16mm bolt and a copper washer, and the new feeds were taken from the bleed nipple locations on the side of the cylinder.

To direct the lines towards the balance block, AN-3 to 1/8" pipe 90's were used at the master. The 3/8 and 7/16 fittings from the old lines were re-used at the block.
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PostPost by: The Veg » Sat Nov 04, 2017 10:00 pm

I found a GIrling one, externally identical to the 7/8" unit that came with the car. Only hitch is that it was missing the pushrod. I have yet to find a pushrod for it, so I may just file down the disc on the one from the 7/8" unit.
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PostPost by: alan.barker » Sun Nov 05, 2017 7:31 am

You will need to check the length also of the rod.
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PostPost by: Mazzini » Sun May 31, 2020 9:53 pm

prezoom wrote:When I replaced the front and rear brake lines on my August 72 Plus2, the lines from the balance block had two different sized fittings. The fronts had 7/16", while the rear had 3/8". The DPO had removed the servos and dumped them at some point, and the 1" original master needed both feet on the pedal to stop the car. I replaced the original master with an 11/16" Datsun dual master, which works without the servos and it provides a pedal feel similar to my S2.


You're just the man I need to talk to :D I have a Datsun dual M/C. What are the bleed nipple/zerks on the side ffor? Can I blank them off? Are the fittings 3/8th UNF?

Many thanks in advance :D
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PostPost by: gav » Mon Jun 01, 2020 6:04 am

If you are planning to omit the servo wouldn’t you replace the master with a 0.625 (ie go down one full size) to prevent having to stand on the brakes pedal each time you want to stop?
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PostPost by: mikealdren » Mon Jun 01, 2020 7:49 am

gav wrote:If you are planning to omit the servo wouldn’t you replace the master with a 0.625 (ie go down one full size) to prevent having to stand on the brakes pedal each time you want to stop?
Gavin


That would help with pedal loads but would increase the travel and you would also have to check that you have enough fluid displacement to fill the calipers and don't run out of travel.
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PostPost by: gav » Mon Jun 01, 2020 8:28 am

Mike

That's true but I have run both in my 2 seater over the years (note - not a plus 2) and have never found a problem.

I think that this would prevent a 'wooden' feel for the pedal.

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PostPost by: Mazzini » Mon Jun 01, 2020 9:02 am

Thanks fellas, but I think some of the American and Australian contributors may have more experience with this specific M/C.

I've run +2 brakes on an Elan previously, but not with this M/C, which I understand a few people have used.
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