Lotus Elan

+2 Front Calpers on a Type 26 - MC Question

PostPost by: Mazzini » Fri Jul 15, 2016 7:34 pm

Anybody running +2 front calipers on an Elan (not a +2)? If so what master cylinder are you using? I don't have a servo, I'm running the original non servo MC. The brakes are outstanding, but the pedal pressure seems too soft - should I try a different MC?
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PostPost by: nmauduit » Fri Jul 15, 2016 8:10 pm

on a type 36, stock tandem MC (0.7") no servo, plenty of brakes... it took me a while to make sure my hydraulics were fine though, I was erroneously blaming my poor bleeding of silicone fluid prone to bubbles (actually during a "professional" rebuild the slave cylinder had most likely been inserted without grease or too roughly, and the very outside of the intermediate rubber was severed and was occasionally blocking the valve when moving around like a hair) - I eventually put in a new kit and the pedal has been consistently firm since.
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PostPost by: Briggs1 » Sat Jul 16, 2016 9:49 am

I have a Plus 2 with Servos removed.

RX7 master cylinder works well. Minor fitting to make the bolt holes line up but not bad.

.75"

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PostPost by: 661 » Sat Jul 16, 2016 10:08 am

No change to MC for me, non-servo set up. Motel 600
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PostPost by: Mazzini » Sat Jul 16, 2016 11:15 am

Gentlemen, thanks for your replies. Maybe I'll try the 5/8 servo MC.
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PostPost by: ecamiel » Sun Jul 17, 2016 11:44 am

I hope you have or are installing a dual circuit MC
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PostPost by: CBUEB1771 » Wed Jul 20, 2016 6:54 pm

Mazzini wrote:The brakes are outstanding, but the pedal pressure seems too soft - should I try a different MC?


Do you mean that the pedal effort is lighter than you would like? Going to the +2 calipers with no other change will reduce pedal effort but increase travel. If this is the case and your existing master cylinder diameter is 0.7" bore you could go up to a 0.75" bore which will increase your pedal effort by about 13% to achieve the same clamping force at the caliper. Going up to a 0.81" bore will increase your pedal effort by about 25%. Going down to a 5/8" bore will reduce your pedal effort by about 25%.
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PostPost by: Mazzini » Wed Jul 20, 2016 10:05 pm

CBUEB1771 wrote:
Mazzini wrote:The brakes are outstanding, but the pedal pressure seems too soft - should I try a different MC?


Do you mean that the pedal effort is lighter than you would like? Going to the +2 calipers with no other change will reduce pedal effort but increase travel. If this is the case and your existing master cylinder diameter is 0.7" bore you could go up to a 0.75" bore which will increase your pedal effort by about 13% to achieve the same clamping force at the caliper. Going up to a 0.81" bore will increase your pedal effort by about 25%. Going down to a 5/8" bore will reduce your pedal effort by about 25%.


Brilliant! Just what I was after! Thanks Russ!
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PostPost by: vstibbard » Fri Jul 22, 2016 9:28 am

I've change to an 11/16" Nissan/Datsun split system master cylinders when upgrading to +2 calipers, lovely pedal and feel

V
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PostPost by: mbell » Fri Jul 22, 2016 8:27 pm

vstibbard wrote:I've change to an 11/16" Nissan/Datsun split system master cylinders when upgrading to +2 calipers, lovely pedal and feel

V


I just did a little bit of research on this, as I might switch to a dual system while my engine is out. Seems to be from a 72/73 Datsun 1200:
http://datsun1200.com/modules/mediawiki ... r_cylinder

Easily available from a lot of parts places.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: Mazzini » Sun Jul 24, 2016 8:29 am

Thanks Vaughan and Mbell. Does the Datsun MC have remote filers?

I have a rebuilt Federal Elan MC, but I'm not sure if it will fit under the carbs on a RHD car - anybody have any experience?
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PostPost by: patrics » Sun Jul 24, 2016 9:52 am

Hi,
The tandem master cylinder will fit under the carbs but it is difficult to get to reservoir cap so the best way forward is to use remote reservoirs like I did on mine in the photo - needs a bit of a clean before engine goes back in.

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PostPost by: prezoom » Sun Aug 07, 2016 1:53 am

I just modified a 72-73 Datsun/Nissan 1200/Sunny 11/16" master cylinder to fit in the Plus2. I found the bottom ports of the new master cylinder interfered with the top of the foot well and the master cylinder would not bolt up cleanly to the pedal box bracket, even without attaching brake lines. I removed the steel bung portions, milled off the needed amount from the protrusions, used a 9/16" end mill to deepen the threaded section (a 14.5mm drill will work as well) and cut deeper M16-1.5 threads. Replaced the original steel bung with shortened bolts and drilled into the side of the protrusion, taping with a 1/8" NPT and using a 1/8"NPT-3 AN fittings. New lines will join the -3 fittings to the balance block.
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PostPost by: Mazzini » Sun Oct 16, 2016 11:12 am

mbell wrote:
vstibbard wrote:I've change to an 11/16" Nissan/Datsun split system master cylinders when upgrading to +2 calipers, lovely pedal and feel

V


I just did a little bit of research on this, as I might switch to a dual system while my engine is out. Seems to be from a 72/73 Datsun 1200:
http://datsun1200.com/modules/mediawiki ... r_cylinder

Easily available from a lot of parts places.


So the 11/16 diameter safety split circuit (tandem), used with disc-brake models is the one to go for?

Remote reservoirs?
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PostPost by: mbell » Sun Oct 16, 2016 1:36 pm

For an elan I think so, bottom connects are good. For a +2 no, the bottom exits foul with the pedal box unless you do extensive modifications to the master.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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