Dual-circuit brake master cylinder

PostPost by: mct340 » Mon Nov 24, 2008 7:30 pm

I'd like to get rid of the original dual-circuit, single piston brake master cylinder on my autocross S4.
Is anyone producing a suitable balance bar, dual master setup that works with the stock pedal?
Thanks in advance,
Mike
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PostPost by: twincamman » Tue Nov 25, 2008 3:52 am

they are available from speed shop and race shops but a huge job to install-they fit in the front ENGINE compartment --why not just hook up an adjustable valve hydraulic bias system to your existing system??ed
Last edited by twincamman on Wed Nov 26, 2008 4:30 pm, edited 1 time in total.
dont close your eyes --you will miss the crash

Editor: On June 12, 2020, Edward Law, AKA TwinCamMan, passed away; his obituary can be read at https://www.friscolanti.com/obituary/edward-law. He will be missed.
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PostPost by: mct340 » Wed Nov 26, 2008 5:59 am

Yeah Ed, I've got a reducer valve on the rear circuit but I was hoping someone would have a better system worked out by now. It's getting to the point where there's not much that hasn't been solved.
Cheers,
Mike
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PostPost by: rgh0 » Wed Nov 26, 2008 10:03 am

Dual pedal box photo I got some time ago. Cant remember from where I got the photo.

Clearance on the brake cylinder side in the engine bay is a problem also I think and requires some fibreglass modes to the wheel well at least in rh drive cars.

26R's had a dual balance bar system I believe but I dont have any photos of one. Its one 26R part that TTR does not make :cry:

cheers
Rohan
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PostPost by: twincamman » Wed Nov 26, 2008 11:35 am

the pics of mine are too many pixels ---email me ill send a pic of mine ----lot of fabrication though - there was another thread on this a while ago ---try brake bias system or check my other posts by twincamman -----ed ----ed
Last edited by twincamman on Wed Nov 26, 2008 4:39 pm, edited 3 times in total.
dont close your eyes --you will miss the crash

Editor: On June 12, 2020, Edward Law, AKA TwinCamMan, passed away; his obituary can be read at https://www.friscolanti.com/obituary/edward-law. He will be missed.
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PostPost by: twincamman » Wed Nov 26, 2008 11:46 am

Ok Mike----most of them have been ---mine has a dual master system and clutch master from the components factory in 1964 --you need a set of front AR brake calipers - -- very costly----and the brake pucks only come in racing compounds so you have to constantly ride them on the street to keep the temperature up ---------- and a rear disc brake set up -[ very similar to an early Jag rear system ]-[Im told by the Dave bean people the rear calipers are unobtainable ] but you may find some ----its a lot of fabrication and cost unless your racing ----and I don't mean vintage --OR GYMKANA --its hardly worth it for the street but email me and Ill send a pic ----- were dealing with with brakes and safety and liability here --------the pic shown in the thread relies on the fiberglass in the foot well for support of the masters ---not a great set up as there is a lot of pressure exerted on the master cylinder mounting through bolts and transmitted to the fiberglass and eventually its going to fail under a hard brake situation ---- a potentially very embarrassing situation ------------ -----ed
dont close your eyes --you will miss the crash

Editor: On June 12, 2020, Edward Law, AKA TwinCamMan, passed away; his obituary can be read at https://www.friscolanti.com/obituary/edward-law. He will be missed.
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PostPost by: batfish » Sat Nov 29, 2008 2:07 pm

Mike

Pat Thomas at kelvedon sells the peddle box. It is a long job to fit requiring modification to the inner wheel arch and steering column, different length push rods etc .

http://www.kelsport.net/parts/product_d ... ectionID=2

Regards
Andy
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PostPost by: cabc26b » Sat Nov 29, 2008 4:38 pm

Hi Mike,

I spoent some time looking into this also so , some things I picked up along the way.

If you have a LHD car then the RHD pedal boxes will have to be cut on to make work, I did not feel good about doing this and so never bought one. However, In my last correspondence with Pat he mentioned that he was looking at making a LHD version so that may be an option in the future.

I looked into the stock pedal route and found a company that developed this for another application and asked for drawing to see if would work, they never got back ( they are a vintage racing brake outfit and also a AR racing distributor out of the UK) if you want I can look them up for you.

I have not had a fiberglass failure yet on an elan so not sure I would spend too much time on that worry, if this was a problem then the regulators make/model notes would have flagged it.

Brake calipers - AR's in the front and 10-8 stock rears are a common set up in vintage .I don't know too many people who wish for more rear brake. Once you get close to a two-inch piston locking the rears will be the problem - That said there is kit out there that will allow you to use a AR/NR set up. but as noted this is very expensive and the AR/NR are kind of antique 50's stuff with limited pad availability - but they will haul a light car down like an elan with no problem.

On my latest project I will be using a AR racing tandem master with a proportioning valve on the rears. I will be ditching the cast iron calipers for alloy but will not be using the AR/NR set up. I want better pad options as this car will be on the street and the track. I am looking to add some lightness in the corners - so wlll also use alloy brackets and hubs up front.
I will be using calipers that have better pad choices that the AR's.

Last thing - There are people out there who are successfully running an elan on track with out a dual master set up - so I think it can be done. I never got the brakes on my elan to work like my Sports racer of formula car so that should not be the objective, but they did work better than a lot of other cars out there on track.


Good luck with the project

George
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PostPost by: Frank Howard » Sat Nov 29, 2008 6:16 pm

Andy,

Nice car! I see you have installed insulation where the headers will go. Do yourself a favor. Add more insulation right below the existing insulation on the chassis. That is where you will feel the heat at your feet. Much easier to add it now than later.
Frank Howard
'71 S4 SE
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PostPost by: twincamman » Tue Dec 02, 2008 3:26 am

George ---the foot well on my car needed extensive strengthening --there were actual cracks at the front of the foot well ---and no sign of other crash damage --and still has a slight movement of the foot well under a hard push ------I strengthened it with 4 oz glass [ a nasty job] ---ed
dont close your eyes --you will miss the crash

Editor: On June 12, 2020, Edward Law, AKA TwinCamMan, passed away; his obituary can be read at https://www.friscolanti.com/obituary/edward-law. He will be missed.
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PostPost by: cabc26b » Tue Dec 02, 2008 2:22 pm

Hi Ed, I must be lucky . I have had 5 early cars. 3 of them "in period" race cars and have fortunately not had issues with the footwell/pedal box area deteriorating. Would be intrested to know what you think caused the failure the was your car cut up to install the dual master ? Fluids soften the glass ? I have seen some older fiberglass get spongy ( early polyesters had the reputation of being hydophilic) was the car well cared for ?
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PostPost by: twincamman » Tue Dec 02, 2008 4:06 pm

it spent 30 years abandoned in a barn dissasembled --this is how it arrived --well kept??????I don theen so -Lucy ----- :shock: --ed
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dont close your eyes --you will miss the crash

Editor: On June 12, 2020, Edward Law, AKA TwinCamMan, passed away; his obituary can be read at https://www.friscolanti.com/obituary/edward-law. He will be missed.
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PostPost by: mct340 » Tue Dec 02, 2008 11:27 pm

George,
Do you have a website for the master cyl you intend to use?
Mike
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PostPost by: cabc26b » Thu Dec 04, 2008 1:26 am

Mike,

This is a current product from AP racing . I think they have the mechanical drawing online with there other product/parts - look for CP4627 - if you can't find it PM me and I will see about getting you the PDF of the drawing .

G
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PostPost by: mct340 » Fri Dec 12, 2008 11:58 pm

The AP Racing part no. for a suitable replacement tandem master cyl. is
CP4627-2PRM100.
It is sold only to Caterham Cars who must be contacted directly.
Thanks to George and Garrett.
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