Cobra brake upgrade-but which MC?.

[blacktop]

Hi Guys,
Thinking of upgrading my SN95 brakes to the cobra brakes front and back.
I have 1996 spindles so the 13" rotors and PBR calipers should bolt straight on.
On the rear I have a 1995 GT axle with the 10.5" rotors and varga calipers. I have already got a pair of cobra caliper brackets aswell as the anti moan brackets. For the rear I just need the 11.65" rotors.

My only concern is regarding the master cylinder and booster.
I have on the car at the moment a remanufacted 1980 booster which I believe is the V8 booster. I am using a 1985 towncar 1" master cylinder. The proportioning valve has been removed and replaced with an adjustable valve with a tee piece to split the line into two pipes.This set up is poor because I have next to no braking force on the rear discs even with the valve set up for maximum brake pressure.

I am therefore thinking of fitting a 1995 cobra master cylinder onto the 1980 booster.Can anybody suggest if the 15/16" or 1" cobra master cylinder will be the best to fit on this setup?.

Thanks for any help you can give,
Blacktop.

[slow84lx]

Blacktop, there is plenty of good information on this to be found in the link below and searching this board. Lots of people have done this swap. I have not although I have all the parts to do so laying in the garage. The master cylinder that I got for the swap is from a Sn-95 car. I will also be adding an aftermarket adjustable proportioning valve.

For good braking to the rear you may need to consider a m/c with a slightly different bore size. I would also consider changing the brake booster to a later model one. It might be easier to just pick up a used v6 sn-95 booster & m/c combo from the junkyard or classifieds.


http://mjbobbitt.home.comcast.net/~m...n95brakes.html

[qtrracer]

On another forum, a member posted a bunch of math on hydrolic ratios related to M/C piston size and related caliper pistons sizes. Basically, his recommendation where the cobra set-up is used (some variation due to later and earlier front caliper piston sizes) was a 1" bore M/C, be it the cobra version or the Lincoln version sold by PPI (this latter version resembles the 86 and earlier M/C). Going bigger than a 1" bore resulted in a stiffer pedal and going smaller resulted in a softer pedal - to what degree I have no emperical experience, but the poster said he preferred the 1" bore over the 15/16" because of the pedal feel.

[blacktop]

Here are the calipers I am considering fitting:
http://cgi.ebay.co.uk/Brand-New-PBR-...QQcmdZViewItem
and here is the booster and 1985 1"bore Lincoln towncar master cylinder I have fitted at the moment:


If I already have a 1" bore MC (towncar), will fitting the 1" bore 1995 cobra MC be of any benefit?. Is there some other difference between the two MC's other than one is cast iron and the other is aluminium?.

Sorry if I am missing something obvious, I just dont want to go to the expense of fitting the cobra MC if it turns out to be exactly the same as the MC I am removing.

[mfpmax]

If you can get a Town Car MC, stick with the town car MC. The later model MCs have metric threads, while using the Town Car MC might only require ONE adapter to work. And also the plastic fluid tanks on the later ones are sometimes fragile and if you hit it right you can break them.

[blacktop]

I dont mind having to change the fittings to metric to suit the cobra MC as I was going to tidy up the brake pipes and change some of them anyway.

Having read through various threads and web sites, I cannot understand why a towncar MC would be better for a front disc/rear drum configuration and a cobra MC would be better for a front disc/rear disc configuration?

[mfpmax]

Probably won't be any difference, but if you already have a town car booster you can keep. Both MCs have the same bore, so I don't see any upgrade or downgrade coming from either end.

[ricko302]

Please tell me that is not copper tubing that you are using for brake line.

[82mustang]

lol, wouldn't copper expand and reduce brake line pressure to the calipers? switch that out man..

[Jax Rhapsody]

Copper is one of the weakr metal, like gold. It may look pretty but please use steel. If you are racing and the fluid gets hot enough it could warp and bend those copepr lines.

I would think of Pascals law and determin what m/c works well with what booster. I dont know alot about brake systems I just know with too small a valve you wont get enough pressure for rear disc. Id use the whole m/c and etc. from a cobra if your using cobra disc. I think panther cars have smaller brakes but I doubt it.

[blacktop]

The brake pipes are not pure copper. They are a copper/nickel mix which has a 17000PSI bursting pressure on a 3/16" pipe. So I dont see the pipes being an issue.

Thanks for your views guys
I think I'm going to keep it simple and go for all 1995 cobra. If I am going to fit the cobra brakes I will try the 1" cobra MC and see how it performs. If I have any problems I will then fit the cobra booster.

Thanks again,
Blacktop.