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Topic: Problems with Cobra brake swap (Read 1735 times) previous topic - next topic

Re: Problems with Cobra brake swap

Reply #15
Other thing I forgot to mention is to make sure you have the caliper bleeder ports at the highest point on the caliper when installed.  You can flip flop the calipers as they do not care which side they mount on until you go and try to bleed them and realize the port is not at the highest point.  With the port flipped you will NEVER get the air out of the caliper.  You can see the bleeder port here in this picture in the correct position.


83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Re: Problems with Cobra brake swap

Reply #16
So what I think I'm reading here is technically what I have should work, but not be ideal. I think I've just gotten multiple bad masters in a row. Now reading off of what you are saying I'm thinking I should use a 93 master/booster due to ease. I have ordered them and I'm going to see what happens. I don't really know what else to do.
88 Cougar
88 T-Bird
other cars that don't apply to this forum

Re: Problems with Cobra brake swap

Reply #17
I really think you are having issues with the booster MC combo so swapping those should cure the issue.  One other question is what is the model number of the Wilwood proportioning valve you are using?

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Re: Problems with Cobra brake swap

Reply #18
So what I think I'm reading here is technically what I have should work, but not be ideal. I think I've just gotten multiple bad masters in a row. Now reading off of what you are saying I'm thinking I should use a 93 master/booster due to ease. I have ordered them and I'm going to see what happens. I don't really know what else to do.
Absolutely yes on the 93 COBRA (very important) master; and the matching booster is IDEAL, but the SN95 V6 booster is functionally identical, only needing 1 hole elongated in the firewall.  93 Cobra boosters are understandably difficult to get a hold of, while SN95 V6 boosters practically litter the streets.  I'll let you make the call.

Protip: (I'm literally an ASE Master)
Don't pump the brakes when you bleed them.  Doing this beats up the air bubbles in the system and makes them into foam, and foam takes a lot longer to bleed completely out.
First take off the master cap, open the bleeder and leave it alone til the bleeder is dripping. Gravity is your friend. Close the bleeder. Then:
1. open the bleeder, push the pedal down
or
2. push the pedal down, open the bleeder
You'll be done faster, with less wasted fluid, and a better result. 
You can pump gas, you can pump iron, you can even pump up the jam; but don't pump the brake pedal when you're bleeding brakes.

Re: Problems with Cobra brake swap

Reply #19
Did this get solved?

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Re: Problems with Cobra brake swap

Reply #20
I can't speak for moonmount, but maybe I can help anyone else who sees this in the future. I had a very similar problem. Brakes felt like crap after doing a TC rear swap (I already had 11" fronts for a while). I ended up trying 3 different master cylinders thinking I had the wrong size. I started with a 94 Mustang GT master, then a 93 cobra, and finally a 94 Mustang v6. Plus bleeding gallons of brake fluid in an attempt to get out any air. No matter what I did the pedal just felt "weird". Best I can explain was soft for the first inch of travel, but felt like it bottomed out early and just would not stop the car no matter how much force I applied.

I finally tried swapping boosters to a 93 Cobra, and that worked! I think the original booster may have got damaged during the initial master swap but I'm not sure, it worked fine with the drums. Either way, a new one, and a new cobra one at that fixed it the problem. Hope this helps!
1988 Thunderbird sport
2004 Ford F150 Lariat
2008  Chevrolet Cobalt Sport
2007 Suzuki DR-Z400S dual sport/Supermoto
1988 Thunderbird LX - sold
1988 Mercury Cougar XR-7 with GST kit - gone

Re: Problems with Cobra brake swap

Reply #21
Interesting thread, I have an '85 Bird and just swapped out the 7.5 to an 8.8" LSD, I'm using the Taurus 43mm rear brake calipers and Cobra 11.65" rotors with Fox 5 lug axles. So far I have not connected up any hard lines to the car due to the fact I will be adding the '93 power brake booster and larger MC. I'm also swapping out the front K-Member from QA1 with the longer adjustable lower control arms and using SN95 spindles. Then I have Cadillac ATS/ Brembo 4 piston calipers and 13" front rotors going on. All of this is going to take a while to get sorted out once it is all back together.