I have a mark 4, base kit( can’t get completes in Canada ). So I have been using donor parts from a 1995 GT. My issue is with terrible brake stop. Can’t lock brakes and if a sudden stop is needed would probably not be nice seen,slows down but no lock. Here is my setup, stock 1995 Gt front and rear caliper,rotors, pads and pedal box. I have no proportional valve,but did I stall a wilwood valve to adjust bias front rear which does nothing in my situation. The mod has been done to change pivot by 1 1/2 inches. No booster was installed, I even modified the push rod and made it adjustable. I can’t figure out what is wrong with my manual setup. So basically do I change master to different bore, or should I just find a way to put a booster, if so, which booster do I use, master cylinder, pedal must be returned original?
Yes someone still uses donor, unfortunately ,Brake issue...
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A different master cylinder would help you a ton as well as upgrading brake pad compounds.
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I have a similar setup but with a 1991 donor. Stock MC, pedal mod, no power. Deleted stock proportionating valve so both fronts are pressured directly from MC. Recently went with Hawk HPS front pads and no trouble locking when system properly bled. It took a couple of times to get it right.
Calipers are sided so be sure they are mounted correctly so that the bleed screw is at the top.
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593 Posts
EBC Yellow stuff pads. Night and day difference, literally! Make sure you break them in exactly like they tell you to. I can't believe the difference it makes. I went from horrible stopping to being able to lock them up. Again break them in like they say to.
Also the above recommendation is all based on everything is bleed properly.
Good luck,
Jim
Also the above recommendation is all based on everything is bleed properly.
Good luck,
Jim
What Gordon said, smaller bore Master Cylinder and more aggressive pad will help.
Or add a brake booster.
On my Cobra, it was braking OK but required really a lot of force with the donor setup... I went Vacuum Brake booster... night and day, I love it now.
On my Daytona, brakes were way too strong (Hydroboost setup):
I reduced the Hydroboost pressure and flow from the PS pump, slightly better but still touchy
I changed the pads to less aggressive ceramic pads, better but still too touchy and still not enough rear brake
I finally replaced the stock Master Cylinder with a larger bore one with a new Proportioning Valve (Willwood MC combo), I finally have a good feeling.
Master Cylinder bore seems to go a long way... but it's not cheap.
More than anything, make sure you set the correct Front / Rear bias.... it's absolutely vital for you.
Or add a brake booster.
On my Cobra, it was braking OK but required really a lot of force with the donor setup... I went Vacuum Brake booster... night and day, I love it now.
On my Daytona, brakes were way too strong (Hydroboost setup):
I reduced the Hydroboost pressure and flow from the PS pump, slightly better but still touchy
I changed the pads to less aggressive ceramic pads, better but still too touchy and still not enough rear brake
I finally replaced the stock Master Cylinder with a larger bore one with a new Proportioning Valve (Willwood MC combo), I finally have a good feeling.
Master Cylinder bore seems to go a long way... but it's not cheap.
More than anything, make sure you set the correct Front / Rear bias.... it's absolutely vital for you.
Round numbers, but a 1/16 smaller master cylinder will result in 13-15% more pressure, (larger diameter)^2 / (smaller diameter)^2.
Some sort of track pad like Hawks, PFC, etc will give you 25-50% more friction. OEM stock is usually around 0.35 for friction and "track pads" are usually 0.45 and higher..
I have had my MKII on the road for 14 years now with unassisted brakes for over 20,000 miles. My car has 4 wheel disc brakes, along with the Jeep master cylinder that FFR recommended for use at that time. My only additional brake modification is the addition of a proportioning valve to allow adjustment of the brake bias from front to rear. Regarding that bias adjustment, I set the valve at mid-range at time of installation and have had no reason to make changes to that setting. Unassisted braking of course requires firm activation of the pedal, but that has been no problem for me. My car has all of the Spec Racer equipment modifications except for the full roll bar, inoperable doors and smaller windscreen. I've never had it on the track. I have needed to brake in emergency situations a couple of times, and I have never locked my brakes. To me, the ability to lock brakes is not necessarily a good one since braking forces are diminished when the tires are sliding on the road. If I felt the need to test brake locking capacity, I would try it on a low traffic paved road with a light coating of sand or fine gravel on the pavement.
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Jim, did you go yellow in both front and back or just the front?
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593 Posts
Yes, front and back. My setup is a little different than yours, but braking was horrible until I switched pads. I have the Wilwood master cylinder and Mustang Gt 11" front rotors with PBR calipers and 11.56" 2004 Cobra rear rotors with a Lincoln Mark VIII rear single piston caliper measures 1.78” diameter. The front rotors are just slightly smaller than the rear. Normally they would be bigger, but that's how it turned out. My plan was to switch to the 13" Cobra setup on the front if I needed more braking power. My kit came with those Gt rotors and calipers for the front and I had to source the rear.
So far it's working good as is.
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10,337 Posts
Switching pads is the very first place to start. They can make a huge difference. If your wheels aren't getting dirty from brake dust quite regularly, it's probably your pads. The better ones always seem to make a mess.
You should find the M/cylinder you have is fine, as is. They were a 1-1/16" diameter from that year donor. The larger diameter m/cylinders were especially desirable for those running non-power brakes, and those that had switched from rear drum brakes, to using rear calipers. Sounds like you've done everything else correctly.
If equipped with a stock 8.8" Traction-Lock differential, the Traction-Lock clutches could be shimmed for minimum axle end play, to help reduce rear pad knock-back. This wouldn't normally be an issue, unless perhaps the clutch discs are completely worn out, and your doing some pretty hard braking.
You should find the M/cylinder you have is fine, as is. They were a 1-1/16" diameter from that year donor. The larger diameter m/cylinders were especially desirable for those running non-power brakes, and those that had switched from rear drum brakes, to using rear calipers. Sounds like you've done everything else correctly.
If equipped with a stock 8.8" Traction-Lock differential, the Traction-Lock clutches could be shimmed for minimum axle end play, to help reduce rear pad knock-back. This wouldn't normally be an issue, unless perhaps the clutch discs are completely worn out, and your doing some pretty hard braking.
I apologize for not replying with the many replies and helpful info. Was missing in action with life circumstances . Very sorry but appreciate all the chime ins.But after already putting new original pads, calipers ,rotors I did not want to get new ones again and get a satisfactory pedal. I find it still needs the effort for manual stopping. So now that the car is in body shop, and the body will be getting removed for painting, I will go the power brakes route. I will install the for booster and Cobra master cylinder. Hope I get a better feel and performance. Again really thank you all.
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1,041 Posts
I had the same brake set up as you and went to power brakes. With the original setup the pedal felt like standing on a rock. Took a lot of effort but, could lock the brakes with enough pressure.
The hardest part to find to convert to power brakes was the unmodified brake pedal. Used a booster from a 87-93 Mustang and kept the same master. Let me know if you want any more info.
Norm
The hardest part to find to convert to power brakes was the unmodified brake pedal. Used a booster from a 87-93 Mustang and kept the same master. Let me know if you want any more info.
Norm
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23,821 Posts
You don't mention your pad compound but w/ those brakes you need all the grip you can get in the rear. I used to use Hawk HP+ in the rear and HPS in the front. I understand from threads here that the EBC are good also but haven't used them myself. The HP+ dust more but this on the wheels really helps w/ that.
www.armorall.com
Outlast™ Brake Dust Repellent
Protect your car’s wheels with one of the best wheel cleaners Armor All® provides. Removes brake dust, road grime and dirt for clean rims and wheels.
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7,671 Posts
Just rereading through this. If you have the 95 master cylinder then that is where your issue is. The 1 1/16 bore is too large for manual brakes, just fine for power. If you don't want the hassle of changing to power, just replace the MC with a 15/15 bore one and you will have much better braking
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