Tuesday, November 7, 2017

1994 GT Brake Upgrade: Mach 1 Brake Swap, Pinion Seal Leak Fix

A good friend of mine named Mike has an 04 Mach 1.  Its really a nice car.  I helped him do the head cooling mod and do some work on his transmission.  I got a call from him telling me that he bought a drag setup (big tires in the back, skinny ones in the front) for his Mach.  He was concerned that the wheels weren't going to fit with his big Mach 1 brakes.  The Mach 1 shares the brakes with the Cobras (model year 94-03).  The front rotor is significantly bigger in diameter than the GT brakes.  Same goes for the rear rotor.  The Cobra rotor is not only bigger in diameter, but it is also vented for cooling.  Mike was asking me if I had an GT brakes laying around.  I told him all that I had was already bolted to my 94GT and we talked about doing a swap between the two cars.  He would get the brakes off of my 94GT and I would get the brakes off of his Mach.  The brakes on the 94 are not stock.
Here is the 94 setup:
1999 front dual piston PBR calipers, with Earls Stainless Steel braided brake lines.
Rear calipers are stock
Rotors are Centric cross drilled and slotted.
Pads are Hawk HPS pads for a 1999 GT

Since my brakes were upgraded, we figured the swap was fair, and I agreed to do the work in my garage.  He brought his car over with the new set of wheels.  We test fit the wheels and he was absolutely correct, they don't fit.  So we got both cars up in the air, on jack stands, and pulled the wheels.

On the front, we would remove the caliper brackets and rotors, then swapped the front calipers and lines.  We kept the stainless lines on the 99GT calipers.  Before installing the Mach calipers, I would replace the factory Mach brake lines with Russel Stainless steel braided lines.  I'll update with all the part numbers below.  So Mike would remove the front drivers side on the Mach, and I would remove the front drivers side on my 94 GT.  While he was installing the caliper on the Mach, I swapped the line, new crush washers for the banjo bolt, and installed it on my 94GT.  We did the same thing for the front passenger side.  Then we installed the front rotors, caliper brackets and mounted the calipers.  The fronts went pretty smooth despite the need to get a little forceful with removing the front rotors from the Mach.  I have a neat trick to put a bolt through the caliper bracket bolt hole, with a nut in between the rotor and the mounting ear.  Then thread the bolt through until it puts pressure on the rotor essentially pushing the rotor outwards.  Then whack the face of the rotor on the other side across from where the bolt is putting the pressure.  Works every single time.

The back brake swap was a little more involved.  The rear axles on both cars would need to be pulled in order to remove the caliper mounting bracket that is bolted to the 8.8 rear end housing.  So with the cars in the air, we removed the 8.8 covers and drained the fluid.  While the fluid was draining, we removed the calipers and the caliper brackets.  This is when I noticed a pretty big problem.  The caliper pins for the rear calipers on the 94 were frozen in place.  I fought with them for a good while before realizing they needed to be replaced.  Because of this, we did not remove the calipers or brackets from the Mach.  All we swapped was the pads and rotors.  On to the mounting brackets.  I removed the axle pin retaining bolt and pulled the big pin out.  Removed the C clips by pushing in the axles.  This was a little bit of a pain because the anti lock brake sensor hits the exciter rings on the axles.  With a little persuasion, the C clips came out, and the axles were removed.

Mike realized at this point that the rear on the Mach was upgraded.  There was an Eaton Posi, 4.10 Gears and 31 spline axles.  I also realized that it was going to be way easier to fill the rear with fluid with an aftermarket 8.8 differential cover.  Luckily my buddy Lou had one for sale and he was local.  We headed over, and Mike bought it.  Its a Drake cover.  I was going to buy it for my car, but I figured since I needed rear brake hardware, might as well order a new one and let Mike get this one so we can finish his car first and he can get it out of my garage.

Back to the brake swap.  With the axles out, we needed to remove the ABS sensors.  I very gently used a socket to tap them out of the axle mounting plates on both cars.  Luckily, I didn't break them.  Then we removed the four nuts and bolts that mount that plate to the rear and swapped them from one car to the other.  This also included the anti-moan brackets, which are specific to the Mach or GT brake setup.  With the plates swapped, I cleaned up the hole for the ABS sensor and re-installed it.  Next up was the axles.  It is MUCH easier to install the axles if the ABS sensor isn't completely seated yet.  It gives a little more room for the axles to push in so that the C clips can be installed.  The axles were installed, the C clips installed, the Axle pin was installed along with the retaining bolt with a little bit of blue loctite.  I then installed the Drake 8.8 cover and torqued everything down.  Then it was on to the rear caliper brackets, anti moan brackets, calipers and rotor.  Once all the brakes were installed, we bled the brakes and fixed a leak on the front drivers side line.  Next I filled the rear using a funnel and 3 ft of 1/2 inch vinly tubing.  I ran the tubing through the wheel well, across the rear and into the fill plug.  I filled it with 2 quarts of mobile 1 synthetic with the friction modifier 75w140.  Later we would find that it needed at least 1 more quart due to the clutches popping in the Eaton Posi.  More on that later!  Once the fluid was added and the fill plug was installed with some thread sealer, we put the wheels on and torqued eveyrthing down.  Then it came down off the jack stands.  That night, Mike took his car home.  Brakes work perfectly!

Next it was time to put the 94 back together.  First I needed to get the rear caliper pins fixed.  I found that it was just easier to order NEW Power Stop Mach 1 rear calipers from Summitracing.com.  Again, part numbers below.  They were about 52$ each, which was the caliper, bracket and hardware.  The pads were not included.  I also ordered a new 8.8 differential cover from Ford Racing.  While waiting for the calipers to arrive, I installed the rear axles, C Clips, axle pin and retaining clip.  I also installed the caliper mounting plates and the ABS sensors.  When the calipers arrived, I painted them with Dupont semi gloss black engine enamel.  This seemed to work great for the calipers I painted in the past.  When it was time to swap the rear calipers, I also replaced the stock rubber lines with Russel stainless steel braided lines.  Good thing too.  I found that one of the rubber lines was chafed from the bolt on the anti moan bracket.  To remove the stock rubber lines, the rear shock had to be unbolted from the rear and moved to the side to get to the brake hose bracket bolt.  To remove the rear caliper I detached the emergency brake cable, then disconnected the line at the hard line and removed the bracket.  I removed the stock brake line from the caliper because I needed the banjo bolt.  I installed the new Russel brake line with new crush washers for the banjo bolt, and connected the hard line to the stainless line.  I did this with the new caliper mocked up (no pads) so I could make sure the routing of the line was correct.  Once it was all good, I tightened the banjo bolt, snugged up the stainless to hard line connection and installed the emergency brake cable.  Then I installed the rotor, caliper bracket, pads onto the bracket, and the caliper.  Then reconnected the shock and torqued that down.  I had to do the same thing for the other side as well.  Finally it was on to bleeding the brakes.  I had to go around a few times, but eventually the pedal feel was correct.  I also had to fix leaks at the front lines.  This completed the brake swap! 

While the car was up in the air, I decided to fix the pinion seal on the rear which is also currently leaking.  I've replaced that seal twice already (rebuilding the rear) and it still leaks.  This time I picked up a new pinion seal, new pinion flange and a new pinion nut from Ford.  The car was already up in the air, and I had not added the fluid to the rear yet.  I removed the driveshaft, then removed the pinion nut with an impact gun.  I removed the pinion flange and used a seal puller to remove the pinion seal.  I installed the new seal and lubricated the new pinion flange with some motor oil.  I installed the new flange and the new Ford pinion nut.  I torqued it to 150 lb ft.  The nice part about having a solid pinion spacer instead of a crush collar is that the solid spacer doesnt need to be replaced like the crush collar once you remove the pinion nut.  This was totally worth the upgrade when the rear was rebuilt!  I installed the driveshaft and filled the rear with two quarts of 75w140 synthetic with the friction modifier.  I also added a 1/2 quart of 80w90 full synthetic with the friction modifier.  This is the fluid Ford recommended before changing the spec to the newer 75w140.  With the fill plug on the front of the 8.8 housing (drivers side) removed, the rear was filled until fluid leaked out of that hole.  Then the plug was installed, and the fill plug was installed on the differential cover.  This completed the pinion seal / flange replacement!

The last step was to put the wheels back on and get the car back on the ground and take it for a test drive.  The drive went well, but I think that the brake pads may be stock replacement.  They certainly weren't as aggressive as the HAWK HPS pads that were swapped to the Mach 1.  Also I'll be happy to note that the pinion seal no longer leaks.   

Part numbers:
Pinion Seal:  Timken 3604
Pinion Flange:  E9SZ-4851-A
Pinion Nut:  M-4213-A
Power Stop Mach 1 rear calipers: PWR-L4824A and PWR-L4825A
Russel stainless steel braided brake lines for a 94 Cobra:  RUS-693350
Ford Racing 8.8 cover / girdle:  FMS-M-4033-G2

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