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88TC - brake upgrade?

I'm trying to figure out if I have an actual problem, or if the mark vii caliper upgrade won't apply to me. It's an 88 Turbocoupe, teves ii hydraulic boost brake system. Do the mark vii calipers work proper here? I made the swap and pedal effort is awful, sloppy, spongy. This is after putting the stockers back on to make sure the unit is bled properly (changed off the parts car.. old one was on it's way out.) Pedal checked out, so put the mark vii's back on and pedal was unchanged from before, spongy/sloppy. I can push it through to the floor. If I work the brakes really good and hard, I start to lose braking effectiveness.

Short question: Is the 73mm caliper upgrade applicable to the 88 Turbocoupe?

88TC - brake upgrade?

Reply #1 –
calipers are too big for the stock MC. same issue as most other fox cars that try to use the 73mm calipers.
gumby - beauty may fade, but stupid is forever!

88TC - brake upgrade?

Reply #2 –
I don't know about  that,the mark used the exact same teves unit+ their not that much bigger.
I have a feeling you have air in the abs block or in the rear lines(i know sounds wierd since you only did the front but it happens).
Turn the ignition to the run position and have a friend sit in the car,crack the right rear bleeder screw and get your friend to push down on the pedal(not pump,just push down,the hydraulic motor will take care of the rest).
When you get nothing but clean clear fluid,close the bleeder and that side is good,bleed the left rear the same then shut the ignition off and bleed the front brakes in the traditional manner.
The rear brake cannot be bled manually,they must be bled with the aid of the teves system.
I had this same problem when i swapped to sn95 front brakes and bleeding the rears solved it.

88TC - brake upgrade?

Reply #3 –
Yep, tried the full bleed. All in total, I've put almost 5 quarts of fluid through the system. Pedal feels good with stock calipers, but sucks with the mark vii calipers on. Let me rephrase. The pedal is softer with the mark vii calipers but it will stop.. until you use them hard.. then you can actually put it to the floor trying to get stopped. Hot or cold, pushing hard enough, but not standing on it, moderate effort takes it to the floor.

88TC - brake upgrade?

Reply #4 –
I don't know a whole lot about the Turbo Coupe's system but here's what I found:

I have a Sport that had stock 60mm up front and 10" drums in the back. The Sport comes with a 1" Master Cylinder. The pedal was hard and people never liked driving the car.

I installed '91 Lincoln Mark VII calipers up front, along with new pads and new 11" rotors. The pedal feel improved greatly. It became softer with more travel but could still lockup the tires. The pedal travel went from 1/2 way down to 2/3-3/4. I did not touch the proportioning valve at this time so it didn't quite lockup most effectively.

I installed rear disc brakes from a TC. I KNEW ahead of time that with how far the pedal went earlier, I needed a larger master cylinder. I got a 1 1/16" bore MC and adjustable proportioning valve. All put in, the pedal seemed extra hard as if I had too much MC and not enough booster. After a couple weeks, the pedal feels much better and the pedal locks up/gets hard at around 2/3 pedal travel. I "may" have been able to get by with the 1" with the new brake system as initially the brakes seemed under boosted/over bored but it has broken in nicely.

Conclusion: The master cylinder may be worn out or you need a larger one to handle the larger fluid displacement. The pedal will get slightly harder though. I'm not sure what can bolt in place of a TC's MC. Also make sure you don't have excess pedal travel before it even begins to engage the master cylinder plunger. You can feel for excess gap easily by just pressing on the brake pedal with your hand.

Edit:
New soft brake hoses may help also if they're worn out. I've got stainless steel soft lines up front. Some MC pressure is going to be lost to the hoses if they're old rubber or worn out semi-metallic. Also I had better luck getting anything out of the rear lines by setting the proportioning to full rear to get 50/50 F/R distribution. A vacuum pump isn't such a bad idea either.

73mm calipers won't do a lot for you if you can already lockup your front brakes. Once lockup occurs, it's your tires that are limiting your braking capabilities. I bought the 73mm as I was replacing my entire worn system and they were basically the same price and bolted in place without a problem. They may work slightly better on aggressive driving due to the larger piston spreading the pressure more evenly across the same size brake pad though - less distortion. You will run into rotor size issues more quickly though. On a street-only car, there is pretty much no point.
1988 Thunderbird Sport

88TC - brake upgrade?

Reply #5 –
Seek: Yea, that sounds like the more typical master cylinder/booster setup. The turbocoupe still has the hydraulic assisted Teves II system on it. There's no alternative swap for an upgrade there, that I know of.. other than swapping to a conventional setup and losing ABS.

Forgot to mention earlier, I'm still thinking like gumby.. based on everything I've tried. Going back to stock calipers restored proper braking.

88TC - brake upgrade?

Reply #6 –
While I was eating lunch.. I had a thought.. Rockauto isn't helping me verify this since it doesn't list the hydraulic unit for the TC, which is a clue...

Wonder if the hydraulics setup for the lincoln is slightly different for the mark vii so they match the calipers.. in that the teves ii systems between the two *aren't* identical.

88TC - brake upgrade?

Reply #7 –
Well I suppose you could swap to a MK VII unit and see(easy huh??? LOL)... Of course that also mean you'd probably need the Lincoln's rear brakes as well... AFIK no one on here has swapped a TC to the Lincoln front calipers...

May try asking on NATO, their specialty is TCs...

http://natomessageboard.com/cgi-bin/Ultimatebb.cgi
 

88TC - brake upgrade?

Reply #8 –
heh, yea.. easy as proverbial pie..

I've got a post on nato in the brakes section.. hasn't seen a lot of activity. Funny thing, I'm thinking about stopping by the boneyard to see if there are any mark vii's there :P

88TC - brake upgrade?

Reply #9 –
i checked my computers at advance tonight. try looking for the ABS hydraulic unit when searching rock auto, not master cylinder.

they do indeed have different part numbers, so they are not "the exact same."
TC #12-3420
LSC #12-3428



*edit. rock auto also calls it an ABS actuator assembly in some places. same part numbers though
gumby - beauty may fade, but stupid is forever!

88TC - brake upgrade?

Reply #10 –
Let's throw some more wood on the fire. You looked up the mark vii for a 1991 or so? 1989 shows different part numbers. Funny enough, the calipers are different too.. 1989 calipers are what I put on.. eh, they were cheaper with the phenolic pistons. Too many differences :/ But them being different between the TC and the mark vii only mankes sense, I suppose.

88TC - brake upgrade?

Reply #11 –
Not many posters check anything but the first "general" forum over on NATO... I'd repost it...