Hey guys I've got a wild hair and finally started working on my car again. That being said I've decided that my brakes aren't that great with the rear discs now. I totally rebuilt the rear brakes so I know they are good to go and I did install a proportioning valve. The car actually stopped better with drums. I was testing it last night in a gravel driveway and when slamming on the brakes the front ones grab and slide but the rear ones won't. They are working somewhat but not enough. I tried adjusting the prop. valve in every direction but it didn't seem to make a whole lot of difference. I've read the Coolcats article many times and it recommends different things such as using different master cylinder and booster etc. What have some of you guys done on your cars? I am considering a front brake upgrade down the road (to 11'' Mustang rotors) but I want to wait until my motor/tranny buildup is done to save some cash for the time being. Right now my main priority is to get the car safe. Would it help to go with steel braided brake lines? Any advice would be much appreciated.
Did you gut the stock proportioning block?
Yeah, what Chuck said. :)
Also, did you adjust the rear calipers? That is a very important step in assuring that they'll work. Do you have parking brake cables on the car now? If not you can manually adjust them. If so you need to apply and release the parking brake cable about 10-15 times before they adjust all the way.
I did the same thing you did. I swapped the rear first and kept the whimpy stock brakes. The rear disks made a big dirrerence on my car but my drums shoes were worn down very thin.
The biggest improvement came when I swapped in the 11" front brakes. I'm still using the stock proportion valve although I'd like an adjustable valve. The brakes work well. The other thing that really helped was adding camber plates. the positive caster really reduced nose dive and made the brakes feel more solid.
The 11" front brakes really do kick major ass over the 10 inchers. I would find a way to do the front brake conversion before putting more power to the ground. Especially if you plan on turning corners at some point.
Yes and Yes. So you guys think my stock MC should be working fine?
Yeah Dogcharmer you are probably right. I definately want to make this car a corner carver as subframes, strut tower brace, and bigger front swaybar are on my checklist. So the 11'' brakes are a major difference? I know I need to do this swap but I just want the car to be fast so bad right now.
It's "possible" the MC is causing the issue....
You might look into an MC for a non-ABS 87-88 TC for your app.
I'd get the fronts upgraded before you put any more power into it.....the 10"ers are just plain inadequate......even if the car is in stock form.
Sorry Chuck there is no such part... The electronic ABS system was std on all '87-'88 Turbo Coupes..
The '93 Cobra M/C would probably be the best bet... Maybe the '94-'95 Stang M/C?
OR has anyone tried a '92-'96 Crown Vic M/C?? They all have rear disc and the ABS was optional...
[Lumbergh] Mmmm, yeah....I'm going to have to go ahead and disagree with everyone. Yeah. [/Lumbergh]
There is no practical reason why a Turbo Coupe rear with 10" rear discs cannot work with a stock 10" front disc setup. There is something wrong with the setup right now. When you bled the brakes, did you get a good volume of fluid to each rear caliper, or was it just a trickle? How about the rear caliper hoses...old or new? It may just be a matter of fluid flow and not a physical adjustment. Can you see if the rear pads are even touching the rotors when the brakes are applied? Are the rear rotors shiny from being used, or still like brand new?
The problem with installing a TC rear in a car that originally had drum brakes in the back is that it will show all of your flaws in the braking system. Drum brakes, in essence, are less taxing on your stock lines and equipment. Once you change over to something that requires more fluid, therefore more pressure and volume, then anything restrictive in your stock system shows its ugly face.
There is nothing wrong with upgrading to the 11" brakes. All I'm saying is, it should work now and it's not. You have something wrong that needs fixed before you think about doing anything to the front brakes.
*shrug* I thought std brakes were an option.
I'm using Cobra front disks, TC rear disks, the original 83 Tbird booster and an original type MC (all metal) with a 1" bore (Lincoln Mk6) and an adjustable prop valve. My brakes are fine.
The 93 Cobra MCs are hard to find I think, and not cheap.
A buddy of mine went through this nonsense with his Mustang. He has the Cobra stuff up front and whatever the SSC brake kit was and evertually had to swap to a 94+ MC and booster to get his to work right.
Yeah, Eric..I didn't figure it would be a problem...but it's hard to know what some folks have actually done or not done during an install. Too many variables.
It could be the rubber hoses at the rear axle are bad and breaking down inside, thus restricting flow...
No truer words ever spoken. No offense, 50tbrd88, we just don't have the car in front of us to double-check things.
I've got a lot of experience with troubleshooting a Ford RWD rear-disc setup under my belt, and everything you're describing is pointing to a problem. I would suspect that if the rear hoses were never changed, they're starting to collapse from the inside and are severely restricing fluid flow to each caliper. That's usually the first place to check. After that, then you have to look to the master cylinder, then the brake booster. Assuming you have a SO or HO engine, you should be producing enough vacuum to operate the booster correctly for rear discs. If the booster was leaking you'd hear it. So that's how I'm armchair troubleshooting your car. ;)
I did the same on the convertible...it worked fine for me as well. Only thing I did was upgrade to the Crown Vic/SVO style larger m/c. I still have the original '86 booster to this day. I noticed a big change in rear disc performance with new rear hoses though.
Well, the MC I'm using is larger than the stock one was (1" vs 13/16"). I didn't like the 1 1/8" bore SVO MC....modulation was all goofy.
I actually also prefer that 1" bore MC over the SVO one for guys doing the 73mm front caliper upgrade. I find it a better match than the SVO one. I've run that combo on a couple cars.
I have full braided stainless hoses as well.
Yes, braided hoses make a world of difference. I really never had a "problem" running the SVO m/c with the 73mm pistons/11" front brakes and the TC rear. However, it always felt like something wasn't as good as it should be. Never really had the time or energy to look into it. Maybe the bore was too big! Once upgraded to the full Cobra 13"/11.65" setup, though, it became perfect. Maybe the dual-piston calipers up front have something to do with requiring more fluid volume and movement. Personally I think dialing in pedal feel is easier with the older cast-iron m/c's. The braking system is much more responsive to a change that way.
I had the SVO MC on the car originally when I got the Cobras up front and didn't like it..but perhaps the bore on the Cobra rear calipers is larger than the TC rears....
I don't know, Chuck...it's hard to tell. The Cobra rear calipers are physically smaller. I'd say they're about 80% the size of TC calipers. The piston looks to be the same size although I didn't measure between the two. I know the Cobra pads are even smaller than those used on the TC, if you can believe that. I'd love to know the fluid volume capacity between the two calipers.
I can believe the pads are smaller. You have a bit more mechanical advantage with the larger disks. Any more pad area would cause issues I bet...
Yeah boys I'm gonna go ahead and order a set of braided hoses. I'm 99.99% sure my MC is fine. All this talk of bigger brakes really has me hankerin for an upgrade. Right now my stock brakes look terribly weak behind by 17'' wheels...not to mention it stops like a '59 Caddy. Any of you guys have pics of your brake upgrades handy? I probably need to slow down and do it right...I want straight line performance but ever since I've started doing suspension upgrades I'm loving turning corners. Right now the major weak spot is the brakes. Well I'll give an update when I try the new brake hoses ...
The Varga calipers have a 38mm bore.
Matt's brake site says the TC calipers have a 38mm bore too. http://mjbobbitt.home.comcast.net/mustang/4lug.html
...
Further googling indicates the TC has a 45mm bore (which would make Varga caliper area 84% of the TC caliper)
http://brazeauracing.com/mustang/tech/rearbrakes.txt
http://www.mustangworks.com/articles/suspension/StopHard/StopHard02.html
http://64.233.187.104/search?q=cache:sfosXYzs0bQJ:racing.kos.net/soloforums/showthread.php%3Fs%3D843df7f37f440de5a0fa3b07f51b4051%26postid%3D15050+45mm+%22turbo+coupe%22+caliper&hl=en&start=4&lr=lang_en
http://www.corral.net/forums/showthread.php?t=546309&highlight=45mm
Just thought I'd add one thing. On your rear calipers make sure your pins are lubed with silicone dielectric compound. Sounds wierd but that's what the book calls for. Also make sure the boots over the pins are in good condition. Any moisture gets in and the pin will sieze up in a heart beat. then those floating calipers will not float anymore and your rear disks will be worthless. Basically if a pin siezes only the pad on the piston side will contact the disk when braking. The siezed pin will prevent the other pad from being pulled towards the rotor as the piston side pushes. this happened to me once when I thought it would be "good enough" to use anti-sieze on the pins instead of what the book called for.
Anyway, make sure everything is mechanically sound and moves the way it should before getting into master cylinders and boosters and stuff. The whole conversion "should" work fine with the stock master cylinder, booster and prop valve if everything is mechanically sound. At least it did on my V8 car.
Hope this helps!
Got the new hoses in and it stops a little better. I had a hell of a time getting them bled properly for some reason. It took me awhile to get all the air out of the lines. Right now I'm thinking that a front brake upgrade is a MUST in the future. As far as being safe to drive its fine now but from a performance standpoint it absolutely sucks! The prop. valve doesn't seem to do much as far as adjusting the front/rear brake bias. Oh well it will do for the rest of the summer.
I put the 84 Crown vic M/C 1 1/8"bore om my 84 turbo coupe that has rear drums and it stops alot better than it did before. Almost everyone told me that it would make my brakes very touchy. It didn't now when I hit the brakes it acutally feels like I have stopping power. I just hope that when I upgrade to the bigger 11" rotors and the lincoln calipers that I still have this kind of stopping power. Yes I still have the factory style rubber lines.