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Front disc brakes

I have the early GM brakes on my T and haven't had any problems. There are several things that can cause front shake or shimmy. Usually it's a bad caster angle. The rule is 5 to 7 degrees. I started at 5 degrees and slowly tilted it back until I had the ride I was looking for. you also have to get your alignment right on the money. 1/8" toe in is where most are set.
 
If you look at friction shocks from long ago, you'll see that they are made up of multipal plates and pads. The more the better. I don't know why there aren't any of this type offered today. I'll try to get some pics this afternoon.
 
Bad pinion angles can also produce a shimmy. This is real common on cars set up with the old Ford bones and an open drive shaft. A 4bar set up or hair pins allow you to tune this out. Too little-low speed shimmy. Too much-high speed shimmy.
 
Here are the friction shocks I'm building for my '27 modified project. The assembled one is for the front of the car. The unassembled one is for the rear. By bolting the plates together you have more friction. The more plates and pads you have, the more friction you have.
 
Front wheel balancing/etc.,even if all other things are right on;this stuff can mess up ride;,
Doing this your self can be done,;
1#,jack both front up.tires off the ground right after a run long enough to warm the tires so there round,not flat spoted. check PSI so there the same.
2#pull the pads out of of cal's so tire turns free*,if it dose not turn free,check wheel bearing.
3#spin tire and check for out of round and side to side run out,about 1/8in max is still OK for ether.
4# for each tire;spin tire and let it stop by it's self,mark side of tire at bottom / lowist point so you can see your mark,check 3 times=they should all be very close=use center mark only from now on.,this lets you know were the heavy spot is,, now by moving the tire ,tell you mark is at 9:00 or 3:00 and let go of it,you will see tire mark go back to 6:00,take note of how fast it moves on it's own back to 6:00,now add a small wheel WT. to tire rim at 12:00 and test again same way as first time,it should move slower back to 6;00 or if it put your mark at 12;00 the WT. was too much. Trick is just play that game tell tire dose not really move anymore with your mark at 9;00 or 3;00.

Some of the things you find out and fix as needed are tire round[if not replace or get ture cut at a tire store///side to side run out,checks rim and or tire////balance and at the same time[as long as you don't take wheel off hub] balances brake disk also if it's off any.
If any of above are bad,all the adjustments of tow or shock mean nothing.:D
Rods should drive nice or it's all wasted.
 
We are going through a complete brake change right now on the front of my Son's T. The original brake setup were GM calipers and rotors on modified 49-54 Chevy spindles. Mickey at Total Performance told us we wouldn't like them, but I had the setup and they were freshly chrome plated and all that good stuff, so we used them.

We also rushed building the car for Daytona Turkey Run, and built it in 88 days, start to finish, so we missed some things in our rush. As soon as the car hit the street we had handling issues. I have built a few cars and they always ran right down the road right out of the chute, so this one really puzzled me. The worst problem was death wobble that was very violent and you never knew when it would happen. You had to hit the brakes hard to get it to stop and it would scare the bejesus out of you.:eek:

So we pulled the car off the street for a complete suspension and brake redo. I found the wheelbase was off 9/16 of an inch side to side, so we realigned that. Our Flaming River steering box had too much play, which we adjusted out. Our caster was way too much at 9 degrees, so I took it back to 6. Toe in was off, it was 3/16 instead of 1/16 to 1/8. One brand new wheel was bent out of the box. Coker sent us a new one and we painted it today and will install it this week. We had all the wheels spun balanced on a very sophisticated machine.

We also found our spindles had been machined badly and the outer wheel bearing had 5-6 thousandths slop, so we pulled those and bought new forged ones from Speedway. While we were at it, we scrapped the GM brakes and have ordered a new Wilwood setup from Speedway too.

Bottom line, everybody seems to agree that for some reason the GM brakes are too heavy or something to make them work well at speed. I see lots of buckets with them, so some must work, but there are many people who don't care for them. We just couldn't take a chance and decided to go with the lighter Wilwoods. We should know this week how all of this worked out when we test drive the car again.

Don
 
Don, I'm running Wilwoods and while I don't have miles on my car yet, I have gotten up to speed and done panic stops to test them. I know you will be pleased with them. Plus, they look sweet. Being smaller, they won't over shadow your wheel selection.:D

Brian at TP explained them to me when I was contemplating trying to save money with the GM setup. He mentioned "unsprung weight" and the fact that GM brakes are not balanced to exact specs. The weight of a full size car lessens the shimmy of the unbalanced rotors. It made sence to me. Combine that weight with a light car, a light front end and friction shocks, it makes sence that shimmy would occur.

But like you said, some people seem to run them and have no problem or are they just living with it.
 
I've used the GM setup on a chopped and channeled Model A coupe. Once we got past the tire balancing and alignment issues, they work just fine. The coupe is alittle heavier than a bucket, maybe that's why it seems to work.

Ron
 
I beg to differ with what has been said about using the GM brake set up. I have been running them on my car for over 5,000 miles and they have been NO problem what so ever. The shimmy that you speak of, I have never encountered. Nor have several other T owners that I personally know. Granted the Wilwood set up does look great but the "EX JUNK" stuff works great for me. (I am running '74 Nova calipers and rotors from a "junk" car.)
 
So, in the end it boils down to installing the GM setup and hoping it works like it does for some or getting what is sure to work. It's a tough choice. All I know is, I couldn't afford to drop $400 on a hope and then turn around and get what would, if they didn't.
 
Re: Front disc brakes,balancing GM rotors

"The Bat" out of hell said:
Front wheel balancing/etc.,even if all other things are right on;this stuff can mess up ride;,
Doing this your self can be done,;
1#,jack both front up.tires off the ground right after a run long enough to warm the tires so there round,not flat spoted. check PSI so there the same.
2#pull the pads out of of cal's so tire turns free*,if it dose not turn free,check wheel bearing.
3#spin tire and check for out of round and side to side run out,about 1/8in max is still OK for ether.
4# for each tire;spin tire and let it stop by it's self,mark side of tire at bottom / lowist point so you can see your mark,check 3 times=they should all be very close=use center mark only from now on.,this lets you know were the heavy spot is,, now by moving the tire ,tell you mark is at 9:00 or 3:00 and let go of it,you will see tire mark go back to 6:00,take note of how fast it moves on it's own back to 6:00,now add a small wheel WT. to tire rim at 12:00 and test again same way as first time,it should move slower back to 6;00 or if it put your mark at 12;00 the WT. was too much. Trick is just play that game tell tire dose not really move anymore with your mark at 9;00 or 3;00.

Some of the things you find out and fix as needed are tire round[if not replace or get ture cut at a tire store///side to side run out,checks rim and or tire////balance and at the same time[as long as you don't take wheel off hub] balances brake disk also if it's off any.
If any of above are bad,all the adjustments of tow or shock mean nothing.:beer:
Rods should drive nice or it's all wasted.
Click to expand...

Balancing your own rotors only, can be done the same way if it turns very free,this needs to have wheel bearing clean with only lite motor on the bearing and the seal out,so best to do just before a new seal and repack job,
Tow tricks are handy to know passed that above,one is how to put some WT. were needed in the rotor=on the inside near hub were fins are,you make a steel "U" of size & WT. needed,so it can be hammered in to fin opening [note you can on some see were GM already did this to a few that were off balance a lot]. Another trick to making rotor move to see heavy side go down,is to bump axle with a hammer handel a few times to put some vibs in to spindel=makes hub find home of haevy spot down.
 
Re: Front disc brakes,balancing GM rotors

OK I was tring to fix spelling and add stuff i left out,and this Forum did not let me,takes way more the 5min. to do anythig at all,what give with that junk????
Left out about you can grind small amounts off fins on out side of rotor from heavy spoy side too,,I speel for crap and try to fix it,but most of the time I just fig you'all are smart and can fig it out.
 
tfeverfred said:
So, in the end it boils down to installing the GM setup and hoping it works like it does for some or getting what is sure to work. It's a tough choice. All I know is, I couldn't afford to drop $400 on a hope and then turn around and get what would, if they didn't.
Click to expand...


Freds thinking was precisely our thinking in not putting the GM brakes back on. For $ 700 the Wilwoods cost it wasn't worth going through installing the GM's back on the new spindles and wondering if and when the problem would reoccur. I wish the GM's would have worked as they are all plated and painted up, but my Son's life comes first, and I don't want him driving a car that might get him hurt.

Don
 
Is there a pattern for the calaper mounts?
vistin
 
Not sure what you are asking, but the caliper mounts come with the Wilwood kit. We just did this install last week, and everything pretty much was in the box. We only had to add a couple of longer bolts because of using steering arms etc that needed additional length..........no big deal.

What was a little bit of a concern though is that there are no instructions or even an exploded view in the kit. They do however supply you with 3 or 4 pieces of paper that are disclaimers saying "only to be installed by professionals" and "not for highway use." I realize some Attorney has advised them that they are not liable if something goes wrong by doing that, but who are they kidding, they KNOW we are going to be doing these at home, and some idea of how the parts go would sure help.

Luckily we were able to figure out the orientation of the parts, but I wonder how many people with less experience would be able to do it? It took us scratching our heads a couple of times, even though we kinda know our way around these things.

But I gotta say, they really made a difference in the handling. They weigh like 1/4 of the weight of the GM setup, and also narrowed our front track by about 2 inches, so that looks better too. So far we like em. :lol:

Don
 
Don, I can't explain why yours didn't have instructions. Mine came with a schematic, but even it was hard to read and I ended up sitting everything down and looking at the pieces to figure out how it went on. It didn't help that a couple extra parts were in my box. It took me a couple test fittings to figure it out and I had to call Total a couple times with questions. As a first timer, I was thinking I had made a VERY expensive mistake, but I stuck it out.

My car stops great, no lock up and the setup is truly impressive looking. Well worth the money.
 
Maybe that is the difference Fred. We got ours from Speedway, maybe TP puts instructions in the ones they sell. It seemed to us that Wilwood is doing everything possible to take a hands off "we didn't tell them to put these on their car" approach. Like I said, there were tags rubber banded to every component saying "professional installation ONLY."

Don
 
It's my understanding from years of reading the NTBA forums about the" Front Tire Bounce" and Friction Shocks...The Friction shocks should have ATLEAST 60 Ft Lbs. of Torque on the center bolt.

As far as GM disc Brake Kits, I have the Speedways kit, using 9" Mustang II Rotors,Pinto Hubs (or do I have that backwards?) and GM "Metric" Calipers. As I understand from "Fat Pat" The Brake Expert on the NTBA Forum, these "metric" Calipers are used with a "FAST TAKEUP M/C", that is a M/C with stepped piston bore. He was skeptical that those calipers would work with a std. Dual Master Cylinder such as the 3/4" Vega that I am using.
One of the guys in Utah, has the same system and his seems to work fine with the std. dual master cylinder.
I think If I was goin to do it again I would use the GM "intermediate" Caliper.... These systems DO NOT use any Proportioning Valves or Residual Pressure Valves as the Residual Pressure Valves may cause the Pads to Drag on the Rotors ...
I suggest if anyone here has any Brake issues you contact "Fat Pat" at the NTBA Tech. Forum, he is a Brake expert having his own business for many years and also teaching the subject...... Hope this is of some help.
"BH"
 
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