I am new to Tbuckets, just starting a build, and have a lot of questions. Does anyone know why most of the part catalogs say that the 78 -up GM front disc kits are too large or heavy for a Tbucket. Seems as they want to steer you to the more expensive Wilwood set-ups. I see lots of pics with the GM system. I am planning on using bolt on steering arms. Anyone have some input ??
Front disc brakes
- Thread starter xkopper34
- Start date
tfeverfred
Well-Known Member
The main complaint I have read concerning the regular GM brakes was a shimmy in the front end while going between 50 and 55 MPH. The problem is that regular GM or like same rotors is that they are not balanced enough for a very light weight car, such as a T Bucket. The frontends they are attached to are heavy cars. So heavy that the shimmy can't be felt. T Buckets have very little unsprung weight and therefore the shimmy is more noticable.
I have also read that a way to get around this is to have the wheel mounted on the rotor and both balanced at the same time. Check with the NTBA website. There is a member there who can explain how this is done. Although finding a place to do it seems hard to find.
I have also read that a way to get around this is to have the wheel mounted on the rotor and both balanced at the same time. Check with the NTBA website. There is a member there who can explain how this is done. Although finding a place to do it seems hard to find.
Mike
Well-Known Member
There must be a terrible imbalance condition in those rotors. The closer you bring an imbalance condition to center, the more insignificant it becomes. And if a rotor wants to vibrate that badly, when it is so close to center, then it must be w-a-y out of balance.
There are two obvious problems with removing metal from the rotor to bring it back into balance. Problem 1 - nobody wants to be liable for carving up a rotor that might fail, bringing the lawsuit of the century down on their heads. Problem 2 - do you want to drive a car with carved up rotors on it?
If you balance the assembly (wheel/tire and rotor) together, then you will always have to be sure to replace the wheel in exactly the same relationship with the rotor, each time it is removed, else it will aggravate the imbalance condition and try to throw you out of the car.
Interestingly enough, everyone talks about the vibration in Harley Davidsons and I'm of the opinion they purposely build that much imbalance into their engines to create their own mystique. Stevie Wonder could see the imbalance in an H-D rotating assembly. :lol: We've balanced loads of H-D's and when we're finished, you can place a cup of water on the seat whilst they are running and not lose a drop.
There are two obvious problems with removing metal from the rotor to bring it back into balance. Problem 1 - nobody wants to be liable for carving up a rotor that might fail, bringing the lawsuit of the century down on their heads. Problem 2 - do you want to drive a car with carved up rotors on it?
If you balance the assembly (wheel/tire and rotor) together, then you will always have to be sure to replace the wheel in exactly the same relationship with the rotor, each time it is removed, else it will aggravate the imbalance condition and try to throw you out of the car.
Interestingly enough, everyone talks about the vibration in Harley Davidsons and I'm of the opinion they purposely build that much imbalance into their engines to create their own mystique. Stevie Wonder could see the imbalance in an H-D rotating assembly. :lol: We've balanced loads of H-D's and when we're finished, you can place a cup of water on the seat whilst they are running and not lose a drop.
digger
New Member
I have the willwood kit on mine that speedway sell, I did'nt think it was expensive at all, more importantly they really work well.
I would spend the money on good brakes, and maybe save the cash somewhere else, I put mine on the road in primer then painted it later when I had some more money.
I would spend the money on good brakes, and maybe save the cash somewhere else, I put mine on the road in primer then painted it later when I had some more money.
lanceks1
New Member
I used to have shimmy, until I did the String Fling..5deg. caster, 1/8" out toe. One of my front tires had radial runout, when it was new. Had to send it back, get another. No more imbalance. Can't believe something as small as a purposly built cylindrical mass of metal, wasn't well balanced at the factory?? Yes my bucket has only 900# on the front end. It is very compliant to the road surface, and moves very well, due to the correct spring rate. I do have a side to side walking action @58-62 mph, but no imbalance..Have heard that the hyd. shocks would cure this?:lol:
flatheadgary
Member
a friend of mine wanted to build a t so we used his '39 chevy that had been center punched by a semi. the axle was still good so we welded plates on it to put the spring behind the axle and made radius rods and it turned out nice. the problem started when it was done and he drove it. it had those big disc brakes too. we solved it by putting a vw steering damper on the tie rod, never shimmied agian. not a real fix, but it is still on the road after 15 years, still running fine. it even was used by edelbrock to mock up t headers and tunnel ram they were going to produce. i'll tell you that thing was insanely fast after that too. lucky dude got to keep it all on his car when they where done too.
joes23t
New Member
I run the 4 pistin Corvett calipers on the front of mine and Jag disc in the rear those are both large calibers I have not had the first bit of problems with this set up. The mid size Gms should be fine. The shimming that every one talks about seems to get resolved by having your caster at 5* positive no more and 1/8 toe in. it can be cured with a angle finder and a tape measure or a basic front end alinment
flatheadgary
Member
lancek1, you put a panhard bar on it and that side walking will go right away.
Leon renaud
Member
You can put in a panhard bar or use a dead perch on the drivers side this will end side movement in your front end.The dead perch is an old circle track racers trick speedway and Pete and jakes sell dead perches
Mine did to and scared the bejusis out of me cause i had to almost stop to getum to stop as far as i can figure it was the shocks the friction ones from Total i have a couple friends with the same set up with out the friction shocks and they have no problems.Only thing different is that and i have the wires.lanceks1 said:I do have a panhard bar on the front end, along with a so-cal steering stabilizer on the tie rod. Maybe I wasn't clear enough about the side to side walking. The wheels which are at the ends of a center pivot bounce up and down alternately to each other @ 58-62mph.
digger
New Member
my T does that when the road is rough, a bit unnerving on a concrete dual-carrigeway [freeway] at 100mph!!
I nipped up the friction shocks and it has helped, I assummed its the reason that tube shocks were invented.... 'cause there better!
But I like the way the friction ones look so wont be changing them!
I nipped up the friction shocks and it has helped, I assummed its the reason that tube shocks were invented.... 'cause there better!
But I like the way the friction ones look so wont be changing them!
engine24355
Member
I have coil over shocks on all four corners of my T and it drives pretty good. My front end did have the bad shimmy / wooble till I adjusted my toe out (radials) and problem solved. I do have GM rotors and they do vibrate around 55 MPH. Not a bad vibration, but enough to notice. I plan to fix this, but have not decided on how yet. Obvious thing would be to balance the wheel and rotor together (as stated already), but not crazy about being limited on how I can put my front wheels back on etc. Not to hijack this thread, but would putting new aftermarket (lighter) rotors only on the front help with the vibration? Thanks!!!
The problem we have is not a vibration it's WHEEL HOP it's like right,left,right,left real fast hopping about 6 inches off the ground.Bad very bad feeling and as he said i tightened my friction shocks till i couldnt tighten them any more they worked good enough and the hop went away till they losened up again.engine24355 said:
engine24355
Member
Rick said:
Thanks for the clarification Rick.
joes23t
New Member
What I HAVE FOUND THAT IF THE FRICTION SHOCK DOES NOT HAVE ENOUGH TENSION ON IT (NOT TIGHT ENOUGH) THE FRONT WHEELS WILL BOUNCE LIKE NOT HAVING ANY SHOCKS AT ALL. ALSO THE KITS COME WITH A THIN PIECE OF RUBBER AS THE FRICTION PAD AND WILL WAIR OUT I SWITCHED TO A TIRE SIDE WALL DRILLING THE SIDE WALL OUT OF A USED TIRE THE DIA. OF THE OLD PAD AND IT'S BEEN WORKING FOR A COUPLE OF YEARS AND A LOT OF MILES.
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