Out of chevy brake troubleshooting ideas

[72Burro]

Helping a friend with his new chevy brake conversion.
Normal braking is great, but going faster or slamming on the brakes causes it to pull to the left.
Last winter it got new steering linkages, bushings, ball joints.
Everything is new on the brakes except the prop valve, the spindles and the flex line from the frame to axle.

Here’s what we’ve done so far with no success.
-tire pressure and tires size the same
-Bled about $40 in brake fluid thru the front right caliper alone
-Swapped pads R to L
-Swapped the new braided lines to the calipers R to L
-Swapped caliper mounting hardware R to L
-Plenty of caliper/knuckle clearance, calipers do not touch the knuckles even with no pads attached
-Swapped the calipers right to left and bled off the brackets with the bleeder screws up
-alignment done last month, toe correct, camber at .5 on both and castor at 1.9deg on both

When jumping on the front bumper, the steering wheel does not turn. But raising the frame with the wheels on the ground about 5or 6 inches and then dropping it does cause the steering wheel to turn to the left, but this seems out of normal driving compression.

As a last ditch, I took the calipers and brackets off my bronco and installed on his, still pulls to the left.
I had him drive towards me and slam on the brakes, I can see the front left caliper is clearly grabbing faster and harder than the right caliper.

Hoping I'm just missing something really simple here. I was thinking maybe the spindle is out of spec, but it behaves likes it's still a hydraulic issue

All thoughts and ideas welcome...

 

[NYLES]

Did you look for a kink in the hard lines? look realy good around places the its already bent...easy places for kinks to hide is where there supposed to be bent.....but after all youve checked thats all I can think of.......I know you bled both and had fluid at both but was it equal?

Kinda dumb way to put that but all it needs is enough to restrict one side

 

[72Burro]

We took off the hardlines on the axle and put on new lines w/ some very soft "S" curves to ensure we didn't have any kinks that were causing the pull.. the new lines didn't change anything so we put the old ones back on.

Maybe the connection from the frame to axle soft line that branches to the Right axle hardline is bad. (ie.. the cone is deformed) or it's just not sealing properly, but haven't found any leaks.

 

[Broncobowsher]

I just read something about a softer casting on some rotors causing different braking.
Have you tried swapping rotors side to side?

 

[scsm76]

If the draglink and track bar are parellel it probably isn't the bump steer issue. It could be debris on one of the rotors have you tried cleaning them. Switchin gthe m side to side could tell you as well. Also could be the T at the end of the soft line frame to axle, I think you could take it off and flip it over this would be a good way to test it.
Have you looked at the back brakes are they adjusted equally? You could pinch the back line and see if it still swerves. Good luck and stay at it you will find it.

 

[broncnaz]

Someone posted a problem like this and found that the rotors had 2 different thicknesses he got new ones and said it fixed his problem. I wouldnt think that that would actually be a problem with disc brakes but it fixed his. My theory on the brake pull is the lenght of the brake lines cause it since the drivers side is the shortest route and when you slam the brakes the D side locks first. (my f150 conv does it sometimes too).
Another theory I havent looked into yet is. The proportioning valve is not hooked up to proportion the front brakes in a Early bronco setup you could hook it up like the 80's up prop valves are hooked up but would require running 2 brake lines to the front axle and 80's up front flex lines from the frame to the axle.

 

[72Burro]

Thanks for the ideas....Here’s what we did tonight.

Plugged the rear hard line on the frame rail with a cap and took it for a drive. Brakes funny with no rear brakes, but still pulls left with the same force. Concluding rear brakes not the cause

Put the front end on jack stands and check wheels for wobble or looseness, none. Disassembled the hubs to check the outer lock nut torque on spindles. The right side outer lock nut was only at 45ftlbs vs. the specified 80-100ftlbs. Not sure this would cause anything unless the wheel wobbled and the right caliper can't grab the rotor square??

Going to swap the rotors this weekend. That was my post a few months back, I had the rotor issue with one premium and one el’cheapo in the same Napa boxes. I double checked these rotors for the same stamping before install, but will swap cause you never know.

 

[72Burro]

just got done swapping the rotors, now it pulls to the right. Swapped pads just to double check and still pulls right after the rotor swap. Hoping this is the problem. Will report back if the new rotor fixes it..

I noted in my last post that the outer bearing nut on the right side was only torqued to 45lbs.. when i reinstalled everything, I could only get it to torque to 65. I backed off the left side to 65lbs and the right side rotor does not spin as freely as the left at 65lbs (which is lighter than spec) I disasembled to verify that the ring is on the pin of the inner lock nut and it was. When i turn the right hub by hand it's hard to do with out grabbing the wheel studs.. Pretty sure it's not supposed to be this tight, but the outer locknut isn't torqued down to spec either. The rotor spins equally to the left side with the outer nut torqued to 50lbs.. Any thoughts?

 

[Broncobowsher]

What was the limiting actor on torquing to only 65? Was the socket jumping off the nut? Are the threads damaged? If everything is right, I don't see what would limit torque unless you start damaging something.

As for the rotors, that's good to know. Someday I will work on my brake pull.

 

[broncnaz]

I never torque the spindle nuts. I've always done it by feel and never had any problems (now I'll probably lose a bearing)
Might want to check to make sure the ring between the nuts is not turning on the spindle and causing a tighter bearing preload for some reason I've seen this happen more on the chebby spindles than Ford spindles dont know if they use a slightly different washer or what I wouldnt think so since they are all DANA parts or should be.

 

[72Burro]

thanks broncnaz.. just checked and the ring has turned on the spindle a bit.. I disassembled everything and i can see where the keyway on the ring has eaten away some of the threads on the spindle.

 

[Skuzzlebutt]

Wheel bearing adjusting nut spec is only 30-40 ft/lb.