M1008 Brakes Pull Left

[AFC1]

Okay, if anyone can help me with this I will send them money for a case of beer as I am completely stumped. I have a 1986 M1008 I bought with 37,000 original miles. Truck was in nice shape when I bought it, just had been sitting for awhile. I removed the original Dana 60 front axle and replaced it with a completely rebuilt Dana 60 removed from a 1978 GMC 1 ton. This new axle has new kingpins, U-Joints, rotors, hubs, locking hubs, spindles, stub axles, gears, tie rods, calipers, wheel bearings, absolutely everything. I rebuilt the FF14 with new gears, carrier, seals, drums, wheel cylinders, shoes, hub assemblies, wheel studs, the works. Replaced the gears with 4.11s, kept the locker in the rear. Driving this truck now, the truck pulls to the left when braking. Here is the kicker- it does it intermittenly and will usually do it after driving for 20 miles. I have a 24 mile commute each way, each day. Usually around the 20-22 mile mark it does it. Highway driving usually provokes it faster than city driving. The brake rotors and hubs were brand new GM. The calipers and $90 pads were from NAPA. I replaced all of the steel brake lines and all of the brake hoses. I replaced the master cylinder with a unit from NAPA. Truck still pulling. I replaced the height sensing proportioning valve in the rear as well the limiting valve mounted to the front crossmember. Still doing it. My dad has a 1986 M1008 as well, I removed the front calipers and pads from his truck (which didn't pull) and installed them on my truck- still pulling. I thought I had a bad left front brake caliper mounting bracket, changed it- no dice. I made sure the caliper mounting brackets were clean, sandblasted and lubed properly. I borrowed a Brake Equalizer tool and measured the psi at each front caliper- I got a reading of 2500 psi at the left front and 3000 psi at the right front. Doesn't make sense as the truck pulls to the left! I am completely stumped.... Took a temperature reading immediately after getting out of the truck and found the left front rotor at 187*F and the right front at 173*F. Tried different wheels and tires, nothing. The only parts that I have not replaced on this truck is the hydroboost unit and the two brake lines coming out of the master cylinder going into the limiting valve. 57,000 miles on it now and am getting pretty sick of it as obviously I spared no expense and plenty of time. I am completely stumped and losing my mind as I have never ever come across this before. I consider myself somewhat intelligent, but I am begging for help here. Anybody?

 

[Chieftawny]

You must have used left-handed brake fluid!
Thats a good one though. Sounds like you covered alot of bases already troubleshooting.
I would have done the same as you so far. Sorry i can't help.

 

[MakersTeleMark]

How are your steering components, specifically you might try swapping out the stabilizer?

Let me know if I win the beer. I like beer.

 

[AFC1]

I sandblasted the sway bar and installed brand new bushings from Offroad Design. I tried three different stabilizers so far, all brand new. The thing that gets me is that it doesn't do it all of the time. Distance is the factor, not temperature as this truck pulled in 9*F weather as well as 99*F. Just don't get it. I had new bushings installed in the front springs and wound up pulling them back out of the truck to check and see if I had a sheared off center pin even. This is just ridiculous....

 

[beanman1]

i would replace the right caliper it could be stuck and not allowing contact with the rotor causing it to pull left

 

[AFC1]

Yeah, I replaced the right and left side calipers already with a pair that was known to work fine. I also filed the caliper mounting areas on the caliper brackets and applied white lube to them. The right side caliper has slightly more psi when applied than the left side. That left front wheel is coated with brake dust too.......ruining my aluminum rim.

 

[porkysplace]

try checking the rotors with a magnetic base dial indicator just because they are new don't mean they run true, bad
parts make it to the end user from time to time

 

[AFC1]

OKay- will check them this weekend. I have another brand new GM assembly I may just throw on. If this rotor is warped, wouldn't it pull all of the time?

 

[MakersTeleMark]

I want beer: wheel bearing?

 

[notsosanestan]

I bet the left hub is bad

 

[AFC1]

All new wheel bearings on front and rear axle, bro.... I had thought the left front might have been loose, had that happen on a Blazer one time. Those front rotor/hub assemblies have been on and off at least four times and they are tight, I am positive. Chipping the chrome off of my Warn hubs I have been messing with them so much! Like I said- this is crazy.....

 

[AFC1]

I have another hub/rotor assembly, I will throw that on tomorrow I guess. Give it a try for a couple days. I will be overjoyed if that is it, don't even care about wasting $170 on the GM assembly at this point.

 

[MakersTeleMark]

Jebus, this is worse than an electrical gremlin. How bad is the pull? Violent or just a let go of the wheel and it wanders?

 

[AFC1]

There are days when it is hardly noticeable, just a slight wander. Then there are days when, a mile from my work, I can change lanes with the b****. I would gladly take an electrical problem over this any day! The randomness of it is what is getting me. I would love it if the truck continued to do it, maybe then you could pinpoint it. I am ready to rebuild the original Dana 60 and put that back in there, but if you can't trust new parts, what's the point?

 

[notsosanestan]

My blazer does this And my hub is bad. It does the same thing only does it after driving for a bit

 

[Barrman]

With all that you have done. Just about the only thing left not listed is your brake hoses. Your left one could have a constriction not releasing pressure that will build as you drive and create heat or your right one could be swelling when you apply pressure or have a constriction in it causing not enough fluid flow.

Besides buying actual new calipers instead of "known to be good" calipers, I am out of ideas.

 

[rnd-motorsports]

OK thought about this last night after reading this post and the only thing that makes since to me.( just being the problem is only there after it warms ) I think I would lean to wheel bearing or hub maybe a liitle on the tight side when you installed them NOT SAYING ANYTHING ABOUT YOU DOING ANYTHING WRONG OR NOT KNOWING WHAT YOU ARE DOING! just making an observation and giving you my thought and to me what makes since. Good luck but with my many years of working on these things I will have to say to check the hub and bearings for maybe being a little snug on that side! let us know GOOD LUCK

 

[AFC1]

Okay here is an update on this issue....Installed another left side hub and rotor assembly. This one is new as well with a different set of wheel bearings. Before installing brake caliper, tested with a dial indicator and found it to be true. Put all back together, truck was still pulling within 3 miles this time, didn't even have to wait for it to be warm. Yet, wasn't pulling at all when I turned onto my street 20 miles later. Prior, it would start pulling and continue to do so until the truck was shut off and sitting for awhile. When I tried the "known to be good" calipers a while ago, I changed the brake hoses as well, so I don't think it is a constriction issue. Going to swap the right side hub/rotor next and see what happens with that.....Losing my mind with this thing.

 

[Cucvnut]

stop turning left when you use the brakes!

 

[CUCV85]

try this

stop turning left when you use the brakes!

Your Horrible ha ha

Try lifting truck, turn to one direction, turn the wheel back and forth - checking for binding!?
I am curious as to how you make out mine pulls horribly to the right all the time beginning to end of movement. Occationally will let up quite a bit but still pulls, sometimes gets bad then jerks left Whom, hang on. I been hoping for something to break so I can figure out WTF is going on.