This is also a good suggestion, thank you. I have gone through three steering boxes however, and finally landed on a Motorcraft one that is working really well. I was just about to move to the one you mentioned, but what I have seems to be quite good. But, I still will not rule out 100% so thank you.

Regarding the ABS sensor, this is an entirely new concept. Very interesting, I think that if all of these things don’t work that I’m having a mechanic do now, I’m going to go ahead and get four new ABS sensors and just put them on. I’m a little bit tired of throwing money at this, but it seems to be just as effective as trying to diagnose the problem and coming up short every single time.

thank you!!

QUOTE=Cocky EX;19864031]I originally had an issue with a sudden pull to the left in my 01 6.8 rwd with firm pedal application and discovered the LR running hot. After servicing the caliper slides it improved but still pulled left some, wasnt too bad so let it go. Like you I had replaced the ball joints, tie rods, center link on the front. One day had to panic stop and it darted hard left again. I believe it crept up on me slowly getting worse over a long time so I didnt realize it was that bad. After reading up on the forum had the wife move the steering back and forth with engine off while I was underneath and the pittman arm wasnt moving despite her saying she was "sawing it back and forth". Long short I replaced the steering gear with a Blue Top and it tracks dead center when braking. Even hard braking. Just a thought.[/QUOTE]

 

If you had a tone ring issue from a sensor, you would feel pulsing in the pedal.

Since you didn't take the hint, what was the brake temp balance when you measured the rotors?

 

OK - good info on the pulsing - My truck does not pulse. Regarding the temp, I did not take the readings the mechanic did so I don't know what they are.

 

Thanks.

It's always a good idea to have an infrared gun. When I bought mine they were close to $300, today they are under $35. I use mine for many, many things, including cooking. With the truck, I check tires and brakes when towing. But doing a diagnostic for brake issues, it's a good tool, with the right sequence. And if you've used it a few times to get a history. Brake temps change in the balance depending on the operation of the vehicle and when you actually grab the temps off the rotors. A coast down will tell if there is a dragging brake; post stops if there is a piston or hose hangup.

 

Thanks man. Yeah I do have an infrared gun, but the shop has had my truck the entire time I've had these issues so I haven't really been able to diagnose anything on my own. With all of this help though, I think once I get it back and if the issues are not resolved with what they are currently doing (1) Master Cylinder and (2) frame to rear axle flex line - then I'll just take the truck back and start trying to work this out on my own, probably starting with that ABS module info you and others have given me.

 

To be clear, one of the two channels out of the master feeds both front brakes; the fluid doesn't hang left or right going down the tube. The other channel has fluid going down the rear flex line splits to the two rear brakes at the axle, doesn't hang left or right going down the hose. Neither of those items will cause a brake pressure differential across an axle, side to side. Both can cause a pressure differential from the front axle to the rear axle, but that is not a pull. Not that changing a master for a new Ford one at this service life is not a good thing. Or the hose.

 

This is really great information @toomanytoys really appreciate your deep knowledge here. You're right, even if I'm not fixing the immediate issue I am handling a lot of maintenance that should be done on my truck with 200K on the clock. I will keep you all posted as this progresses, I won't ghost the thread!!

Jim

 

Hi Everyone,

I called the mechanic this morning and he actually found a good used ABS brake module over the weekend and they installed it this morning. He's going to get it nice and warm and go for a long test drive this morning. We are BOTH crossing fingers this will be the issue. @TooMany Toys he echoed your sentiments about the MC being only front to back so he was really thinking that isn't it and wanted to go down the road of the ABS module.

Keep ya posted! If this doesn't fix it he's throwing in the towel so if it's still there I guess my next stop will be the dealership.. I don't know honestly what else to do at that point.

Jim

 

Well, long story short - the mechanic gave up. I can't blame him. After replacing all the parts.. and all the time.. nothing worked. I can't say it's pulling really hard anymore though, it's not bad and is controllable, but it's annoying. So I guess this thread ends with - it's unresolved. If anyone has ANY other ideas, I would love to hear them.

Thanks for everything, I'll be back with more no doubt about it.

Jim

 

Stumped is no way to go out on this.

Not sure if its a 4x4 but are either of the hubs locked? And, if unlocked, can you spin the axles freely by hand?

Does the steering wheel jerk or is it forced....or does it just pull left?

Sounds stupid, but have you tried pushing the brake pedal really hard? I did that once and a slight pull went away.

 

Hey Carbon - It IS a 4x4, but no both hubs are unlocked I can confirm. I can spin the axles free, I was able to do this back when I did the brakes initially. The steering wheel doesn't jerk, it's more of a subtle pull, and it really is much worse after driving for a while. It seems to be pretty good when the truck is cold.

Funny you mention the brake pedal push.. I HAVE done that, and I'm going to keep doing it. I'm also going to go and do some hard stops, medium and soft stops somewhere and well maybe the brakes just need to bed in really well. I'll keep driving it for a another 1000-2000 miles I guess and after that I might take it to the dealership.

 

If it gets worse as you drive, seems like you have something rubbing that shouldnt. The pad carrier bracket can get rusty under the clips that hold the pads. Whenever I take mine apart, I file those 3 surfaces really well. That way the pad is not jammed in there and can retract from the rotor.

The other thing I did when I first got my truck is gut and pitch the parking brake innards. Just a complete nightmare that I havent needed. If that is rubbing, it can cause a pull as well.

Not sure if you acquired a heat gun yet but it can help diagnose rubbing issues.

 

Thanks man. Yeah I have laser heat gun and I'm going to start carrying it in the truck and do a lot of tests to see if I do have rubbing. That parking brake idea is a good one. I tell you if that's it.. I'm gonna DIE.. haha

 

We are getting down the rabbit hole.

I would try flipping the brake pads on the left sides to the right sides and see if the pull follows the pads. During the initial launch of the Superduty in the '99-00 time frame, the production of the brake pads had to be altered to tighten up the normal specs for mixing and processing. A TSB went out for pulling to make sure that the batch numbers of the 4 pads on any axle set were the same. These trucks have a high scrub radius, so they are more prone to torque pull. That kind of process control is too expensive for aftermarket pad production.

Next, if the pull does not follow the pads, I would check both the rotor and hub runouts on the front. The service rotor runout was maxed at 0.0015," and on the assembly line, the installed runout spec was 0.0010". The weight of the caliper and hysteresis of the slide pins do not allow for much knock-back of the caliper pistons. Knock-back for pad clearance has been abandoned since the '90s in brake design, and now you want the truest running rotors. The caliper o-rings control piston retraction, and pad retraction is controlled at the pads. For the Akebono caliper design, the wishbone springs were added to the top of the pads to assist in pad retraction within the brackets.

But a higher runout allows the pad to rotor contact, which can lead up to a 100º variation side to side running down the road without braking. That differential will cause pulls, sometimes even 75º.

New brake test being installed on a 2000 Excursion, circa 2003. A good image of one of the two wishbone springs.

 

As usual, this is great information, thank you. As I'm driving it, I'm noticing the problem lessens.... I think. I don't know if my mind is playing tricks on me here or what. I'm hopeful that maybe some amount of break-in/bedding is working in my favor. I'm going to keep driving it and I have my laser gun at the ready to take temps now (I just picked the truck up and haven't put it in there yet).

SIDE NOTE / QUESTION: What do you set your tire PSI at front and rear?

Thanks!!