2001 Econoline E-350 braking/steering weird

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#1
I'm trying to figure out what's going on with a Ford E-350. It has a 5.4 engine and 200,000 miles on it. I will try to describe the problem.
From a cold start, while braking with average pressure, it pulls slightly to the left. After 1 or 2 brake applications. it seems to brake properly, but then it starts to pull to the right (while braking, average pressure). When the brakes are at a normal temperature, and you press the brake at highway speed, it does some thing that feels somewhat different. Instead of the steering wheel being pulled slightly in one direction or the other, it seems more like the rear end gets pulled to the left, then you need to turn the steering wheel to the left to keep the vehicle from changing direction.
The owner of the van tried to fix the problem with an alignment and tire rotation. The tires (that are now on the rear) look rough, not with wear on inner or outer edges, but kind of cupped all over, and both tires look the same. He says that since the alignment was done, the pulling issue is the same, and now it also has a problem with "wandering" at highway speeds. I agree with him, seems like you have to make constant corrections on the highway.
I have inspected the steering and suspension several times. Found no problem other than a slight popping sound/feel in the steering, most noticeable when parking. Steering does not seem sloppy or binding.
At the customer's request I have replaced front brake parts... rotors, bearings, pads, calipers, hoses. These new parts seem to have made no change in the problem.
This vehicle has Ford's "twin I-beam" suspension in the front and leaf springs in the back. It has "4 wheel ABS" with sensors at front wheels and a sensor in the rear axle housing above the ring gear. It has rear disc brakes. A single line "tees" at the rear axle, then hoses connect to each caliper.
Wear on all brakes seems to be normal and even. Rotor temps measured with infrared immediately after test drive seem to be balanced.
I'm hoping some one will tell me they have fixed this kind of problem by changing rear hoses. Or that the ABS hydraulic module can cause these symptoms. The ABS light is not on, and ABS seems to work normally under slippery conditions.
Any ideas or opinion on how to diagnose of repair this problem would be greatly appreciated.
Thanks, Dan
 

oldtimer53

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#2
Sounds like the rear radius arm bushings (ibeam)are letting the axle deflect rearward when braking.
With the truck on the ground, have someone (you trust) apply the brake while the torque up the engine in drive and reverse. While you lay on a creeper and watch the distance between the bushing washer and the frame bracket. You should see no change if the bushings are good.
Typically these are 60-100k items, sometimes less, especially on the RH side. The exhaust cooks them. They are not easily spotted on a hoist, because of the axle dropping when lifted.
FFFFFFord's term for this is "recessive steering"
 

jigfeett

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#4
Agreed just did mine on my E150 plus did the pivot bushings fixed all braking issues.
 
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#5
Thanks for the input, guys!
I did see some movement during torque load. So I put hose clamps around all four bushings to "firm them up".
Customer called back later to say it fixed both the brake pull and the wandering! Looks like I'll be changing those bushings. I'm optimistic that it will be fairly easy because the radius arm brackets look to be bolted to the frame, rather than welded or riveted.
Thanks again,
Dan