Pulls To The Left When Accelerating

[TOMKLU]

My Bronco pulls to the left when I apply the gas. If traveling at a steady speed and let off the gas it tries to go right, the same on dirt or pavement.
The tire air pressure is the same in all 4 tires. Alignment was checked not to long ago.
Is it possible that the TrueTrac limited-slip is engaged more on the right side and doesn't unlock?
Need Help!

 

[BwoncoHowie]

When this happened to me it was because I had too much Bump-Steer. This was caused by the Steering link not being paralell with the track bar. I found that if I installed a drop bracket without installing a drop-pitman arm it caused severe bump-steer. So since i was only running a 2.5" lift, I decided to remove the drop bracket and install a Superlift adjustable track bar. This allowed me to re-center my front axle under the frame. After I installed the caster adjusting urethane C-Bushings from Duff, the Bronco became a Joy to drive again. I don't know if this is your problem but something to consider... BH

 

[Rustytruck]

Try increasing tire pressure on the left rear 2 Psi over the right side and see if it gets better. I would jack up the rear untill the tires are off the ground and make sure the pressure is the same and take a Tape measure and wrap it around the tire and measure the circumfrence they need to be really close and can be varried due to wear tire pressure and rim widths not counting MFG tolerences.

 

[TOMKLU]

Thanks guys.
I don't have any noticable bump-steer. If I'm driving at a steady speed and hit bumps, nothing happens.
I noticed this drivability problem last week after spending 2 weeks in a rental car on a business trip, then coming home and driving the Bronco. The tires are not new (from the dealer) and I just had them installed a few months ago. I went from 31 all-terrain to 33 mud-terrains. I didn't notice anything after the installation.

 

[77bronko]

I have the same problem. I replaced all bushings on front, new tie-rods and drop pitman. No bump steer at all. If I gun it I nearly run off the road. If I let off the gas the opposite happens. Braking is no problem. The only things I have left to replace are the rear spring bushings which are shot and the ball joints, which aren't terrible but loose. If a spring bushing in the rear is bad it could cause one side to walk up a bit. I also may have a cracked add-a-leaf, which could also cause the problem.

 

[76Broncofromhell]

I have that problem too, but it's because the 3 way adjustable tie-rod conversion kit from Jeff's is actually too short for a '76-'77. Eventually I will get a cut-down F-150 linkage from BC. That should fix my problem permanentley.

 

[Jimmyjames]

I had a problem like this and it was my c bushings and raduis arm bushings. My c bushings looked ok but the raduis arm bushings were worn out. Good luck finding the problem.

Jimmyjames

 

[Bear1911]

I had the same problem after installing my Detroit locker. I was seriously considering removing it when I discovered that one rear tire was about 10 psi down. I aired up and problem solved.

 

[bert]

Check the U-bolts that hold the axle to the springs in the rear. My first thought after reading your post was the rear axle shifting around. The springs have a centering bolt in them that locates the spring to the axle. Broken leafs or bad mounting bushings would allow it to walk around also. Let us know what you find.

 

[Broncobowsher]

I have to ask a question. What are you running for suspension lift? What about the track bar (drop bracket)? Are you running a drop pitman arm? Basicly list what you have for the front suspension and steering.

Before I here your list I am going to state that I think you have bump steer. Before you say you don’t because it doesn’t do anything when you go over bumps, it can still have bump steer. It took a lot of expermenting to get rid of mine with only a 3½” lift. Track bar brackets, different tie rod combinations, etc.

To check for bump steer, it is quit easy. You need to clamp your tierod to the axle tube. I just used a piece of scrape metal, a pig pair of vice grips, and a big C-clamp. If you are running the inverted-Y setup then this doesn’t work.
Cycle the suspension and watch the steering wheel. As the front end lifts, the wheel should stay straight. I was using the high lift to bring the front end up 4 to 5 inches. About what my front end does when I get on the gas. As the track bar and drag link move, the difference will show up in the steering wheel. Since the wheels are aimed straight (tierod clamped to the axle) the bump steer show up in the steering wheel as movement needed to drive it straight.

So list what you have in your front end and lets see if we can get you on the straight…

 

[Bronco_Rider]

Hi,
If it happens under acceleration and under de acceleration, tire pressure is the 1st think to check and the other thing to check is the circumference of the tires. Rotate the tires so the ones at the rear are matched the closest.
Running Detroit lockers and have experienced the problem.

Bronco_Rider

 

[TOMKLU]

Broncobowsher, I do have a B.C. 3 1/2" lift front and rear. The only thing that has changed recently is the increase in tire size to 33's. It never moved with the 31's, unless the larger tire amplifies the problem. I know it sucked the power out of the 289.
I was out the other day and tried to find bumps to drive over. If the speed is held steady the steering does not move, and I do not have a drop trac-bar bracket.
I will start on this list tonight and keep all informed.

 

[SteveL]

mine did that when I cracked a rear u-bolt

 

[TOMKLU]

Measured tire circumference, 1/4 difference between the rears, not much. Added air to left side to make equal. Didn't find any broken or loose U-bolts. The limited-slip seems fine. Still need to the bump-steer check suggested by Broncobowsher.
Pluggin' along.

 

[Skuzzlebutt]

Check the leaf spring shackles for binding or unenven movement.

 

[Rustytruck]

[quote author=TOMKLU link=board=5;threadid=16120;start=0#msg123694 date=1050068027]
Measured tire circumference, 1/4 difference between the rears, not much. Added air to left side to make equal. Didn't find any broken or loose U-bolts. The limited-slip seems fine. Still need to the bump-steer check suggested by Broncobowsher.
Pluggin' along.
[/quote]

Try swappiny the tires from left to right and see if it pulls in the oppsite direction if it is tire induced it should.

 

[70bucks]

I've never posted on the topic because I thought I was just nuts. I have got a spool in the rear and a detroit in the front. When I am in four wheel drive, no matter what the speed or accelerating or decellerating it pulls hard to the left. Tire pressure equal, haven't checked circumfrence, but it feeels like running a 33 on one side and a 31 on the other.

 

[mrcat88]

Do you guys that have this problem have power steering or manual? I have about 3.5 inches of lift, 33's, and power steering and I don't have that problem....(that is, when I CAN drive it) :


Mrcat88

 

[70bucks]

Yes I've got power steering and if you nail it in 4x4 you better be holding on to the wheel tight.

 

[TOMKLU]

After being on the trail this weekend, I found a set-up that works for me. I was running 32 psi all the way around. Then I added 4-5 psi to left rear (smaller circumference). Driving was better.
This weekend After reaching the road I aired-up to 30 psi and 34 psi inthe left rear.
Results :drives alot better.
I'm going to checking circumference of the rest of the tires. Don't just check pressure. If you think about it a 1/4 difference is quite a bit.
Thanks for the ideas.