Suspension Tech General discussion of suspension for the Ford Ranger.

Bad Bump Steer

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Old Jun 29, 2008
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KnightTremors's Avatar
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Bad Bump Steer

Hey guys, I gotta question for you guys. I am having some bad bump steer going on. It started doing it a little bit after I turned my T-Bars. But it really started doing it really bad after I got my new Tires and installed my Shakles and AAL's. I went up to 33's with the tires. Is there anything I can do to eliminate the Bump steer I am getting??
Thanx in advance.
 
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Old Jun 29, 2008
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Mine does it as well, with no lift or tbar cranck. Just anticipate it and be ready. Choose a forgiving line on bumpy corners.
 
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Old Jun 29, 2008
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Did you get the alignment checked after you cranked the t-bars?

That could have something to do with it.

How much pressure are you running in your tires, I'm running 30psi with the same tires, I have a SFA and the bump steer isn't bad.
 
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Old Jun 29, 2008
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My alignment is good (I did have it checked and am within limits). I checked it first before I posted anything on it. I havent checked my tire pressures yet, I will do that today if I have some time. What should I be running on them?
It really started when I did the tires so I am guessing cause the added weight and size against the steering system might be causing it.
Is there a kit that is made to help out with the Bump steer?
 
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Old Jun 29, 2008
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well when you get tires mounted they usually put alot of pressure in the tires like 45+psi (at least thats what mine had in them) you should run 30psi
 
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Old Jun 29, 2008
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From: bomba shack
Noob question: What is "bump steer"?
 
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Old Jun 29, 2008
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Originally Posted by mossyoak1992
well when you get tires mounted they usually put alot of pressure in the tires like 45+psi (at least thats what mine had in them) you should run 30psi
In LT285/75R16's?? That seems a little low. I would think maybe around 35psi.
 
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Old Jun 29, 2008
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Originally Posted by 08XLT4x4
Noob question: What is "bump steer"?

Bump Steer is the term for the tendency of a wheel to steer as it moves upwards into jounce. It is typically measured in degrees per metre or degrees per foot.

On modern cars the front of the tire moves outwards, as the suspension is raised, a process known as the front wheels "toeing out". This gives roll understeer. The rear suspension is usually set up to minimise bump steer, where possible.

A typical value is two degrees per metre, or perhaps more, for the front wheels.

Excessive bump steer increases tire wear and makes the vehicle more difficult to handle on rough roads.

Solid axles generally have zero bump steer, but still have roll steer, in most cases. That is, if the wheels move upwards by the same amount, they tend not to steer.

Roll steer is an important part of the budget used to define a vehicle's understeer, known as a Bundorf analysis
 
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Old Jun 29, 2008
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From: bomba shack
Originally Posted by 4LO 4.0
Bump Steer is the term for the tendency of a wheel to steer as it moves upwards into jounce. It is typically measured in degrees per metre or degrees per foot.
whats "jounce"?

so basically, when you hit a bump, the car will not track straight?
 
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Old Jun 29, 2008
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hit a bump and the wheel turns in easy words its not that 'safe' to have but its not life or death just the wheel jolts when you hit a bump
 
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Old Jun 29, 2008
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From: Livonia, Mi
Originally Posted by KnightTremors
My alignment is good (I did have it checked and am within limits). I checked it first before I posted anything on it. I havent checked my tire pressures yet, I will do that today if I have some time. What should I be running on them?
It really started when I did the tires so I am guessing cause the added weight and size against the steering system might be causing it.
Is there a kit that is made to help out with the Bump steer?
Originally Posted by KnightTremors
In LT285/75R16's?? That seems a little low. I would think maybe around 35psi.
Like i said in my first post, I'm running 30psi with my 32x11.50x15's.
My dad is running 30psi with his 33x12.50x15's.
 
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Old Jun 29, 2008
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How could there be loose parts on my 07 though? I havent done anything to the front of the truck other than cranking the T-Bars and had the tires put on.
What kind of loose parts are you talking about?
 
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Old Jun 29, 2008
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anything, control arms, spindles, anything
 
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Old Jun 29, 2008
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sounds like too much air in the tires. i think you are over playing it. bump steer usually an IFS truck does not have. are you sure you are using hte correct term?
 
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Old Jun 29, 2008
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dude it would have nothing to do with air pressure its worn tie rods or control arms something with the steering colum is loose or worn
 
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Old Jun 29, 2008
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Originally Posted by zabeard
sounds like too much air in the tires. i think you are over playing it. bump steer usually an IFS truck does not have. are you sure you are using hte correct term?
I Have bump steer It is not too bad though. My truck has the stiffest springs from the factory and my tires are 36 psi.
 
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Old Jul 1, 2008
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Well, I checked the entire front end and everything is tight. I checked the tires and they all had 42 psi in them. I brought them down to 34 psi and when I get out in the truck again I will see if it is an better and if not, I will bump them on down to 30 psi and see if that is any better.
I really think that will help it alot. I will keep you guys posted on it next time I take the truck out, lol.
 
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Old Jul 1, 2008
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check the shocks mine werent completely tightened down and i had bad bump steer which also led to bruised bushings and the next day replacing of the shock bushings.. my retarted ness led to this misfortune though... got overly excited when i somewhat finished my lift......
 
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Old Jul 1, 2008
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Yeah, I checked the shocks as well. They are also good. I think it might have been the overinflated tires. We shall see shortly, lol.
 
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Old Jul 5, 2008
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Okay, Well I just got back from running some errands and stuff in the truck. The bump steer is MUCH better but is still there on really harsh bumps. It is tolerable and I am good with that.
Just thought I would give you guys an update and thanx to everyone that helped.
 
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Old Feb 27, 2018
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What is "bump steer"?

Originally Posted by 08XLT4x4
Noob question: What is "bump steer"?
Bump steer is a condition that happens when the suspension path (in this case of the upper and lower control arms) does not match the steering arch between the inner and outer tie rods. The tire will turn slightly (called “toe change”) as the suspension moves through it's travel. This results in wandering. All production cars have some small amount of bump steer.

Raising or lowering the car can place the suspension out of the intended toe curve and create bump. Older cars have shock towers that can be anywhere with regards to the upper arm location. It is possible that the tower could be out far enough to affect the steering geometry. A bump steer kit can correct the steering angle for matching the suspension movement.
 
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