Terrible bump steer
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Senior User
Joined: Sep 2006
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From: Littleton, CO
Terrible bump steer
I have an '06 F350 CC, SB, Diesel, that has really bad bump steer (steering wheel shimmies back and forth when hitting a bump) at any speed (0-80mph). I've had it to the dealer three times for this issue already, and they are telling me know that it's because I have the f-350 with the camper springs. It's very noticable and dangerous, I was driving the truck at about 35-40 mph and hit some washboard on the pavement, and the truck shook into the next lane. Has anybody else had/have this problem? If so, what did your dealer repair on it? Did it work? Thanks
Tuned
Joined: Oct 2005
Posts: 331
Likes: 3
From: St. Louis, MO
You do not have enough positive caster on the front axle. Ford offers caster shims which are not a complete solution. Might try buying just the lowering brackets from a lift kit that lowers the radius arms. You need between 5.5 and 6 degrees of positive caster.
A bandaid would be a new steering stabilizer or dual stabilizers. Your toe could also be in or out too far. Check for wear on both ends of the radius arms, it is unlikely they've worn already.
If the camper springs make the rear of the truck sit higher, then that will effectively decrease your positive caster, going towards negative caster. If you lowered the height of the rear of your truck, that would help alleviate bump steer. It can be very scary and dangerous, get it fixed.
A bandaid would be a new steering stabilizer or dual stabilizers. Your toe could also be in or out too far. Check for wear on both ends of the radius arms, it is unlikely they've worn already.
If the camper springs make the rear of the truck sit higher, then that will effectively decrease your positive caster, going towards negative caster. If you lowered the height of the rear of your truck, that would help alleviate bump steer. It can be very scary and dangerous, get it fixed.
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Senior User
Joined: Sep 2006
Posts: 260
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From: Littleton, CO
Originally Posted by 7.3 Ex
You do not have enough positive caster on the front axle. Ford offers caster shims which are not a complete solution. Might try buying just the lowering brackets from a lift kit that lowers the radius arms. You need between 5.5 and 6 degrees of positive caster.
A bandaid would be a new steering stabilizer or dual stabilizers. Your toe could also be in or out too far. Check for wear on both ends of the radius arms, it is unlikely they've worn already.
If the camper springs make the rear of the truck sit higher, then that will effectively decrease your positive caster, going towards negative caster. If you lowered the height of the rear of your truck, that would help alleviate bump steer. It can be very scary and dangerous, get it fixed.
A bandaid would be a new steering stabilizer or dual stabilizers. Your toe could also be in or out too far. Check for wear on both ends of the radius arms, it is unlikely they've worn already.
If the camper springs make the rear of the truck sit higher, then that will effectively decrease your positive caster, going towards negative caster. If you lowered the height of the rear of your truck, that would help alleviate bump steer. It can be very scary and dangerous, get it fixed.
Postmaster
Joined: Jun 2004
Posts: 2,646
Likes: 1
From: Milky Way Galaxy
This TSB says it's for '05 and '07's, but it sure sounds a lot like what you're talking about:
Steering Wheel Shimmy After Riding Over Bumps/Ruts:
Some 05 and 07 F-Series trucks may exhibit an oscillation/shimmy in the steering wheel after hitting bumps or ruts in the road. Typical steering wheel movement is 5 degrees and usually smooths out after about 5 oscillations. This condition is more prevalent on 4X4 trucks with steering wheels that have radio and climate controls. The truck will need to be inspected: tire pressure checked; steering damper inspected (replace with 5C3Z-3E651-D if needed); all suspension and steering fasteners torqued; steering checked for binding; steering gear adjustment checked/adjusted. The caster may need to be reduced by 0.5-0.75 degrees. After this, trucks build prior to 10-8-04 should have the steering wheel replaced.
King Ranch tan/pebble: 5C7Z-3600-ABA
Charcoal black: 5C7Z-3600-CBA
TSB 05 22-1
Thanks to Dieselmann's for the TSB info.
Steering Wheel Shimmy After Riding Over Bumps/Ruts:
Some 05 and 07 F-Series trucks may exhibit an oscillation/shimmy in the steering wheel after hitting bumps or ruts in the road. Typical steering wheel movement is 5 degrees and usually smooths out after about 5 oscillations. This condition is more prevalent on 4X4 trucks with steering wheels that have radio and climate controls. The truck will need to be inspected: tire pressure checked; steering damper inspected (replace with 5C3Z-3E651-D if needed); all suspension and steering fasteners torqued; steering checked for binding; steering gear adjustment checked/adjusted. The caster may need to be reduced by 0.5-0.75 degrees. After this, trucks build prior to 10-8-04 should have the steering wheel replaced.
King Ranch tan/pebble: 5C7Z-3600-ABA
Charcoal black: 5C7Z-3600-CBA
TSB 05 22-1
Thanks to Dieselmann's for the TSB info.
Tuned
Joined: Oct 2005
Posts: 331
Likes: 3
From: St. Louis, MO
Tightening that allen head on the steering gear will make the box tighter. It will also make the steering seem heavier and wear out the box faster. Especially if trying to compensate for that much wobble. This would not solve the problem, only cover it as another bandaid. You still have a cause that needs repair.
Look for a lift kit that either drops the frame mounts for the radius arms, or has caster brackets where the radius arms mount to the axle. I converted a 2000 Excursion to 2006 F-350 suspension and axles. I planned for the larger tires which on most 4x4s require 5-7 degrees of positive caster for good street manners. I made custom radius arm mounts that dropped the mounting points a few inches, also moved the front axle over an inch forward. Everything had to be perfectly precise, i've been through it.
No, i'm not a Ford tech, i'm a musician. Dealerships have never made me happy so i've ended up fixing things myself when they couldn't. The FTE is a far better resource than a dealership.
-Matt
Look for a lift kit that either drops the frame mounts for the radius arms, or has caster brackets where the radius arms mount to the axle. I converted a 2000 Excursion to 2006 F-350 suspension and axles. I planned for the larger tires which on most 4x4s require 5-7 degrees of positive caster for good street manners. I made custom radius arm mounts that dropped the mounting points a few inches, also moved the front axle over an inch forward. Everything had to be perfectly precise, i've been through it.
No, i'm not a Ford tech, i'm a musician. Dealerships have never made me happy so i've ended up fixing things myself when they couldn't. The FTE is a far better resource than a dealership.
-Matt
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Senior User
Joined: Sep 2006
Posts: 260
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From: Littleton, CO
Originally Posted by 7.3 Ex
Tightening that allen head on the steering gear will make the box tighter. It will also make the steering seem heavier and wear out the box faster. Especially if trying to compensate for that much wobble. This would not solve the problem, only cover it as another bandaid. You still have a cause that needs repair.
Look for a lift kit that either drops the frame mounts for the radius arms, or has caster brackets where the radius arms mount to the axle. I converted a 2000 Excursion to 2006 F-350 suspension and axles. I planned for the larger tires which on most 4x4s require 5-7 degrees of positive caster for good street manners. I made custom radius arm mounts that dropped the mounting points a few inches, also moved the front axle over an inch forward. Everything had to be perfectly precise, i've been through it.
No, i'm not a Ford tech, i'm a musician. Dealerships have never made me happy so i've ended up fixing things myself when they couldn't. The FTE is a far better resource than a dealership.
-Matt
Look for a lift kit that either drops the frame mounts for the radius arms, or has caster brackets where the radius arms mount to the axle. I converted a 2000 Excursion to 2006 F-350 suspension and axles. I planned for the larger tires which on most 4x4s require 5-7 degrees of positive caster for good street manners. I made custom radius arm mounts that dropped the mounting points a few inches, also moved the front axle over an inch forward. Everything had to be perfectly precise, i've been through it.
No, i'm not a Ford tech, i'm a musician. Dealerships have never made me happy so i've ended up fixing things myself when they couldn't. The FTE is a far better resource than a dealership.
-Matt
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Tuned
Joined: Oct 2005
Posts: 331
Likes: 3
From: St. Louis, MO
If you don't have enough positive caster now, the spacers with no other modifications will amplify your problem. Less than 5 degrees and you will likely experience the "death wobble." You could go to your uncle's shop first and have him check the caster first so you know for certain if that is your problem. Good luck.
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