Chevy and GMC Duramax Diesel Forum banner

1 - 20 of 20 Posts

·
Premium Member
Joined
·
133 Posts
Discussion Starter #1
I have a 2012 that was t-boned in the passenger side. Point of impact was passenger front door. Damaged both doors and edge of front fender. Frame was slightly bent and no visible evidence of a hit to the tire or wheel. I drove it after the wreck and noticed the steering wheel is almost 1/4 turn to the left when driving straight down the road (yes it was straight before the accident). The truck has since been rebuilt, frame was straightened to factory specs and the only thing left to fix is the steering wheel alignment. I took it to the alignment shop and had it checked out. Alignment was close to correct, nothing bent or visibly tweaked to indicate a reason for the steering wheel being off. Tie rods are showing the exact same amount of threads on both sides. The alignment tech said that the problem is most likely inside the steering gearbox- may have skipped a cog on the gears. This seems unlikely to me due to the size of the gear cogs. Any ideas? If it us the steering box, which brand to you recommend?
 

·
Registered
Joined
·
260 Posts
These trucks have a problem with bending frames even without doing wheel and suspension damage. When you say you had it straightened, what was wrong with it? How was the truck hit? Where was all the damage? Does the panels, fended and hood fit well? If your gear box has no play, I dont think it is the gear box. Never seen a gear box skip. Usually shears the shaft off.
From my experience in autobody and straightening a handful of these frames including my rebuilt duramax, I think your front section is swayed over behind the motor to the drivers side. Let me know if this sounds plausible.
 

·
Premium Member
Joined
·
234 Posts
I have a 2012 that was t-boned in the passenger side. Point of impact was passenger front door. Damaged both doors and edge of front fender. Frame was slightly bent and no visible evidence of a hit to the tire or wheel. I drove it after the wreck and noticed the steering wheel is almost 1/4 turn to the left when driving straight down the road (yes it was straight before the accident). The truck has since been rebuilt, frame was straightened to factory specs and the only thing left to fix is the steering wheel alignment. I took it to the alignment shop and had it checked out. Alignment was close to correct, nothing bent or visibly tweaked to indicate a reason for the steering wheel being off. Tie rods are showing the exact same amount of threads on both sides. The alignment tech said that the problem is most likely inside the steering gearbox- may have skipped a cog on the gears. This seems unlikely to me due to the size of the gear cogs. Any ideas? If it us the steering box, which brand to you recommend?
Lazy alignment tech. I just rebuilt the front end on my truck. Prior to the rebuild, even after 235k miles the steering wheel was straight although the truck had never been aligned since new. After I got the front end aligned the wheel is about 1/8th turn to the left. Nothing wrong with the truck, they just didn't want to take a minute to set the wheel straight.
 

·
Premium Member
Joined
·
133 Posts
Discussion Starter #4
Yes the frame was bent exactly how you described DailyDmax. The main point of impact was the bottom on the passenger side front door. The frame was not visibly bent or wrinkled anywhere on the frame but the front end had shifted of spec by about 2.5" measured on th e front end. After the body shop took the bed and cab off, i took the rolling chassis to the frame shop and they straigtened it to within factory specs on a computerized frame machine. I saw the printouts before and after the job and they guarantee their work so I have no reason to doubt that it is straight. Before the frame was straightened, the truck pulled to the right. Now it drives straight, but the steering wheel is still off. All of the panels, fenders, hood, body lines etc look and fit straight.
 

·
Registered
Joined
·
260 Posts
It sounds to me like its still bent. The measuring system is only as good as the person using it. They can be scued to show correct or they could of not been measuring the correct points. Either could show a straight frame but still could be bent. My experience in a shop is that it doesn't always get fixed correctly the first time. Can have issues with panel fitment or an alignment and then have to repull.
If remember correctly there is only a point or 2 on each side in that location. Usually its a combination of the front being over as well that helps to show what's really going on. Also knowing how to pull it can make the difference in the end result.
My first advise would be to measure wheel base center from rear hub to center of front with wheels straight compared to rear.(not steering wheel straight). Depending on offset of wheels it can be difficult with a tape measure. If it is more than 1/8 in, something is definently bent.
Here is a picture of mine bent. It's an 05 so slightly differing frame design, but they bend the same. Yes thats the downpipe it hit. Fixed in 2013.
 

Attachments

·
Registered
Joined
·
260 Posts
Kinda rough sketch of what I think is happening. Red is frame. Blue is the direction of movement at points. And dotted blue is current frame alignment. Can you see why to go straight the wheel is quarter turn to the left?
 

Attachments

·
Premium Member
Joined
·
133 Posts
Discussion Starter #8
That makes sense and i get what you're saying without the illustration. If the front end is slightly pointed to the right, the steering wheel would have to be turned to the left to compensate. I will do that wheelbase measurement and if its off, back to the frame shop it goes. They guarantee their work so at the very least they should hook it up and re- measure it.
 

·
Registered
Joined
·
141 Posts
On our 2016 Duramax when we had it aligned the tech had it straight going down the road but steering wheel was off a little. He said he had to hook up a computer of some sort to make the steering wheel straight on the newer models.
Now bare with me as i might have this somewhat screwed up as my memory isn't always the best since my stroke.
On older models i know you had to adjust the tie rods to straighten the steering wheel.
 

·
Premium Member
Joined
·
133 Posts
Discussion Starter #11
I know I could adjust the tie rods to get it straight but i want to find out the root of the problem first. The tie rods are both showing the same amount of threads on the adjusters so I know they havent moved. I would hate to adjust them to get the steering wheel straight and then not be able to turn as far on one side.
 

·
Premium Member
Joined
·
483 Posts
If you want to check it yourself you can do what they call a frame diamond check with a plumb bob, a chalk line and a level concrete floor (and tires inflated to the correct pressure). You just drop from the same points on each side of the frame with the plumb bob, like front and rear spring brackets, body mount brackets and so on, and mark the floor where the plumb bob is pointing (I put down masking tape and mark it). You need 8 minimum and more is better. You also want to measure from the floor to the frame on each side, front, center and rear, to check for frame twist. Then you roll the truck off of area measure and mark the center of the front marks and the rear marks. Then you snap chalk line "X's" between the marks, i.e. from left front and right rear points of the front spring mounts and the right front and left rear. Once you have the X's marked you snap a single line from your front center point that you marked and the rear one. With a straight frame the last line should intersect at the X's. It'll give you a picture of where the problem is.
 

·
Premium Member
Joined
·
133 Posts
Discussion Starter #14
Campingguy i like that idea, will try that. I talked to the shop that did the frame work and they said if its not correct to bring it back and they would make it right. They wanted their alignment tech to check it out first so i did that today and he seems to think the frame is still bent. I might do the diamond check first in case they try to tell me its straight when it isnt. And Redwingr i havent checked the steering column but will do that also. I'm not sure exactly where to look in the steering column.
 

·
Registered
Joined
·
9 Posts
Input shaft is bent. I just built a 15 lml that was hit in front wheel. Box looked fine but my steering wheel was off 180 degree. I installed a new gm box and it was fine.
 

·
Premium Member
Joined
·
133 Posts
Discussion Starter #16
Carys15duramax is there anything to look for on the outside of the steering box to see where its bent or twisted? I'm still going to check the frame and if I rule that out I guess the next step would be the steering box.
 

·
Registered
Joined
·
4,933 Posts
I have a 2012 that was t-boned in the passenger side. Point of impact was passenger front door. Damaged both doors and edge of front fender. Frame was slightly bent and no visible evidence of a hit to the tire or wheel. I drove it after the wreck and noticed the steering wheel is almost 1/4 turn to the left when driving straight down the road (yes it was straight before the accident). The truck has since been rebuilt, frame was straightened to factory specs and the only thing left to fix is the steering wheel alignment. I took it to the alignment shop and had it checked out. Alignment was close to correct, nothing bent or visibly tweaked to indicate a reason for the steering wheel being off. Tie rods are showing the exact same amount of threads on both sides. The alignment tech said that the problem is most likely inside the steering gearbox- may have skipped a cog on the gears. This seems unlikely to me due to the size of the gear cogs. Any ideas? If it us the steering box, which brand to you recommend?

the only thing that would explain that (and still allow the truck to be driven away and check out on an alignment rack) is that something skipped inside the gear box. Since the steering wheel to the box is u joints, its likely inside the gear box. Keep in mind how much force a moving vehicle has to transfer to the side of your truck. If they hit the front door and front fender, most of the impact was transferred to the tires in a direction they are not really designed to take significant loads in, so it is very likely that you could drastically exceed the mechanical limits of the steering gear box. I would personally replace it, i think its unlikely that there is no internal damage given it almost certainly had to have moved internally to allow the steering wheel to change location. ALSO a warning on the wheel. It only take about 1/2-1 turn over the limits to rip the clock spring apart, which is not fun to replace so be careful when repairing that the wheel doesent turn more and get into an even worse orientation.

The other option is that you could have twisted the steering shaft beyond the metals yield point and permanently deformed it. You should be able to see this misalignment though from the u joints on the shaft if this were the case. I think this is much less likely though unless you have the grip strength of the hulk since the wheel would need to be held stationary against that twisting force.


Campingguy i like that idea, will try that. I talked to the shop that did the frame work and they said if its not correct to bring it back and they would make it right. They wanted their alignment tech to check it out first so i did that today and he seems to think the frame is still bent. I might do the diamond check first in case they try to tell me its straight when it isnt. And Redwingr i havent checked the steering column but will do that also. I'm not sure exactly where to look in the steering column.
If the frame is bent, the truck may not be tracking straight and may require that steering wheel offset to keep it going straight.
 

·
Registered
Joined
·
9 Posts
No. You could take box off and set it side by side with a new one. Then all the way one way and see if the input shaft is in the same spot as the new one. The box should be 3.25 turns lock to lock. Make sure your splines on the output shaft are not spun. The dust cover in-between the pitman arm and the bottom of box may be hiding a bent sector shaft.
 

·
Premium Member
Joined
·
133 Posts
Discussion Starter #19
Any recommendations on steering gearboxes? I have heard good things about Redhead but they seem pricey. If there is benefit to them vs stock, I don't mind spending a little more.
And as far as the frame still being bent and driving off-track, being compensated by the steering wheel being turned to the left makes sense. However with the steering wheel being turned almost 1/4 turn to the left, the truck would have to be dog-legging by an extreme amount, right? I had my wife following me on the road the other day and she said it looked like it was tracking straight.
 

·
Registered
Joined
·
9 Posts
I purchased a new one from GM for $450.00 with the dealer discount. If there is any chance the front wheel was hit in the accident I would check the steering box.
 
1 - 20 of 20 Posts
Top