New Shocks And Now...

blackout07 · July 22, 2011

I swapped out the rear shocks on my wifes 07 Tahoe and now I have the above messages. I checked the lines and they look okay. I did have to push them out of the way to remove the lower bolt on the d-side shock, but nothing extreme. Anyway, I just disconnected the battery hoping it may reset. I'm a little worried because my wife is leaving this evening to head to Houston (roughly 75 miles away) for the weekend. Any ideas? Is it safe to drive? Also the ABS light came on.

ujtruck · July 22, 2011

if you have a code scanner you will see

you have a wheel speed sensor issue, yah you broke it

Zak_LScrew · July 22, 2011

I swapped out the rear shocks on my wifes 07 Tahoe and now I have the above messages. I checked the lines and they look okay. I did have to push them out of the way to remove the lower bolt on the d-side shock, but nothing extreme. Anyway, I just disconnected the battery hoping it may reset. I'm a little worried because my wife is leaving this evening to head to Houston (roughly 75 miles away) for the weekend. Any ideas? Is it safe to drive? Also the ABS light came on.

Is your steering wheel still centered? There is a sensor (Inside the clockspring) and if that is not picked up as you drive down the road after 2-5 miles it will disable your traction and stability control. The ABS may be disabled because you have no stability control. Its annoying but should be safe to drive until you can get an alignment done. I had the same thing happen to me when I swapped rear blocks.

blackout07 · July 22, 2011

I just scanned for trouble codes with my Diablo and it showed no codes. IDK what the deal is. I never had this problem with my truck.

ChevyTech77 · July 22, 2011

Sounds like you disturbed a connection for one of the rear wheel speed sensors.

As long as your wife is capable of driving that vehicle without the assistance of abs, traction or stability control, it is safe to drive and the base braking/steering/suspension systems will work normally but just without the assistance of the previously listed systems.

blackout07 · July 22, 2011

Sounds like you disturbed a connection for one of the rear wheel speed sensors.

As long as your wife is capable of driving that vehicle without the assistance of abs, traction or stability control, it is safe to drive and the base braking/steering/suspension systems will work normally but just without the assistance of the previously listed systems.

Indeed I did. I found the issue. I had inadvertently knocked a blue plug loose on the d-side just in front of the spare. I'm assuming it was where the wheel speed senors plug in. Thanks for advice guys.

levigarrett · July 23, 2011

I swapped out the rear shocks on my wifes 07 Tahoe and now I have the above messages. I checked the lines and they look okay. I did have to push them out of the way to remove the lower bolt on the d-side shock, but nothing extreme. Anyway, I just disconnected the battery hoping it may reset. I'm a little worried because my wife is leaving this evening to head to Houston (roughly 75 miles away) for the weekend. Any ideas? Is it safe to drive? Also the ABS light came on.

Is your steering wheel still centered? There is a sensor (Inside the clockspring) and if that is not picked up as you drive down the road after 2-5 miles it will disable your traction and stability control. The ABS may be disabled because you have no stability control. Its annoying but should be safe to drive until you can get an alignment done. I had the same thing happen to me when I swapped rear blocks.

I dont understand how to align rear leaf springs in an alignment that has no adjustment capabilities? please explain.

AzDragonLord · July 23, 2011

Glad you found it!

Doug_Scott · July 23, 2011

I swapped out the rear shocks on my wifes 07 Tahoe and now I have the above messages. I checked the lines and they look okay. I did have to push them out of the way to remove the lower bolt on the d-side shock, but nothing extreme. Anyway, I just disconnected the battery hoping it may reset. I'm a little worried because my wife is leaving this evening to head to Houston (roughly 75 miles away) for the weekend. Any ideas? Is it safe to drive? Also the ABS light came on.

Is your steering wheel still centered? There is a sensor (Inside the clockspring) and if that is not picked up as you drive down the road after 2-5 miles it will disable your traction and stability control. The ABS may be disabled because you have no stability control. Its annoying but should be safe to drive until you can get an alignment done. I had the same thing happen to me when I swapped rear blocks.

I dont understand how to align rear leaf springs in an alignment that has no adjustment capabilities? please explain.

If you change or remove the blocks you stand a good chance of not getting the housing lined up perfectly. Even though there is pin an hole that lines the housing up, there is play in them. The pin is slightly smaller than the hole it goes in to. If you get the left side pushed back, and the right sight pushed forward, the axle housing may be 1/16 of an inch off of centre line. That effectively means the housing is pointed slightly to the left. To drive the vehicle straight, you need to hold the steering wheel turned slightly to the right to make the truck drive straight. If you watch NASCAR you will see an extreme example of what I mean. Those cars when going do the straight sections of the track are dog tracking to the left. You can see the right side of the car when it is coming straight at you.

To answer your question though, you would just loosen the u-bolts and push the housing in the direction you want it to go, it is very limited, but there is some play there.

levigarrett · July 25, 2011

I swapped out the rear shocks on my wifes 07 Tahoe and now I have the above messages. I checked the lines and they look okay. I did have to push them out of the way to remove the lower bolt on the d-side shock, but nothing extreme. Anyway, I just disconnected the battery hoping it may reset. I'm a little worried because my wife is leaving this evening to head to Houston (roughly 75 miles away) for the weekend. Any ideas? Is it safe to drive? Also the ABS light came on.

Is your steering wheel still centered? There is a sensor (Inside the clockspring) and if that is not picked up as you drive down the road after 2-5 miles it will disable your traction and stability control. The ABS may be disabled because you have no stability control. Its annoying but should be safe to drive until you can get an alignment done. I had the same thing happen to me when I swapped rear blocks.

I dont understand how to align rear leaf springs in an alignment that has no adjustment capabilities? please explain.

If you change or remove the blocks you stand a good chance of not getting the housing lined up perfectly. Even though there is pin an hole that lines the housing up, there is play in them. The pin is slightly smaller than the hole it goes in to. If you get the left side pushed back, and the right sight pushed forward, the axle housing may be 1/16 of an inch off of centre line. That effectively means the housing is pointed slightly to the left. To drive the vehicle straight, you need to hold the steering wheel turned slightly to the right to make the truck drive straight. If you watch NASCAR you will see an extreme example of what I mean. Those cars when going do the straight sections of the track are dog tracking to the left. You can see the right side of the car when it is coming straight at you.

To answer your question though, you would just loosen the u-bolts and push the housing in the direction you want it to go, it is very limited, but there is some play there.

I understand your point but my dealership shows that there is no rear adjustment available. At least that is what he paper work showed. those pins are designed to maintain tolerances. Your front alignment has tolerance perimeters and might not be exactly perfect, as long as they fall within tolerance it is considered aligned, would you assume that the pin slop on the rear blocks have that tolerance accounted for?

Just saying.

ChevyTech77 · July 25, 2011

Thrust angle changes made by movement of the rear axle on it's locating pins in the leaf springs/blocks while minimal, can show up during a wheel alignment. If front toe is set off the thrust angle (like it should be) the steering wheel CAN be off center if the rear axle is shifted. It won't be much but it is possible.

levigarrett · July 25, 2011

Thrust angle changes made by movement of the rear axle on it's locating pins in the leaf springs/blocks while minimal, can show up during a wheel alignment. If front toe is set off the thrust angle (like it should be) the steering wheel CAN be off center if the rear axle is shifted. It won't be much but it is possible.

So the best way to install a rear block lift would be to take measurements prior to dis-assembly and make sure each side reads exact to limit the movement in the pin holes

Just curious.

Doug_Scott · July 25, 2011

Thrust angle changes made by movement of the rear axle on it's locating pins in the leaf springs/blocks while minimal, can show up during a wheel alignment. If front toe is set off the thrust angle (like it should be) the steering wheel CAN be off center if the rear axle is shifted. It won't be much but it is possible.

So the best way to install a rear block lift would be to take measurements prior to dis-assembly and make sure each side reads exact to limit the movement in the pin holes

Just curious.

Dealer is correct, there is not official adjustment for this. It is such a small amount of play that I would just either push the housing all the way back or all the way forward on both sides. We are talking about maybe an eighth of an inch in total, and I would not be surprised to see it is only a thirtysecond of an inch. As another has said, it is such a small amount it is negligible in most cases. Keep in mind that the longer the wheelbase, the more effect it has.

From my own experience doing alignments years ago, it was not all that uncommon to see vehicles with the rear end not square with the chassis. As ChevTech77 points out, a good alignment shop and tech will set front toe based on thrust angle to compensate for it. It was also not unusual to do a front end alignment after changing leaf springs, so much so that it was unusual to not have to.

levigarrett · July 26, 2011

well all this discussion is great to understanding the rear alignment.

This guy is F$#@&*

http://www.gmfullsize.com/forum/showthread.php?t=231686

LOL

rkcharles · January 1, 2013

The setting that you're looking for is setback. An easy way to ckeck if anything changed in the rear axle area, while driving down the road, is to take note of your steering wheel placement before any procedures (is it low on left of steering wheel, dead nuts centered, etc.) and take note of any change afterwards, all should be exactly the same as before you did anything. The variation will be slight unless you made your own. A machine made dowel at the hidden part of the bolt will almost be a perfect fit. Just go get a thrust angle alignment and it should be in tolerance, close to zero.