Feels like I get rear ended when sitting at a red light

[Jkust]

Hi all, recently when i'm at a red light in the Rainier just sitting there with my foot on the break, it feels like someone hit me from behind. Basically after a few seconds of sitting it feels exactly like the car behind me bumped me. It just happens one time each red light. Any ideas what this could be? We just hit 52,0000 miles on the Rainier.

 

[MDBT]

Giant thread on this over on the OS. Seems to be a lot of people suggesting it was a poorly lubricated slip yoke.

 

[DJones]

Pull your driveshaft out and genereously grease the slip yoke. Just be careful removing the rear u-joint from the diff. You don't want to spill the needle bearings at all (if a cap were to come off), or do what I did and take a hammer to bang it out. That cost me my u-joint.

 

[RayVoy]

The problem is not a poorly lubercated rear yoke (although that will fix it for awhile), the problem is the material the rear yoke is made with. A new rear yoke will be made with a different steel mix.

 

[Bhaasie]

I had this same problem. Once I drained and refilled the transfer case the bump went away.:wootwoot:

 

[Sparky]

The problem is not a poorly lubercated rear yoke (although that will fix it for awhile), the problem is the material the rear yoke is made with. A new rear yoke will be made with a different steel mix.

Hmm... given the cost of the yoke vs the cost of some grease, I'd be tempted to try the grease first.

 

[RayVoy]

Hmm... given the cost of the yoke vs the cost of some grease, I'd be tempted to try the grease first.

It might be under warranty

 

[Simon01]

I believe for some vehicles there was a bulletin to replace the slip yoke with a nickel plated slip yoke to take care of the "slip-stick" condition.

I also know that fuel slosh can cause this. Usually if you have over 3/4 tank of gas and come to a harder stop, the fuel sloshes in the tank and gives the sensation you have been hit.

 

[tricguy007]

(We just hit 52,0000 miles on the Rainier). WOW that's a lot of miles LoL!!!!!

 

[Jkust]

(We just hit 52,0000 miles on the Rainier). WOW that's a lot of miles LoL!!!!!

Well it's my wife's and she's lucky if she puts 4,000 miles on it each year. If I don't drive it every now and again, I'll never know anything is wrong. So it seems the yoke may be the problem then according to most that have posted since the gas was almost empty the other day and was still doing this. The car has one of those GMPP warranties with a zero dollar deductible for another 60,000 or so miles but the dealers are so unbelievably inept that I literally need to guide them and tell them what is exactl wrong and even then they it's a crap shoot if they get it right. Having the warranty in the first place is the result of GM's ineptitude and me calling to complain and them providing it to me as a consolation for poor service.

 

[deepblue]

It's the Bump/Clunk problem... There is a Service Bulletin on the problem and fix. Had mine done last fall under my CPO warranty. A common problem. I'll dig up the details.

Edit:

The Bump/Clunk fix involves replacing output shaft and drive shaft yoke in the transfer case.

Technical Service Bulletin #07-04-17-001C: EI07148 - Bump/Thump Noise Heard/Felt from Driveline or Rear suspension After Braking (Replace Output Shaft/Drive Shaft Yoke) - (Aug 25, 2008)

Condition

Some customers may comment on a bump or thump noise heard from the rear suspension or felt in the floor. The information below will affect vehicles with G67 Automatic Level Control rear suspension. This noise will typically occur at traffic lights after rapid stops. This noise is due to a combination of the rear electronic suspension attempting to level the vehicle and the driveline becoming unbound after these rapid stops.

Correction

Contact your DVM (District Service Manager) for approval prior to making any repairs. 4WD Vehicles - Replace the Output Shaft of the Transfer Case and the Drive Shaft Yoke and grease with P/N 12345879 (in Canada, use P/N 10953511) . Reinstall and evaluate operation. 2WD Vehicles - Replace the Output Shaft of the Transmission and Drive Shaft Yoke. Reinstall and evaluate operation.

 

[DJones]

It affects vehicles without air suspension systems too. Like mine.

The TSB doesn't provide P/Ns for the output shaft of the transfer case or transmission, or for the yoke. For that matter, I didn't know that the output shaft could be replaced.

 

[ahimon]

So I got this reoccurring problem on my Envoy XUV. It's got 160K on it and I pulled the shaft and greased the splines. That helped some but, the problem still exists. Any long term effects if I don't fix this?

 

[The_Roadie]

I can't imagine any downside.

 

[Denali n DOO]

So I got this reoccurring problem on my Envoy XUV. It's got 160K on it and I pulled the shaft and greased the splines. That helped some but, the problem still exists. Any long term effects if I don't fix this?

Funny this came up today. I'm actually dropping mine off at the Stealership tomorrow morning for this repair as per the TSB I found in this thread a couple weeks back. I've had that condition since about 43000km, and now at 135000 and can say that my bump is now way more frequent and stronger than before. But my rear air system pumps much more frequently now as well, so it's probably deflating much faster than before maybe allowing for a bigger drop (bang) when stopped. I finally found out how to make the bump happen, stand on trailer hitch to turn in pump and raise the back, go for short drive, wait at least a full min or so and slowly release the brake and Bang. I had to do it that way to show the dealership guy. I hope tomorrow's visit goes well, parts about $1200 and labour $500. That will most likley be the last warranty repair I get, it expired in Dec 2011. If you have warranty I'd be getting it done. That's my 2cents.

 

[Jkust]

Funny this came up today. I'm actually dropping mine off at the Stealership tomorrow morning for this repair as per the TSB I found in this thread a couple weeks back. I've had that condition since about 43000km, and now at 135000 and can say that my bump is now way more frequent and stronger than before. But my rear air system pumps much more frequently now as well, so it's probably deflating much faster than before maybe allowing for a bigger drop (bang) when stopped. I finally found out how to make the bump happen, stand on trailer hitch to turn in pump and raise the back, go for short drive, wait at least a full min or so and slowly release the brake and Bang. I had to do it that way to show the dealership guy. I hope tomorrow's visit goes well, parts about $1200 and labour $500. That will most likley be the last warranty repair I get, it expired in Dec 2011. If you have warranty I'd be getting it done. That's my 2cents.

I still have to get this addressed but it isn't happening as often now. I'll have to try your method above so when I bring it in I can show them. I'm getting a small noise in both sides of the front end as well now when going over a sharp bump slowly so will bundle up the service.

 

[ahimon]

Funny this came up today. I'm actually dropping mine off at the Stealership tomorrow morning for this repair as per the TSB I found in this thread a couple weeks back. I've had that condition since about 43000km, and now at 135000 and can say that my bump is now way more frequent and stronger than before. But my rear air system pumps much more frequently now as well, so it's probably deflating much faster than before maybe allowing for a bigger drop (bang) when stopped. I finally found out how to make the bump happen, stand on trailer hitch to turn in pump and raise the back, go for short drive, wait at least a full min or so and slowly release the brake and Bang. I had to do it that way to show the dealership guy. I hope tomorrow's visit goes well, parts about $1200 and labour $500. That will most likley be the last warranty repair I get, it expired in Dec 2011. If you have warranty I'd be getting it done. That's my 2cents.

How could you be getting this done under warranty? By the way, I have new air bags and shocks in mine so that has nothing to do with it in my opinnion.

 

[McGMT]

How could you be getting this done under warranty? By the way, I have new air bags and shocks in mine so that has nothing to do with it in my opinnion.

Certain things GM will sometimes cover under warranty even if you have over 100k on the vehicle... Depends on the circumstances and the dealer also...

 

[deepblue]

By the way, I have new air bags and shocks in mine so that has nothing to do with it in my opinnion.

"This noise is due to a combination of the rear electronic suspension attempting to level the vehicle and the driveline becoming unbound after these rapid stops."

 

[Denali n DOO]

How could you be getting this done under warranty? By the way, I have new air bags and shocks in mine so that has nothing to do with it in my opinnion.

The dealership could never duplicated the noise when I took it in during warranty. On my last visit before the warranty ended (Dec 2011)they looked again but found nothing. when I was able to duplicate the bump for them 3 weeks ago and provided them the TSB I guess they felt compelled to doing the repair.

 

[CLEAR]

Same issue here. 2004 Rainier V8 AWD with rear air suspension. Very annoying. I tried greasing the yoke, no better. It even clunks like crazy in the morning when I first start it and the airbags are filling. I dont really want to spend a bunch of money on it though. Any cheap advise?

 

[ahimon]

I have no ideas. I greased it and it was better for a while but, now it has come back again and is like 2xs a week.

 

[deepblue]

Unfortunately, the fix is not cheap or easy...

Replace the Output Shaft of the Transfer Case and the Drive Shaft Yoke and grease with P/N 12345879

 

[Denali n DOO]

Unfortunately, the fix is not cheap or easy...

Replace the Output Shaft of the Transfer Case and the Drive Shaft Yoke and grease with P/N 12345879

For my warranty repair the "Shaft AR-GM part 15194472" was the only part changed. Part cost was $626 and labor was 1 hour @109. I have had no issues since it was replaced.

 

[madklicker2]

I've had this problem since I bought my truck a couple years ago at about 183,000 miles. Now it has over 208,000 miles. I also have rear air suspension. I usually get this bump/clunk in the mornings, especially when it's cold outside, as the airbags inflate to raise the truck. Sometimes, the sticking is bad enough to keep tension on the driveline until about a quarter to half mile away at the first stop light, where it finally releases. I've read before about how greasing the yoke would fix the issue, and was thinking about taking care of it soon for a relatively cheap fix. But, now I find this thread and read that the grease may not help much after all. Bummer....

It's good to hear GM has a fix for it, even if it is expensive. I wonder if the repair would be considered warranty work and covered for my truck, considering its age and the miles on it.... I don't have any extended warranties on it, though (bought it as-is).

If not, does anyone have any advise on doing the work myself (assuming the parts are available)?

 

[deepblue]

For my warranty repair the "Shaft AR-GM part 15194472" was the only part changed. Part cost was $626 and labor was 1 hour @109. I have had no issues since it was replaced.

Good deal, glad it worked...

 

[Denali n DOO]

Good deal, glad it worked...

Didn't last long though....only 7 months or about 20,000 kms, now the bump is back

For my warranty repair the "Shaft AR-GM part 15194472" was the only part changed. Part cost was $626 and labor was 1 hour @109. I have had no issues since it was replaced.

The part above is the only part they changed...

It's the Bump/Clunk problem... There is a Service Bulletin on the problem and fix. Had mine done last fall under my CPO warranty. A common problem. I'll dig up the details.

Edit:

The Bump/Clunk fix involves replacing output shaft and drive shaft yoke in the transfer case.

Technical Service Bulletin #07-04-17-001C: EI07148 - Bump/Thump Noise Heard/Felt from Driveline or Rear suspension After Braking (Replace Output Shaft/Drive Shaft Yoke) - (Aug 25, 2008)

Condition

Some customers may comment on a bump or thump noise heard from the rear suspension or felt in the floor. The information below will affect vehicles with G67 Automatic Level Control rear suspension. This noise will typically occur at traffic lights after rapid stops. This noise is due to a combination of the rear electronic suspension attempting to level the vehicle and the driveline becoming unbound after these rapid stops.

Correction

Contact your DVM (District Service Manager) for approval prior to making any repairs. 4WD Vehicles - Replace the Output Shaft of the Transfer Case and the Drive Shaft Yoke and grease with P/N 12345879 (in Canada, use P/N 10953511) . Reinstall and evaluate operation. 2WD Vehicles - Replace the Output Shaft of the Transmission and Drive Shaft Yoke. Reinstall and evaluate operation.

This says replace "output shaft" and the "drive shaft yoke", so there is suppose to be 2 parts to solve the problem? If so, are the 2 parts under 1 product code or did I only get 1 part changed? Which part did I not get, mine said "shaft AR" and I don't know which one of the two parts this refers to...Why would they only put one part in if it calls for two?

I'm gonna ask that it be fixed again...now I'll have to go back to the other incompetent dealership.

 

[mrphoenix80]

Parts are normally broken down per part and not 2 under the same part number unless its a kit. But judging by the fact that they only billed 1hr labor they replaced the yoke and not the output shaft. To replace the output shaft would mean disassembling the transfer case and replacing the shaft. I am giving an educated guess of 4 to 5 hrs warranty labor time + fluid and sealant.

In the past I have had good luck with lubing the shaft. GM has a special lube for this oddly enough its called "Special Lube" on the pint can. I dont have the P/N handy as the can is on my bench at work. But I remove the shaft and PACK the inside of the yoke about 1/2 full with a screwdriver so its down in the bottom of the yoke. Then when I reinstall the shaft if it is hard to put in due to the grease I know I got enough in there. This normally lasts for 15 to 20k miles so it is a cheaper route than replacing the output shaft. But if memory serves me right the grease is like $30-$40 for a pint can and it will do about 5 shafts.

 

[Denali n DOO]

Parts are normally broken down per part and not 2 under the same part number unless its a kit. But judging by the fact that they only billed 1hr labor they replaced the yoke and not the output shaft. To replace the output shaft would mean disassembling the transfer case and replacing the shaft. I am giving an educated guess of 4 to 5 hrs warranty labor time + fluid and sealant.

In the past I have had good luck with lubing the shaft. GM has a special lube for this oddly enough its called "Special Lube" on the pint can. I dont have the P/N handy as the can is on my bench at work. But I remove the shaft and PACK the inside of the yoke about 1/2 full with a screwdriver so its down in the bottom of the yoke. Then when I reinstall the shaft if it is hard to put in due to the grease I know I got enough in there. This normally lasts for 15 to 20k miles so it is a cheaper route than replacing the output shaft. But if memory serves me right the grease is like $30-$40 for a pint can and it will do about 5 shafts.

Thanks for the information, I'm going to ask about this since it's an issue again. I'll let you know how I make out with it.

 

[Zapp Brannigan]

Glad I searched the New Posts. I have been having this problem intermittently, now I know what to tell the guys at the shop, maybe I can get it taken care of!!

Thanks Guys!!

Anyone have a link to this on the OS, as was referenced?

 

[MDBT]

I read a number of threads on the topic but IIRC this was my focal point.

Feeling of being bumped when stopped - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

 

[Skypie]

I had this same issue with my 2006 Saab. It felt like the car would jerk forward when sitting at a light. I had amechanic diagnose it as amajor miss-fire. I changed my spark plugs and the issue went away. One of the old plugs was quite corroded and another was missing sone ceramic covering. At the time I was at 100,000 miles or so.

 

[deepblue]

I had this same issue with my 2006 Saab. It felt like the car would jerk forward when sitting at a light. I had amechanic diagnose it as amajor miss-fire. I changed my spark plugs and the issue went away. One of the old plugs was quite corroded and another was missing sone ceramic covering. At the time I was at 100,000 miles or so.

The "Bump/Clunk" issue has a distinct feel and comes from the center of the vehicle towards the rear. It really feels like someone tapped your bumper.