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Westlotorn

Front Differential Noise

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Just curious if this is a common issue with GM Tahoe. My 2002 which uses the 4wd feature a lot in the winter has developed a loud bearing growl in the front differential. 4.10 gears, 5.3L.

Fluid has always been full and has been changed once even though the truck has only 80,000 miles.

 

I expect to do a full rebuild on this unit but I thought I would see what you guys have seen.

 

This is a Lake Tahoe truck so 4wd for snow is used frequently. I would guess maybe 20,000 miles total in 4wd. I would think this to be no problem.

 

Any tips for a quick fix are appreciated.

 

Thanks

 

Mark

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Pull the diff apart and check it out, simple enough. If you have never done this before just get yourself a solid pinion spacer so you dont have to use those crappy crush sleeves when you put it back together so if you make a mistake your not running back to the store to get a new crush sleeve. Would definitly check the hub bearings first though as stated above.....

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Pull the diff apart and check it out, simple enough. If you have never done this before just get yourself a solid pinion spacer so you dont have to use those crappy crush sleeves when you put it back together so if you make a mistake your not running back to the store to get a new crush sleeve. Would definitly check the hub bearings first though as stated above.....

Thanks for the reply, This truck operates smoothly and without noise when not in 4wd. Noise is speed related, increase linear with speed.

 

Do you think it could be a Hub Bearing when it is only noisy when in 4wd? I assume you are talking of the Front Wheel Hub Bearing.

 

Mark

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This is difficult to judge without hearing it myself. If it ONLY does it in 4wd its most likely a differential problem but it could be anything from a Driveshaft to a CV shaft issue. I dont know what your mechanical ability is or how familiar you are with these trucks but if it were mine id start with the driveshaft, check stupid stuff like U-joints. Probably check the hub assembly as well but I doubt that is the issue. Then id make my way into the differential, it can be pulled out, gone through and put back in, in a matter of hours, its not difficult.

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This is difficult to judge without hearing it myself. If it ONLY does it in 4wd its most likely a differential problem but it could be anything from a Driveshaft to a CV shaft issue. I dont know what your mechanical ability is or how familiar you are with these trucks but if it were mine id start with the driveshaft, check stupid stuff like U-joints. Probably check the hub assembly as well but I doubt that is the issue. Then id make my way into the differential, it can be pulled out, gone through and put back in, in a matter of hours, its not difficult.

Thanks again, I have only rebuilt rear differentials in the past. I am very comfortable inside an engine but a rookie in these aluminum case front ends. I will wait till I can spare this car and open it up. Trying to get prepared in advance. At this point I am pretty sure the noise is in the Front diff but I won't take it apart without a serious check to find that noise.

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This is difficult to judge without hearing it myself. If it ONLY does it in 4wd its most likely a differential problem but it could be anything from a Driveshaft to a CV shaft issue. I dont know what your mechanical ability is or how familiar you are with these trucks but if it were mine id start with the driveshaft, check stupid stuff like U-joints. Probably check the hub assembly as well but I doubt that is the issue. Then id make my way into the differential, it can be pulled out, gone through and put back in, in a matter of hours, its not difficult.

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This is difficult to judge without hearing it myself. If it ONLY does it in 4wd its most likely a differential problem but it could be anything from a Driveshaft to a CV shaft issue. I dont know what your mechanical ability is or how familiar you are with these trucks but if it were mine id start with the driveshaft, check stupid stuff like U-joints. Probably check the hub assembly as well but I doubt that is the issue. Then id make my way into the differential, it can be pulled out, gone through and put back in, in a matter of hours, its not difficult.

 

Well, it is time to fix the Front Differential.

I put the whole truck up on sturdy jackstands. Had the 4wd engaged and ran it. Noise in Front Diff starts at low speed and increases with speed. Put a listening Stethescope on the Front diff, input shaft bearing has a low growl and the Drivers side output bearing is leaking and has a louder growl. Pass side output shaft is pretty quiet. I did finally find my slight vibration that started at 65 and stayed on at all faster speeds, the front of the rear driveshaft had lost its balance weight and there was a detectable vibration at the transfer case rear output shaft because of the missing weight. A shaft balance cured this issue.

 

When driving the diff growls loudly on sharp 4wd turns. Never done on dry pavement.

 

I guess it is time to pull the whole thing out and rebuild it. I see many low mileage diff's for sale but always 3.42 or 3.73 not my 4.10 ratio.

I have a Magnetic mount dial indicator and basic pullers is that enough to set up this front differential. i think this is an aluminum or Magnesium case on the differential.

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Parts all arrived and I chickened out after removing the differential. I was going to attempt this repair myself but decided to take it to a pro, I took it to a friends shop that has experience with these IFS GM differentials, builds a few every month.

He claims the GM design wears out the front carrier bearings and in some cases spins a bearing making carrier replacement mandatory. They don't cost much so not a large issue.

 

I asked about the noise issue in these. I was told the noise is most often caused by bad wear on the gears, the ring and pinion are reverse cut for this differential and he said when the bearings go out many times the ring and pinion get damaged. He says he can assemble with this wear if a person accepts the fact that the gears will whine. If you want them quiet he recommends new ring and pinion if there is damage to the old units. Claims this wear and damage is most common in the Full Time version rather than the part time units.

 

Most common failure involves the Drivers side Carrier bearing. First sign of wear on this bearing is a leaking shaft seal on the drivers side of the differential, mine is leaking.

 

I will install the rebuilt unit this weekend providing no troubles and it is ready to go, and report on noise levels.

Edited by Westlotorn
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Rebuilt Differential is installed and very quiet!!!!!!!!!!!!!!! Tested in 4wd up to 80mph. I barely detected an increase in sound to tell me I was actually engaged in 4 x 4. I am very happy. I had this one rebuilt by a friend Jerry at Prentice Enterprize in Rancho Cordova, CA.

I have known Jerry for 25 years and trust his work.

I had him build it because I was afraid I would miss something and have to do this job twice. It was worth it for his experience.

I pulled it out, an easy 2 hour job from lifting the hood till cleaned up. I put it back in. Took me 2 1/2 hours, needed help with the floor jack to work it back in to position.

Both in and out would have been faster but I had previously broken my puller and I could not get the idler arm or pitman arm to break loose so I could move the control arm out of the way to drop the differential.

I ended up removing the bolts for the Power Steering box to gain the clearance necessary to drop the differential. Mark it first to make sure you get it back in the same position.

 

The Carrier in my differential had worn and needed replacement. When the factory bearing adjustment lock comes loose the Carrier bearings start moving side to side and the extra play places the axle load on the needle bearing in the Carrier which now starts to pick up the weight of the axle shaft that the Carrier bearing holds when properly adjusted.

The loose Carrier Bearing was self destructing from the pounding it was exposed to working while loose, the Needle bearing cage spun in the Carrier and wore it out to the point where a new needle bearing was too loose to install making carrier replacement necessary.

 

A sure sign of the loose drivers side Carrier bearing is the leaking oil seal where the axle shaft enters the differential on the drivers side. Jerry says this damage is very common to this differential. He also says that many times the loose bearings will cause damage to the ring and pinion, once the Ring and Pinion are damaged from operating while loose they need to be replaced or you will never get it quiet. These reverse cut Ring and Pinion gears will be noisy if not perfect.

 

I can say mine was noisy before and quiet now. Glad I went to Jerry. He new all the tips for a quiet rebuild and I got it back in 2 days.

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Glad to hear that it worked out!

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So I have the same problem. I have a 1999 Chevy Tahoe. It makes a lot of noise when slowing down in 4 wheel drive. My mechanic diagnosed it as front carrier bearing wear which caused coast side pinion wear. He says that it needs replacement, I think he wants to replace the whole axle with a used one. estimated cost $1100. is it hard to just switch out the front drive carrier and pinion gear? are their any pressed in parts or is it bolt up? If I went and got one from a junk yard with low miles ($350), could I do it my self? I have not been able to find anything about how to do it on line or in books I have looked at. Any and all help would be welcome, the more detailed the better.

Edited by 99 chevy tahoe

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" The Carrier in my differential had worn and needed replacement. When the factory bearing adjustment lock comes loose the Carrier bearings start moving side to side and the extra play places the axle load on the needle bearing in the Carrier which now starts to pick up the weight of the axle shaft that the Carrier bearing holds when properly adjusted.The loose Carrier Bearing was self destructing from the pounding it was exposed to working while loose, the Needle bearing cage spun in the Carrier and wore it out to the point where a new needle bearing was too loose to install making carrier replacement necessary.A sure sign of the loose drivers side Carrier bearing is the leaking oil seal where the axle shaft enters the differential on the drivers side. Jerry says this damage is very common to this differential. He also says that many times the loose bearings will cause damage to the ring and pinion, once the Ring and Pinion are damaged from operating while loose they need to be replaced or you will never get it quiet. These reverse cut Ring and Pinion gears will be noisy if not perfect. "

 

 

 

Good Job Sir - wow good information

 

Thanks

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Sounds sorta like my truck. Mine makes a humming noise in 2wd at random, mainly under acceleration and always at 50-65 mph. it's very loud and constant under acceleration in 4wd hi/low and "auto". Oddly, with the front drive shaft removed, the sounds go away entirely in 2wd and the u joints seem fine.....

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