: Is my front transfer case going out?



mikedyk43
10-15-12, 01:04 AM
Hey all,

Over the last month or so I've noticed a vibration in the front end of my Escalade and at first I thought it was an unbalanced tire, but recently it has gotten worse and I notice that it is not constant. It seems to be most noticeable on hard acceleration and not as bad on deceleration. I've had the wheels aligned knowing that an alignment shop would tell me alignment isn't possible if I had any bad bushings, ball joints or tie rods. I got under the truck the other day and don't feel any play in the CV joints so I'm thinking it is most likely the transfer case. I found some bearing rebuild kits for my transfer case, but wanted to know if anyone here has had this before or had any insight on a solution other than the one I mentioned. Thanks in advance for any help.

the cadillac man
10-15-12, 01:32 AM
Hey all,

Over the last month or so I've noticed a vibration in the front end of my Escalade and at first I thought it was an unbalanced tire, but recently it has gotten worse and I notice that it is not constant. It seems to be most noticeable on hard acceleration and not as bad on deceleration. I've had the wheels aligned knowing that an alignment shop would tell me alignment isn't possible if I had any bad bushings, ball joints or tie rods. I got under the truck the other day and don't feel any play in the CV joints so I'm thinking it is most likely the transfer case. I found some bearing rebuild kits for my transfer case, but wanted to know if anyone here has had this before or had any insight on a solution other than the one I mentioned. Thanks in advance for any help.

The way it sounds it may be like the transfer case and not the front differential but without hearing it in person it is hard to pinpoint where it is coming from(like my ac tensioner whine)
Given the wheel alignment went good I doubt it's the front differential
Ps my ac tensioner pulley does the same thing with the whine coming and going with the engine rpm(kinda annoying)
One way to tell is find a down hill slope and drop the truck in neutral and turn off the engine to see if you can pinpoint if it does come from the transfer case(most likely) or the differential
Keep in mind that the drive shafts has u joints at each end also(which are hard to pinpoint)

Just make sure there is no traffic in the area you try the steps I mentioned(don't want you to wreck)
I hope I was helpful

mikedyk43
10-15-12, 02:32 AM
I have put it in neutral going down hill and the vibration is still present. So it is not RPM related, but certainly suspension/drivetrain related. BTW there is no noise, just vibration.

the cadillac man
10-15-12, 02:52 AM
I have put it in neutral going down hill and the vibration is still present. So it is not RPM related, but certainly suspension/drivetrain related. BTW there is no noise, just vibration.

Then it most likely is the transfer case it may not be causing the rear to vibrate due to the way it's setup(the front is geared at a different ratio then the rear)
The transfer case is a 60 rear 40 front hence the different gear ratios
Also the front axle (if I am right) is a 4:10 ratio while the rear is a 3 something (I forgot what it is for the rear)

smelly$cat
10-15-12, 02:08 PM
Is this really true? Different gear ratios on the front and rear? Why would they do that? If hypothetically the transfer case spun the front and rear outputs at different rates (to match the diff gear ratios) the wheels would still turn the same. I just don't get the point of this.


Then it most likely is the transfer case it may not be causing the rear to vibrate due to the way it's setup(the front is geared at a different ratio then the rear)
The transfer case is a 60 rear 40 front hence the different gear ratios
Also the front axle (if I am right) is a 4:10 ratio while the rear is a 3 something (I forgot what it is for the rear)

the cadillac man
10-15-12, 04:16 PM
Is this really true? Different gear ratios on the front and rear? Why would they do that? If hypothetically the transfer case spun the front and rear outputs at different rates (to match the diff gear ratios) the wheels would still turn the same. I just don't get the point of this.



It is true as I pulled up the rpo codes on the sticker in the glove box and it shows a different axle ratio for the front and rear axles the transfer case does not spin at different speeds
And plus if the front and rear axle ratios were the same it would be more like a 50/50 power split instead of 60/40 like it is now
The last part of your question I don't know as I have yet to see a transfer case that does(unless it does it automatically)

smelly$cat
10-15-12, 04:32 PM
That is interesting. I would say though that if the diffs actually do have 2 different ratio's, then the outputs (front and rear) from the transfercase would have to be spinning and different speeds, else, I would think everything would bind up. Maybe the outputs do spin at different speeds and the diff with the higher ratio (rear I presume) would then have a higher power advantage over the other. The higher the ratio, the more torque you will have.

For example in my 2wd suburban, it came from the factory with 3.73 gears and I had them replaced with 4.88's due to the 37" tires (don't ask...). It now has a lot more torque (easier for the engine/tranny) to turn that axle.

Do you know what the 2 different ratio's are?

This has got me curious for sure...

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Honestly, I would have guessed they had the same ratio's front and rear and that the transfer case electronically controlled how much power it would send to the front or rear drive lines.

the cadillac man
10-15-12, 04:48 PM
That is interesting. I would say though that if the diffs actually do have 2 different ratio's, then the outputs (front and rear) from the transfercase would have to be spinning and different speeds, else, I would think everything would bind up. Maybe the outputs do spin at different speeds and the diff with the higher ratio (rear I presume) would then have a higher power advantage over the other. The higher the ratio, the more torque you will have.

For example in my 2wd suburban, it came from the factory with 3.73 gears and I had them replaced with 4.88's due to the 37" tires (don't ask...). It now has a lot more torque (easier for the engine/tranny) to turn that axle.

Do you know what the 2 different ratio's are?

This has got me curious for sure...

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Honestly, I would have guessed they had the same ratio's front and rear and that the transfer case electronically controlled how much power it would send to the front or rear drive lines.

I ain't sure what they are

I pulled up the info almost 2years ago when I first got my truck but I think the rear is a 3.73 no doubt the front is a higher number
I forgot that the transfer case can be geared with different ratios for front and rear output shafts
But each transfer case is different so you can't compare the all wheel drive escalade to say a hummer h2 because they have different transfer cases and different axle ratios I know the rear in the hummers (not the ones with the 6.2) is 4:10

mikedyk43
10-15-12, 10:38 PM
The gearing uses different ratios to achieve different torque values front to rear, but the speed of the wheels is the same. 40% torque in the front 60% torque in the rear.

Back to my original question, has anyone had experience with a failing transfer case and was able to resolve it without replacement or taking to a shop?

CaddyDude10
10-18-12, 10:49 AM
The gearing uses different ratios to achieve different torque values front to rear, but the speed of the wheels is the same. 40% torque in the front 60% torque in the rear.

Back to my original question, has anyone had experience with a failing transfer case and was able to resolve it without replacement or taking to a shop?

Naw my case was making a loud noise when turning,had to fully replace.got a good deal on a used one though

mikedyk43
11-08-12, 01:55 AM
I finally found the source of my vibration and it was not at all what I had expected. A little over a year ago my wife had a rear tire blow out while on the highway. We put a new tire on and everything was good to go. As it turns out everything was not good, that rim hit the ground when the tire blew and made it slightly out of round. It was slight enough that four different tire balances by four different professionals didn't notice it including the Cadillac dealer that was looking for a vibration. It ultimately wore out the bearing in the rear axle which is why the shaking had got so bad recently. I replaced the rim and it is smooth as silk now.

the cadillac man
11-08-12, 02:25 AM
I finally found the source of my vibration and it was not at all what I had expected. A little over a year ago my wife had a rear tire blow out while on the highway. We put a new tire on and everything was good to go. As it turns out everything was not good, that rim hit the ground when the tire blew and made it slightly out of round. It was slight enough that four different tire balances by four different professionals didn't notice it including the Cadillac dealer that was looking for a vibration. It ultimately wore out the bearing in the rear axle which is why the shaking had got so bad recently. I replaced the rim and it is smooth as silk now.

That's great news

I am wondering if a bearing is going in my tranny as i can put it in n and no noise regardless of engine rpm or speed(never noticed until after I had the belts and tensioners replaced other then that it shifts fine and doesn't slip(just whines)