Changing Differential gears

Has any one changed gears and what tools were used? I'm thinking about doing mine. The 3.42 gears seem about right for towing. I think an open carrier is best for towing. Anyone think different?

Thanks in advance

Randy

A posi is always better for everything. The FSM has all the info you need. You should get one if you are going to go that far into the car. When you run into a situation, and panic, you can rely on the FSM to walk you through the install.

Fred Kiehl wrote:

A posi is always better for everything.

Other than lighting up the tires and getting out of a snow bank, what else is a posi good for? After you have done racing for 10 seconds and youv'e climbed out of the snowbank, I find that posi is more of a hinderence than anything else. I have always preferred an open axle for towing and normal driving, especially in bad weather. Its far more predictable. Guess its all about what you want, where you drive your car and what you want your car to do.

As Fred said, start out with the FSM and do some research on the net. Most gear companies have good videos and or installation manuals to read. Only you can decide if you feel your mechanical abilities are up to the task. Its not hard, but needs a ton of patience. Special tools remove some of the frustration but it can be done out of most tool boxe except for maybe a can of witness grease (to check your pinion depth and gear lash) and an inch/lb torque wrench to set your pinion bearing pre-load. The first time is always the hardest.

Bill.

I like a posi for towing. Particularly in a muddy situation, snow or pulling a boat out of the water.

convert2diesel wrote:

Fred Kiehl wrote:

A posi is always better for everything.

Other than lighting up the tires and getting out of a snow bank, what else is a posi good for? After you have done racing for 10 seconds and youv'e climbed out of the snowbank, I find that posi is more of a hinderence than anything else. I have always preferred an open axle for towing and normal driving, especially in bad weather. Its far more predictable. Guess its all about what you want, where you drive your car and what you want your car to do.

As Fred said, start out with the FSM and do some research on the net. Most gear companies have good videos and or installation manuals to read. Only you can decide if you feel your mechanical abilities are up to the task. Its not hard, but needs a ton of patience. Special tools remove some of the frustration but it can be done out of most tool boxe except for maybe a can of witness grease (to check your pinion depth and gear lash) and an inch/lb torque wrench to set your pinion bearing pre-load. The first time is always the hardest.

Bill.

If the situation occurs that you need a posi, and have an open rear, you will regret not installing it. An ounce of prevention is worth a 100 pounds of regret. It is nice to know you have it when you need it. You generally do not know it is there, unless you need it.

Posi and icy/slushy/snowy roads sucks.

jayoldschool wrote:

Posi and icy/slushy/snowy roads sucks.

Precisely

Bill

I never had a problem on any kind of road with a posi, and was thankful for it in snow, on ice, and in any poor driving condition.

Quote :

Has any one changed gears and what tools were used? I'm thinking about doing mine

I changed from an open 2.56 gears to posi with 3.08 gears.
Did the work myself ,but on a lift.
To save a lot of fitting time you will need a Pinion depth gauge.
This allows you to set the pinion gear at the proper depth the first time.
If you don't have a press ,you can make or purchase a fitup bearing for the pinion gear,which is used to determine the shims required for the proper pinion depth,without having to use a press to remove the bearing.The fit up bearing slides on and of by hand.
Once the proper shim thickness is determined you slide the fitup bearing off and press on the permanent pinion bearing.
You will also need a dial indicator.
Other than that it only requires a socket set ,and standard tools.
The gears must be set very precisely in accordance with manufacturers specifications or you will have problems.
I find the posi a big improvement over an open differential under all driving conditions,if you know how to use it.

I had the honor to "help" with my 3.42 and posi install...glad I got the posi too
You can see some pics on page 9 of my thread.

https://gmlongroof.4umer.com/t6058p160-getting-jade-ready-for-wagonfest-and-other-updates-as-they-come

Chris

Fred Kiehl wrote:

... FSM has all the info you..., ...you can rely on the FSM to walk you through the install.

Please forgive my ignorance here, I can usually figure out most acronyms, but what in the world is FSM? I have thought through many possible ideas but none make sense to the topic. PLEASE enlighten me! Or should I just contract The "FSM" to find out what it means? I've been WAG'n the wagon lingo, but the FSM throws me for a loop. Call me a newb.

But what I can tell you is that when the STFT is running a (?)% the LTFT will follow suit depending on how far off the MAF or O2 is skewed. The EGR can can also skew the MAP. Engine typically runs in CL for proper Stioch to occur, but many other factors can be involved whether it is the HO2S B1S1 or B2S2... you get my point

gmtech wrote:

Fred Kiehl wrote:

... FSM has all the info you..., ...you can rely on the FSM to walk you through the install.

Please forgive my ignorance here, I can usually figure out most acronyms, but what in the world is FSM?

Factory Service Manual.

I think you're being serious, as it's my "default state" to take people at their word, but...

gmtech wrote:

But what I can tell you is that when the STFT is running a (?)% the LTFT will follow suit depending on how far off the MAF or O2 is skewed. The EGR can can also skew the MAP. Engine typically runs in CL for proper Stioch to occur, but many other factors can be involved whether it is the HO2S B1S1 or B2S2... you get my point

Lolwhut? I got dizzy and fell off the Internet reading that. It's a long way down.



Be careful if you're joking around, someone will take you seriously if you're not clear about that. I know most of those abbreviations are real and what they mean, not sure about a few of the others. And you have an "i" in the wrong place, which I just had to tell you.

uxwbill wrote:

Factory Service Manual.

Thanks for the info! I can now sleep tonight.

uxwbill wrote:

And you have an "i" in the wrong place, which I just had to tell you.

Apparently so, as my "I" could not see what FSM stood for. I'm good to go now.

Thanks again.

etsfl wrote:

Quote :

Has any one changed gears and what tools were used? I'm thinking about doing mine

This allows you to set the pinion gear at the proper depth the first time.
If you don't have a press ,you can make or purchase a fitup bearing for the pinion gear,which is used to determine the shims required for the proper pinion depth,without having to use a press to remove the bearing.The fit up bearing slides on and of by hand.
Once the proper shim thickness is determined you slide the fitup bearing off and press on the permanent pinion bearing.
.

So where does one get this "fitup" bearing? I have never seen one and it sounds like a good investment.

You make it. You take a pinion bearing, put it in a vise, and grind out the inside so it slips on and off the pinion easily.

Quote :

But what I can tell you is that when the STFT is running a (?)% the LTFT will follow suit depending on how far off the MAF or O2 is skewed. The EGR can can also skew the MAP. Engine typically runs in CL for proper Stioch to occur, but many other factors can be involved whether it is the HO2S B1S1 or B2S2... you get my poin

Got it all except " HO2S B1S1 or B2S2".

jayoldschool wrote:

You make it. You take a pinion bearing, put it in a vise, and grind out the inside so it slips on and off the pinion easily.

Also check to be sure that your test bearings are the same make and number as the ones you are finally going to install (I just buy two sets and modify one). There are dimensional differences between bearings, sometimes within the same manufacturers. Measure both with your calipers to make sure they are both the same thickness.

Bill

jayoldschool wrote:

Posi and icy/slushy/snowy roads sucks.

The worm-gear units like the truetrac are a lot nicer to drive in the winter than the clutch type.

I do have to crawl under the wagon. I don't have a friend with a hoist. I do have a FSM. I'm looking for the tools to help me with the gear change. I'll have lots of pics. I may pull out the whole rear to work on it. Then I can acid treat all the mounts and Por15 everything. If I lived in Florida or SC, I would not worry about traction for the snow. Nice pics of the gear change.
Oh yea the fit up bearing. You have to polish a little metal off the pinion bearing I.D.. That helps to shim the pinion. I wish I could do it without replacing the carrier. But, when you go up in ratio from 2.56:1 it will take a different carrier. Randy's ring and pinion looks like they have all the parts. I have a magnetic dial indicator base. I can use that for backlash.

Thanks for the ideas
Randy

There are 2 types of pinion heigth tools. Check with Summit for them. If you are using aftermarket gears, the one for them is about $28. The others are about $180+.