Regearing a 12 bolts.Please help

[COKE]

Good day,

I,m changing my 3.42 gears for a 4.10 set from Motive Gear.
I think that i have read every article wich talks about how to regear a 12 bolts,but i have a lot of doubts.

For example,when should i check the carrier preload?
Can i check it with the pinion installed?

Thanks for your time

 

[COKE]

This is my contact pattern in this moment.Is it too much Toe?
It has 0.010" backlash so i can,t increase it very much to pull the mark toward the Heel.

Please if somebody knows about how to set up differentials,any help will be very much apreciatted.It is important.
I have some doubts ,and i don,t find the answer in the web pages.

Thanks in advance
Jorge

 

[rufusbooth]

There are people here that have set up way more differentials than I (never done a 12 bolt myself) but from what I can see on your pattern it appears that your pinion is set too deep. Pull that pinion back a little bit. Once you pull the pinion out a bit you will need to shift your carrier over closer to the pinion to correct your backlash again. It is a dance .

The preload is generally set in 2 steps.

First check pinion preload with just the pinion installed, no carrier at all.

Once that is set, you then do a combined preload check of both the pinion and carrier together.

Hopefully someone with more experience than I will jump in to correct me if I am incorrect.

Cheers,

Rufus

 

[COKE]

Thanks Rufusbooth,
These pics are taken with 0.078" pinion shim wich i think that is very much according to charts like this http://image.hotrod.com/f/9544893+w750+st0/p159696_image_large.jpg

That is why i,m thinking that i,m doing something wrong.

Regards
Jorge

 

[rufusbooth]

I would call those shim thicknesses "starting points" to get you in the ball park. You are actually fairly close to having a runnable pattern there from what I can see.

Pull out .010 of shim and run another pattern and see where you sit. Make sure that when you run the pattern that you put as much tension on the ring while you are turning the pinion as you can. That will give you a better pattern.

Rufus

 

[COKE]

Good day,
I removed the pinion and i started from 0.30" shim like the chart says ,just to see what happens.
The contact pattern was in the top of the tooth so i went increasing the shims .
This is with 0.062" pinion shim.Still too much close to the top:

Coast:

This is with 0.070" pinion shim.Better centered between the top and the root:

Then i can get the correct pinion depth ,the pattern is well centered between the Top and the Root.(It was better with 0.078" like you can see in the other day pictures)
The trouble is to center it between the Heel and the Toe.

Regards.

 

[Hogback Fabrication]

The trouble is to center it between the Heel and the Toe.

Don't worry about centering the pattern between the heel and toe, due to housing differences etc. that's often impossible. The only real important thing is the contact pattern in relation to the tip and root.

Look at page 15 here.

Also, your pinion looks too deep in all of your pictures.

 

[COKE]

Thanks Chris
That is a good new because it was driving me crazy.
I also found this page wich says that a distance of 3/8" between the toe and the pattern would be correct.
http://www.roadranger.com/ecm/groups/public/@pub/@eaton/@roadranger/documents/content/shais-168.pdf


Maybe the picture does not show the pattern very well,but in this one it is decently centered.It has a 0.078" pinion shim between the gear and the bearing.I could increase it a little more ,but not very much.
Maybe 0.005 at most.