Can I build a diff myself, and anybody used this tool?

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CultClassik

CultClassik

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I may be getting ahead of myself as I've got other issues going with the car right now but I'm trying to plan some things out.

I've never touched a RWD diff before. I have a bare 741 housing, a new Truetrac diff and new 3.55 gears. I'll pick up the full install kit, and I should have everything.

I do already have a dial indicator with adjustable arm/mag base. Now if I have to buy a pinion depth tool, I'd probably just pay to have the thing done as it won't save enough money for me to go through the hassle. However, I saw this and have read a few good things about it:
http://www.summitracing.com/parts/rat-10007

Has anyone tried it? People that have assembled a diff and set up gears before, should I attempt this myself or just bite the bullet and pay the $250 to have it done?

As always, thanks in advance for your help and opinions.
 
For what it cost to replace a set of ring gears and knowing how long it takes to wipe them out (about30 second), I figure I'll pay to have Randy ring and pinion build my next one.
 
Right...but I'd think you'd know looking at the pattern if it's bad enough to kill your gears in 30 seconds. How about guys that have done this? I've been reading what I can find on the procedure. Is this FSM sufficient?
 
With the internet there is a wealth of information and visual aids that make doing this as a DIY project easier than ever - if you have the right tools.

Take a look at what tools you still need to get to do the job right and add up their cost. If you are "one and done" with the gear change you might be better off having someone else do it for you. However if you think you might be doing more than one gear change in the future it might be worth it to invest in the tools, learn how to do it, and save $$$ over the long-haul.
 
No. It's never been done before.
 
I have done many set up's over the years. Probably the most important thing is getting the Pinion depth correct. The tool you referenced from Summit may do the job. I have never used one. That being said, the correct tool to use is much more comprehensive that that one. The tool I'm talking about. mounts in the diff bores, and does a much better job. I will add, that if you are only changing pinion bearings, most of the time, you can reuse the original set up shims and be fine. I does sound, however that you are changing the set completely. In that case you will have to set the pinion depth from scratch. On most gear sets, the pinion depth is scribed on the nose of the pinion gear. You can try it initially with the original shims, but you may need to add or subtract from there to get it correct. That depth scribed, is from the centerline of the diff to the face of the pinion after installed. After that, you need to make sure that you set the preload on the pinion bearings. Then you can install the ring gear carrier and set side preload. As you set preload on the ring carrier you will have to check the ring - pinion clearance. Most are somewhere around .07 - .011. Double check that a few times and maybe run a test pattern. It is not as hard as people make it out to be, If you take your time and have the correct tools. Hope that helps.
 
I would get a second large pinion bearing exactly like the one in the kit. Take a sanding cylinder and increase the size so it slides on and off the pinion and you can try a shim pack, put it together and try it several times if needed. When you have it correct press on the kit bearing, this is usually called a Set Up Bearing.
 
Coronet 500 said:
I would get a second large pinion bearing exactly like the one in the kit. Take a sanding cylinder and increase the size so it slides on and off the pinion and you can try a shim pack, put it together and try it several times if needed. When you have it correct press on the kit bearing, this is usually called a Set Up Bearing.
Click to expand...

Yup!! My fingers got tired of typing. LOL
 
Thanks for the info everyone. I've read about getting another bearing just for that purpose, Coronet. MoparMitch, I figured if that tool will do the trick, probably not a big deal to do myself. But the actual pinion depth finders at $100 and up, I'd probably just have someone else do it. Assuming it will take me several hours to do for my first time. These sub-projects on the car are what kills me!
 
Yeah so far, everything is 100% me, including the 904 rebuild (which was a first for me, auto trans anyway).

Some things though, with the extra specialty tools and time it may take me, are less expensive to pay out for labor!! :)

In the end, I like doing my own work for the pride factor, and I've seen way too many shops turn out worse work than I might do on something my first time...just have to see if this tool will work for me.
 
Have to weigh the cost of the tools and time I guess, I would like to set up my own but don't see doing more than a few in the next 20 years so for me I'm leaning on going to a good driveline shop to get it done.
 
As said before, if it's a one-time-only deal, farm it out. If you might do 2 or more in the future, take the time to learn it. After the frustration of the first one, it's kind of fun.
 
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