3.08s with a posi or....?

[RangRayy]

'87 8.5 10bolt open rear end with 3.08 gears. Should I even bother with these gears by adding a true-trac carrier? I've never done any work internally on a rear axle before but a fluid change. Pretty stock engine minus headers, dual plane intake and carb. So maybe 200hp or so??? Bolted to a non lock up TH350 and 29" tall tires.

Should I look at 3.42, 3.73 or 4.10 gears instead to add the posi to? Also it's probably a 28 spline would going to a 30 be better? As I would like to tackle this on my own, I have access to the right tools, the posi addition seems relatively easy to tackle for a beginner on axles. I am not as confident with having to change the pinion gear and all that goes with it, preload and bearing install and the removal process.

Thoughts? Should a novice tackle this big of a project or let a shop do it? I'm not a novice when it comes to other repairs and turning wrenches just something about the rear axle that makes me hesitant.

 

[SkinnyG]

I've installed just LSD's, and I've set up ring & pinions. I'm not sure I would give this to a novice.

The easiest would be throw the true-trac into the 3.08 gears, so you don't have to mess with the pinion and pinion depth at all. You WILL, however, need to ensure you have the correct backlash, which may be fine with the shims you have, or you may need different shims.

Having said all that,

If your engine is pretty much stock, and you intend on keeping it stock, 3.08's would be just fine. If you wanted to throw money at it, 3.42's are said to be a good compromise for non-overdrive transmissions.

 

[RangRayy]

I've installed just LSD's, and I've set up ring & pinions. I'm not sure I would give this to a novice.

The easiest would be throw the true-trac into the 3.08 gears, so you don't have to mess with the pinion and pinion depth at all. You WILL, however, need to ensure you have the correct backlash, which may be fine with the shims you have, or you may need different shims.

Having said all that,

If your engine is pretty much stock, and you intend on keeping it stock, 3.08's would be just fine. If you wanted to throw money at it, 3.42's are said to be a good compromise for non-overdrive transmissions.

That's what I was thinking. The pinion might be a booger without having someone whose done this before helping me in person making sure it's done correctly and how to properly install it. I do have to replace the pinion seal though while I'm working on the axle.

I figured I'd have to check backlash. Seems easy enough to do.

Okay just wanted make sure if I spend the $$$ on the true-trac it wouldn't be wasted with the 3.08s. I have the swirl port heads and do not plan to change anytime soon and highest cam I might throw in it is comps 260h but most likely the 240h.

 

[SkinnyG]

I ran an open diff with 3.07 gears, behind my lumpy-cammed 2500 stall 350 for two years. Then I installed 3.73 gears (which the cam and torque converter needed), and a Detroit True-Trac. The gears seemed to make a reasonable difference, but the True-Trac was hands down a phenomenal upgrade.

You will be very happy with the True-Trac, even with the 3.08 gears, especially with swirl port heads and a torque cam.

 

[RangRayy]

Thanks for the input. What did you notice differently with the true trac? Kind of hard to answer since you installed new gears with it.

 

[SkinnyG]

Despite a significant change in gearing, I had a significant reduction in wheelspin.

It's not really noticeable in operation. I have a 2-way clutch type in a 1275lb Lotus 7 replica, and you totally know when it locks in acceleration and locks in deceleration. The True-Trac is seamless. There isn't anything strange about how it works, it just puts the traction down for you.

In winter, icy conditions, it's...... different. You're always moving forward, but the back is kinda doing it's thing. Whatever that thing may be. I chose the True-Trac to be the most forgiving on ice, which is largely what our winters are where I am. It's never frightened me, though you ~can~ certainly steer with the throttle a whole lot more than before. I'd say it's a win in winter, but it's a strange sort of win. But worth it.

 

[highdesertrange]

personally I wouldn't put 2 cents into a 10 bolt. highdesertranger