rear troubles...

[shmoov69]

Ok, I have a Detroit Locker in the 9" and it seems to have some play in it. I got the car back together and it clunked really bad when you went from R to D or vice versa, also when you were driving and let out and got back in it. So I pulled it all apart and changed U joints (both ends) and took the center section to someone that works on them. He said that the pinion was a little loose and reset it up for me, (there was no wear since I cought it soon). I put it back in and it is still the same. Had a buddy look under neath it while I went from R to D and so on. He said that the pinion was definately moving about a 1/8 turn or so. It is pretty ratchety turning (wich is somewhat normal). But other than that, it feels normal
So, if is the locker, what is the symptoms? I bought a used one on here a few years ago from someone and it was junk (left me stranded on a hill about 2 miles from the house), but this one was new (3 years ago and one Power Tour trip). If it is not the locker, what else could it be from my breif description.
Thanks!

[MrQuick]

Have your guy go through it again. Pull the pinion support and inspect for cracks.

[z65mm6]

Do you know what the backlash on the gearset is?

[shmoov69]

I have no idea on the backlash. And I will have him check that when I pull it back out. It is a FoMoCo casting with the 31 spline stuff.
I really need to learn how to set up a rear don't I!? LOL! As many times as I have had to have one setup, I should really learn! What specific tools/parts do I need to be able to do so?

[MrQuick]

9"?.... 1/2" & 9/16" 5/8" deep socket, ratchet, #2 hammer, a screw driver, a bench vise and some pattern compound. Also a set of shims, a clearenced set of pinion bearings and a seal installer.

[shmoov69]

Any other ideas from anyone else?

Also Vince, what is a "clearenced set" of pinion bearings? Is that something different than normal pinion bearings? I have rebuilt several engines and several tranny's but never a rearend, surely it must be easier than that!
Thanks

[Thumpin'66]

Did you figure it out? Mine does the same thing and I think it is just the fact it is a locker. Mine has 1/4 rotation of slop before engagement so I get a nice bang into gear. I plan to pull the locker apart and inspect it but think I may find no problem parts.

[Apogee]

You want a pair of pinion bearings that have been "clearanced", had their bores opened up a few thousandths, for setup purposes. The only shims in a 9" to mess with are for the pinion which requires you to remove and reinstall the bearings each time you want to add or delete a shim. Once you determine the shims to use, you assemble the pinion shaft with new bearings and you're good to go.

All of my 9's seem to have about that much slop...I've always attributed it to how low the pinion is relative to the ring gear and just the slop in the splines and/or side gears.

[Bowtie1z28]

My locker does exactly the same, 1/8 turn on the pinion before you feel it engage. Call the manufacturer and was told that 1/8 to 1/4 turn is normal. I think it is just the nature of the beast and nothing to worry about, 2 years and maybe 30 launches on mine and other than the same clunking and popping it has made since new it is fine.

[shmoov69]

Well, I took it to a guy and he looked at it and said it was fine.
Put it back in and it does it still. So, I guess it is just the nature of the beast.. Although, my chic said that it only laid a single stripe the other day instead of two. But maybe she just saw a single, because after that, I smoked them again and saw two. The tires I got are just super hard and don't leave much of a mark, just pretty much a white stripe on the pavement.
I'm not too fond of how it feels in the corner in and out of the gas though. It seems to load and unload a bit when you either let out or get in it again.

[chicane67]

9"?.... 1/2" & 9/16" 5/8" deep socket, ratchet, #2 hammer, a screw driver, a bench vise and some pattern compound. Also a set of shims, a clearenced set of pinion bearings and a seal installer.

You want a pair of pinion bearings that have been "clearanced", had their bores opened up a few thousandths, for setup purposes. The only shims in a 9" to mess with are for the pinion which requires you to remove and reinstall the bearings each time you want to add or delete a shim. Once you determine the shims to use, you assemble the pinion shaft with new bearings and you're good to go.

All of my 9's seem to have about that much slop...I've always attributed it to how low the pinion is relative to the ring gear and just the slop in the splines and/or side gears.

WHOA !!

Both of you... put the crack pipe down and please, step away from the crack.

If you are taking apart the pinion support everytime you want to make a pinion depth change on a 9"... you shouldnt be TOUCHING the differential to begin with. That is not how pinion depth changes are made on a 9". The only shim that is required for a pinion depth change is the pinion depth shim itself. That shim is located and placed between the assembled pinion support and the differential case. It does not require any "set up" bearings at any part during the initial set up or the final assembly. Pinion depth shims come in various thicknesses from 0.003" to 0.050" and they look like this:



shmoov... the amount of play that you have described... is right about normal for a 9" Detroit locker. In fact, you are luck to only have about an 1/8 of a turn. Most Detroits have about a 1/4 to 1/3 (or even more) turn in mechanical tolerance. That mechanical tolerance is accumlative from the amount of clearance in the ring and pinion, in the form of back lash... /and in your case with a dovetail type locker side gear assembly, the forcing surface of the dovetail "window" (the opening between the dovetails)... and in some cases, even the tolerance in the axle spline themselves.

Yes... you are right. It does take some finesse to learn how to load the doves right for a 1320 launch... and yes, it can seem a little unstable while in a turn and being on throttle or on light decel. It your not at a neutral throttle point... the doves will be engaged and it will have positive lock up.

[shmoov69]

At the strip it hooks (or seems to) just fine on stickys. It just feels goofy in the twisties. Should I have went with something else? Now that I know that the "slop" is normal, I am just trying to figure out the car in the turns, with the new rear suspension that is.

[Monzsta]

My locker acts the same way. I hate it in traffic on the freeway. Everytime you're in and out of the throttle the car moves around. The first opportunity I'm replacing it with a Quaife or a Detroit True Trac. (helical geared diffs)

[another69]

Trutracs are nice for the price- its so quiet I forget its even there. I have the preloaded version in a 9" and the stripes I lay are even and consistent.

[shmoov69]

I was going to go with the trutrac, but at the time they were still new enough that they weren't sure if it would handle the TQ on long term.... They know better now!

[chicane67]

At the strip it hooks (or seems to) just fine on stickys. It just feels goofy in the twisties. Should I have went with something else? Now that I know that the "slop" is normal, I am just trying to figure out the car in the turns, with the new rear suspension that is.

Should you have gone with a different diff ?? I dont believe so... as soon as you stated "strip" time... I think you made the right decision. The idea of a True Trac is just about perfect for regular driving... twisties... and the like, but they just dont hold up to the impact loading of stickies on the 1320.

A locker will feel a little unsettled when entering a turn... with the only exception being, if you were on or off power 100%... it will feel tight in and loose out... with some trail braking ability.

The finesse' talked about... comes when to apply power or when and how fast you come off the throttle to make it "set" into or out of the turn.

[shmoov69]

Thanks.

Being serious here, where can I go to learn how to drive (properly) in a road racing style? I hate OJT with the Camaro! Actually, just with MY Camaro!

I don't have a ton of money, so money IS an object! LOL! Anywhere close and any idea on cost?

Thanks!

[Monzsta]

The idea of a True Trac is just about perfect for regular driving... twisties... and the like, but they just dont hold up to the impact loading of stickies on the 1320.

Can you validate this? I'm curious to see how they fail.

I build diffs for a tuner in my area (using only Quaife's) and they withstand 1,000's of hp/tq and have been in the 7's on slicks. I've never seen a broken or damaged Quaife. If the TrueTrac, which shares the design isn't as rugged, than it's a no brainer, as the TrueTrac is $495, with a Quaife for a 9" comes in around $850.

[HWYSTR]

Ditched using a locker years ago in favor of a TruTrac, will never go back. They hold up fine at the strip from my experience, and the 5-oh guys seem to have great luck with them too. They make Auburn Pro posi's for 28 & 31 spline 9s too. There are aftermarket covers for the TracLoc to make it strong enough for bigger power, but it becomes more expensive to do it that way than other options.

Entered an exit ramp at speed once, let off, and had my hands full when I had the locker in it. No gaurd rail or jersey walls, but one heck of a deep drop off! I had driven lockers for years and know how to 'finesse' them, they can still catch you off guard.

.

[chicane67]

Can you validate this? I'm curious to see how they fail.

I build diffs for a tuner in my area (using only Quaife's) and they withstand 1,000's of hp/tq and have been in the 7's on slicks. I've never seen a broken or damaged Quaife. If the TrueTrac, which shares the design isn't as rugged, than it's a no brainer, as the TrueTrac is $495, with a Quaife for a 9" comes in around $850.

Validate... ?? Sure. Just place a True Trac next to a Torsen Gleason, DPI or a Quaife... and you will surely 'see' the reason to why it happens.

The finish work on the TG, DPI and the Quaife is far superior than what you get with a True Trac. The case fails from the stress risers of the machined surfaces. There are also different True Trac's utilize either a three pinion (six total) or a four pinion (eight total) design. That too has an impact on its overall strength.

Like the direction of your previously mentioned point, I would also guess that the price will also explain some of it as well. The higher cost of other units on the market is evident on the finish machine work. The cheaper it is... the less work that goes into producing it:

(Relative to specifically the 9")

True Trac = $495

Torsen Gleason = $1395

DPI = $850

Quaife = $850

If you find a need to read about True Trac failures... click on over to LS1tech.com... they seem to break everything they can spend money on. I have however... found some commonalities with that crowd that may explain the majority of 'their' failures... and that is #1. MOSER #2. Incorrect application #3. Driver inexperience.

I'm not bad mouthing them... its just an educated observation.