jimmyblue

iTrader: (11)

I got some 3.42s at a nice price. Never messed
with rear ends, what I read about that is, it's
kind of fussy to set up right (and I'd want to
do it a maximum of once on this car). Looking
for opinions (experience-based preferred) on
whether this is a good shade tree project or
best left to a pro (and then the question
would be, how to tell a good rear end shop
from a bad one).

The local GM dealer service dude didn't seem
enthused about doing this kind of thing. I'd
want the mechanical done, and also the speedo/
odo recalibrated. 3.23s -> 3.42s is only 6%
but I'd rather have the speedo right. What's
the portion of "regular mechanics" who have
ECM diddling capability? Do I need to get the
gears done one place, and then find an E-tuner?

MilDot

Don't do it yourself.
Go to your regional forum on here and ask for recomendations of a good shop in your area.
The speedo can be corrected with a HPPIII.
If your car is an A4, you need one anyway to adjust the shift points, its a good investment...

2xLS1

iTrader: (25)

I just did my first gear install about a week ago. I had seen it done by someone who showed me exactly how to set them uprright, had just never done one. It's not that hard. You must have a inch lb torque wrench, a dial indicator and base, and a press, or access to one. My first install turned out perfect. For what you will pay for the install, you can buy all the tools.

wrencher

iTrader: (2)

If you do it yourself make sure you use a pinion depth gauge also or you will tear up any r&p set. this tool check for proper pinion shiming (could be old shim) so that contact pattern between r&p is correct.Then you adjust backlash with side shims and thats thats the short version. I know for a fact it WILL suck tightening pinion nut on a car on jack stands to their proper torque of 200 + ft lbs to properly set crush sleeve. Skimp on any details and it might go south. <img border="0" alt="[whiner]" title="" src="graemlins/gr_cry.gif" />

pekkaz

Pinion depth gauge is for getting the best initial guess for the pinion shim. The original shim is also a good starting point. After that it's trial and error with getting the right contact pattern as the right depth can slightly vary with the gear brand and ratio. This is a lot of work. Most of the time just re-using the original pinion shim works fine but not always. I believe many shops just do this to save time and if it doesn't work then it must be the r&p set ...

wrencher

iTrader: (2)

There's no guessing involved. Every r&p set has a pinion depth setting it's usually etched on pinion gear. Then assemble with original shim and NEW crush sleeve and check pinion depth. If your a few thousanths off either way you add or subtract with shims accordingly. The p.i.t.a. part is you have to assemble to check, if wrong tear apart crack bearing off install new shim and new crush sleeve again & recheck. This is the proper method. Can get labor intensive but a good shop will do it right. I set-up a fair share of diffs most of the time the p.i.t.a. ones are new gear set/ new carrier. Just r&p sets o.e. shim usually is right but you have to check every time you never know.

pekkaz

Hmm, what you say is equivalent to not necessary to read the contact pattern for correct depth. Can you trust this ? I was under impression the tool is normally used when the original shim is missing and you need a starting point. Why a new carrier is PITA ? Shouldn't it only contribute to backlash shimming ? Some folks don't use the crush sleeve on trial assemblies but just tighten the nut for correct preload and then use the sleeve when the depth is right. Will this cause difference in depth ?

thechef

iTrader: (13)

pay the guy you REALLY need to know what you are doing for gears....get a HPP3 for your year car and adjust you speedo,shift points,rev limiter etc...

pekkaz

I went to a 'reputable' local shop and now I wish I did the install myself. These shops don't always spend the same effort on every customers car but just re-use the original pinion shim and slam it quickly togehter. Then they put the blame on a bad r&p set. This happens especially if you bring your own parts and don't use theirs.

Once you start the rear-end game you are extremely lucky if it's one time install and then never again. My opinion is you better master the 10-bolt becouse it will be apart many many times and you will be paying many many installations.

Gag_Halfront

Awesome Thread. TTT.

sited12

I was told that you dont use the crush sleeve when checking the depth. I got a video from Jegs that shows you how to install the gears on a GM 10 bolt 7.5 just like the stock rearends we have. It also has the 12 bolt on the video also and it said after you found the right depth then you put the crush sleeve on.

wrencher

iTrader: (2)

No what I say is you can't get a good contact pattern without checking the depth. Use this tool on any r&p install have shim or not. there is alot more set-up w/new parts. To check pinion depth would you rather check it with crush sleeve holding pinion bearings apart or the races in the diff. housing? Remember we're mesuring to the thousandth. Maybe it,s **** but I don't have diffs I set up go south from a poor install.My .02 How much does a crush sleeve cost?

geardoc

Pay someone to set your gear set up that knows what they are doing. Ask them if they have a pinion depth guage, dial indicator, inch pound wrench, ect..... Gearsets can be done with out them from an experienced person by contact pattern. I have done thousands and I still use my guages. Also no matter what kinda of rear you have, use a solid crush sleeve. Crush sleeves fail! For the 7.5 guys its a Ratech#4111.

Let me let you all in on a little secret:
Gears do not wine. Its from the install.
I have used every brand of gears there are. Name brands to cheapo's.

nthnwbr

The crush sleeve sets the pinion bearing pre-load, NOT the pinion depth. Check pinion depth WITHOUT the crush sleeve in place. Even though the depth is indicated on the gear, slight adjustments may be necessary. Experienced installers may like the pinion to run closer to the "toe" or "heel" of the ring gear depending on the application. For a high torque/drag racing situation, the pinion is better slightly toward the "toe" side of the ring gear, because under extreme torque load the pinion "walks" on the ring gear toward center, putting it in the ideal position.

pekkaz

I would pay if I really could trust the installer. I guess I'm pessimistic now but I feel 1/3 are morons, 1/3 don't care or have too little time and the rest are good but don't always bother. I made the mistake of having the gears installed on monday...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> No what I say is you can't get a good contact pattern without checking the depth. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Good contact pattern is equivalent to correct depth, right ? Which leads to either you adjust the depth by pattern or trust the gauge and don't make corrections by the pattern. If you finally adjust because of the pattern wasn't the depth tool useless ? Do you guys usually check the pattern after using the tool ? If so what's the success rate with the pattern, no further depth adjustments ?

Though I guess interpreting the pattern isn't easy unless the pattern in the real life is as clear as in the install guides. We'll see.

geardoc

The pattern is the final step. Thats what really counts. I have set about 3 gearsets up to the correct pinion depth and had a crappy pattern, so I corrected it. The pattern is what counts.

<small>[ September 07, 2002, 07:06 PM: Message edited by: geardoc ]</small>

pekkaz

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by geardoc:
<strong>I pattern is the final step. Thats what really counts. I have set about 3 gearsets up to the correct pinion depth and had a crappy pattern, so I corrected it. The pattern is what counts.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks. So, if you are good with the pattern you don't necessarily need the depth tool given you have the original shim to start with. Can you give quick guidelines how to do the setup with a solid sleeve ?

wrencher

iTrader: (2)

Think about it, all you can do is move pinion front to back on it' centerline & ring & carrier side to side on axle's centerline RING & PINIONS ARE A MACHINED SET & when they are made they get a depth setting from the machinist. Of corse pattern is final but would you do a r&p without checking the depth? Is this were the whining starts?There is alot of steps I don't know anyone who skips any! This thread started as a diy & the depth issue was not discused & I brourht it up . By no means do I say just set depth & slap 'er together & it will be ok .There is a proper method of doing r&p AND every step is necassary.

nthnwbr

wrencher: You are right, that IS the proper method of doing it. And if I was building a rear end from scratch, I would measure pinion depth first. That gives you the starting point for the final gear pattern. And, it often IS the final measurement. But, in most cases, when rebuilding a rear end that was previously set up correctly, most builders use the same shim thickness that was removed, as their starting point(given the gear pattern on the old R&P is OK). This is a quicker way of doing it, because properly measuring pinion depth can be a tedious task for someone who doesn't do it very often(and doesn't have the tool).

Another problem for the DIY'er, and just as important as proper pinion depth, is bearings. If you don't have a press or at least access to one, you can't *properly* install the bearings. I have seen people beat them on the pinion and the case with a hammer and punch, but that is a VERY half-*** way to do. Those bearings will not last as long, and will probably fail under extreme load. (Like when you rev to 6600 rpm and side-step the clutch, with slicks, or do those massive neutral drops like you used to do in your Dad's Buick) <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" /> <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />

<small>[ September 07, 2002, 10:49 PM: Message edited by: nthnwbr ]</small>

pekkaz

Wrencher, I just wanted to get everything on the table as the tool issues you brought up can be decisive from DIY perspective. I'm trying to learn all I can about this.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />