[doug70]

ok here goes, i have a 8.5 open carrier unit (GM-2:73) i want to swap it with posi carrier(GM-3:73) ,ok, can i do this with"ordinary" tools? or would i be better off to take it somewhere? any suggestions? thanks in advance....

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70camaro(350)ground-up restification,350 slightly modified

[This message has been edited by doug70 (edited 12-17-99).]

[gheatly]

Replacing gears takes special tools. If you only want to change one set of gears, have someone else do the work. If you are going to replace more than one set, there are tool kits you can buy with instructional videos that are supposed to be good. I think either Hot Rod or Super Chevy had an article in the last month or so on one. The tool set costs about the same as having someone install your gears.

[1st & 2nd GENGuy]

Carrier swaps are not too difficult but, when you start changing gears that becomes more difficult. The February 2000 Chevy High Performance also has a 10 bolt upgrade article.

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68SS ZZ4, 4sp T-10, 12 bolt, getting painted

78Z28, 330hp vortec, TH350, 10 bolt (just finished)

[mike brown]

jan. car craft had a pretty good article on it. sounds like you might be better to take it somewhere unless you have a lot of tools, but look at it and see what you think.

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pages.prodigy.net/mtbmtb/rf396ss.jpg

[doug70]

i have read magazines,books,etc. they say you need to adjust things like backlash? shimming,etc..the swap i am doing is GM ,not aftermarket stuff,thats why i would think if i watch "how" it comes apart i can drop in the posi unit? the problem i am running into (my area) is there is no one around that does this? i guess i'll keep looking ...thanks for replies..

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70camaro(350)ground-up restification,350 slightly modified

[Scooter]

Doug:
Take it from me, I work in a driveline shop and do rearend setups everyday. Think twice about trying to do this yourself!!! Check out this site for reasons why:
www.ring-pinion.com/Gear%20Talk/Myths.html
& this one:
www.ring-pinion.com/Gear%20Talk/RepairShop.html

There is way too much money involved as well as the critical tolerances that need to be set when installing a carrier &/or gears. It is very easy to mess up. I get vehicles in quite often that were not done properly at regular auto repair shops, let alone the average muscle car owner. This in no way means that these auto Techs are incompetent, it's just that the setup of gears is such an art, and needs to be done on a regular basis in order for someone to be good at it. The average auto repair technician does not do enough rear differentials to be consistently good at it.

I got a call from a local shop technician (AMOCO) the other day who was asking about setting up gears. He told me he installed new bearings and a new gearset and it was making noise. I asked him what his backlash was and if he had a good pattern on the new gears. His reply was, "What's backlash and what does a good pattern mean?" I told him to have it towed to my shop so I could fix it. He did, and after another new gearset, on top of the new one he put in (he ruined it) I fixed it for him. It cost him an extra $195 for the gears and another $250 for labor. He couldn't charge the customer the extra $$, so it came out of his pocket. Keep in mind that he wasn't charged the full retail amount as a regular customer would have been. Hopefully you can see the disadvantage to trying it yourself.

I also understand that people want the satisfaction of doing something themselves. If you keep these things in mind as you are attempting this yourself, and are prepared to spend the extra money if it doesn't go well, (and have enough pride to admit there is something you can't do) and you do end up taking it in somewhere, at least you tried! And you may end up getting it right on your first try. It does happen.

Whatever you decide, good luck, and if I can help at all, please e-mail me.

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70 & 1/2 RS
SB406 & M20 4spd
9" rear

70 Malibu 350/TH400

Gold member #103




[This message has been edited by Scooter (edited 12-17-99).]

[Rob.Canada]

Scooter said it all I agree with him 110%

[CarlC]

Amen Scooter.

[sixtsevnssrs]

Thats why I don't even sell rings and pinions. Definatly a job to leave to the profesionals. I am ASE certified and would not mess with one. I would not go with cheepo parts either. Spend the extra bucks and get something decent.

[Go69]

It is not nearly as difficult as some would have you believe that it is.. Call me luck but I have set up 3 rearends in the past two
years and have not had a problem with any of them. Backlash is very important and must be within the gear set manufacturers reccommendations (Most Chevy 12 bolts are .008-.012") then the other all important tolerance is the pinion depth. Both back lash and pinion depth are adjustable with shims that you can purchase from the aftermarket or directly from a GM parts counter. To do it right plan on taking some time. This is not an afternoon job by any means but YES you can do it yourself! There are several good books on the market that can get you through this. If any one ever tells you that you can't do something-know that they are probably telling you that "they" can't do it themselves.. This has been my experience.

[68SS396]

I am with Go69. I have found out the same thing as you concerning your last remark. Like I said it before concerning this, if you do everything right and all your measurements are right it doesn't matter if a professional does it or a anybody. Clearances are clearances no matter who does it. If you don't have the time or do have the money to pay a professional then by all means do it as its not a walk in tha park. But please, lets not discourage everyone from a learning experience or even trying by scaring everyone. If your not mechanically inclined and don't usually tinker around then you probably don't want to try. If your handy, have some time, and can read guages and follow instructions then whats the issue. I can't believe with all the knowledgable people here with all the experience and all the tales of what some of you have accomplished that there are so many people terrified of doing this. Like Go69 said, "If any one ever tells you that you can't do something-know that they are probably telling you that "they" can't do it themselves. As far as the guy Scooter dealt with, if he didn't even know the terms then he obviously didn't do any research, had no manual, no guides, no tools, no clearances to go buy, no book to tell him what to do. Obviously not a candidate for this job. But not a good enough reason for someone "smart" to attempt. If I bolt together a bunch of motor parts laying around and the motor blows up in two minutes should no one try to rebuild a motor?? C'mon guys really. Think it through

[SSMark]

I just changed my 3.08 open to a 3.55 Richmond with an added Powertrax automatic locker. The car is not in running condition yet so I don't know how I did ( other than a good wear pattern ). The instructions that came with the set as well as the mentioned articles were sufficient to do the job. The only thing that gave me trouble was getting the crush sleeve to crush. A lot of torque needed there with a good system to hold the gear in place. Your note says you are changing the carrier with the gearing. Rings and Pinions are matched sets so I assume you have the pinion with the carrier. The shimming done is to fit a specific setup ( carrier / ring & pinion ) into a specific housing in order to meet the required pinion depth and backslash. When these are right the proper 'wear pattern' will be there. Oh yeah , the locker installation was pretty straight forward as well.
Good luck,
Mark

[This message has been edited by SSMark (edited 01-05-2000).]

[Go69]

To SSmark,
I have purchased and installed the same Powertrax Locking Differential.. Want to know how well they work??? They work like a champ!! I have heard stories about people breaking them but I have had no problems with mine at all. The installation literature that comes with them is just awesome! If others had the opportunity to read this literature there might be more people attemtpting their own gear swaps. Kind of takes the "Magic" out of the process. You do need to know that I advise against driving your locker equipped car on wet roads. IT WILL DRIVE JUST LIKE A SPOOLED CAR!!! On wet roads this means no fast turns, no acceleration through a turn. If you heed this advise you will be fine, if you do not you will find yourself spinning out quite easily. Nothing like the sound of barking tires as the carrier unlocks when you go into a turn. Not very cool though when a cop is sitting at the gas station that you are turning in front of. You will get attention-both good & bad. I like the very agressive mannerisms of my locker and the sweet manly noises that it makes as it locks/unlocks while driving. Kind of freaks other people out when they ride in my car!
Good luck

[68SS396]

Those are good units. Have them front and rear in my 87 fullsize Blazer with 35 inch tires and a four inch lift. Have at least 50 thousand by now on the setup with no problems. Unstoppable off road but sensitive on the street. I like them alot.

[Scooter]

To Go69 & 68SS396:

Did you guys read my message all the way through? Or did you just read the first two or three paragraphs?

If you got the impression I was telling anyone not to try this themselves, you'd better go back and read my message again. I also urge you to check out the links I posted above. I have been doing this type of work for a long time and believe me, I've seen my share of people who have tried it and failed. I simply wanted to point out that fact as I have no way of knowing the competence level of anyone posting on here.

I would also like to give both of you a big "Thumbs Up" for succeeding in setting up your own rears. You both have obviously been thorough in doing the work. I agree that if the backlash and pattern are good, you will be OK. The problem with the average muscle car owner is that this is where they lack the perserverance to get it right. Obviously there are several people out there, like both of you, who are very talented that can do more than the average muscle car owner. Those are the people that will succeed.

I would caution you, however, that to say anyone can do it is far from correct. It is not as easy as changing oil, or spark plugs, or even pulling a motor. You need to remember that a majority of the people out there that own muscle cars may not have ever attempted pulling a motor, and by no means should those people be messing with a rearend setup.

I hope I cleared up any confusion & again, please re-read my original post.

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70 & 1/2 RS
SB406 & M20 4spd
9" rear

70 Malibu 350/TH400

Gold member #103
Driveline Technician