Black91Z28

how much would it cost to put in 3.42 gears??????? would it be expensive to have a shop do it?

thanks guys

Kevin91Z

Putting in gears is not something an amateur can do in his/her backyard. Its a complicated process that requires knowledge and special tools. So definitely take it to a respected shop. It should cost anywhere from $150-250.

Black91Z28

thanks man...i'll start lookin around.....and also should i get Richmond Gears? or whats a good brand and also what do we have as far as rearend...sorry i dont know much about the rearend (9 bolt, 12 bolt, etc.)

AutoRoc

From what i've seen. The gearset alone will cost roughly $180-250 depending on what brand you are looking at. You also might need new bearings and an install kit also. You never know

Installation from a GOOD shop will be roughly $200-350.

just my .02

Luckily we have a local guy here that is nice enough to charge a $150 rate for whatever swap you want

87DJP2001

First thing I would do is find out what Rear Axle Assy I have and if it is compatiable with the gear changes I want to make. All rears assy's are not the same.

Kevin91Z

A 1991 Z28 will have a 10-bolt 7.625" (7 5/8") ring gear. Verify that by counting the number of bolts holding the differential cover on. You should count 10.
Motive Gears are stock used by GM. Richmonds tend to whine a bit. Ask around your local shops which gears they recommend and how much they charge.

Black91Z28

thanks guys, ur a big help

TheGreatJ

Richmond gears do whine, but it's because of a steeper gear pitch which allows for more material in the teeth and makes the gears stronger. Just FYI.

Oh and depending on what gears you have now you might have to get a 3-series carrier for those 3.42s.

Kevin91Z

A 91 Z28 350 TPI will have dual cats and 3.23 gears in the rear. 3.42's will bolt right in. If you need a new posi, pick up the $100 take off posi unit from SLP.

91 Redd Sledd

I would stay away from richmonds if I were you. They do whine a little.That does'nt bother me at all.What does bother me is My car and 2 of my friends cars have the same Richmond gears.All are 3.73's,all are the "thicker" gear for the 2 series carrier,and ALL of the cars have a high speed vibration around 70-80 mph.The gears were set up in my car and the 86 Iroc by the same guy.and the 89 Iroc was set up by another shop.They all have the same problem.Does anyone have any Ideas why?? I thought it might be a problem stemming from going from a 2.73,2 series carrier to a 3.73 using the same 2 series carrier, but if i am wrong please let me know as I am not trying to dog on richmonds.I know other people that are perfectly happy with them and have no complaints.Just my .02.

James

Black91Z28

i swapped a 350 in mine, and i didnt have dual cats so i have the 2.73's stock.....what would i need to get them to 3.42's?

TheGreatJ

Easiest way is to get a 4th gen 3.42 rear off ebay. It'll be posi too so that'll be nice and you can probably get it for the cost of setting up gears alone. Also disc rear brakes are a good thing. And you can swap it in yourself, in the driveway with some help. No shop required. The only thing is that the 4th gen rear is about 2" wider so your wheels will stick out some. But if you ever change wheels you can just get 4th gen wheels for the back and that'll correct it.

87iroc-vert

is there a way to put 4th gen rims on 3rd gen w/o adapters(or spacers)? What would have to be changed?

Black91Z28

how much would it cost me to get a posi for it also?

TheGreatJ

To put 4th gen wheels on a 3rd gen you need either some really thick spacers (not recommended) or a 4th gen rear.

AFAIK 4th gen rears with 3.42's only came in 6-speed cars, and therefore all have posi. Even if it doesn't (or if it's broken/worn out) the SLP take-off posi is only like $100 and is an easy install that anyone can do (no gear setup required.)