3:73 Rear Gear Insallation
 

So my programmer Scott Hansen suggested that I look up WVZR6 in order to source a Teflon gear required for a 1986 Chev IROC-Z Transmission / 3:73 Rear end gear application.

My transmission is a 1986 700R4 which will have a shift kit, Red Wing Clutches and a 2200 stall convertor installed / Engine is a 90-95 ZZ4 Crate 350 TPI / .502 grind cam / Edelbrock 90765 vortec heads (64CC) and a Edelbrock High-Flo intake/runner paired up with with a stock plenum ported to match 52 MM TPIS Throttle body with coolant bypass. Hope someone can help. I had the car out for two days out of my buddie's shop and she is back in there for some serious tranny issues. We have a plan, but Scott's suggestion really intrigues me. I finish this build. Been at this whole project for two years and miss driving it. Engine runs like a top, but transmission shudders like you wouldn't believe, and it started whining. When I back it into the garage, I am hearing some nasty thumping and feeling vibration

So we came to simple explanations for the following questions:

1) The thumping was the header contacting the frame... :)

2) The 700R4 that came with the 86 IROC already has the servos that were also in the vette...

3) The whining was the sump pump failing...that sucks

4) Transmission is out:
- Replacing sum ump
- Having Red Wing Clutches installed
- Also installing a 2000 stall convertor since when in gear she likes to walk around with the extreme street cam installed
5) Still at the shop...

with 3.73 you will hit the notorious 4-fk tpi wall pretty quick.
Id keep the gears you have now, get the motor in, drive it for awhile see how you like the current gear.
TPIs make good low/mid range tq, gearing it like a cammed up carb'd car may be a mistake. Will be fun at lower speeds but-

With the Eldebrock TPI peak torque will be around 4k and hp around 5k. With a 3.73 you will likely have traction issues in 1st and 2nd. A D44 with a 3.45 might be a better choice. A 3.07 D36 would be better than a base 2.73.

I have a 65' SB 4 speed. The only modification I can identify so far is the engine; switched to a 1970 350ci which is "reported" to have 375hp. Sounds like a cam present at idle, has Edelbrock intake, double hump heads, and Holley 585; but that's all I know other than it pulls pretty strong. I've confirmed the original 3:08 posi-traction and was considering switching to a 3:70 for stronger pull through the gears - not to race. Your thoughts on doing this? and Best rear reco?

3.70 will definitely make it more peppy. Only downside increased highway rpm, I would look for a assembly to swap in. Unless the 3.08 needs repair.