Rear End Gear Ratio Change
 

First post as a ZR-1 owner.

Recently purchased 1990 ZR-1 #2875 with 13,000 miles, all stock. Awesome car and a big step up in performance from my 93 LT1.

Initially I had a slight misfire at idle. Ohm'd injectors. 3 bad primaries. Replaced all 16 with new Delphi stainless injectors from FIC using Jerry's gaskets and o-rings (great products!). No more misfires.:)

I plan to eventually do the following upgrades to the car in this order:
-4.10 gears
-Long tube headers/exhaust (delete cats)
-Ported plenum/IH (and heads if I ever pull the engine).
-Updated PROM

So onto the first item, 4.10 gears.

The car pulls like crazy when RPM's are 4k-7k, but it feels a bit sluggish down low and the ratios are too tall in all gears for my tastes. That said, and considering future modifications, I have decided to go with 4.10:1.

Which brand, where to get, what additional parts needed, things to do while I'm in there, tips and tricks, etc.

Thanks

Re: Rear End Gear Ratio Change
 

Welcome & Congrats, you came to the right place. 4.10s are one of the most popular upgrades good bang for the $. I'm sure someone will post up for you a good builder in your area. I think it is Cory Henderson?

Re: Rear End Gear Ratio Change
 

I'll leave the gear "branding" alone but if you're doing the 4.10 ratio "for sure" you need Marc's speedometer correction gear set. You might as well do those "NOW" so that they're in hand. Regardless of "branding" I believe I'd make sure I bought a gear set that included a 226mm ring gear vs. the 216mm stock. You may have to massage the housing or the cover OR maybe both but it would I believe the preferred.

Speedometer stuff:

http://www.zr1specialist.com/HAT%20W...on%20Gears.htm

Re: Rear End Gear Ratio Change
 

Sounds like a good, logical plan.

Re: Rear End Gear Ratio Change
 

Welcome to the brotherhood.
Several of us run the lager diameter ring gear Dana Spicer 4.10 gear set designed for the Dodge Viper which also uses the Dana 44 rear end. It's available from your local Mopar parts source under PN P5007043.

Re: Rear End Gear Ratio Change
 

Congrats and welcome :handshak:

Are you planning on doing the work yourself?

You're three hours from Henderson's shop in New Braunfels. If you haven't investigated Corey's services, you should.

Re: Rear End Gear Ratio Change
 

Welcome, Josh! Congrats on the new Z!

I have 4:10's in one of my Z's and love them. Great choice, IMO.

Let the fun begin!!!

Re: Rear End Gear Ratio Change
 

I would do a port and tune first

Re: Rear End Gear Ratio Change
 

defiantly go see corey he did the same thing to my 90 as you want to do to yours . my car went from 331 rwhp to 409.9 wrhp . makes the car way fun to drive .

Re: Rear End Gear Ratio Change
 

Thanks ya'll. Yes I will install them myself, that's half the fun!

My list so far:
-Mopar Viper 4.10 gear set PN P5007043
-Haibeck 4.10 Speedo gears
-Amsoil SEVERE GEAR 75W-90 Synthetic EP Lubricant (2 qts)
-Amsoil Slip lock additive
-Pinion & Axle yoke seals
-RTV silicone
-Pinion shims

What am I missing?

I was not planning to replace bearings, u-joints, etc. as everything works properly now and the car only has 13,000 miles, but I will inspect everything while it's apart of course.

Corey's site is down right now, but I hear he makes some nice headers, so I'll definitely be considering him for those.