Rear End Gear Ratio Change

[Josh]

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

[We Gone]

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?

[WVZR-1]

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

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%20Web/products/Speedometer%20Correction%20Gears.htm

[alnukem]

Sounds like a good, logical plan.

[Jagdpanzer]

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.

[ghlkal]

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.



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.

[Blue Flame Restorations]

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!!!

[LGAFF]

I would do a port and tune first

[bradley]

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 .

[Josh]

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.

[902066]

That Dana Spicer [viper] gear set I believe uses a crush sleeve, not pinion shims. While you have it all torn down I would also do a cover plate drain hole. I have the 3:73 gears, wish they were the 4:10's.

[XfireZ51]

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.

You may want to check but I have heard Corey doesn't make the headers on order but as part of an overall engine package.

Doing the rear will present you w a number of "while ur there" moments. Like the u-joints and rear end bushings which no doubt are pretty dried out by now. And yes install a drain bleeder for the rear end fluid.

[WVZR-1]

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

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.



The install will require 4 bearings "minimum" if you plan on using your differential. An install kit generally includes pinion shims (front/rear), the taller crush-sleeve, 3 seals and 6 bearings. The package would be the "wise buy". You mentioned DIY and generally that's not accomplished easily or effectively by a "first timer".

With a 13K build if you'd like to spend some more money I've an NOS housing you could use for the build with a new carrier and just slip out and use your short-axles and keep the 13K build intact. It's worth substantially more assembled with those miles than the gears by themselves. I'm not rushed to sell but if I had a 13K rear it's certainly what I'd do. If it interests you email me.

The drain is a something to consider but study the options at length.

[USAZR1]

John Smarsh has a fresh 4.10 pumpkin for sale,for $950 plus shipping. Chris Rinehart's dad did the set-up so you know it was done right.

[WVZR-1]

John Smarsh has a fresh 4.10 pumpkin for sale,for $950 plus shipping. Chris Rinehart's dad did the set-up so you know it was done right.

That would certainly be something to consider - branding of the gear set and if it were a new install or previous installed gears used might need to be considered but if it were complete with short-axles it's a reasonably priced option.

[USAZR1]

All new parts were used,Dave. The gearset is Viper. It's just a third member/pumpkin,not axle to axle,although John does have a Dana 44 rear complete except brakes. Ratio on it is 3.45. He wants $1250 plus shipping for that rear.

[WVZR-1]

All new parts were used,Dave. The gearset is Viper. It's just a third member/pumpkin,not axle to axle,although John does have a Dana 44 rear complete except brakes. Ratio on it is 3.45. He wants $1250 plus shipping for that rear.

Clint,

When I mention "short-axles" I'm speaking of the left and right shafts that are retained in the differential with "snap-rings" and they're generally considered as "part of" 3d member but it would be possible for someone to offer up a build less those axles and the buyer would use his to complete it. I'd say the buy is reasonable and a person would need to question only the "clutch pack" maybe. If that were fresh I'd say it's a real good buy.

[Josh]

Sounds like its a good idea/necessary to replace the bearings as well.

I've rebuilt GM 12 bolts with the crush sleeve so I am familiar with those, but I thought the D44HD just used shims for the pinion bearing preload. What's different about the 4.10 gears that changes it to a crush sleeve?

I was also thinking about replacing the original ring/bearing cap bolts with ARP bolts/studs.

[WVZR-1]

Sounds like its a good idea/necessary to replace the bearings as well.

I've rebuilt GM 12 bolts with the crush sleeve so I am familiar with those, but I thought the D44HD just used shims for the pinion bearing preload. What's different about the 4.10 gears that changes it to a crush sleeve?

I was also thinking about replacing the original ring/bearing cap bolts with ARP bolts/studs.

Nearly all of the "service" gear kits use a crush sleeve regardless of the "branding" Dana/Spicer included - OE for most D44-HD Corvettes were "shims" but in late production even the production Corvette got a crush sleeve. I believe the ARP stuff might be overkill but I'd guess it's something to consider.

[Jagdpanzer]

All of the Viper Dana gear sets I've seen come with new ring gear bolts.

[Jagdpanzer]

On a few of the Dana 44 gear changes I've done I converted the carrier caps from 1/2" grade 5 bolts over to 1/2" ARP studs.
ARP Part Numbers:
4 x Stud - AR4.060-LB
4 x Hex Nut - 200-8607
4 x Washer - 200-8514
To order call ARP Order Desk & Technical Support: 800.826.3045
Use a 1/2"-13 bottoming tap to deepen the threads in the housing.

[USAZR1]

Clint,
When I mention "short-axles" I'm speaking of the left and right shafts that are retained in the differential with "snap-rings" and they're generally considered as "part of" 3d member but it would be possible for someone to offer up a build less those axles and the buyer would use his to complete it. I'd say the buy is reasonable and a person would need to question only the "clutch pack" maybe. If that were fresh I'd say it's a real good buy.


Thanks for the info,Dave. You can tell I've never had a Dana 44 apart.