Mods in signature. Next logical step for my setup would either be HSR or gears. I vote to remove the 3.07 gears for something closer to 3.23 or 3.42.


What kinda rear gear will I need and where can I buy it from? Will a 1999 tahoe 3.42 rear gear fit the dana 44?

 

Tahoe gear will NOT fit. If the 4 + is factory then you have a D44 already and you've got choices of 3.45, 3.54, 3.73, 3.91 or greater. These are the easiest availabilities and you just need to watch when searching Vette/Viper and make sure you buy a package for 3/8" ring gear bolts. If you could find a used 3.33 it would be ideal maybe. There's no new or aftermarket.

There are some Jeep rears that will fit but if you don't know what you're doing you're best not to try.

If you want used there should be likely a few available as a WTB here on the forum.

An install depends upon ones talent, if you need to pay then discuss it at length with the shop/individual that you expect to do it. You'll need an install package of 6 bearings, 3 seals, the shims and hardware generally done in one package. It can be done with less hardware but there's no good reason to half a$$ it.

Availability/vendors up to you - everybody has them. Good luck!

 

I will certainly not be doing the gear install myself.. that is beyond my skill and knowledge. I can make do with a 345 or 354 though... I just dont want TOO much gear to where I'm having massive traction problems all the time on my 255's.

Thanks a ton for the help bud!

 

Next logical step would be to fix your idle first before doing the other stuff.

Obviously, the most "fun" thing is gears. If you want to do a HSR, you are going to need ECM tuning. You also need to cut a hole in your hood to let the HSR fit.

 

lol. I think my idle has been fixed by cleaning the TB. If not, tuning would probably be needed to dial in the idle better.

I really think some gears would wake the car up over the 3.07's.

 

I meant to mention and forgot, I'd consider shopping for a 3.45 3d member already assembled and then you could resell your 3.07 as an assembly and maybe reclaim most of your expense. I'd post your 3.07 for sale while still in the car so it could be driven and confirm that there are "NO ISSUES" or if there are issues it's known by the buyer.

 

Who's going to be selling the whole diff with the gear that I'm wanting? Seems a good idea but I'd have to get pretty lucky. Which I'm not.

 

You are going to need a tune to optimize it. I'd get gears based on the combination I have.

 

So you think 35x or 34x will suffice based on mods?

 

3.45 should be OK but I'd ask the person setting up the system.

 

Nearly every D44 out there for sale is a 3.45 ratio, there's none/little "luck" involved. Wise shopping maybe but "luck" I'd say NOT.

 

Think about this

Gears allow the car to accelerate faster, an engine makes power as rpm climbs at 1000 rpm a 400 hp engine makes say 100 hp 2500 250 hp and so on till max hp at or near max rpm 3.08 gears you are out past 60ft before you hit max rpm which =max power w/4.88's you've already hit max rpm and are in second gear,so for that first 60 even though the guy in the next lane had same power as you his power was available sooner, and he's ahead of you. In case w/c5 vettes equipt w/3.42 vs 4.10 w stock motors they are very close (et & mph) as fuel and timing curves were optimized for the 3.42 gear equipt cars from the factory.Thats why a tune is import when mods are done; as tune to the 4.10 car takes advantage of the quicker accelerating engine by adjusting fuel delivery and spark curves and as mods are done (heads cam) remember to make more power more air /fuel must get in and out of engine cam opens sooner closes later to take a bigger gulp of air/fuel mixture end result more power on top but start to lose on bottom end (as valve is opening sooner in the cycle and closing later and there is a loss of cylinder pressure) [squeeze]so a loss of low RPM POWER. This is where gears come into their own as they allow the engine to get up to where it makes power.

Gears like every other mod are just a part of the whole package very few things by itself will be a "MAGIC BULLET" So to answer gears help a stock equipted car marginally but modded are necessary. If gears are the plan and car is to stay totally stock a tune would be advised and if any mods are planned it is probably one of the better mods you could initially do.

 

You also need to know what speed your Trapping at.

This is a great website, pan down, select your car, tire height, redline, etc and see where you stand at redline with various gears.

http://xse.com/leres/ss/calculator.html

 

I ran 3:73 for 8 years on my stock '93. Loved every minute of it as long as I didn't think about fuel costs. And changed the speedo gears.
I'm back to 2:58 now. Bought both pumpkins off Ebay

 

So a dana 44 came in more than just our Corvettes??? I thought 307 and 2.x were the 2 biggest ratios offered in these cars?

I thought that rear-gears were an item that wont need tuning?


Only time I went to the track and trapped a 9.6 @ 77..... with a 2.6 60ft... on my OEM 27 year old tires :shame:

 

The C4 Corvette uses what is called a D44HD.

It is similar to a regular D44 (same size ring gear) but the D44HD uses a 29 spline pinion like the Dana 60/70 and larger ID pinion bearings. The carrier bearings are actually smaller ID than the regular D44's.

The gear set is used in some Jeep WK Grand Cherokees, Wrangle Rubicons and Dodge Vipers. but the housings are different between all of them. Some of the ring gears have a different bolt size... 2nd GEN Vipers and most Jeeps use a 7/16" bolt while some early Jeep Rubicons, 1st GEN Vipers and the C4 Corvette use a 3/8" bolt...

Most aftermarket gear sets are drilled for both sizes but OEM SPICER gear sets are one or the other.

Factory ratios for the C4 Corvette D44HD were 3.07 (common), 3.33 (very rare), 3.45 (common) and 3.54 (rare).

Aftermarker gear sets are availiable in 3.73, 3.90, 4.11 and 4.30 from Yukon Gear. I have used a number of thses gears and like them... they set up easy and it's easy to find what you need on their main sellers web site (Randy's Ring and Pinion)....

Also be aware there is a Ford front end in 4WD trucks that is often refered to as a "D44HD"... this front end does not share any compatible parts with the Corvette/Viper D44HD.... This is a very obscure front diff.... not common at all..... It was a reverse rotation D44 front end with 8 lug 3/4 ton outer hubs. This diff makes things even more confusing for those that don't understand differentials.....

As for tuning... depends on the year of the car. OBD2 cars can have the speedo changed via the PCM to read correctly.... earlier cars have to have the gear changed on the speed cable that goes in the tranny tail shaft.. sometimes both gears (speedo cable gear and the tranny output shaft gear).
Will

 

Thank you so much for the abundance of information. I'm going through randy's for my tahoe, will probably just scope out a gear-set for teh corvette from there too.

 

Checked out Randy's and thats where I'll be ordering gear from. Thank you so much guys, thats exactly what I need.


Also,
I'm not calling anybody a liar.. but I've NEVER heard of needing to retune a car when installing different gears other than to set the speedometer. What kind of engine parameters need to be changed for a lower gear???

 

None, you don't need to retune the chip for a gear change. You only need to fix the speedometer.

 

It is worth noting that the factory bins were tuned for each axle ratio, since there are some gear dependencies in the tune...things like the n/v ratio limit values for gear detection purposes and tcc lock/unlock speeds, etc.

Although, these changes are relatively minor, they do affect TCC and/or 4+3 overdrive control and overall drive-ability.

In general, it makes sense for the tune to fit the car's configuration and driver's preferences. Since tuning is so easily accomplished on these cars, and can be done for very low cost, why compromise?