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Changing rear to 3.73 from stock

  • Thread starter Thread starter wookiebear
  • Start date Start date
W

wookiebear

Guest
Just wondering if anyone has done the above modification to their Vette? Just bought a 3.73 complete rear and was wondering, just how much of a difference I will notice.
 
I was running the stock ratio (3.07:1) with the Doug Nash 4+3 and upgraded to a 3.73:1 rear. It'll please you immensely with the seat-of-the-pants difference in acceleration. :D

You gas mileage won't suffer too awful much if you stay off the go pedal. ;)

_ken :w
 
gear change

in my opinion a gear change will give you the best bang for the buck the difference is amazing no other mod is as dramatic :beer :_rock :w steve
 
I got 2 words. Holy $hite. You will not believe the difference. I did this about a month ago and I still drive around with a smile on my face. I would aslo throw a shift kit and a new Torque convertor in to compliment the gears. It will feel like you bolted on a SuperCharger.
 
3.73 gears WOW!!!!!!

You guys have me really pumped about the gear change! I am presently awaiting shipment of the rear, hopefully it won't take to long! Will let you know how it all works out!! Now I really can't wait! LOL
 
3.73 complete rear

Hey Wookie if you dont mind what was the cost and where did you get it from? What was your previous gear ratio? I'm looking into buying complete unit with 3.45 or 3.54 ratio.
 
Cost of 3.73 Rear

I bought the rear on E-bay, it cost $510. bucks, but it comes complete with cross members and shaft, this is the whole unit case and all. I presently have the 3.07 rear in the car, I figured that I can just bolt the the unit in and then try to sell mine with the 3.07 on E-bay when the time comes. Alot of guys have the stock 2.59 gears and are looking to step up to something that will pull harder like the 3.07 but still get the economy on the highway. I have seen new units (reconditioned) that are selling on E-Bay for $1,200 to $1,300 without the shaft and crossmember, not that you need them, but I just figured that what I don't use I will sell on E-bay to lower my total cost, Then maybe I will spring for those AFR Heads that I have been seriously looking at! LOL!
 
In the distant past I went from a 3.73 to a 4.56 in a wide ratio 4-speed GTO because all the car would do was burn the tires.
The gut who told me to do it said "you'll think you got a new motor".
he was right.
a 3.73 behind a 700R4 has the same launch ratio.
 
www.vettepartsonline.com

Ethan,
Check out these guys they offer a Dana 36 Gear conversion for $799. with your core exchange. Just saw there flyer in my Vette folder, I have never used them, but the flyer looks interesting.

Wookiebear
 
Cold Water

I was not at all happy with my change to the 3.73 from the stock 3.07. When I did it, I was running a modified CrossFire engine, and the unit I bought was all I could find, save a set of 3.36 gears for tons of dough. The X-fire just ran out of revs way too fast!

The speedo error required a conversion electronic box or a gear change, in and out of the tranny.

Now with all the low end power and increased upper end revs of this 406, I light my tires at will in first, but believe the car would be better with 3.36- 3.54 gears.

Enjoy; I do hope you like it.

:w
 
Whalepirot

Thanks for the comeback, I am not worried about the speedometer adjustment, since I have the Hypertech Programer and can dial in the correction right into the computer in a matter of a few minutes.
When you say modified crossfire, exactly what type of modifications are we speaking of? I appreaciate your reply I always like to hear both sides of the story.


Wookiebear
 
The Hyper Tech will only allow you to put 3.70 into the car, but that is close enough.
 
I had enlarged throttle bodies, headers and Flowmasters and a hotter camshaft. (Sounds like a medical thing.)

The Flows and headers made the biggest difference. Wrapping the headers with Thermo Tec made another jump! The cam was hot enough to mess up the ECM, by dropping the MAP a few psi.

The still-stock intake restricted the torque curve at the high end. (HA! What high end?) GM built these engines to be torquey down low and geared the cars accordingly, to raise the CAFE, while giving the 'boot' that Vette drivers must have.

True, the 3.73s allowed for a quicker launch, but the 'show was over' quite quickly, at about 4500 rpm. I needed a lower ratio or a higher revving engine, or both. The spun #7 main bearing answered that question.

My new 406 is quite happy above 3000 rpm; quite unusual for a Vette guy to like. It sounds wonderful, too. It pulls like stink to 6200+. (dash lag)

I spin my 335x17s at will in first, so the 3.54s or the 3.36s I had in my (crate motor) LS-6'd '71 would not be a better choice here again. I just cannot hook up in first.

It comes down, again, to what do you want? Just take your time; save some dough until you decide; then take a reasoned, well advised and total system approach; step by step as most of us mu$t. These cars are sophisticated and engineered as never before, as a system. Modding them demands the same approach to yield the results we want. OR, we spend and waste a lot of bucks trying parts.

Good luck with your new gears. I hope you love them!

:w
 
UB2 SLOW said:
The Hyper Tech will only allow you to put 3.70 into the car, but that is close enough.

When I changed from the stock 2.59 to a 3.54 my track times went from 13.90's@101 to consistent 13.30's and 20's@105+mph.
I would expect you should see similar results with the 3.73.
A gear is probably one of the best mods you will do to your 96.

I also agree with just using the 3.70 in the programmer. You can fiddle around with the tire height to get it exact but it's not worth it IMO. I did this with mine, the programmer only has a 3.45.
I found that by using just the 3.45 in the programmer the car shifted better and I also discovered that my spedo is dead on according to local police ;)

have fun with the new gears
 
2800 Stall Converter

Vettn94,
How does your 2800 stall converter compare to your stock converter? Are you happy with it?

Wookiebear
 
It's a huge change. My 60' times went from mid 1.90's and 2.0's down to low 1.80's/high 1.70's.
My first run with the converter in the car was about 15 mins. after a 75 mile drive to the track and yielded a 1.81 60'.
So far I have only gained 2 tenths in ET from my previous best but I think in cooler weather I can easily drop another tenth or two.
 
Looks like I am headed in this direction fast on my 90.

I have checked out TPiS and Richmond gear. I have a local guy that does nothing but rear gears in his spare time. Very high quality work for good prices.

Looks like the Richmond is actually a 3.75:1 as if that .75 vs. 73 makes any difference.

I need to do this for several reasons. Mainly to help the clutch live longer, launch harder, and get more out of the miniram intake and free flow exhaust.

I will save the 3.30 gears for now, but think that this will make a significant improvment to a car that is already very strong.
 
This posting has given me MORE reason to search out a 3.73 rear end. I have the standard 3.45 on there now and have been considering the upgrade since I got the car. I know the price is gonna kill me, but I am sure the first time I step on the gas, i'll completely forget how much it cost.

John
 
just my .02 sense here but I don't think you'll notice much with the change from 3.45 to 3.73. Being that you have a 6-spd (from your sig.) you might want to reconsider and go with a 4.11
 
69MyWay said:
Looks like I am headed in this direction fast on my 90.

I have checked out TPiS and Richmond gear. I have a local guy that does nothing but rear gears in his spare time. Very high quality work for good prices.

Looks like the Richmond is actually a 3.75:1 as if that .75 vs. 73 makes any difference.

I need to do this for several reasons. Mainly to help the clutch live longer, launch harder, and get more out of the miniram intake and free flow exhaust.

I will save the 3.30 gears for now, but think that this will make a significant improvment to a car that is already very strong.

Chris,
Get the Super Dana 44 gears from a Viper, you need to file a bit on the housing of your current Dana 44 but they will fit..

Sounds like you have the 3.33 gears.. the 3.73 would be good too, I have the 3.45 in my car and I don't want to swap just yet, if I do it will be a 4.10. but I am not even thinking of it at this point
 

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