professorX

I was just woundering if this rear end could be upgraded with 373 gears, and if any of you guys have done this. Where and how mush it costed you would be helpful also and thanks for reading.

corvette Stu

I just put a 3.75 in my Dana 36 for my 95. I found it on Craigslist it was a fresh rebuild in the case for $500. Sold my 3.07 for $400, paid $300 for the install. So $400 installed all said and done for me.

jispr

Red got a steal! Corvette Central wants $1700.00 for a rebuilt 3:73!
plus your core. I run 3:73's and thought I would never change.....till I broke the pinion last weekend. Going back to my old stock 2:58? If you can do it yourself it's pretty straight forward. Got mine out in 3 hours and had not done the job in 6 years. Gas mileage is crap with the 3:73 but what a launch!!

corvette Stu

I made the change for the launch at the track with my 2800 stall. Did not want to tackle it in the driveway when I got my man Josh at Horse Power Addics (who is a vender here) to do it for $300 out the door, oil and posi oil to. Made the trip to Carlisle in it 5 hour round trip and came back with a 1/2 a tank, not bad for a 3.75.

professorX

So if you had around 480HP would you stick with the 307's or go for the 373's?

856SPEED

I think I paid $350 for my ring/pinion 3.73 unit and I don't remember what I paid for the labor as the whole unit was rebuilt when we did it....bottom line is been running the D36 with a 6speed manual ZF with the 3.73's on the rebuild for about 4 or 5 years and my car just dynoed at 332.5 at the wheels on a Dynomite which reads lower than a DynoJet unit....no problems at all, but I don't run DR's....run 285's in the rear; no differential problems at all.....knock on wood....

pologreen1

Traction is what will kill the D36 with anything more than stock and even stock IMO with traction and 3.75 can start to wear it out Quick.

You should be able to blow the tires off in 1st with an auto trans and 3.75, but if you make all that torque hook it hurts. The 1st gear in the 700 trans is low so that mixed with the lower gears makes it like 4.56 gear in other cars for first gear.

What everyone says is don't mix hp with traction in a D36 but especially with low gears. Some say they did it for a season or 2 and others say it blew out after a couple runs. The fact is it will break if you push it.

C4in mesa

I have a stock Dana 36 in my 1988 C4. My rebuild is 330HP at the crank. It will be on the road in a couple weeks. Before my stock L98 **** the bed I could go 140mph. I am hoping with the additional 90HP that I can reach 160mph. Any thoughts ? Are the 3:07 gears best for top end ? I don't stomp on it at red lights turning green. Looks dumb and a new Corvette would make me look even worse ! I am all about top end since driving from Mesa to Los Angeles is where I open it up. Will the Dana 36 handle high speeds for hours on end ? I don't know what is hard on rear ends other than burn outs ?

vetteoz

What engine mods to get that?
If still with a TPI stye intake then 3.07 is the most recommended for all round TPI use but if all you are interested in is top end mph then the taller the better
so long as the engine has the ***** to pull them and the wind resistance factor

c4cruiser

I would suggest getting a D44 and install the gearset you want for the intended use of the car. The D44 is stronger and will handle more abuse.

A D36 should handle high MPH as long as everything is fresh and assembled properly paying attention to critical specs. Same with the trans.

Stock L98 motors should be capable of pushing the car to 150 and maybe 2-5MPH higher. By '87 or so, car magazines were reporting top speeds of 150 with the manual trans being a little faster than the A4. Cars with the ZF6 manual trans attained their top speed in 5th gear. The 6th gear ratio at 0.5 didn't allow the engine to push the car faster because of aerodynamic drag and the much lower RPM range in 6th.

Auto trans cars typically have gears in the 2.45 or 2.73 area while manual trans cars will have 3.07 in the early C4's to as high as 3.54 in the later C4's. All manual trans C4's got the D44, auto trans cars got the D36.

My '87 coupe with the 4+3 and 3.07 gears (D44) has about 300HP at the flywheel with the mods I have. On local road courses, I can hit almost 130 in 4th gear without the OD engaged. That is right at 5000 RPM.

OF course these speeds are measured at the track; driving like this on the street and talking about it here may not be a good idea...

C4in mesa

The engine has a full roller rocker kit, Comp cam 12-417-8 plus all the changes needed to use this cam springs and such. A reduced pulley set. A ported (the right way !!!!!!!!!!) gasket mated intake manifold and SLP ported and gasket matched runners. The heads are stock and have been ported to give more air flow and better exhaust flow. A Hypertech coil and 24lb Bosch fuel injectors. Hedman long tube headers 68487 with Flowmaster cats and mufflers 2.5". A Edelbrock water pump. I have not had this car Dyno tuned for that matter it isn't on the road yet ! From this web site I was turned on to Wongs Performance in Vancouver WA. Wongs told me mail them my stock chip and he will modify it to handle the upgrades for $200. I need to get my ducks in a row and send it off to him. He warned me as others have of trying to use a Hypertech or JET chip. Your thoughts ? Am I over looking anything ? Am I dreaming of getting 300-330HP to the crank ? Will my 3:07 gears get me to 160-170mph ? Should I buy new tires or attempt to open it wide open with old rock hard tires !!! Another $700 for tires. I run 275-40-17 so I can rotate and extend the life.

C4in mesa

It will cost me another $2000 in parts and labor to put a Dana 44 rear end my car. I suppose I will have to drive it as is until I have the cash to change out the rear end. I have found a Dana 44 rear end complete for $1500 but then the labor cost. I am leery of putting used gears so they will have to be new. I have been waiting for this project to get wrapped up for 4 months. The engine rebuild $2700 with the roller rocker kit and cam kit oh and TAX !!!! The engine was pulled by my friend and stripped down. he is also going to put the crap back on it and put it back in. He is also the guy who ported and gasket matched the manifold and runners. He wants $1000 for his end. I am also having him put J55 calipers on and I need to buy some 13" rotors.

ZD1

what rpm? What rpm are you running at the traps

C4orce2

I have a D36 with 3.73 gears in my '92 with the auto (700r4) and a LS3 Hot Cam crate engine from GMPP. As tuned now it is putting out 429rwhp and 442rwtq (as measured on a loaded dyno). My builders told me not to put drag radials on it and take it to the track since that would certainly ripe out the rear end. I took it out to a safe spot one time and floored it. Smoked the tires until it was half way through 2nd gear. You will love the 3.73s but depending on your tq you may destroy the D36. When my D36 is trashed I plan on going with a D44 and probably gears similar to the 3.73s. Have fun.

ghoastrider1

the lower the NUMBER, the better for high speed...307 will let the engine turn over at LESS rpm that 373 gears. The higher NUMBER is for quick accelaration NOT high speed numbers. 307 means the drive shaft will turn 3.07 times the wheel does..3.73 means it will turn almost 4 times the wheel does.

jhammons01

That's being a bit overkill...the D36 is plenty strong enough to handle 330hp and 160MPH for as long as you can run it on "HIGHWAYS" between LA and Mesa.....

jhammons01

Another Fallacy......High torque may destroy a 100k mile Dana out of some hoopty with sloppy Pinion.......

A correctly working D36 will stand up.

C4in mesa

Let me say after just driving to Venice here now, that I will never run my car wide open. I was driving a new Corolla at 80mph. To my surprise getting passed like you are parked with no room to spare made me think wtf ! Had one of those idiots screwed up God only knows ? Anyway if there isn't any traffic and I can see a couple miles ahead I will open it up next year when I come back. I won't be hard on the rear end and will post results of the build. Bought an edelbrock 3860 rather than port my stock manifold. Question ? Should I gasket match the holes feeding air to the heads ? They aren't any different than the stock holes. I'm gonna ask the engine shop what they think too. Reason being I want the heads ported some for better air flow. Again is this a smart move or not necessary ?

jhammons01

So for a "Few miles" on the highway you want to put a D44 in?? At the cost you described? For what you described, save your money for beer in LA.

I think that is a different topic, maybe start a new thread and ask this question. there are some really talented motor Guru's in here that would love to answer that question. Only thing is that you buried it in a D36 thread......

C4orce2

The company in Scottsdale, AZ, that tuned my car, and the manufacturer of the loaded dyno that they tuned it on, both say that on their loaded dyno you loose 27% from SAE net to the wheels. Taking their figures and the 442rwtq we ended up with, that converts to approximately 605 SAE net tq. Even using the more traditional 20% loss, the 442rwtq converts to 552 SAE net tq. All the people involved in the build of my car, and several car nuts who are much smarter than I, have all told me that my D36 with the 3.73 can not take that much tq. Are you saying that it can? Just curious.