Ally or 4L80?

[TheBac]

Mike,

In a Drag racing application, if the vehicle is 2wd, weighs approx 4200lbs and runs min 14" wide slick wth a stock G80 3.73 rear and an LB7 at 575rwhp or possibly running Trent's S475/stocker twin setup at 650+rwhp, what trans would you recommend? Built Allison or built 4L80 or maybe something else? If 4L80, what would you recommend be done to it?

 

[03-GMC]

This should be interesting.

Subscribing

 

[gmduramax]

I would say 4L80E. I seen a guy with a half ton 4wd using a 4L80E with just a shift kit and converter running 9's at 140+mph. I think he was 5000lbs+

Edit. Not sure if it could handle the torque of the LB7. The guy was running 1100hp not sure how much torque

 

[TheBac]

I figure torque between 1100-1200ft/lbs.

 

[JOHNBOY]

4L80.

300M billet input and a good solid build should work great for that.

There is a very good and reasonable trans builder in Mi.

Mike Wood has been 9.2@149 with a 4L80. 600lbs and 2 seconds slower it should be fine.

 

[ChevyDieselLLY]

This should be interesting.

Subscribing

x2 opcorn:

 

[lotsofmiles]

I got one of each in the 2wd versions I'd donate for testing. I get them back after the build tho

 

[Mike L.]

If you can get 4th gear to stay alive the 4L80 would be great and faster than a Duraflite.

 

[03-GMC]

Are parts for the 4L80 pretty cheap?

 

[Mike L.]

Are parts for the 4L80 pretty cheap?

Nothing is cheap.

 

[03-GMC]

Nothing is cheap.

Ok, well compared to building a alli?

 

[408.Luke]

4th gear is the weak link, if you are geared to pass the traps at the top of third you are golden, I just had a 4l80e built for my SS silvy, i think parts alone were 3500$ it got all billet Shafts, machined out drums to hold extra clutches and steals, blah blah blah. Alot of gasser guys are running nothing but alto red frictions and steals and a shift kit and run 9's and 10's and do alot of roll racing.

 

[ChevyDieselLLY]

That's not a bad price on parts alone for what you listed

 

[TheBac]

Ok, next question....

Would a Dmax van 4L80 be a better starting point than a gasser 4L80?

4L80.

300M billet input and a good solid build should work great for that.

There is a very good and reasonable trans builder in Mi.

Mike Wood has been 9.2@149 with a 4L80. 600lbs and 2 seconds slower it should be fine.

Who in Michigan, John?

 

[JOHNBOY]

If you can get 4th gear to stay alive the 4L80 would be great and faster than a Duraflite.

Mike shifts into 4th with the converter locked. Never had issues with 4th gear. Weight probably makes the issue worse but at 3600lbs 4th gear is not an issue.

 

[Mike L.]

Ok, next question....

Would a Dmax van 4L80 be a better starting point than a gasser 4L80?



Who in Michigan, John?

I used a Duramax 4L85E when I built Diesel 5's Grand National because it had hardened parts from the factory. We were going to use the Alli but that would have put the Alli pan 1 1/2 inches off the ground.

 

[ChevyDieselLLY]

Tom what you got up your sleeve?

 

[JOHNBOY]

I used a Duramax 4L85E when I built Diesel 5's Grand National because it had hardened parts from the factory. We were going to use the Alli but that would have put the Alli pan 1 1/2 inches off the ground.

From what I have seen the OEM hardened shafts are a wash.

They did not hold up any better than the stock 4L80 did.

I like the 4L80 because you can get them easier and 300M goodies are available.

 

[TheBac]

Tom what you got up your sleeve?

An idea Ive been toying around with for about 3 years.
This is all speculation and theory at this point, but doesnt hurt to ask the questions now...

 

[Mike L.]

From what I have seen the OEM hardened shafts are a wash.

They did not hold up any better than the stock 4L80 did.

I like the 4L80 because you can get them easier and 300M goodies are available.

You might be right. I have never tried to build a killer 4L80 because of the breakage that I have seen with 4th gear. I question the use of 300M because it might be too hard and brittle. I have had better luck with 4350 as it tends to give a little and actualy hardens with stress. I am not a metalurgist and I am only going with what I have seen.