Stock lm7 turbo build

[Drunkcanuk]

I had to get a replacement one at a salvage yard sense it didn’t fit right. I found something on the drivers side door but it’s all warm off. She has 200,000 miles so it’s expected.

I may be wrong, and someone will surely correct me if I am. But I think I read somewhere that there is a stamp from the factory somewhere on the axle housing itself that says what it shipped from the factory with. Obviously someone could have changed it along the way.

Could also try and run a VIN lookup, they usually have that info on there as well. But the free ones my not be 100% accurate.

Can also jack the rear end up and mark the tire and driveshaft, put it in neutral and see how many revolutions of the tire it takes to do one revolution of the driveshaft.

 

[Romanheystek]

And then that tells me what? Like are dif’s based off of that? Arnt all 5.7 4l60e’s of that year going to have the same rear end?

 

[Drunkcanuk]

And then that tells me what? Like are dif’s based off of that? Arnt all 5.7 4l60e’s of that year going to have the same rear end?

It will tell you the gear ratio. There were a few different ratios and if it came factory with a limited slip.

 

[Romanheystek]

okay makes sense thank you. I’ll hold off on that then till I have the motor and trans in because I’m still dailying it. Thank you for your help

 

[RDF1]

Id be willing to bet it has 3.42s since those were the most common.
You can call a dealership with your VIN and ask for a part number and price for the gear set. That will atleast tell you what it would have had if nobody has been in there swapping parts.

You have the 8.5" 10 Bolt rear.

I put this in the '98 C1500 with the Twin turbo 4.8

EATON 913A481 Eaton Detroit Truetrac Differentials | Summit Racing

Free Shipping - Eaton Detroit Truetrac Differentials with qualifying orders of $109. Shop Differential Carriers at Summit Racing.

www.summitracing.com

Bearing LM102949
Race LM102911

 

[Romanheystek]

Id be willing to bet it has 3.42s since those were the most common.
You can call a dealership with your VIN and ask for a part number and price for the gear set. That will atleast tell you what it would have had if nobody has been in there swapping parts.

You have the 8.5" 10 Bolt rear.

I put this in the '98 C1500 with the Twin turbo 4.8

EATON 913A481 Eaton Detroit Truetrac Differentials | Summit Racing

Free Shipping - Eaton Detroit Truetrac Differentials with qualifying orders of $109. Shop Differential Carriers at Summit Racing.

www.summitracing.com

Bearing LM102949
Race LM102911

Yeah I just figured that out after searching for a min in class. How much does the ratio matter like is there a way to change the ratio for better performance?

 

[Drunkcanuk]

Yeah I just figured that out after searching for a min in class. How much does the ratio matter like is there a way to change the ratio for better performance?

The "higher" say a 3.42 gear ratio ,the lower the rpms at speed.
The "lower" say a 4.11 gear, the higher rpm at speed.
So a lower gear will get you going faster but you won't be able to go as fast as the same rpm.
So your engine will be screaming at 100mph with a low gear vs humming along with higher ones.
Man....I hope that makes sense! Lol

Ya, you can just buy a new ring and pinion set from your favorite parts place, like Summit or Jegs.
It's not the easiest thing to change, especially if you haven't done it before, but not rocket surgery either.
I believe you were asking about limited slip/locker, changing gears and adding that at the same time is the best way, get it all done at once.
I really hope that all made sense.

 

[RDF1]

Yeah I just figured that out after searching for a min in class. How much does the ratio matter like is there a way to change the ratio for better performance?

For a turbo setup I always use 3.42s unless it has larger tires than 32".

 

[Romanheystek]

The "higher" say a 3.42 gear ratio ,the lower the rpms at speed.
The "lower" say a 4.11 gear, the higher rpm at speed.
So a lower gear will get you going faster but you won't be able to go as fast as the same rpm.
So your engine will be screaming at 100mph with a low gear vs humming along with higher ones.
Man....I hope that makes sense! Lol

Ya, you can just buy a new ring and pinion set from your favorite parts place, like Summit or Jegs.
It's not the easiest thing to change, especially if you haven't done it before, but not rocket surgery either.
I believe you were asking about limited slip/locker, changing gears and adding that at the same time is the best way, get it all done at once.
I really hope that all made sense.

That makes sense thank you very much.

 

[Romanheystek]

For a turbo setup I always use 3.42s unless it has larger tires than 32".

Would a say 4.11 be that much of a difference for say a 0-60 time?