What rear axle ratio's are you running
 

Good morning Gentlemen,

As my build is now approaching the physical rather than the esoteric, my shopping list for upgrades is becoming more defined.

So, today's series of question:-

What axle ratio are you running and what is the rest of the drive line?

Mileage?

Are you happy with your choice?

Eventually I will run a LM7, TKO 600 (road/race gearing) and a 265/65/15 tyre/tire.

My initial thoughts were to copy the Tahoe gearing (3.42-3.73- 4.11) but get conflicting reports and, as I wont be towing a 3000lb ski boat, a lot of it is irrelevant.

I will be using the truck as a DD but also for track days/autocross events.

Previous experience with a DNE 4+1 saw me use a 3.25 with 29" tyres. With a BBC I got over 18mpg and ran a very low 12second quarter.

Look forward to hearing your thoughts and comments.

P. :D

Re: What rear axle ratio's are you running
 

I run a 3.73 in my 12 bolt 71/72 rearend. I have a 4.8/4l60E. with this ratio, I feel it hits the sweet spot with the OD trans and also quick starts off the line when needed. I also use a 29" tire ( 275/60/15BFG)

Re: What rear axle ratio's are you running
 

Thanks for the reponse

What sort of mileage are you achieving?

P.

Re: What rear axle ratio's are you running
 

I'm running 3.73 in my stock 12 bolt truck axle....30 inch tire...Feels like I need and OD trans at 65...but cruising at 55 at 2500 rpm gets me around..oh...15 mpg...my 292 is old an worn out..so once I rebuild it I'll be able to figure the mileage a little better. :chevy:

Re: What rear axle ratio's are you running
 

Re: What rear axle ratio's are you running
 

""" My initial thoughts were to copy the Tahoe gearing (3.42-3.73- 4.11) but get conflicting reports and, as I wont be towing a 3000lb ski boat, a lot of it is irrelevant.""?"

If never towing and using as DD I would run the 3:42

Re: What rear axle ratio's are you running
 

250/Richmond 5-speed/3.08

You can only expect so much mileage as you push a brick through the air...

Re: What rear axle ratio's are you running
 

I have gotten 19.5 on mostly highway ( 75/25) I think if there wasnt much wind ( yeah right) I could get 20.5 on all highway.

Re: What rear axle ratio's are you running
 

I have a 3.08 and 28" tall tire. I wish I had more gear.. I run 70 @ 2600 rpm.

Re: What rear axle ratio's are you running
 

The original rear with 3.73 gears and 29" (275'60x15) tire. I have no clue what I get for mileage as I have not gotten the speedometer gear in the tranny replaced yet. It does wind at 65/70 on the road, but it does it well.I plan on going to a 3.08. I am running a 3 speed manual tranny. Best guess is around 13-15.

Re: What rear axle ratio's are you running
 

In my truck at present is a 3.90 with 26" tire.
it revs way too high at only 50mph.
I'm going to swap it to a 3.08 this winter.
If it bogs it down too much, I'll put the 3.73 I also have.

Re: What rear axle ratio's are you running
 

Wow,

A lot of information! I have used an online gear calculator that shows with the .84 5th gear and a 3.73 gear 70 comes up around 2500, with a 3.42 the same rpm gives me 76mph.

I suppose my real question is where is the sweet spot for the LM7? Think I will try one of the LSx forums unless anyone knows better?

Thanks for the input.

P. :D