Opinion's wanted

[BigRed76]

Originally Posted by redbaron

With your 4L60E and 28" tire at 75 MPH the engine RPM would be at 2155 running a 3:42 gear ratio in overdrive.

That is good to know. Even with the power of my stock 5.3 it doesn't need to be running 2500 rpm or more on the interstate just cruising.

[Andy4639]

Originally Posted by redbaron

Ok Andy here goes the various RPM your engine pulls with the 4L80E and 29.5" tires in 4th gear or overdrive.

4:10 @ 80 is 2800 RPM, 70=2450 and 60=2100.

3:73 @ 80 is 2550 RPM, 70=2230 and 60=1900

3:42 @ 80 is 2340 RPM, 70=2045 and 60=1750

3:08 @ 80 is 2100 RPM, 70=1840 and 60=1580

Hope this helps, Mike

Thanks redbaron,
this is going to make the decision a lot easier for me. The 3:42 looks like the best for all round driving. I think the 3:08 would be a little off the mark.
I run 10% ethnol.
My motor combo came out of a 2003 H/D 2500! The motor had 89,000 miles on it so he said when installed. I haven't done nothing but plugs and new Knock senor's when installed. Oh and new water pump.
Ok now I've pretty much decided on the 3:42 how about positraction units!

[TwinsSpeedShop]

andy, with the ease of driving that you do, you will see the best MPG pick up ditching the 80!! Have someone build you a good 60 and change your harness out and see what that nets you. The simple fact that its a 6.0 means its not going to get great fuel numbers but it will make great HP and TQ numbers. LIke someone stated before, 6.0/4l60 combo will get in the upper teens.

As for Posi units, I put a Detroit Tru Trac in my step side truck and liked it a lot. Its all gears and no clutches so it will last much longer and had great smooth engagement.

Just my .02

[Andy4639]

Originally Posted by TwinsSpeedShop

andy, with the ease of driving that you do, you will see the best MPG pick up ditching the 80!! Have someone build you a good 60 and change your harness out and see what that nets you. The simple fact that its a 6.0 means its not going to get great fuel numbers but it will make great HP and TQ numbers. LIke someone stated before, 6.0/4l60 combo will get in the upper teens.

As for Posi units, I put a Detroit Tru Trac in my step side truck and liked it a lot. Its all gears and no clutches so it will last much longer and had great smooth engagement.

Just my .02

If I could get 18MPG I'd be happy. I'm not wanting 22-25MPG just better than 14!
As far as the posi units I don't know. I'm going to be looking over the holidays and seeing what I can find.

[redbaron]

Originally Posted by Andy4639

If I could get 18MPG I'd be happy. I'm not wanting 22-25MPG just better than 14!
As far as the posi units I don't know. I'm going to be looking over the holidays and seeing what I can find.

As stated early the Eaton Detroit Locker True Trac is an excellent choice for posi options. We run them in about everything except Jeeps where ARB airlockers work better. Currently putting the True Tracs in two supercharged LS vehicles.

The final gear (overdrive) difference between the 4L60E (.70) and 4L80E (.75) is only .05. This equates to less than 200 RPM reduction at 80 mph with your 4:10 gear ratio. I think you're on the right track by changing your gears to 3:42.

[Andy4639]

Originally Posted by redbaron

As stated early the Eaton Detroit Locker True Trac is an excellent choice for posi options. We run them in about everything except Jeeps where ARB airlockers work better. Currently putting the True Tracs in two supercharged LS vehicles.

The final gear (overdrive) difference between the 4L60E (.70) and 4L80E (.75) is only .05. This equates to less than 200 RPM reduction at 80 mph with your 4:10 gear ratio. I think you're on the right track by changing your gears to 3:42.

Where do you get your Posi units from? Would I have to change anything else in the rear end other than normal stuff like bearings and seals and such?

[XwalkerX]

this is what i went with

http://www.summitracing.com/parts/et...-010/overview/

dont forget you will want a series 3 carrier for the 3.42 combo

[toolboxchev]

Out West these guys are pretty well known in the business. They know their stuff on Dana.

http://www.sixstates.com/products/products.jsp

p.s. I do not work there, or am employed by them in any way.

[redbaron]

Originally Posted by Andy4639

Where do you get your Posi units from? Would I have to change anything else in the rear end other than normal stuff like bearings and seals and such?

I buy mine through a warehouse that we get a lot of parts from. In all honesty Jegs or Summit prices are hard to beat. The parts you mentioned should be all you need if your axles are good and without a wear ring where the seal rides.

Do you have a local speed shop in your area that sells parts at a fair price?

[redbaron]

Originally Posted by XwalkerX

this is what i went with

http://www.summitracing.com/parts/et...-010/overview/

dont forget you will want a series 3 carrier for the 3.42 combo

What Walker said. Can't believe I forgot about the carrier.

[Andy4639]

I have a buddy who has his own shop. I plan to go by tomorrow and talk to him since I'll let him do the install anyway!
He was taught by the best Mechanic I have ever known and that would be my dad.
My dad was the GM training center Chevy head instructor in Charlotte NC for several years and my friend went through his classes on all the stuff he taught back in the late 70's early 80's.

[Andy4639]

Originally Posted by XwalkerX

this is what i went with

http://www.summitracing.com/parts/et...-010/overview/

dont forget you will want a series 3 carrier for the 3.42 combo

You have to buy the gear set also right? This is just the posi unit?

[XwalkerX]

yeah ring and pinion is separate and you'll need an install kit (bearings/shims/seals)

[XwalkerX]

here is mine

[Andy4639]

Cool! Thanks. I'll be checking prices over the next few weeks and buying one I hope.
This is a complete kit with everything.


http://www.ebay.com/itm/GM-8-875-CHE...FUvTv6&vxp=mtr

[redbaron]

Originally Posted by XwalkerX

here is mine

Hey Andy,

I see Eaton doesn't make a True Trac in the 3:42 and higher gear ratios. They only build them for 3:73 and lower in our trucks.

Walker is using the Eaton Posi which is a very good unit also. I have used this system in a 69 Camaro with a big block that truly made over 500hp, pulled over 7000 rpm and power shifted the heck out of it with absolutely no problems. Sure wished I still owned that Camaro.

Mike

[davepl]

You -might- be able to get away with a True Trac and a spacer in the lower numerically range.

I too have the Detroit Locker True Trac - haven't driven it enough yet to know much about it. Seems pretty tight at the moment, I'll have to do some circles. But I have one in my Camaro as well and have never had a problem.