More Gear Talk

[Jason4x4]

OK, SO I have an 83 Longbed, see sig, Got a good deal on a set of 4.88's, and I have a 700r4 to go in. Now this truck is gonna be semi retired off roader, but will be promoted to Tow Rig to tow my Blazer.

According to my calculations, This should be a pretty good set up for towing, right? Or should I go with some different gears?

 

[Hogback Fabrication]

If you really want to tow a load as heavy as your Blazer with a 700R4 you will want the deeper gears and don't use overdrive.

IMO a 700R4 isn't up to the task of towing a 7000 lb. trailer along with moving the 5000 lb. truck.

 

[Jason4x4]

by deeper gears you mean the 4.88's I got? If I go anywhere I was planing on od on flat, but manual 3rd on anything else, the 700 will be built pretty good. Right now with the turbo 350 and 4.10's and 35's it isn't too bad, but any hill just kills it.

 

[Hogback Fabrication]

Swap to 4.88's and keep the TH350.

I know you're trying to help fuel economy with the 700 but it will be more money and hassle than its worth. Even on flat ground towing that much weight with a 700R4 in OD is a bad idea. Just my .02 of course

 

[Hossbaby50]

4.88's will help you tow but you won't want to tow anything heavy in OD, I don't care how built it is it wasn't designed to tow heavy in OD. With a 700R4 the 4.88's will be a very nice gear for 35's, especially since BFG's run small. You won't be able to tow at 75mph but you should have plenty of power to tow with 4.88's. Towing heavy with a 700R4 means BIG COOLERS (multiple is probably best) and a GAUGE. You should consider those manditory, not options. A deep aluminum pan and an aftermarket filter kit will help too. More fluid = cooler fluid = longer life & happier tranny.

You will love 4.88's with 35's on your truck. If I had to do it over I would have went with 5.13's instead of 4.56's when I built my axles because I had the 700R4. 4.56's with my 32" BFG's was AWESOME. Every time I bumped up a tire size though I liked my 4.56 gear choice less and less.

Harley

 

[Jason4x4]

ok, now, where is that gear calculator...

 

[Hossbaby50]

4lo.com has one, I know there are better ones out there, I just forget where.

4.88's and 33.5" tall tires = 2200 @ 65 in OD, 3200 @65 in D. Those are great numbers for a 700R4.

Harley

 

[Jason4x4]

cool, So, 35's, 4.88 75 not towing puts me in a nice rpm, since right now when I do 80 it's about 3200, yea, I know, slow down. anywho, the couple times i've pulled my trailer was never over 65, so 4.88's with a 700 in D, towing @ 60 would be ~ 2800.

so I need to get that 700 in the broken case I got from you, put it in with my 4.88's and tow in "D".

I got the 4.88's for a steal, so I couldn't pass them up, I figured if all else fails I could trade them off for something different.

 

[Hossbaby50]

P.S. The only problem with that gear ratio choice is unless your motor spins some good HP's and your are ok with higher RPM's is you don't have much passing gear, but you don't really need it that much. That setup is very close to my old 4.56's and 32's combo which I loved. It wouldn't shift out of OD much unless I was on some decent hills and it had nice power in OD.

It ran right up the mountain passes in CO with power to spare @ 65mph in D. It would run Sunset Point going to Flagstaff with ease too which my truck never did with 3.73's. This wasn't towing but it was loaded down with camping supplies. This was also before I did the TPI swap. With the TPI the power would have been freakin crazy on the passes.

My truck had a 300hp GM crate in it with a Qjet and dual exhaust when I had the 4.56/32" BFG combo.

Harley

 

[Hossbaby50]

Make sure you get the lockup working on that trans you got from me. Even if it is a manual switch thats cool as long as you can get lockup. Double check everything in that trans too. I used it pretty hard before the case busted so make sure it is all kosher.

Harley

 

[Jason4x4]

yea, I am gonna order the lockup kit from street and performance, Mtnman got one from them and liked it, and I am actually thinking about taking it to a guy that Mtnamn knows that builds them in his sleep, since I've never done a 700r4 before, and I've heard the horror stories about them, I don't want any problems.

 

[Drey]

The truck Im building is getting 4.88s, 35s, and a 700R4 I cant remember but I wanna say it was like 1500 - 1600 RPM at 60 i think off of a calculator I found. Sounds like a good RPM for not frying stuff. Im going to have a Healthy 406 too though.