3/4 Ton Sub, towing questions on driveline

[Mudbug1979]

OK, I'm in the process of building a sub to tow my camper and be the all purpose recovery rig. I'm debating about tire size and need and outside nudge. Currently going to be running a tbi 350/ 700r4/208 Cucv axles, 456's and What TIRE SIZE? I'm ok with 33's because it's a tow rig, but I would go 35's if it would do better. Now take in to cosideration this is going to be mostly a tow rig/dd/what ever we want to do vehicle. I can't go to high becuase of the camper and the camper probably only weighs about 6-7k. Bueller, Someone? Thanks as always.

 

[GMCJason]

If it were me I'd probably go with the 33s. 35s might work and would be nice for the Burb unloaded in OD but I'm not so sure with 6-7k behind it. The smaller diameter tire would make it pull better and put the hitch another inch closer to the ground.

I don't tow with my Burb, at least not the lifted one. It has 35s, 4.10s, a Th400 and the tbi350. I can't imagine tugging around 6-7k with it. On flat ground it may get the job done but in the mountains it would be a different story.

With the 33s you'll be in the 3000+ RPM range at 65 MPH in 3rd since you probably don't want to tow in OD. 35s would put you a couple hundred RPM less. Get into OD while not towing and your down to about 2100 RPM at 65 with 33s; about 2500 at 75. Not too bad in my opinion.

 

[twoslo4five0]

i tow with my burb all the time...i pull a 20 foot equip. trailer with my blazer on it...havnt towed it with the motor in and yet...but i have pulled a truck with a diffrent trailer that was about 800 lbs lighter...im in the process of changing some stuff to make it more tow friendly...taking the 6 inch lift off and going 4...i run 35s now and when they go bad i will prolly go 33...just my .02...

 

[woody9]

not sure how your 3/4 ton ended up with a 700R4 in it, but.. DO NOT TOW in O/D! It'll cook the tranny in no-time! I have a half ton with the 700R4, but i've done quite a bit to improve towing (14FF/4:10, HUGE tranny cooler & gauge, bigger brakes F&R with the axle swap to FF, 4 row radiator, etc)... but i still won't tow in O/D. I prefer to tow on the back-roads than I-state and keep the speed/RPMs down a bit.....
I'm running 245.75.16 revo's and not sure if that'd equiate to 33 or 35, but would guess closer to 33... Good luck with it!

 

[imiceman44]

not sure how your 3/4 ton ended up with a 700R4 in it, but.. DO NOT TOW in O/D! It'll cook the tranny in no-time! I have a half ton with the 700R4, but i've done quite a bit to improve towing (14FF/4:10, HUGE tranny cooler & gauge, bigger brakes F&R with the axle swap to FF, 4 row radiator, etc)... but i still won't tow in O/D. I prefer to tow on the back-roads than I-state and keep the speed/RPMs down a bit.....
I'm running 245.75.16 revo's and not sure if that'd equiate to 33 or 35, but would guess closer to 33... Good luck with it!

That size is actually closer to 31, it measures 30.45"

 

[88sub4x4]

If it were me I'd probably go with the 33s. 35s might work and would be nice for the Burb unloaded in OD but I'm not so sure with 6-7k behind it. The smaller diameter tire would make it pull better and put the hitch another inch closer to the ground.

I don't tow with my Burb, at least not the lifted one. It has 35s, 4.10s, a Th400 and the tbi350. I can't imagine tugging around 6-7k with it. On flat ground it may get the job done but in the mountains it would be a different story.

With the 33s you'll be in the 3000+ RPM range at 65 MPH in 3rd since you probably don't want to tow in OD. 35s would put you a couple hundred RPM less. Get into OD while not towing and your down to about 2100 RPM at 65 with 33s; about 2500 at 75. Not too bad in my opinion.

I agree with the 33's. My old sub had 4" lift, 4.10's and 35's and towing a 5K trailer was OK. I always wanted 4.56's for it so it could take the hills better. Also, like has been mentioned, get a big tranny cooler (a stacked plate type like the B&M Supercooler or equivalent, not the tube and fin) and a gauge to monitor the temps. Also stay out of OD unless you're over 65mph and on flat lands. If it starts to struggle just drop it back down to third. The nice part of the gauge is you will know if you are stressing the trans too much, and if not you can take advantage of OD to save on some gas and give the engine a little break.