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Towing Question - Lets talk RPM's, Tire sizes and gear ratios

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Mudzer

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Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

I am trying to figure out which tranny will offer me the best towing for my rig. I recently bought a 18' camper with 2800 pound dry weight. GVWR of the trailer is 4000 pounds. I am going to install an auto tranny in my rig when I do the WMS Dual Case swap. I would like to try to tow this trailer by installing some "skinnies" on the truck to lower the truck. I will be using a load distributing hitch setup and probably a sway control. I have done some number crunching and would like to find out if I should use a TH350 or 700R4 for my application.

I used the formula to figure MPH, then factored out the RPM's by giving a constant 65 MPH. Here are my numbers:

TH350 - 3213 RPM with 31" tires
700R4 - 2249 RPM with 31" tires
TH350 - 3018 RPM with 33" tires
700R4 - 2113 RPM with 33" tires
TH350 - 2845 RPM with 35" tires
700R4 - 1992 RPM with 35" tires

These figures are with the 700R4 in overdrive and the TH350 in drive. Which would be a good RPM range for pulling this trailer? Give me some input. Thanks.
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

you can't tow with the 700R in OD. So with 3rd in the 700R and TH350 both 1.00 i vote for the TH400
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

I hae heard alot of people say it is not good to two in OD. I would compare the 2 head to head in 3rd.... Either way, I would go with the 700 for the OD option for other driving and the lower 1st gear. If you get a 700 built right, keep the fluids topped off/clean and run a big cooler, you will be fine!!!!
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

What motor are you going to run? Small block I would want between 2200-2400 rpm. I am not sure about the rpm range for a big block.
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

At this point the TH400 is not an option. I clocked my NP203 upside down for clearance and do not want to pay to have the TH400 adaptor machined for this. I have seen the Okie-Style crawlers running 44's and Rockwells and a TH350 witout problems - but they dont drive to and from the trail like me. I have a TH400, but opted not to use it.
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

Okie-crawlers with TH350's are one thing, but you want this to be dependable, i presume. I run a TH350 and wish it was a th400.

If this the the tow vehicle, why clock the t-case? or is it the trail rig and your going to tow with it, too? /forums/images/graemlins/confused.gif
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

If'n it were me, I'd do a 700R with 33's. I think that would keep you decent. The only other thing I'd do is get a 700 built right.

Are you concearned about little tires big lift stability? I'm guessing you've got swaybars still? If you don't, holler, you can have mine. Shoot, you might want to try and adapt it to the back-end.

KP
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

Sure you can /forums/images/graemlins/smile.gif
Let's get you a real 700 and you'll never turn back. I wouldn't tow mine from the factory with a 700, but the one I've got now, sure I would. Up next for mine is a switch for the convertor and a full manual shift. All for less than one bill. /forums/images/graemlins/smile.gif
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

TH350 and 35's. I've towed our 21 foot trailer thousands of miles on 35's so the tire size isn't an issue. I beleive the TH350 is a much more durable tranny and 2800 RPM will keep the truck in it's power range.

Rene
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

[yoda] Yes, yes! To Rene you listen [/yoda]

I am soooo funny /forums/images/graemlins/rotfl.gif
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

Sharks won didn't they?? /forums/images/graemlins/smirk.gif

rene
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

you know it! It's getting pretty easy to find out my mood based on the previous night's game, isn't it? /forums/images/graemlins/grin.gif
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

You're a true 'Homer' (not the simpsons kind...) You live and die with the team./forums/images/graemlins/thumb.gif

We play the 'Buds' tonight...without Jovo-cop. He busted his heel the other night.

Can you believe Ottawa lost to the Predators?/forums/images/graemlins/shocked.gif

rene
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

Jovo-cop has always been underrated, IMHO. when the Panthers stupidly traded him away, i hoped we had a shot at landing him.

Ottowa is hot, but they are not a playoff team. not enuff grit.

The canucks are the team to be scared of, and if Cloutier can hold his head together and not get spooked in the first round like last year, Crawford could squeeze enuff talent out of that squad to get to the Conf. Finals.

My sharks are still looking for thier identity.

BTW, this thread has been offically hijacked /forums/images/graemlins/grin.gif
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

I think Cloutier has come into his own this year...and Skudra is doing a fair job as back-up. I hope we can keep Jovo...

I'd love to see the 'Nucks come up against Detroit again in the play-offs...

Sorry for the hi-jack Neil... /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif

TH350 and 35's... /forums/images/graemlins/thumb.gif

Rene
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

I know Rene is going to disagree but for the amount of weight you're pulling, I would go with the 700R4 and not tow with any great application of power in OD. Having the lower 1st and 2nd gear will help in towing as well as having OD for the non-towing miles. I've towed many a mile on 33's and 35's with no problems. Not sure what your axle ratio is but it appears to be 4.56's. I've run a 4.56 and 35's with an NV4500 for 4 years now and have had no problems. With the exception of the deep low 1st gear, ratios are virtually identical for 2nd thru OD when compared to a 700R4. Built right, the 700R4 will tow fine in 1st thru 3rd using at minimum a 12000 - 16000GVW trans cooler.

Over the years, I've added about every known gauge to moniter the engine and trans while towing. I strongly suggest a vacuum gauge and trans temp gauge, as nothing will give you an indication of how hard you're working the engine and trans as well as these two. I tow in OD but only under light throttle applications. No reason to work an engine in OD. Better fuel mileage towing is almost always in 3rd gear. With a small block, try for 2600-3000 in 3rd @ 60-65mph, 427-454 big blocks, 2200-2600 in 3rd.
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

I go with 700R4 and 35s, IN 3rd gear!! NEVER tow with a 700R4 in overdrive.

I love the 700R4. I like a manual a lot better, but the 700R4 is a great transmission if it's kept cool.
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

Have you considered a 4L80E? /forums/images/graemlins/thumb.gif
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

Shut up!! MR I already have EVERYTHING that EVERYONE wants!!
 
Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios

If you meant that as a joke, try putting a smiley after the comment. /forums/images/graemlins/laugh.gif

If it was meant in a mean spirited way (and I'm sure it wasn't) I was simply suggesting he consider the 4L80E as option three, since it seemed he was open for suggestions. /forums/images/graemlins/usaflag.gif

Happy New Year, Tim!
 
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