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Whos running: 3.73+700R4+33/34in tires?

DieselWarrior

DieselWarrior

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Ive got 3.08 now, gutless. Regearing/Reaxeling a rig aint exactly cheap for a poor working boy, so I want to do it right the first time.

I have 700R4, 6.2L.

I am wanting to hear from others with similar setup running the size tire I intend to run which is either 33inch or 34inch (metric 305/70R16) and get some feedback from them as to how they like there 3.73 for a daily driver.

Thanks much,
Andrew
 
DieselWarrior said:
Ive got 3.08 now, gutless. Regearing/Reaxeling a rig aint exactly cheap for a poor working boy, so I want to do it right the first time.

I have 700R4, 6.2L.

I am wanting to hear from others with similar setup running the size tire I intend to run which is either 33inch or 34inch (metric 305/70R16) and get some feedback from them as to how they like there 3.73 for a daily driver.

Thanks much,
Andrew
Click to expand...
I had the 3.42 with 35" tires, but with a th400. it was OK but I think 3.73 would have been better, I think you are in a better ratio with 33" tires and the overdrive, I need to search to see the RPM's with that ratio though.
BRB
 
one thing to point out, is that you should arrange things so that your highway crusing rpm is around 1800rpm for that 6.2 diesel.

http://www.csgnetwork.com/multirpmcalc.html

with the 700R4/3.73/and 33in tires, at 65mph, youd be turning 1728rpm

with 4.10 gears youd be turning 1899rpm.

Personally if youre going with 700R4 and 33in tires for sure, id go with the 4.10's myself.

not to play devils advocate... but the 700R4/4.10 gears/35 in tires would cruse at 65mph at 1791rpm.... youd be hard pressed to get a setup closer to the 1800rpm optimum point for the 6.2diesel.

dunno if the 35in tires are at the point of causing issues with the strength of the 700r4 though.
 
I ran the 3.73 for a few years then switched to 4.10 recently and the truck feels like it has 50+ more HP. Obviously the horsepower is the same but it really gives you the "seat of the pants" dyno boost in power. Ive noticed that in town with a very light pedal my mileage is 2mpg better than it was before with the 3.73. As mentioned above the 3.73 did hunt for the 3-4 shift on the freeway and in passing situations. Now it's much easier to keep it in OD and still apply the gas and pass without that annoying 3-4 shift. I use to hit long hills outside of town that would make the truck shift down into 3rd but now it stays in OD and cruises.

My motor is a stockish 355 EFI with cleaned up heads. No cam, aftermarket heads, etc. With a motor that doesnt make a lot of power it was a great upgrade.
 
Wow, great information and feedback!

Thanks so much guys, you all have been so helpful!


In the mean time, Ill be running 31's... hows that gonna do with 4.10 until I can upgrade my rims/tires??

Thanks much!
Andrew
 
I'm running 35's and 3.73's with a 700R4, the truck drives real well, just make sure if you're going up a steep hill downshift or you'll be hunting a bit.
 
i ran 35s with 4.10s, didnt like it that much. Life got better with 4.56s. I would suggest the 4.10 with the 33s.
 
Even with 31's and 4.10's your cruise rpm will only be 2021 rpm at 65 mph. A few things to keep in mind when looking for recommendations is that your 6.2 is not a small block. A lot of people think nothing of running a sbc at 2400-2800 rpm on the highway...which is fine for a small block. Not as "fine" with a 6.2. Your mileage will be in the crapper, and you will hate listening to it.

Ideal cruise rpm for a 6.2 for maximum economy is 1800 rpm. This would be with stock small tires, and no lift. My stock '83 6.2 pick-up is geared this way and nets me close to 25 mpg on the highway. Once you add a lift (worse aerodynamics) and larger heavier tires you should compensate by aiming for slightly more cruise rpm. With your small lift and planned 33-34" tires I would shoot for a 2000 rpm cruise rpm in OD.

31" tire 4.10's...2021 rpm
33" tire 4.10's...1899 rpm
33" tire 4.56's...2112 rpm
34" tire 4.56's...2050 rpm
35" tire 4.56's...1991 rpm

It really depends on what size you end up with. If you're truly going to stay with 33's the 4.10's will work just fine. For more grunt you could sacrifice about 1 mpg and go with 4.56's...it would be quite snappy around town and do quite well on the highway. 2112 rpm at 65 is not screaming by anyone's definition.

As for the hunting a 700R-4 can do, it's usually just the convertor unlocking, not actually shifting down from OD to 3rd. If you're curious like I was try this on a nice flat stretch of highway. Steady throttle at 60-65 mph, now use your left foot to slightly depress the brake pedal. That manually unlocks the convertor. I was surprised to see a 600 rpm jump with only the convertor unlocking.

Rene
 
Rene, you always amaze me at your willingness to help and knowledge base, a true asset to CK5!

Thanks for the added info... Sounds like, 4.11 is the ticket, 3.73 will likely leave me unhappy.

Now, quick followup question... In searching for prices and such for R&P, I am seeing the GM 8.5 inch R&P, is that the right carrier size for my stock GM 10 bolts? Thats the same for front and rear, right? The same set will work in both axles?

Thanks,
Andrew
 
Yessir, your 10 bolts are 8.5". Now would be the time to look at full case LSD's or lockers for the rear at least. Chances are you have a gov-lock right now, which is a time bomb. If you have an open diff it's not terribly strong either, and of course doesn't offer any extra traction.

If you are patient you should be able to find good used lockers out there for your 10 bolt rear. I found a full case Detroit for a 10 bolt for $300 here at CK5...which was a great deal. Too bad i didn't look under my truck more carefully. You could say I was somewhat surprised to see a 12 bolt under my '90. :doah:

Now another CK5er has that detroit. :waytogo:

Rene
 
I used to run 34x10.50x15 LTBs on my DD (stock '96 K1500). It had a l31 (first year 5.7L vortec, so a bit more torque), 4l60e (same thing as 700r4), 3.73s. I did not notice a difference in performance at all from the stock tires 265/75/16?.
 
DieselWarrior...you might want to put the fact that it's a 6.2L diesel in the title. Pretty much as tRustyK5 said, take all the advice for/from gassers and throw it away (even though it was all well intended). Diesels have a different power/torque curve so their gearing is a little bit different.

I have 3.73's in mine and 32's (265/75R16). Power is good and I didn't notice any lose stepping up from the worn out Goodyear 31's it had on it when I got it.
Interestingly enough mine came from the factory with 29's (235/75R15's) and the 3.73's...musta been one heck of a loud, slow tug boat.
Anyway, I'm planning on stepping up to 33's next. Either some 285/75R16's or 305/70R16's. I'm not too worried about power loss as there really wasn't much and it sorta feels overgeared to me now.

For the money and expense of a gearing swap in your 10 bolts I'd start looking for a set of 4.10 geared axles. Either someone's take out half tons or even a set of 3/4 tons. Don't need 3/4 ton axles? Big whoop, swapping a set in will still be cheaper than regearing your 28 spline half tons.
tRustyK5 said:
Now another CK5er has that detroit. :waytogo:

Rene
Click to expand...
Yep.:D

Holding down my work bench quite nicely.:doah:
 
DieselWarrior said:
Ive got 3.08 now, gutless. Regearing/Reaxeling a rig aint exactly cheap for a poor working boy, so I want to do it right the first time.

I have 700R4, 6.2L.

I am wanting to hear from others with similar setup running the size tire I intend to run which is either 33inch or 34inch (metric 305/70R16) and get some feedback from them as to how they like there 3.73 for a daily driver.

Thanks much,
Andrew
Click to expand...

I thought he was pretty clear about what engine his truck had... :dunno:

is SN is diesel warrior, and its also in his sig.... just sayin. :waytogo:
 
Yeah, but it's not in the title and half the responses he has gotten are from folks with gassers about their gassers...which makes their replies pretty much irrelevant and just misleading and confusing.
 
AJMBLAZER said:
DieselWarrior..

For the money and expense of a gearing swap in your 10 bolts I'd start looking for a set of 4.10 geared axles. Either someone's take out half tons or even a set of 3/4 tons. Don't need 3/4 ton axles? Big whoop, swapping a set in will still be cheaper than regearing your 28 spline half tons.
Click to expand...

X2 Probably gonna be 8 lugs but can be had cheap, way cheaper than a gear swap at least around here, heck you could get a set of 1 tons cheaper than a gear swap.
 
AJM, missed seeing your post in my "stupid questions", thanks for following up!

And thanks to everyone for there input.

I think Ill go 4.10, because a poor ****er can only afford to regear once. :D

The .70 OD ratio should tame it pretty good for 65mph highway, but still give me the grunt I need for towing/hauling (In 3rd at 55mph or so...).

Thanks again guys!
Andrew
 
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