Rear Gears

[54Caddy]

i am going to be swaping in a 700R-4 soon in my truck, i was wondering what would be the best set of gears to put in my 12 bolt. I was thinking a set of 3:73 but i dont know what would be the best.

[f.monroe]

A friend had a 93 1/2 ton Chevy he installed 4.10's in . Low gear way way too steep for me . I think 3.73 is about perfect.
Frank

[cochino12]

How tall are your tires? I had 4:10 in my 85 (zz4) with ~28" tall tires and loved it. Of course I love being able to roast the tires and really dont do much long distance highway driving though

[54Caddy]

current tires are about 27 inches tall when there not bald like they are right now ahah. Next set will be 26, but when i order my 20s they will be about 27 also. Im not trying to roast them or anything, not like the cheap 2 barrel carb would let me, I think 3:73 should be fine. My brother has an 89 c1500 and i like the way the stock set up is but cant find out what they have stock and he lives about 400 miles away. I also want the gears to be good for long distance driving

[cochino12]

Originally Posted by 54Caddy

current tires are about 27 inches tall when there not bald like they are right now ahah. Next set will be 26, but when i order my 20s they will be about 27 also. Im not trying to roast them or anything, not like the cheap 2 barrel carb would let me, I think 3:73 should be fine. My brother has an 89 c1500 and i like the way the stock set up is but cant find out what they have stock and he lives about 400 miles away. I also want the gears to be good for long distance driving

Id say you would be better off with the 3:73 then

[54Caddy]

Also the rear should have a 8.875 ring gear correct??

[Tx Firefighter]

For a mix of highway and in-town, I like 3.42 gears and the overdrive. The overwhelming majority of 88-98 trucks had this combo.

[Jonboy]

I'm with Kevin. I like the 3.42's with a 700R4. However, my truck already has the 3.73's in it, so I plan on just leaving well enough alone.

[N2TRUX]

Originally Posted by Tx Firefighter

For a mix of highway and in-town, I like 3.42 gears and the overdrive. The overwhelming majority of 88-98 trucks had this combo.

Originally Posted by Jonboy

I'm with Kevin. I like the 3.42's with a 700R4. However, my truck already has the 3.73's in it, so I plan on just leaving well enough alone.

I agree too. I have found that 3.42 is a great "all purpose" gear that gives good low end torque and decent MPG's. If you want a bit more low end and are willing to give up 1-2 MPG, then 3.73's are your answer.

[AceX]

Maybe a set of 3.55's would be a good compromise between the 3.73 and the 3.42

[54Caddy]

what are you running in your truck N2TRUX? The 3:73s sound like they might be just a bit much but having that advantage of greater overall lower end torque doesnt sound bad at all.

[N2TRUX]

I currently have an open carrier 3.08. I plan to add a locker and 3.42 gears. If you enjoy blasting around town and arent worried about MPG go with the 3.73. If you want a really good gear that pulls well and gets decent MPG then go with a 3.42

[BIG V]

my old suburban 2wd 3:73 with 27 inch tires 295-50-15 in the rear perfect all around gear it even was fun to run stop light to light

[rruss86]

i have a 1987 chevy suburban 3/4 454 2wd. that lays frame on 22's it has the 700r4 and 410 gears.. im contemplating 3.42 or even a 3.21 if i can find it.. it has the 10.5 ring gear 14 bolt.. tire is 28" tall...

[cory d]

i have 2.73 and a th350. needless to say i want to gear down to a 3.42 or 3.73

[slugish]

Originally Posted by cory d

i have 2.73 and a th350. needless to say i want to gear down to a 3.42 or 3.73

Do yourself a favor .the 342 is about the steepest gear you should go wth on a street driven th350 . Ioriginally went from a 2.73 to a 3.73 . Didnt stay in for long ( 3000 rpms at 55-60 mph) if you had overdrive (700r4) 373 would be perfect.

[Corts60]

Are you going to be towing?

If not, I agree with everyone else above that 3:42's would be great for you. But if you're towing I would go with 3:73's.

My set-up is 3:73, 28" tire, TH400 and Gear Vendors O/D, I run about 2200 RPM at about 70-75 MPH.

[silvereagle07]

I have the 3.42 and 700r-4 setup in my 84 and I love it. It gets decent gas mileage and drives really well. I've had all the setups over the years from 2.73's to 4.10's. By far, I like the 3.42's better for overall driving.

[stroker87]

700r4 & 3.73 was made for each other take advantage of the over drive and do the 3.73

[wilkin250r]

The 700r4 has a pretty steep 1st gear, and a pretty tall overdrive on the opposite spectrum.

For any other transmission, I'd say 3.73 is a little low for 28 inch tires. However, the tall overdrive of the 700r4 makes it tolerable, you'd be looking at a little over 2000 rpms at 65mph. The Chevy 350 is certainly capable of pulling a little taller gearing for better gas mileage, especially with the low 1st gear of the 700r4, so you could certainly get away with a 3.55 or even 3.42 and still be okay for occasional towing.

If you plan on doing heavy towing, or if you want serious, tire-roasting acceleration, then I'd suggest the 3.73. But for long-distance driving and occasional towing, I think you'd be better served with just a little taller gearing.

[stroker87]

Originally Posted by wilkin250r

you'd be looking at a little over 2000 rpms at 65mph.

I have the 700r4 and 3.73 combo and can run 70mph @ about 1900 rpms 29 inch tire if i remember right

[wilkin250r]

Originally Posted by stroker87

I have the 700r4 and 3.73 combo and can run 70mph @ about 1900 rpms 29 inch tire if i remember right

And I obviously don't have every transmission/gearing/tire combo to go out and test first-hand, the only thing I have are calculators. My calculators say that's either 2200rpm, or that's a 31 inch tire (like a 265/70R15).

I've got 3.73 gears and a .8 final transmission drive ratio in my Ford, and I'd say my gearing is spot-on with 31 inch tires (if I was towing more, I'd like to go a tad lower). My gearing would be a little low if I was running a smaller 28 inch tire, but a .7 overdrive might be just fine with that situation. I know a few people running 350 engines and 3.55 gearing with 28 inch tires, and I would say their gearing is a little tall for the amount of towing they do, but if they weren't towing, their gearing would be spot-on.

The 700r4 has a first and final ratio that are really spread out, so it really gives you a lot of versatility. You've got the low 1st gear that allows you to pull tall gears capable of good gas mileage, and the also the tall final drive ratio that still gives decent gas mileage even with short gearing. I would say the in-between would depend on where you want your focus to be and what you intend to do with your truck. I'm not sure there really is a wrong move with versatility like that.

[gchemist]

3.73 for tires over 28"
3.42 for tires under 28"

A stock engine should turn 1900-2100 RPMs at highway speeds.