Who's running a TH700R4 with lower gears than 3.73? 3.90? 4.10?

Currently running 3.42.

I'm likely doing a gear vendors install next month and with that, there's the future option of running even lower gears very comfortably on the highway. For example, a 4.10 axle ratio with GV unit engaged is the equivalent of ~3.20 ratio. Such that I'd actually be running at a lower cruising rpm than I'm now with 3.42's.

That said, the only thing is you can't leave the line with the GV unit engagaed (according to what GV told me). So whatever axle ratio I choose is what I'm stuck with off the line.

The question I have for those of you running lower than 3.73 is how do you like it in terms of everyday type driving while leaving from a stand still? Does it feel like too steep of a gear ratio? I think 3.73 is pretty safe from that respect, but I'm curious about going beyond that.

 

4.10, 10 bolt with 28" tall tires. I like it just fine.
Where will you find the room to fit a GV unit under the car?

 

It's a 2nd gen Camaro

 

It depends on the type of car

Drag racing vehicles that ONLY 1/4 mile drag race need to put their max MPH at the end of 1:1 gear so there isn't any overdrive use during the race.

Daily drivers care more about fuel economy, the rear gear could be numerically lower (slower car but more economy) and engines with more torque in the low/midrange

Steep gears help engine RPM quickly develop, but the engine needs to have usable power in that range or it's not favorable

for example:
3000lbs, 3.5:1 gear, 26" tire, 1:1 final gear, top speed will be limited 120-130mph if spin the engine 6k 7k with ~400hp
But if the car eventually gains enough power to go 150mph or 160mph a 3.5:1 may no longer be low enough to finish in 1:1

So these are (most of?) the factors we account for:
weight, tire diameter, final gear (assumed 1:1), top speed requirement, Engine max RPM requirement, power output, type of racing

 

What do you want the car to do well?

Drivability as a daily?

Highway speed?

Mileage?

Tractor / stump pulling?

Impress an uncle who kept Pabst in business?

You can do really well with a good lockup converter and leave the 3.42 in place.

I have had 3.73 rear gears with the 700-R4 for tens of thousands of miles. With a powerband past 6000, going beyond 3.73 wasn't going to overall help anything. And having a granny gear or an intractable final drive ratio isn't an accomplishment either.

 

Car is built like a daily driver even though it isnt one. But I like the pleasant manners the car has now.

100% street driven with some spirited driving.

SBC with minram, AFR 180 heads and mild to mid-range cam... although the engine will pull hard to 6000 rpm.

I currently get 28-29 mpg with highway mode engaged.

Based on feedback from another board, I'm leaning toward 3.90.

 

You dabbled in very relevant numbers on another board; might as well go there here.
700-R4, GV OD you mentioned and 3.90.
11.934 1st gear, as 3.06 x 3.90 - realistically usable but "a bit much" for the short 1st gear of the 4L60 unless running taller tires.
2.73 OD as 0.70 x 3.90 - drivable anywhere but I like more OD than this, by far.
2.1294 final gear, as 0.70 x 3.90 x 0.78 - tractable with a relevant powerband. GM put out cars with 2.41 rear and 200-4R, and with 2.14 and no OD. But as you discussed elsewhere, will this actually help mileage or cabin noise or anything? Probably not compared to what you have.

Since you likely have no fear of the controllers, why not consider 6L80?

I pulled a freshly rebuilt, ideal-geared, absolutely nothing wrong T5 in order to gain 6th gear in a T56. I gained nothing. I lost an ideal stall ratio of 1st x rear gear. And 6th wasn't tractable. So I totally know the desire. But I'd be hard pressed to expand a floor to install a GV for that little extra. Yeah, it could gain you some gear spread. But usually, "where it counts" like a massive road trip for mileage, is such a small gain, it doesn't amortize well for the effort and cost.

 

Unfortunately the 6L80 doesnt really fit that well in a 2nd gen. The pan hangs down to low.

Theres not much to putting a GV in a 2nd gen. Only thing you have to do is trim a floor stiffener a little where it interferes.

 

i have this combo (700R4 and 3.73's) and i have to say its a lot of fun. I do happen to get in a bit of trouble with it now though. my only issues with it though are

1.) my LSD doesnt engage properly. It could be that its worn out, but sometimes after spinning a bit it'll hook up the other tire. I see summitracing sells a different carrier for this rear for 3.73 and higher ratios, which has me wondering if that the issue, that the axle isnt spinning quick enough to engage the LSD

2.) my trans almost always starts in 2nd gear now. with such a short first gear, i guess theres not much reason for it to stay in it? I know 1st gear works because i can put it in that gear manually and it is fine, but if i'm punching at a redlight or going from a slow crawl it wont stay in 1st. Not that it really needs to with this ratio IMO

 

idk what models GV has but pretty sure you can use it off the line. My buddy has one in a th400 i believe and i think it was accidentally engaged at the strip and functioned fine. May want to double check but either way no big deal

i tuned a lt1 swapped thirdgen with 4l60e with 4.10’s. It was fun but first is pretty useless. With miniram and mild cam it should work out ok. If you make anywhere near 300-320 whp, it wont be a terrible match on a 26” tire. 27-28” might be better but you’ll cross the 1/4 in the 6000-6300 range. If much over 350 whp which i dont see if your cam is smallish, then 3.90 would be better
either gear starting line ratio will be steep but possible if suspension is tweaked right and good tire

 

Yeah, 1/4 mile trap speeds and ETs are not really factored into my decision here since the car never sees the track.

It's just about having fun with some spirited driving around town and occasional long cruises with various Camaro groups.

 

Anything above 3.42 starts getting weaker in the ring and pinion gears but should last on the street