Strike3

I have located a dealer I feel good about and was originally looking at 3.73 gears to go with my conversion to a 700R4 trans. He has a great price on the 3.73 gears but pointed out that even with 4.11's my engine RPM at crusing speed would still be lower than the TH350 and my stock 3.08 gears. There's about $80.00 differance between the 3.73 and the 4.11 gears so the price isn't a big deal one way or another. Does anyone out there have any advice on which set would be most advantagious for everyday driving.

Chris@VetteFinders

That first gear will be VERRRRYYYY low. I'd think it would be too low geared.

SmokedTires

Check out the 200R from BowTie Overdrives, with the 4.11's, 1st gear of the 200R will be a better match :) . BTO is very good about answering e-mails also :yesnod: .

bence13_33

I believe Aaron (Stingy) is running/will be running 4.88s with his 700R4. First gear is going to wind up VERY quickly. With 4.11s and the 700R4s low first gear it should get you moving really quick if you can get traction. If nothing else you could take it out back and pull some stumps out of the ground :jester.

FYI You want your effective first gear (rear end ratio x 1st gear ratio) to be around 10 or 11.

Corey_68

3.73's would be the biggest I would go. 4.11's would be too much on the interstate IMHO.
:cheers:

Budman68

I think your ears will bleed because of the speed. Just my .02 I got a neighbor with a old buick skylark with 4.11 and a 200r4. I don't think he has any complaints.

Racer16k

I have 4.56 with my 700r4. You know how the mid 60's 427 tri-powered Corvettes could rip tires in just about any gear, any time? Yeah, it's like that and still gets 18mpg on the highway. :D :D

GARY1973

I am doing the 3.90 in mine. Check the price of Richmond Gear in the Summit Racing. All ratios are the same price. :yesnod:

Stingy74

Bence is correct, I am in the midddle of getting the 4.88's setup. Before those I had 4.11's behind my 700R-4. Reved 2400 at 60mph. I've had 3.08, 3.55, and 4.11 behing my old engine/transmission combo and they 4.11's kicked azz hands down.

Stingy74

PS: The 1st gear wasn't tractor low. Check out the videos in my signature, you can see the 4.11's in action in the second one.

Strike3

Thanks guys for all the input. I'll try some of the math for first gear and try to e-mail BTO but there's nothing like your voices of experiance. Thanks again.

Stingy74

Also, the .70 overdrive gear and 4.11's netted a very good final drive of about 2.80 (2.87 actually) which is great for high speed runs. My car was the fastest it ever was when it had the 4.11's. Top speed, acceleration, and response.

norvalwilhelm

I ran this combination for 2 year and the 4.11s become 2.8 with the .68 overdrive. You rev about 2200 at 60 and 2500 at 70mph. I liked it until I started to eat transmissions. 3 in one summer and 4 torque convertors

MIKER

Norval, are you saying that the 4.11s were the cause of your transmission failures? I was under the assumption that lower gears (numerically high) would make life easier on the transmission.

gkull

miker - Norval ate them because of 800+ hp.

After putting @ 100,000 miles in the last 12 years on my 4.11 and 700R4 I have decided that 3.90 would best suite my needs. If you never drive over 80 on the freeway 4.11 is a good choice. It's also about the best for the 1/4 mile because your up in rpm in 3rd at the end of a quarter.

Tire Diameter: 26.1 inches Rear Gear Ratio: 4.11:1
Transmission Ratios:
1st: 3.06 2nd: 1.63 3rd: 1 4th: 0.7

MPH
RPM 1st 2nd 3rd 4th
1000 7 12 19 27
1500 10 18 29 41
2000 13 24 38 54
2500 16 29 48 68
3000 19 35 57 81
3500 22 41 67 95
4000 25 47 76 108
4500 28 53 86 122
5000 31 58 95 135
5500 34 64 104 149
6000 38 70 114 162
6500 41 76 123 176
7000 44 82 133 189
7500 47 87 142 203

73 Teach's Pet

Since I have 2 80's Trans Ams, and the 700R4 is a popular automatic in those cars, I can impart some wisdom on this subject, since I have done a lot of reserch on it.
The F-body guys like 3.42's for all around general use and mild performance. A 350 and 3.42's with the 700R4 typically run high 13's and don't have the wheel spin, traction problem you will get with higher gears.
Many aritcles state that if you don't mind the noise from the lower gears, that 3.73's are ideal for a more performance gear and quicker et's, but rear suspension mods are in order to reduce traction problems. I have selected 3.73's to be coupled to my 700R4, in my 86 T/A project car that I am running, which is spun by a mild 355 small block with fluid harmionic balancer and aluminum drive shaft, but I don't have the rear in yet. I have read that 3.73's run around 2,800 Rpm's in overdrive at highway cruising speeds.
My all stock 305 fuel injected 87 T/A came with the standard rear, which was 2.73 posi with aluminum drums connected to the 700R4. The performance ratio option on the fuelie car that year was only 3.23.
So, I hope I have imparted some factory engineered insight to your dilemna, but if I was choosing a gear set that was going to be more for crusing than performance use, then I would go 3.42, if I was using it more for a strip than street car I would choose 3.73. I would not choose any thing higher for street car use. But then again, even though I work at a drag strip, I enjoy driving my car, more than racing it, so I have learned to NOT build around my wants, but build around my needs and primary use.
More info related to this can be had at http://www.thirdgen.com my primary source of F-body info.
Hope that helps.
Be cool!
"TEACH"

gkull

I will impart some more knowledge as to what Teach's Pet was saying.

I had 3.55's when I first put in my first of many 700's. If your motor is built up at all it's not going to run well below 2000 rpm in top gear OD in lockup. Because your lugging the motor at less than 80 mph. So I would find myself out on little two lane highways and I couldn't even put it in top gear because you can't drive 80 mph on a curvy roads

So I got to thinking about how can I best use the 700. Normal guy's are never going to hit red line in top gear with 4.11's and it's not so over geared that you can still excelerate in 4th gear with out shifting down.

TP is correct on traction issues in first. It's no big deal you just never floor it till your in second. Just a minor change in driving technic.





[Modified by gkull, 11:37 AM 2/28/2002]

73 Teach's Pet

gkull's insight does bring up the issue of driving style. The overdrive lockup in a 700R4 in my 2.73 rear T/A has little to no power in overdrive. I don't put the car in overdrive unless I am on a straight road flat road above 45MPH or cruising above 55MPH on the highway. I assumed that GM intended overdrive to be just that, a gear for cruising and maximizing fuel economy, not for power or acceleration. Gkull is correct in his gearing recommendation if that is the driving style and intended use of the tranny you have in mind. But, that type of configuration would render first gear rather pointless to having, since the car would be geared so low in first and you would spend most of your top end in overdrive. I have never driven a low geared 700R4 combo, so I can't speak from experience, but I am configuring my car to use first gear as such and use overdrive to maximize fuel economy, not for power use. When I want power, I just manually down shift from overdrive to drive on the highway or on a hill.
Another good point Gkull raises that you have to decide about what RPM band you want to run in and what gears of the tranny you want to assign their duty to.
Be cool!
"TEACH"

ENCHANTMENT

Strike3,

I am running 3:73's behind a 700R-4 in my 420 injected 1980. This gearing is about as low as I would go for normal driving (a mix of some city-some highway). Cruising at 65 I am just over 2200 and I feel that this RPM range is fairly comfortable for both myself and the engine. In a stop and go environment the first gear ratio of the 700R-4 with the 3:73 is more than stout enough, in fact, if there is any moisture or snow on the ground problem can happen.

MikeT

Nobody has mentioned the 3.36 gears that alot of us have!!! Has anyone used them with the 700R? Seems to be close to the 3.42s that you were talking about Teach for good all around driving!?!
Mike