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Discussion Starter · #1 ·
so im in need of help i bought a zz4 355 hp with th700 trans and was thinking 370 would be a fun but not crazy gear ratio .am i wrong?i hv 17 in wheels on an art morrison frame. thanks
 

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so im in need of help i bought a zz4 355 hp with th700 trans and was thinking 370 would be a fun but not crazy gear ratio .am i wrong?i hv 17 in wheels on an art morrison frame. thanks
Had a 700R4 trans. with 3.70 gears in my '56. Unfortunately, only went for about a 5 mile ride before the trans. took a crap. From what I recall, I kind of liked the combo. I think the OD gives you a nice option.
 

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Wheel size not a factor on ratio. Tire diameter is. I have the same set up. ZZ4/700R/3.73

Tire diameter about 28.5. It is not on the street yet but I think the combo will give me good acceleration and decent cruising RPM with the OD
 

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so im in need of help i bought a zz4 355 hp with th700 trans and was thinking 370 would be a fun but not crazy gear ratio .am i wrong?i hv 17 in wheels on an art morrison frame. thanks
No, I don't think you are wrong.
However, I think a 3.55 would be just as much fun and a better choice. Both would smoke 'em.
 

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I think you will be just fine with that combo.
I have a 3.42 gear with a 700R and its a bit tall for my liking.
I have a 3.42 and a 4L60E (same ratios as 700R4) in my El Camino. It's not too tall at all in that car. However, I have 26" diameter tires on it.

If the OP would say what size 17" tire he is going to go with, it would help us to give more guidance.
 

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I have a 3.42 and a 4L60E (same ratios as 700R4) in my El Camino. It's not too tall at all in that car. However, I have 26" diameter tires on it.

If the OP would say what size 17" tire he is going to go with, it would help us to give more guidance.
My tires are over an inch taller, and like I said it is "a bit" too tall geared.
I don't have a cam and I saw that he does, so that was my reasoning behind telling him that I thought he would be fine with the 3.70 gear.
 

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I had a 3.70 rear gear (9" F**d) with my Tremec 5sp (30% od like the 700R4) and this is a very good combo.. Then when I needed to change the gear-set, I bought a new 3rd member from Speedway, and I decided to go with 3.50's. I think the 3.70's were good and the 3.50's a bit better with the OD. I'm running about 28" tall tires.
 

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I think that another factor to consider in this decision is how the tranny is set up to operate. My converter locks just as soon as it shifts into overdrive. That is where I feel that I might be happier with a bit more gear. A guy with a lumpy cam might experience more of a drop in power at that low of an rpm. But anywhere from a 3.42 to a 3.70 should be in the ballpark IMO.:shakehands:
 

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Discussion Starter · #11 ·
the zz4 is the turn key from classic ind. and the tranny is from them as well as for tires i still hvnt committed but the rears will be as big as the art morrison chassis will allow im assuming arond 28'' tall 11.5 wide i just hvnt had time to fully research the exact dim.
 

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If highway mileage or quietness is not a priority, then it sounds like maybe you would be happiest with the 3.70.
With a 28" tire, that's right about 2,200 rpm at 70 mph. Not a high rpm by old standards but a little high by today's standards.
 

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I have a 700R4 with 3.73's out back on 11.5" x 17" Mickey Thompson ET Street tires that are 26.5" in diameter.

First gear is pretty steep and it's really easy to burn the tires (I have a warmed over ZZ383 clone, so it has more torque than a ZZ4). Driving around town is good, although I usually keep it in 3rd because the speed limit in my little Wyoming town is 30 MPH. The highway RPM's are very comfortable from 50 to 75 MPH...like a modern car really.

My only complaint is first gear...it's almost too steep. Other than that I really like it. 3.55's might be better with 26" tires, but with your tall rear tires and 350 (that makes less lower end torque than a 383), I think you'll like the 3.70ish gear out back. I really don't think you would be disappointed.
 

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3.70 gears

It all depends on who you want to smoke at your fridaynite "cruise" the 370 gears with a 700 r are a very quick setup with good highway manners. Myself and two 56 Chevs did 5600 miles on a Route 66 The two 56 guys both had 700R one with 383 with 373 gears and one a350 engine with 4.10 both with 15 in wheels my 55 had a 350 hp 327 with tko600 with .63 od with 26 in tires and 4.11...we all averaged 22 mpg {converted to imp galllons}on the trip from B.C, Canada. We drove the 75 mi speed limits and all three engines had .485 and higher lift cams. Our cruise RPM was 22oo for the 373 gears and 2450 for the 4.10/4.11 as I recall. One consideration as someone said is your HAPPY SPOT for your cam and cu.inches of eng. it makes a huge diff how your Heavy TriFive will handle lock up. Small cubes { read 265 or 283} big cam and BIG wheels and highway gears {eg. 3.08}will kill your O.D. performance and your trans will continually drop in and out of lock up. This is my own Recipe for good TriFive Hotness and comes with no user beware warnings or decals.. CHEERS TERRY
 
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