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Topic: 3:07, 3.55 or 3.70 rear end ratios

in Forum: C3 Driveline Components

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3:07, 3.55 or 3.70 rear end ratios (15/25)
2/17/09 9:37am

KeBo
Former Member
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Kendall Park, NJ - USA

Vette(s):
1981 - 59 Beige over Cinnebar leather. Edlebrock top end, 2200 stall w/shift kit, 3:55s, Mufflex maniback exhaust, nice stereo, 16 in AREs w/BFGs

Joined: 3/9/2005
Posts: 789

I have an 81 also and went from the stock rear to a 3:55. Of the line is a BIG diff. At 75mph its a little to buzzy. I was planning to run a 700r but we all know how that goes..

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3:07, 3.55 or 3.70 rear end ratios (16/25)
2/17/09 5:45pm

VETTERBOB

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DUNEDIN, FL - USA

Vette(s):
1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp

Joined: 10/22/2004
Posts: 832

i went from 3.08`s t0 3.55`s. running headers and sidepipes . roars like a lion , and will break loose the shoes without any trouble. drove it from fl to bowling green with a smile on my face. it`s a personal preference so decide what`s comfortable for you.

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3:07, 3.55 or 3.70 rear end ratios (17/25)
2/17/09 6:28pm

my7t1

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Dorr, MI - USA

Vette(s):
71 Colonnade Hardtop Coupe Torch Red with black interior originally L48 built to push around 360hp

Joined: 8/21/2002
Posts: 2581

I like Joel am running 3:36 with M/T in my 71. 3000RPM @70mph. I'm getting 18 mpg as long as I keep my foot out of it,which is really hard for me. With the HP to back it up I can break em loose and burn em for pretty good stretch. 3:36 works for me.

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3:07, 3.55 or 3.70 rear end ratios (18/25)
2/17/09 6:40pm

tuxblacray

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Greensburg, IN - USA

Vette(s):
Previous: 1984 Silver / Charcoal Coupe, 1988 Maroon Coupe / 1989 Artic White Coupe / 2001 Speedway White Roadster / Present:1976 Stingray Black / Black, Auto, 350 slightly modified (355 hp) Luxor Wires Redline Tires. / 1989 Roadster Bright Red...

Joined: 9/24/2003
Posts: 5188

[QUOTE=gurtz] I think ya'll have answered my questions.� With the existing th350, motor and 2.72 rear, she is peppy but won't smoke da tires and she tach's out at 2600 rpm at 70 mph, which I don't care for.

�

Not saying I plan on smokin da tires all the time, it would be nice to on occasion.� I am hoping�to tach out in the 2400 to 2500 rpm range at 70 mph yet smoke da tires on occasion with the 4 speed.�

�

Dats my goal!�

�

I know I should have dropped the clams on the 5 speed, but�concerened about the economy and could not pass the deal on the 4 speed plus I wanted to keep her as stock looking as possible.�

[/QUOTE]

Welcome Back Gurtz after a small hiatus away from us. I like the part where you are wanting to keep her stock looking as possible.

Brother if your gonna do that you better get her to the body shop and have um glass the hood down. Cuz that motor will burn their eyes when the go to lookin for the stock stuff......

I side with the 355 gears myself. They should give you what you want for performance and comfort.

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Tuxblacray: She's Back In Black! Check out my pics @ My Link

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3:07, 3.55 or 3.70 rear end ratios (19/25)
2/17/09 9:00pm

gurtz
Former Member
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baton rouge, LA - USA

Vette(s):
1981 dark metallic blue, dark doeskin leather interior, mirrored glass T Tops, 330hp/350ci GMPP crate engine, billeted aluminum serpentine system, Dewitts with dual spalls

Joined: 8/12/2006
Posts: 391

Well you know TUX, Lil T, my girls name in BLUE, doesn't show her motor to just anyone.

I was talkin' bout the stick! IF I knew how to post pics, I would post updated photos of da motor, looks mucho better than what you see now, but I am a DUNCE on da computa!

I gotta tell everyone, since I read KStyer and Chultu's response, it sure has me thinking about the 5 speed again, I really want to bring the tach down on the Interstates. I take Lil T on long drives alot. Don't care for the traffic in south LA roads in town.

I am very close to dropping the existing 350, but I think I'm a gonna drop the diff this weekend instead and study the quotes from Keisler and Classic Chevy 5 speed before I put the manual in.

I have been doing more reading here in the past few months than posting, but I have been looking in nightly!

Hope all is well with everyone and thanks for the responses!

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3:07, 3.55 or 3.70 rear end ratios (20/25)
2/18/09 8:32am

I also failed to mention TUX that I manage a commercial roofing company here in BR and we had a little bit of a set back in time with Hurricane Gustav! Been a little busy keeping clients dry and happy!

BUT everyone is happy and dry now and I'm back to the more important things ini life - FAMILY LIFE & OLD CARS!!!!!

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3:07, 3.55 or 3.70 rear end ratios (21/25)
3/8/09 9:11pm

JimG

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Gloucester, VA - USA

Vette(s):
1979 T-Top, Metallic Green ZZ4 350/355 hp 405 ft/lbs torque Dual Spal Fans 700R4 4 Spd O/D Transmission 2004 Z06 Commemorative Edition

Joined: 1/29/2005
Posts: 1453

Okay Just reread this post...

Ya'll know I put the 700R4 in a while back and I'm unhappy with the performance as far shifting. Reading this thread makes me think the problem might be that the gearing in the 700R4 and the stock rear rations might be too close?

Am I just babbling? I'm guessing it's still the 3.55:1.

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The Money Pit.... and my niece

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3:07, 3.55 or 3.70 rear end ratios (22/25)
3/8/09 10:06pm

cthulhu

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Hot Springs, AR - USA

Vette(s):
69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans

Joined: 4/24/2004
Posts: 3231

[QUOTE=JimG]Okay Just reread this post...

Ya'll know I put the 700R4 in a while back and I'm unhappy with the performance as far shifting. Reading this thread makes me think the problem might be that the gearing in the 700R4 and the stock rear rations might be too close?

Am I just babbling? I'm guessing it's still the 3.55:1. [/QUOTE]

your 700r4 has 3.06, 1.63, 1.00 and .70

so your launch ratio is 10.863

should be pretty good.

OD final ratio is 2.485

what about your shifting dont you like?

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3:07, 3.55 or 3.70 rear end ratios (23/25)
3/9/09 1:23am

Gribble123

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Kingston, PA - USA

Vette(s):
1977 L-82 originally white/buckskin interior. Currently undergoing a frame-off resto. and modifications.YEEHAW!!!

Joined: 11/26/2003
Posts: 636

I had the Super T-10 with a 3.70 final drive. The 1:1 ratio in 4th gear gave me 4000rpm at 80 mph. That's too much screaming for highway speeds.

I'm currently in the process of installing a Tremec TKO600 in my never-ending rebuild. I'm counting on this to take that "problem" away.

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3:07, 3.55 or 3.70 rear end ratios (24/25)
3/9/09 6:43am

Gribble, If I could do it over, I would do exactly what you are doing. Your rpm's are supposed to drop off about 33-36% off the 4k at 80 or 2680 - 2560 plus your first gear is much better also!

What are your plans with your t-10? Are you keeping her or selling off whole or in parts. I ask because a buddy of mine is putting a t-10 in his 59 vert and needs a BW shifter.

Let me know what you do!

Thanks, Rick

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3:07, 3.55 or 3.70 rear end ratios (25/25)
3/9/09 9:30pm

JimG

[QUOTE=cthulhu][QUOTE=JimG]Okay Just reread this post...

Ya'll know I put the 700R4 in a while back and I'm unhappy with the performance as far shifting. Reading this thread makes me think the problem might be that the gearing in the 700R4 and the stock rear rations might be too close?

Am I just babbling? I'm guessing it's still the 3.55:1. [/QUOTE]

your 700r4 has 3.06, 1.63, 1.00 and .70

so your launch ratio is 10.863

should be pretty good.

OD final ratio is 2.485

what about your shifting dont you like?

[/QUOTE]

Hard to explain...Just doesn't feel "right".

I am on the other hand running about 1800 RPM at 70 MpH.

I'm also getting a sound like something is slipping. I dunno, I just need someone else to drive it and see if I'm losing my mind.

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Lifetime Member #73

The Money Pit.... and my niece

(click to see a slightly larger version)

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