Only 3:08's, now What!!!
Thread Starter
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Only 3:08's, now What!!!
After disassembling the rear end tonight I ran the code on my rear end it is a OK. Dang it. All this time I thought I had the 3:55. Do I need 3:73 with the new 700R4 of is the 3:08 good. Right now my car pulls a 1.9 60 ft time and with the 700R4 it should drop to 1.8 or 1.7. Do I need more gear?
Melting Slicks
Joined: May 2002
Posts: 2,508
Likes: 0
From: Wisconsin
Re: Only 3:08's, now What!!! (Budman78)
What's your overall 1/4 mile time? I think that you are probably fine with 3.08s. The car can move pretty well and you'll get better gas mileage (hopefully) than with some steeper gears when you travel. Plus that higher top speed is fun. I have a little goal to peg the 160mph speedo (and still run 12s)... I doubt I will anytime soon though (peg the 160. 12's by spring if all goes well :D)
Drifting
Joined: Nov 2001
Posts: 1,502
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From: Elyria Ohio
Re: Only 3:08's, now What!!! (frC3)
Race Director
Joined: Apr 1999
Posts: 11,520
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From: CORVETTE 77 385 C.I. TEXAS
Re: Only 3:08's, now What!!! (Budman78)
The main advantage of O/D is for lower rear gears. You will have an effectively lower rear gear in 1st if you install the 700R4. Consider the 200R4.
If someone is not going to install lower gears, then the trans. can be fitted w/ 2.75 first gears which effectively lowers rear gear in 1st.
:cool:
If someone is not going to install lower gears, then the trans. can be fitted w/ 2.75 first gears which effectively lowers rear gear in 1st.
:cool:
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Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Only 3:08's, now What!!! (Ganey)
IMO with the 700 or other OD trannies with a @ .70 top gear. 3.90 is the best choice. My 4.11 is a little overkill and 4.30 & 4.56 are for drag racers who use all four gears in the quarter.
3.73 is way overgeared in top gear for anything less than big blocks or low rpm big small blocks.
If I had it to do over again I would get a 5 speed manual without OD and install a 2.73 rear end
3.73 is way overgeared in top gear for anything less than big blocks or low rpm big small blocks.
If I had it to do over again I would get a 5 speed manual without OD and install a 2.73 rear end
Thread Starter
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Re: Only 3:08's, now What!!! (patsnitrovette)
That's strange, the mid eighties vettes had 3:07 gears with the 700R4. Pat are you sure your ECM is not shearching for a fuel map, because of a bad sensor.
Melting Slicks
Joined: Dec 2000
Posts: 2,198
Likes: 2
From: Eastern Connecticut
Re: Only 3:08's, now What!!! (patsnitrovette)
With the 3.06 first gear in the 700R4, the 3.08 rear will seem like you had a 3.80 gear with your old TH400. I wouldn't change it unless you like wheelspin. Joe
[or 3.74 if you had a TH350 before]
[Modified by joe73vette, 12:10 PM 2/4/2003]
[or 3.74 if you had a TH350 before]
[Modified by joe73vette, 12:10 PM 2/4/2003]
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Only 3:08's, now What!!! (Budman78)
Budman78. Pat has a zz4 cam and it lugs at low rpm. All those early to mid 80's vettes were low rpm motors and if you ever rode in one the first thing that you would notice is constant shifting in and out of OD 4th gear. They didn't have enough power to pull it and would shift down at the touch of the throttle.
I originally had a 700R4 and 3.55. In lockup 4th I had to drive 70+ mph to keep from lugging. Now with a bigger motor with 4.11 I don't have to worry about down shifting once I've over 45 mph
[Modified by gkull, 4:37 PM 2/5/2003]
I originally had a 700R4 and 3.55. In lockup 4th I had to drive 70+ mph to keep from lugging. Now with a bigger motor with 4.11 I don't have to worry about down shifting once I've over 45 mph
[Modified by gkull, 4:37 PM 2/5/2003]
Thread Starter
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Re: Only 3:08's, now What!!! (gkull)
Forgot about the ZZ-4 hot cam. Mine doen't tend to clean up until after 2000 grand, so I will probably be experiencing the same issue. Sometime the O2 sensor jump in and out of loop when they are mounted in the headers and cause the same effect. lean/rich/lean/rich.
Burning Brakes
Joined: Jul 2000
Posts: 963
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From: melbourne,Australia
Re: Only 3:08's, now What!!! (Budman78)
My 74R has 700r4 & 3.08 behind a strong 383,i am struggling to control wheel spin as it is and i have tried with a 3.55...even on a drag strip,it spins all through first gear and most of second,so it was a total waste of time with 3.55......the best time i had with carb and traction problems is 13.5 @108mph......it will clearly go much faster when i get everything sorted...great fun cruising at 70mph and less than 2000 rpm....i dont put it into O/D below 50,but from 50 to 70 it will stay in O/D with a very light throttle.....john :chevy ;)
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Only 3:08's, now What!!! (jdunne)
3.90 will fit in the 3 series carrier. Go for the max. The O/D will make up the difference. Im runnin 3.90 with 26"tire and locked in 4th I rev 2250rpm @65mph.
Burning Brakes
Joined: Apr 1999
Posts: 1,162
Likes: 17
Re: Only 3:08's, now What!!! (Budman78)
Budman -
The only thing the code confirms is the gear set ratio originally installed in St. Louis. You could have any ratio from 3.08 to 3.70 in that case.
Suggest you jack the rear of the car up, place two jackstands securely under the frame, put the trans in neutral, and count the number of driveshaft revolutions per one complete revolution of a rear tire. You may need a helper to turn the tire while you observe the driveshaft.
This will equal the gear set ratio.
The only thing the code confirms is the gear set ratio originally installed in St. Louis. You could have any ratio from 3.08 to 3.70 in that case.
Suggest you jack the rear of the car up, place two jackstands securely under the frame, put the trans in neutral, and count the number of driveshaft revolutions per one complete revolution of a rear tire. You may need a helper to turn the tire while you observe the driveshaft.
This will equal the gear set ratio.
Thread Starter
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Re: Only 3:08's, now What!!! (Mike Smith)
Will count tonight. Looks original and never serviced. :crazy: Got the jackstands covered. Basically the only thing left on the rear is the pumpkin and brace.
