Rearend for 700r4?
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
[QUOTE=Fast81;1595003924
What do you want the car to do -- 1/4 mile KING, Cruiser, Best MPG ?????
Most go with 3.55/3.73/3.90/4.11[/QUOTE]
If you post your engine specs, it would help!
Overall "average" I would say 3:73
In OD (3.73x0.7) that puts you at 2.6 overall for nice cruise RPM.
What do you want the car to do -- 1/4 mile KING, Cruiser, Best MPG ?????
Most go with 3.55/3.73/3.90/4.11[/QUOTE]
If you post your engine specs, it would help!
Overall "average" I would say 3:73
In OD (3.73x0.7) that puts you at 2.6 overall for nice cruise RPM.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Stock 82 rear is 2:78 because of the very low first gear the car takes off as if you had 3:55 with a th400. So if you are running the stock 3:08 rear, I would run it like that and then make the decision later. I think you'll be happy with the stock gears.
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
You don't specify year or engine specs but If you have a 2.87 gear and any kind of cam, you will be very unhappy.. the car will labor in OD at 55mph.. and be miserable at 40-45 when TCC locks up.. I tried my 2.87 stock gear, behind my 383/525hp .. awful .. then went 3.31 ratio.. But my cam is very radical , it still was not right.. I then switched to 3.73 and found it to be the " GOLDILOCKS" ratio...[ that's JUST RIGHT]... Its smooth at 40mph in OD, its jack rabbit quick from a launch, runs 80 mph down the Interstate @2500 rpm all day , get 18-19mpg and has hit 160 mph with some left but not enough road..
Last edited by fishslayer143; Jun 23, 2017 at 12:31 PM.
Melting Slicks
Joined: Dec 2009
Posts: 3,212
Likes: 639
From: Thunder Bay
I had a 700R4 behind the 383 in my 79 for many years. I had 3.55 gears and found them to be about perfect on the highway. The only problem was first gear. With 3.55s and a 3.06 first gear the overall drive ratio is 10.86. That's a little but too deep and first gear goes by a little too quick. Otherwise it was a great combination. And that is really a function of the transmission more than the rear end.
Thread Starter
Drifting
Joined: Aug 2002
Posts: 1,452
Likes: 190
From: Zion NC
Sorry for not being more specific. I want it to be a hoot to drive, quick 0-60. Not to worried about fuel efficiency et all. has a 383 stroker in it. We blueprinted at 450hp.. No idea what its actually making...
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,113
From: Crossville TN
If you want a good highway car, install a 3.36 rear gear. You will be turning about 2050 rpm at 70mph and the engine will not lug down on you in the 35-45 mph range.
If you want the car for being good off the line, you'll want a 3.73 rear gear. Anything steeper than that will render the first gear useless.
If you want the car for being good off the line, you'll want a 3.73 rear gear. Anything steeper than that will render the first gear useless.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I drove around with 700R4 and 4.11 for 20 years. I had my tranny setup for no kick down and a manual lockup switch for 4th gear only. I wanted to be able to run wide open in 4th gear OD.
I did all the math with a 28 inch tall rear tire. It takes lots of power and correct gearing to go fast. Your peak HP and top speed intended have to match up.
first gear is unchangeable and smarter people figure out RPM/ top gear/tire diameter/and rear end gear.
I always used high efficiency 9.5 in 3500 -3800 stall. right into the power range and very few rpm of slip cruising down the road
I did all the math with a 28 inch tall rear tire. It takes lots of power and correct gearing to go fast. Your peak HP and top speed intended have to match up.
first gear is unchangeable and smarter people figure out RPM/ top gear/tire diameter/and rear end gear.
I always used high efficiency 9.5 in 3500 -3800 stall. right into the power range and very few rpm of slip cruising down the road
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
U get to tall a gear 3.08 or so and U WILL have issues in O/D if you do NOT have fuel injection. This was covered extensively on this forum in many topics.
The best all around is 3.55 with a carb and a 700r4
U want burn out power go 3.73 to 4.11
The best all around is 3.55 with a carb and a 700r4
U want burn out power go 3.73 to 4.11
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
When ever you are thinking about a transmission or gear change you should use your head and some calculators. Personally I always thought that a 3.90 rear end was about the best comprimize on motor capable of higher rpm.
Spain used to have very high speed driving I have not been back in 5 years so I don't know the speed limit status. My cruising speed was often up around 135 - 150 mph and I tried to catch a few cars that blew by me, but my bmw was topped out at less than 180 mph.
http://chevellestuff.net/tools/rpm_calculator.htm
Spain used to have very high speed driving I have not been back in 5 years so I don't know the speed limit status. My cruising speed was often up around 135 - 150 mph and I tried to catch a few cars that blew by me, but my bmw was topped out at less than 180 mph.
http://chevellestuff.net/tools/rpm_calculator.htm
Last edited by gkull; Jun 25, 2017 at 04:15 PM.
Drifting
Joined: Jul 2009
Posts: 1,531
Likes: 13
From: Dallas-Fort Worth TX
I got a 3:54 and wish I would of gone with a 3:73 with the cam I got.
I am playing with the TV cable, to get more rpms out of each gear. I was rolling 15 ft into a intersection and already shifting into 2nd gear.
I am playing with the TV cable, to get more rpms out of each gear. I was rolling 15 ft into a intersection and already shifting into 2nd gear.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Rebelrob, The governor determines the WOT max rpm shift point. The TV cable has more to do with when it shifts determined by the throttle position.
I bought two a 5000 and a 6500 for race days. It is a easy 5 minute change if the tranny has enough room for tunnel clearance. Just pop the side cap off and R&R the gov. Some people like to play with the weights and springs. I just bought mine preset from Art Carr the company not the person
I bought two a 5000 and a 6500 for race days. It is a easy 5 minute change if the tranny has enough room for tunnel clearance. Just pop the side cap off and R&R the gov. Some people like to play with the weights and springs. I just bought mine preset from Art Carr the company not the person
Safety Car
Joined: Dec 2007
Posts: 4,229
Likes: 39
From: Beautiful East Texas
I'm having a bit of an issue with the throttle cable and the carb is only opening about 75% (rear throttle blades about half open when it's on the floor) so I've gotta' get that resolved, but it runs great otherwise, shifts good, hydraulic lock up on converter works perfectly... the 700R4 has been a great addition to my car.
mardyn
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
The 80 I had with 3.07 gears and the engine and 700R4 tranny in my signature wasn't a happy camper until about 80 to 85 MPH, as any engine with much cam might run. On a near stock engine, might be OK, but then the acceleration would be lacking geared like this.
My speed was about 120 MPH in second gear at 7500 RPM.
Mike
My speed was about 120 MPH in second gear at 7500 RPM.
Mike
Advanced
Joined: Sep 2006
Posts: 97
Likes: 0
The 80 I had with 3.07 gears and the engine and 700R4 tranny in my signature wasn't a happy camper until about 80 to 85 MPH, as any engine with much cam might run. On a near stock engine, might be OK, but then the acceleration would be lacking geared like this.
My speed was about 120 MPH in second gear at 7500 RPM.
Mike
My speed was about 120 MPH in second gear at 7500 RPM.
Mike
Racer
Joined: Jan 2015
Posts: 314
Likes: 50
From: Woodbury NJ
I have a similar set up and after quite a bit of research on this forum and others, i decided on a 3.73.
my set up:
74 coupe. 700r4 trans, 2800 stall.
355, 10:1 static compression, 64cc aluminum heads, comp cams 12-601-4, 2 3/4 primaries, 2 1/2 exhaust out the back. About 400hp/400tq +/-. The range of the cam is 2100-6200. I expect about 2200 rpm at 70mph with lockup. (Half shafts were upgraded at suggestion of Mike Dyer) My wheels are 15x8 currently, but they may change to 18x9's.
My test drives before turning the car over to the body shop were crazy-fun.
my goal is spirited driving, weekend cruise trips without screaming rpms on the highway, and a 12 second car at the track. We'll see about the track, but it looks promising.
good luck; I'm super happy with this configuration.
my set up:
74 coupe. 700r4 trans, 2800 stall.
355, 10:1 static compression, 64cc aluminum heads, comp cams 12-601-4, 2 3/4 primaries, 2 1/2 exhaust out the back. About 400hp/400tq +/-. The range of the cam is 2100-6200. I expect about 2200 rpm at 70mph with lockup. (Half shafts were upgraded at suggestion of Mike Dyer) My wheels are 15x8 currently, but they may change to 18x9's.
My test drives before turning the car over to the body shop were crazy-fun.
my goal is spirited driving, weekend cruise trips without screaming rpms on the highway, and a 12 second car at the track. We'll see about the track, but it looks promising.
good luck; I'm super happy with this configuration.