Rear gears selection help needed.
Thread Starter
Instructor
Joined: Dec 2000
Posts: 242
Likes: 0
From: Stony Plain AB.
Rear gears selection help needed.
I have a well built 383, TH350 with shift kit, 2500 stall, Edlbro performer RPM, Edlbro 750 carb, MSD, Headers, Dual exhaust, Flowmasters etc...
Unfortunately I have 3.08 gears.
I want advice on two things.
1. What gears should I get that will really work well on the street, strip, and occasional highway cruise?
2. What sticky tires should I consider buying? I currently only have BFG TA's.
Unfortunately I have 3.08 gears.
I want advice on two things.
1. What gears should I get that will really work well on the street, strip, and occasional highway cruise?
2. What sticky tires should I consider buying? I currently only have BFG TA's.
Race Director
Joined: Mar 1999
Posts: 10,258
Likes: 1
From: Calif.
Re: Rear gears selection help needed. (John Dirks)
1. 3.55s are about the best all-around rear end gears for a 'Vette with a TH 350.
2. I think you're fine with T/As on the street. Goodrich also makes some pretty decent drag radials for the track.
2. I think you're fine with T/As on the street. Goodrich also makes some pretty decent drag radials for the track.
Le Mans Master
Joined: Apr 2000
Posts: 7,562
Likes: 9
From: B'Ville NY
Cruise-In III Veteran
St. Jude Donor '05
Re: Rear gears selection help needed. (John Dirks)
If your going to see some occasional highway, I wouldn't go above 3.70's unless you plan on a O/D in the future. I love my 3.90's and won't be changing them, but will be installing a O/D to be able to drive for longer distances.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Rear gears selection help needed. (John Dirks)
Without overdrive stay with 3.55. The 3.70 will make the car a dog on the expressways, about 3500 at normal cruiseing. I like the idea of a 700-R4.
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: Rear gears selection help needed. (John Dirks)
John:
To answer your last question, http://www.smokemup.com has an RPM calculator that does exactly what you were asking about. To figure out your RPMs you will need to know the gear ratios in your transmission, tire height and rear gear. It's a very useful site! Enjoy :cool:
To answer your last question, http://www.smokemup.com has an RPM calculator that does exactly what you were asking about. To figure out your RPMs you will need to know the gear ratios in your transmission, tire height and rear gear. It's a very useful site! Enjoy :cool:
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Instructor
Joined: Jul 2001
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From: kennett square,pa,us
Re: Rear gears selection help needed. (John Dirks)
John,
You can go to Richmond Gear and use their calculators to get the information you want.
As for the gears, 3:55 for highway, 3:70 for around town, 3:90 for all out performance.
Bud
You can go to Richmond Gear and use their calculators to get the information you want.
As for the gears, 3:55 for highway, 3:70 for around town, 3:90 for all out performance.
Bud
Melting Slicks
Joined: Nov 2000
Posts: 2,738
Likes: 53
From: Bogart GA
Re: Rear gears selection help needed. (John Dirks)
I have thought about doing same with my TB400. Is changing rear gears something for the home mechanic, or is this best left to the pro's? The way people talk about changing gears it sounds it should be as easy as changing your pants!!! :crazy:
Le Mans Master
Joined: Oct 2001
Posts: 6,925
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From: Paradise City
Re: Rear gears selection help needed. (John Dirks)
Well, I have 4.11 gears out back, and its a blast-especially when coming out of a turn or from a dead stop. W/ the TH-350 trans. 1st gear, its a real hoot. although w/ its 1.00:1 third gear, the highway is a friggin' nightmare. You really have to decide. I'd say 3.73's are a good compromise. :seeya
Melting Slicks
Joined: Apr 2000
Posts: 2,145
Likes: 1
From: Ft. Walton Beach, Fl USA
Re: Rear gears selection help needed. (John Dirks)
For street/strip a 700R4, 3:70's and drag radials for racing is the setup. I've pulled a 1.54 and a 1.55 60' AND get 15 mixed and 21 hwy mpg with a Q-Jet. And if you get lazy after racing you can drive around town with the Drag Radials on until you feel up to changing them again. Just don't get caught in the rain!
Thread Starter
Instructor
Joined: Dec 2000
Posts: 242
Likes: 0
From: Stony Plain AB.
Re: Rear gears selection help needed. (nastee383)
Nastee, what tranny did you have before the 700R4?
Did you buy a new 700 or used?
Did you do the swap?
How hard was the swap, and what changes were needed?
Did you buy a new 700 or used?
Did you do the swap?
How hard was the swap, and what changes were needed?
Safety Car
Joined: Apr 2001
Posts: 4,795
Likes: 1
From: Regina Saskatchewan, Canada.
rear gears
I have 4.11's with a 700 and it revs about 2400 at 60mph. Reved 1900 with 3.08's and I think 2100 or so with the 3.55's. By far the 4.11's was the best choice I ever made but also the worst choice I ever made. It all boils down to the 700-R4. The 1st gear and 4.11 combo was too much for autocrossing. I could never get enough speed out of it and when I shifted to secong I lost all the grunt and response and ended up going to fast. Also, first gear was unusable on the street. For showing off to friends only. If I were to do it all over again it would be 4.56's and a TH350. I'll save the highway driving for my Riviera.
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Re: Rear gears selection help needed. (John Dirks)
I'm no expert on this but it seems to me that you should analyze final drive ratios along with your torque curve to determine what will work for you.
My experience has been that a first gear final drive ratio (first gear multiplied times rear end ratio) of about 9.25 works well with a medium-high HP vette to get out of the hole without losing traction. For second and third, select a final ratio that puts your RPM right in the middle of your torque curve at speeds you normally drive. For fourth or final gear ratio, lower final drive ratio will save your engine and use less gas.
Run the numbers with several different combos before changing and get it right the first time.
My experience has been that a first gear final drive ratio (first gear multiplied times rear end ratio) of about 9.25 works well with a medium-high HP vette to get out of the hole without losing traction. For second and third, select a final ratio that puts your RPM right in the middle of your torque curve at speeds you normally drive. For fourth or final gear ratio, lower final drive ratio will save your engine and use less gas.
Run the numbers with several different combos before changing and get it right the first time.
Melting Slicks
Joined: Apr 2000
Posts: 2,145
Likes: 1
From: Ft. Walton Beach, Fl USA
Re: Rear gears selection help needed. (John Dirks)
Nastee, what tranny did you have before the 700R4?
Did you buy a new 700 or used?
Did you do the swap?
How hard was the swap, and what changes were needed?
Did you buy a new 700 or used?
Did you do the swap?
How hard was the swap, and what changes were needed?