Need advice on a performance transmission
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,900
Likes: 2
From: Green Cove Springs FL
Need advice on a performance transmission
My '81 Vette has a close-ratio T10 4-speed in it right now with a 3.73 rear end. It's great for launching, but at 65mph the engine is at about 4,000RPM. I'm looking to get a different manual transmission with an overdrive. I've considered the Richmond 6speed, but it's too expensive for my taste. Now I'm looking at the Tremec TKO 5-speed which is a little more reasonable. I've found the Tremec is good to about 525 ft/lbs and the overdrive is .68. Here is the comparison of the T10 and TKO based on my research:
T10: 2.43, 1.61, 1.23, 1.00
TKO: 3.27, 1.98, 1.34, 1.00, .68
I'm very open to suggestions, recommendations, horror stories, and success stories. My goal is to keep the great launching of the T10, but have an overdrive gear for cruising. Please help!! Any and all advice is welcome, thanks!! :seeya
[Modified by FroDaddy, 4:08 PM 9/26/2001]
T10: 2.43, 1.61, 1.23, 1.00
TKO: 3.27, 1.98, 1.34, 1.00, .68
I'm very open to suggestions, recommendations, horror stories, and success stories. My goal is to keep the great launching of the T10, but have an overdrive gear for cruising. Please help!! Any and all advice is welcome, thanks!! :seeya
[Modified by FroDaddy, 4:08 PM 9/26/2001]
Drifting
Joined: May 2001
Posts: 1,329
Likes: 12
Re: Need advice on a performance transmission (FroDaddy)
Take my opinion lightly since I'm not an expert but I think you'll hate the 1st gear..way too much distance with the 2nd...that looks like a 3k rpm shift...so you'd go from 6000 to 3000? I'd say you'd want to spread out the gears more equally.
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,900
Likes: 2
From: Green Cove Springs FL
Re: Need advice on a performance transmission (Lohkay)
Thanks for the response Lohkay. I'll have to take that into consideration as well as the other concerns I originally posted.
Please keep the comments coming c3'ers! Thanks!
Please keep the comments coming c3'ers! Thanks!
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Need advice on a performance transmission (FroDaddy)
A .68 with 3.73 & 28 inch tall tires is good for 200+ mph at under 7000 rpm what do you think you need?
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,900
Likes: 2
From: Green Cove Springs FL
Re: Need advice on a performance transmission (gkull)
gkull: Thanks for the response. The overdrive gear seems to be exactly what I want, especially since it's good to about 200+ mph @ 7k rpm! Lohkay has me concerned about 1st to 2nd ratio though. The first to second shift seems to have a very wide ratio, how do you think this would affect my straight line acceleration (the quarter mile)? Which would I need, a 3.55 or a 3.08 rear to keep the shift points similar to what they are now?
I apologize in advance for being so ignorant :crazy:
[Modified by FroDaddy, 11:21 PM 9/26/2001]
[Modified by FroDaddy, 11:21 PM 9/26/2001]
I apologize in advance for being so ignorant :crazy:
[Modified by FroDaddy, 11:21 PM 9/26/2001]
[Modified by FroDaddy, 11:21 PM 9/26/2001]
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Need advice on a performance transmission (FroDaddy)
I'm not a good person to talk too! I have a 700R4 where first gear is worthless with a 4.11. It has a .70 OD Tomorrow I will send you some Gear/Tire/Ratio sites Idavette here has something. I went for a high speed car years ago and failed horribly at both.
I just have an old 79 that I drive to work.
I just have an old 79 that I drive to work.
Pro
Joined: Jun 2001
Posts: 683
Likes: 0
From: Calgary
Re: Need advice on a performance transmission (gkull)
Go to 5speeds.com, they have a rpm calculator there where you can tell your rpm's in any gear at any mph.
For best acceleration, a rule of thumb is to shoot for a total first gear ratio (trans *diff gears) of around 10. So multiply your rear end gears by the first gear ratio and see what you come up with. With your 3:73's you would need a first gear ratio of around 2:70 to equal 10. With the Tremec you might want to consider 3:36's or 3.08's.
With the torque of your 383 you should have no problem with the rpm drops between gears.
[Modified by 74vetteman, 10:45 PM 9/26/2001]
For best acceleration, a rule of thumb is to shoot for a total first gear ratio (trans *diff gears) of around 10. So multiply your rear end gears by the first gear ratio and see what you come up with. With your 3:73's you would need a first gear ratio of around 2:70 to equal 10. With the Tremec you might want to consider 3:36's or 3.08's.
With the torque of your 383 you should have no problem with the rpm drops between gears.
[Modified by 74vetteman, 10:45 PM 9/26/2001]
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Melting Slicks
Joined: Oct 1999
Posts: 2,581
Likes: 14
From: Tolar Texas
Re: Need advice on a performance transmission (FroDaddy)
FroDaddy,
Have you checked out the ratio calculator at smokemup.com?
Here's the link.
http://www.smokemup.com/utilities/calc/mph_range2.cfm
The gear ratio comparison calculator at this site has 35 default transmissions to choose from or you can plug in your own gear ratios for 1st through 6th gears.
Have you checked out the ratio calculator at smokemup.com?
Here's the link.
http://www.smokemup.com/utilities/calc/mph_range2.cfm
The gear ratio comparison calculator at this site has 35 default transmissions to choose from or you can plug in your own gear ratios for 1st through 6th gears.
Advanced
Joined: Jul 2001
Posts: 56
Likes: 0
From: Marietta GA
Re: Need advice on a performance transmission (LT1driver)
I was also looking at a Tremec. Does anyone have any experience with them? I've heard you need to modify the drive shaft, and rear trans mount. What other issues are involved? Also is the shifter in the same place as stock?
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,900
Likes: 2
From: Green Cove Springs FL
Re: Need advice on a performance transmission (1969Diver)
Thanks for all of the input! Those websites were very helpful, as well as everyone's responses.
I'm with 1969driver though, is there anyone that can answer his questions as well? Thanks again! :seeya
I'm with 1969driver though, is there anyone that can answer his questions as well? Thanks again! :seeya
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Need advice on a performance transmission (FroDaddy)
I bought my Tremec TKO this month for $2760 CDN with tax. I priviously as an experiment ran the T5 to see how I like the manual over my 700R4. I loved it so sold the T5 and bought the Tremec only for reliablility. I have 4.11 gears and with the 3.27 low it is a little tricky out of the hole but with .68 overdrive it is fantastic. 2200 rpm at 60 2500 rpm at 70. I would like less gearing in first and considered 3.08 in the rear but 1500 at 60 was lugging the motor too much. I also have 3.73s in the mustang with the T5 and it is good also. The richmond 6 speed is alot more money and bigger. As for a mount the tail on the Tremec has a little extra casing hanging down to if you want mount the stock counter balance weight that comes on the mustang. The tremec is a mustang transmission. Companyies modify it for chevs. This extra casting hangs up on the crossmember. I don't need nor want this so a little hawksaw cutting and grinding will quickly eliminate this extra troublesome casting. Some modified the cross member to clear it but it doesn't add stength and is easily removed. Remember this is a FORD MUSTANG transmission so anyone running one must remember a FORD MUSTANG donated it.
Norval
Norval
Thread Starter
Melting Slicks
Joined: Aug 2000
Posts: 2,900
Likes: 2
From: Green Cove Springs FL
Re: Need advice on a performance transmission (norvalwilhelm)
Thanks for the help Norval. It's okay with me to have some mustang parts in my vette. I'll give respect where it's due, but I'm not going to volunteer that it's a mustang tranny. If they don't know, I'm not going to tell them. 
I originally posted that I have a T10 transmission, and that is wrong. I meant to say that I have a M-21 4-speed. Sorry for the confusion. Keep the comments coming! Thanks!
I originally posted that I have a T10 transmission, and that is wrong. I meant to say that I have a M-21 4-speed. Sorry for the confusion. Keep the comments coming! Thanks!
