Borg T5 gear ratios
Thread Starter
Instructor
Joined: Dec 2018
Posts: 215
Likes: 86
Borg T5 gear ratios
First a big thank you to the guys on this forum for sharing lots of great information on fitting a Camaro WC Borg T5 into my 1979 L82. Wouldn’t even have known about this without your help. So I have a transmission builder who will supply me with a totally rebuilt unit for $1450 including shipping which I do not think is a bad price for a rebuilt unit, am I correct in this assumption? Secondly my car has a 3.7 ratio rear end. I am going with .063 for 5th, 1.0 for 4th. What about 1st thru 3rd? What ratio would you guys recommend? Thank you
Pete
Pete
Racer
Joined: Jan 2011
Posts: 336
Likes: 81
From: Southeastern MASS
Cool that you're going with a WC T-5, I'm doing the same in my 76. I also have one in my 69 Z/28 and found that the 3.73's were way too steep for the T5. I wasn't even using first gear, would start off in second with no problem and I was disappointed with the OD on the highway. I felt the car was still screaming, even in 5th gear. I switched to 3.08's in the rear and this really made the car more fun to drive. First and second gears are pretty steep in the T5 so the initial acceleration is still pretty sporty but the car calms right down in 3rd through 5th and is much more civilized. I don't know if higher (lower numbers) gears are available for the T5, you might want to ask your rebuilder about it. Good luck-cool swap!
Peter
Peter
Thread Starter
Instructor
Joined: Dec 2018
Posts: 215
Likes: 86
Cool that you're going with a WC T-5, I'm doing the same in my 76. I also have one in my 69 Z/28 and found that the 3.73's were way too steep for the T5. I wasn't even using first gear, would start off in second with no problem and I was disappointed with the OD on the highway. I felt the car was still screaming, even in 5th gear. I switched to 3.08's in the rear and this really made the car more fun to drive. First and second gears are pretty steep in the T5 so the initial acceleration is still pretty sporty but the car calms right down in 3rd through 5th and is much more civilized. I don't know if higher (lower numbers) gears are available for the T5, you might want to ask your rebuilder about it. Good luck-cool swap!
Peter
Peter
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
I would not switch the gear until you drive it and see what you think. The early gen 3 camaros came with 3.73 gears and the t5. I thought they drove fine and at 60 mph you had a cruising rpm of 2250.
Last edited by bjankuski; Jan 2, 2020 at 05:36 AM.
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Guys, something is not right here. I understand the issue with the high numerical low speed gears for the T-5 with 3.70 rear gears but some of the RPMs posted above for the T-5 with a .62 OD do not calculate correctly for a 3.70 rear gear and 27 inch. A 27 tire with a .64 Tremec OD @2,200 RPM is 75 MPH!
http://www.tremec.com/calculadora.php
You guys all know that most of the T-5's did not have a .62 OD but higher numerical OD's and probably the reason the RPM's are so high with the 3.70 rear gears @ 60 MPH...it can't be a .62 OD going 60 mph and screaming RPM.
I was looking at the T-5 as well over the last few years since the aftermarket 5 speeds are so expensive and not worth it to me for an occasional cruiser. I would go hands down for the lowest OD (lowest number .64/.62) I could find with a big V8 and 3.70 gears (or just about any rear gear) and have zero concerns about the OD lugging........My 355 roller cammed AFR heads with 10.2 compression can pull effortless from 1,000 RPM in any gear from any speed with the 4 speed with zero lugging or bucking.....
http://www.tremec.com/calculadora.php
You guys all know that most of the T-5's did not have a .62 OD but higher numerical OD's and probably the reason the RPM's are so high with the 3.70 rear gears @ 60 MPH...it can't be a .62 OD going 60 mph and screaming RPM.
I was looking at the T-5 as well over the last few years since the aftermarket 5 speeds are so expensive and not worth it to me for an occasional cruiser. I would go hands down for the lowest OD (lowest number .64/.62) I could find with a big V8 and 3.70 gears (or just about any rear gear) and have zero concerns about the OD lugging........My 355 roller cammed AFR heads with 10.2 compression can pull effortless from 1,000 RPM in any gear from any speed with the 4 speed with zero lugging or bucking.....
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
very few were .63. google final drive ratio calculator or start multiplying tire dia times phi (pie, not philadelphia) and dividing inches by miles times rpms. and different OD gears can be bought and installed cheaply and easily. every T5 that blew got stripped and 5th gear was not hurt, so it is for sale. first gear. 2.95 times 3.7 is 10.9. decent drag strip ratio. too high for everyday street. 2.95 times 3.08 is 9.086. about optimal for street. launch ratio is first gear times final drive. street comfortable is 9:1 dumping clutch and hitting second at 7000 rpm 11:1 is better. dumping clutch and hitting second at 7000 is something you will not do with a T5. not very many times, anyway. here is T5 tag and gear ratio chart. http://www.britishv8.org/Articles/Bo...T5-ID-Tags.htm
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