TKO 600 versus Richmond
03-29-2015, 07:55 PM
#21
Le Mans Master
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St. Jude Donor '05, '09, '15
I have a Richmond 5spd in my SB 65. Like you I love the gear ratios with a 3.08 rear. Pulls like a 4.56 in 1st and cruise on a 3.08. It is not the smoothest shifting car I have driven but it's Ok and the gear match is great! I also agree with you the super low 1st on a Richmound or Tremec is not a good match with 4.11 rear IMO. If my math is right even the 2.89 1st gear Tremec the overall ratio is about a 5.36 rear and a M21. I don't expect you need that with a BB. Top gear with the .82 overdrive is equivalent to a 3.37 rear. Not bad for hwy cruising. So you end up with a super low 1st and an OK top gear.
Tom
Tom
Last edited by Sky65; 03-30-2015 at 01:01 AM.
03-30-2015, 06:40 AM
#22
Team Owner
There used to be a rule of thumb that your rear end ratio multiplied by your first gear ration should ideally be close to the number 10. So, my Tremec 2.87 first gear times my 3.7 rear yields 10.619. 2.87 x 4.11 yields 11.80. Over a 10% numerical difference but in practical use probably a HUGE difference.
03-30-2015, 09:53 AM
#23
If you want a benchmark:
4.11 rear x 2.20 1st (close ratio) = 9.04
3.73 rear x 2.20 1st = 8.20
4.11 rear x 2.52 1st (wide ratio Muncie) = 10.35
3.73 rear x 2.52 1st = 9.40
3.55 rear x 2.52 1st = 8.95
To compare new gearboxes to old, most guys use the (close ratio and 4.11) as the HiPo standard SO lets assume a 2.87 1st TKO, 4.11 rear. Note for the sake of a more accurate comparo; lets assume a 26" tall tire (if you use taller tires, you're effectively going to reduce the rear axle ratio).
2.87:1 x 4.11:1 = 11.80:1 total gear reduction
11.80 / 2.20 = 5.36
OR
11.80 / 2.52 = 4.68
So; with the 2.87 1st and 4.11 rear gear; its like an old school close ratio with 5.36s in the rear axle or a wide ratio with 4.68s in the axle.
4.11 rear x 2.20 1st (close ratio) = 9.04
3.73 rear x 2.20 1st = 8.20
4.11 rear x 2.52 1st (wide ratio Muncie) = 10.35
3.73 rear x 2.52 1st = 9.40
3.55 rear x 2.52 1st = 8.95
To compare new gearboxes to old, most guys use the (close ratio and 4.11) as the HiPo standard SO lets assume a 2.87 1st TKO, 4.11 rear. Note for the sake of a more accurate comparo; lets assume a 26" tall tire (if you use taller tires, you're effectively going to reduce the rear axle ratio).
2.87:1 x 4.11:1 = 11.80:1 total gear reduction
11.80 / 2.20 = 5.36
OR
11.80 / 2.52 = 4.68
So; with the 2.87 1st and 4.11 rear gear; its like an old school close ratio with 5.36s in the rear axle or a wide ratio with 4.68s in the axle.
03-30-2015, 11:58 AM
#24
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St. Jude Donor '05, '09, '15
Hi Dave,
I've been following along and would like to comment. I really think you can work with your 4.11 rear . . . and the .64 5th gear will work great with that ratio. You shouldn't be so concerned about the 5th gear ration, but the 1st gear ration in the overdrive you choose.
I have a G-Force Street 5-Speed Transmission (remanufactured GM World Class T5) with a .63 5th gear in my '66 L79 with 4.11 rear gears. I can drive it in 5th gear with no issues as low as 35-40 mph - and the cruise on the highway @ 70 is only @ 2400 - it's awesome. Part of the rebuild of my T5 to the G-Force 5 speed was a replacement of the 1-4 gears . . . including a swap from a 2.95 1st gear to a 2.42 1st gear. The 2.95 (with the 4.11) was way too steep . . . the 2.42 1st gear is now perfect! Again . . . with the 4.11 rear pay close attention to the 1-4 gears vs the 5th gear ratio! Good luck!
Tom
I've been following along and would like to comment. I really think you can work with your 4.11 rear . . . and the .64 5th gear will work great with that ratio. You shouldn't be so concerned about the 5th gear ration, but the 1st gear ration in the overdrive you choose.
I have a G-Force Street 5-Speed Transmission (remanufactured GM World Class T5) with a .63 5th gear in my '66 L79 with 4.11 rear gears. I can drive it in 5th gear with no issues as low as 35-40 mph - and the cruise on the highway @ 70 is only @ 2400 - it's awesome. Part of the rebuild of my T5 to the G-Force 5 speed was a replacement of the 1-4 gears . . . including a swap from a 2.95 1st gear to a 2.42 1st gear. The 2.95 (with the 4.11) was way too steep . . . the 2.42 1st gear is now perfect! Again . . . with the 4.11 rear pay close attention to the 1-4 gears vs the 5th gear ratio! Good luck!
Tom
Tom
03-30-2015, 12:35 PM
#25
03-30-2015, 12:42 PM
#26
Racer
Thread Starter
This is awesome , you guys are really walking me through this, using the formulas above, if you take the richmond 3.28 first gear and times it by 3.08 rear end gears, you get 10.1024, compared to the tremec TKO 600 with 2.87 first x 3.55 rear you get 10.1885, both close to 10 total, and I liked first gear in the richmond , so this would probably be my best bet. Plus with the Tremec you get lower rpm in fifth than the richmond on the highway.