Best Diff Ratio with Keisler 5sp?
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I don't know if it is the best but I like it. I'm running a 3.70 rear with a TKo 500. First gear is a little short but it does get moving in a hurry. I run 2200 rpm at 70 mph. With the cam I have I don't make a lot of power below 2000 rpm so to cruise below this would be a waste. I have not run the new motor at the strip yet so no times yet.
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I am running a 3.36 rear gear with my TKO. It puts me around 2000 at near 80 MPH. I have a small cam with loads of torque and it handles it well.
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
I tried 411's but found 1st gear too short. Hardly moved before needing to shift. I dropped back to 308's and it really improved 1st gear but my motor makes tons of low end torque. 1200 at 50, 1600 at 60 but this is too low for most.
I would go with 3.55
I would go with 3.55
Drifting
Joined: Oct 2003
Posts: 1,426
Likes: 1
From: VetteMOD
St. Jude Donor '05-'07
Most recommend this formula. Multiply the first gear ratio times the rear ratio. The ideal is 10. This is what Norval has 3.08 x 3.27. Remember, you are in 1st gear 10 times more that you are in 5th. It can be aggravating if 1st gear is so short that you can't clear an intersection without shifting to 2nd.
Instructor
Joined: Aug 2005
Posts: 138
Likes: 0
From: Virginia
My '80 has a 3.54 (pre '80 was 3.55) and it's perfect, for my driving style. 1st and 2nd launches and pulls real hard. In 5th, at 2000 rpms, she's around 75 mph; great for highway cruising. The engine is nearly stock; Hooker Super Comps and no emission control. In other words, I don't have an engine to haul me down the road. It's the transmission and rear gear combination. She's really fun to drive. I've been a stick shift man from way back.
80 Black Vette/Travis
80 Black Vette/Travis
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Pro
Joined: Aug 2004
Posts: 562
Likes: 1
I've got a 3.08 with a 454 stroker; gobs of power from first through fifth. Went with classicchevy5speed.com because of two choices of transmissions and the McLeod short throw shifter. It needed no "breaking in" that I've heard others talk about and really makes the best of the shifting experience with high torque. Cruising at 60 is pulling roughly 1400 rpm. 80 is closer to 2100. Still can't wipe the smile off my face.
Melting Slicks
Joined: Dec 2005
Posts: 2,441
Likes: 0
Originally Posted by BBShark
Most recommend this formula. Multiply the first gear ratio times the rear ratio. The ideal is 10. This is what Norval has 3.08 x 3.27. Remember, you are in 1st gear 10 times more that you are in 5th. It can be aggravating if 1st gear is so short that you can't clear an intersection without shifting to 2nd.
Maybe with a big block the ratio should be in the nines?
Last edited by shafrs3; May 3, 2006 at 09:16 AM.
Former Vendor
Joined: Aug 2005
Posts: 322
Likes: 0
From: knoxville tn
Gear Ratio's
When selling the TKO-500 we recommend that the rear end be no lower than 3.55 the TKO-500 3.27 1st is to low for anything deeper. We recomend the TKO-600 with 2.87 1st for any one with a 3.73 or lower.
If you have a motor with a good amount of torque you can run the TKO600 with a higher rear end. The 1st gear is still deeper than the Muncie's they were desinged to replace. Hope this helps
If you have a motor with a good amount of torque you can run the TKO600 with a higher rear end. The 1st gear is still deeper than the Muncie's they were desinged to replace. Hope this helps
Melting Slicks
Joined: Nov 2003
Posts: 2,668
Likes: 119
From: St. Charles Mo
CI 5 & 8 Veteran
I opted for the TKO 500 for Project RamJet. With the 3.08 rear differential, I get what is equivalent to 3.99 rear in first gear. This is just about right for me coming out of the hole (assuming I had some traction
). The .68 OD 5th gear works out great putting me at about 70 mph at 1900 rpm. Best of both worlds The RamJet 502 has a sweet (high and flat across the rpm range) torque curve which can more than handle the low rpms. There is a pretty good step from 2nd to 3rd, so a healthy / high torque engine is needed maintain a good acceleration curve. Bottom line, I agree with Norval, if you plan to go with 3.08's make sure you have the engine to handle it
Bullshark
P.S. I have the 17" TT II with 245x50x17 tires
). The .68 OD 5th gear works out great putting me at about 70 mph at 1900 rpm. Best of both worlds The RamJet 502 has a sweet (high and flat across the rpm range) torque curve which can more than handle the low rpms. There is a pretty good step from 2nd to 3rd, so a healthy / high torque engine is needed maintain a good acceleration curve. Bottom line, I agree with Norval, if you plan to go with 3.08's make sure you have the engine to handle it Bullshark
P.S. I have the 17" TT II with 245x50x17 tires
Thread Starter
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Thanks for the input, fellas.
I'm currently running a 3.08 with my 383 and Keisler 5sp. At 65, I'm at about 1750 RPM. At that RPM, I'm not quite up on the flat portion of the 383 torque curve and I've got bad resonance in the exhaust. So I'm thinking about stepping up to a 3.36 or 3.55 to get up on the torque curve and hopefully eliminate the resonance.
Any comments?
I'm currently running a 3.08 with my 383 and Keisler 5sp. At 65, I'm at about 1750 RPM. At that RPM, I'm not quite up on the flat portion of the 383 torque curve and I've got bad resonance in the exhaust. So I'm thinking about stepping up to a 3.36 or 3.55 to get up on the torque curve and hopefully eliminate the resonance.
Any comments?
Former Vendor
Joined: Aug 2005
Posts: 322
Likes: 0
From: knoxville tn
Gear Ratio's
IF YOU CHANGE TO A 3.36 TO DO 65 YOU WILL BE AT 1920 RPM'S
IF YOU CHANGE TO A 3.42 TO DO 65 YOU WILL BE AT 1950 RPM'S
IF YOU CHANGE TO A 3.55 TO DO 65 YOU WILL BE AT 2000 RPM'S
These figure's are aproximate and based on the TKO-500 with a 26 inch tire
IF YOU CHANGE TO A 3.42 TO DO 65 YOU WILL BE AT 1950 RPM'S
IF YOU CHANGE TO A 3.55 TO DO 65 YOU WILL BE AT 2000 RPM'S
These figure's are aproximate and based on the TKO-500 with a 26 inch tire
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I bought the TKO 600 with a more useable 2.87 first. My 4.11 rear is good with a .64 OD. It's like having a 2.63 rear end. I'm going to drive it for awhile and eventually I might drop to 3.90 or 3.73 rear end.
Right now with my tire diameter puts me at about 3000 rpm at normal freeway speed. I usually only drive 15- 20 over on our 75 mph posted roads. With OD and 4.11 I'm into the power band enough that I don't ever down shift at anything over about 50 mph even with my smaller 383's
I've had a 4.11 rearend since the late 80's in my Vette. About 18 years and over 120,000 miles. OD trannys are the way to go.
Right now with my tire diameter puts me at about 3000 rpm at normal freeway speed. I usually only drive 15- 20 over on our 75 mph posted roads. With OD and 4.11 I'm into the power band enough that I don't ever down shift at anything over about 50 mph even with my smaller 383's
I've had a 4.11 rearend since the late 80's in my Vette. About 18 years and over 120,000 miles. OD trannys are the way to go.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I have a 3.08 rear end and it is nice crusing at a very low RPM on the highway. Like mentioned above you need some torque to do it. If you don't have gobs of torque a 3.36 or 3.55 would be a better option.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I only use 5th on the highway, the average speed is about 80mph and I am at 2000RPM. I can drive it much lower if I want but 1700RPM is about as slow as I would go in congested traffic.
YOu seem to have alot of torque, I would change the mufflers before the rear end, especially with that 3.27 first gear.
YOu seem to have alot of torque, I would change the mufflers before the rear end, especially with that 3.27 first gear.
