5spd OD gearbox ratio question
Thread Starter
Pro
Joined: Aug 2010
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From: Stockholm Sweden
5spd OD gearbox ratio question
Im planning to replace my old Muchi M20 4spd the next winter with a TKO or a Richmond or some other gearbox that will give me an overdrive 5th gear.
Im wery interesting in getting inputs, not only of the good things with these boxes but also the bad or/and problematic things.
Since i dont do dragracing with large rear tyres and prefer using the car on ordinary roads and occationally trackdays i would like a box with a high (numreric low) 1st gear.
Today i have the M20 with a 2,52 first gear and that one is a little bit to "short" when going down on first in for exaple a cicane.
For me an optimal solution would be a M22 with its 2,20 first gear and with "close ratio" first four gears (1-1 on 4th gear) togheter with a overdrive 5th gear.
Does a gerbox like that exist?
The TKO i have seen has 2,87 first gear wich is even lower than my old M20.
The Richmond 6spd i have seen has a 3.28 first gear wich will propably be good for large DR slicks.
Since im running a 454 i dont think acually need 6 gears..
Inputs or ideas?
//Ricky.
Im wery interesting in getting inputs, not only of the good things with these boxes but also the bad or/and problematic things.
Since i dont do dragracing with large rear tyres and prefer using the car on ordinary roads and occationally trackdays i would like a box with a high (numreric low) 1st gear.
Today i have the M20 with a 2,52 first gear and that one is a little bit to "short" when going down on first in for exaple a cicane.
For me an optimal solution would be a M22 with its 2,20 first gear and with "close ratio" first four gears (1-1 on 4th gear) togheter with a overdrive 5th gear.
Does a gerbox like that exist?
The TKO i have seen has 2,87 first gear wich is even lower than my old M20.
The Richmond 6spd i have seen has a 3.28 first gear wich will propably be good for large DR slicks.
Since im running a 454 i dont think acually need 6 gears..
Inputs or ideas?
//Ricky.
Thread Starter
Pro
Joined: Aug 2010
Posts: 698
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From: Stockholm Sweden
I feel that the OD ratio on the 5th are OK ither way since it only will be used as a highway cruise overdrive.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
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From: Graceland in a Not Correctly Restored Stingray
Good rule of thumb for the street is to aim for ~10:1 total 1st gear multiplication. With a 3.36:1 rear, while a hypothetical 2.98 1st would hit that on the nose, the 2.87 and 3.28 yield 9.64:1 and 11.02:1, respectfully. I'd go for the 2.87 of the two.
FWIW, the Richmond SS 5-speed w/OD is available with 2.89:1 1st and 0.77 5th. By comparison, the TKO 600's 0.64 5th is going to yield you a very tall 2.15:1 final ratio, while the 600-RR version's 0.82 a 2.76 top.
Unless you've massive top end power, your terminal velocity will be a bit lower than such ratios might seem to suggest, but don't assume the tallest possible combination will necessarily equate to the best economy in cruise mode.
FWIW, the Richmond SS 5-speed w/OD is available with 2.89:1 1st and 0.77 5th. By comparison, the TKO 600's 0.64 5th is going to yield you a very tall 2.15:1 final ratio, while the 600-RR version's 0.82 a 2.76 top.
Unless you've massive top end power, your terminal velocity will be a bit lower than such ratios might seem to suggest, but don't assume the tallest possible combination will necessarily equate to the best economy in cruise mode.
Thread Starter
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Joined: Aug 2010
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From: Stockholm Sweden
Thanks for the input. 
No i dont have "massive top end power".
The engine is a mild but solid 454 with a hydraulic roller that puts out 462hp on 5500rpm.
If i take it flat out on the 5th gear with a Richm or TKO (overdrive) the topspeed will be way more than i need (im getting old and like to live).
But the overdrive will make the car more usable and i hope i can catch up with the newer cars on normal highway driving.
No i dont have "massive top end power".
The engine is a mild but solid 454 with a hydraulic roller that puts out 462hp on 5500rpm.
If i take it flat out on the 5th gear with a Richm or TKO (overdrive) the topspeed will be way more than i need (im getting old and like to live).
But the overdrive will make the car more usable and i hope i can catch up with the newer cars on normal highway driving.
Thread Starter
Pro
Joined: Aug 2010
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From: Stockholm Sweden
Looking at the "Hurst Driveline RPM Calculator" i belive that a 0,82 5th gear will work well.
It will give me an 18% reduction of rpm:s on the highway.
I got the feeling that the 0,64 may be rediculous high for my use.
Anyone that runs 3,36 final gear that would like to sheare there experiences of ther OD:s with me?
I guess that there are no 5spd overdrive box with a 2,20 (or close) first gear?
It will give me an 18% reduction of rpm:s on the highway.
I got the feeling that the 0,64 may be rediculous high for my use.
Anyone that runs 3,36 final gear that would like to sheare there experiences of ther OD:s with me?
I guess that there are no 5spd overdrive box with a 2,20 (or close) first gear?
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
Looking at the "Hurst Driveline RPM Calculator" i belive that a 0,82 5th gear will work well.
It will give me an 18% reduction of rpm:s on the highway.
I got the feeling that the 0,64 may be rediculous high for my use.
Anyone that runs 3,36 final gear that would like to sheare there experiences of ther OD:s with me?
I guess that there are no 5spd overdrive box with a 2,20 (or close) first gear?
It will give me an 18% reduction of rpm:s on the highway.
I got the feeling that the 0,64 may be rediculous high for my use.
Anyone that runs 3,36 final gear that would like to sheare there experiences of ther OD:s with me?
I guess that there are no 5spd overdrive box with a 2,20 (or close) first gear?
the 064 would be too tall although some would argue that
2600 rpm is 75 mph with mine in 5th and i have good get up at that speed also which was important in my decision
i also have a 454ho crate and like you i wish low gear were a little taller but the 287 is not all that bad either...good luck.....
ps...tires are 235 15 70's on the rear
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Pro
Joined: Aug 2010
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From: Stockholm Sweden
Thanks.
I run 255/60/15 on all four on my ralleywheels and they stays on for the road driving.
Acording to the "Hurst Driveline RPM Calculator" those tyres together with the 3,36 rearend will give me a cruising rpm at 75 mph of 2600rpm.
I run 255/60/15 on all four on my ralleywheels and they stays on for the road driving.
Acording to the "Hurst Driveline RPM Calculator" those tyres together with the 3,36 rearend will give me a cruising rpm at 75 mph of 2600rpm.
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Thread Starter
Pro
Joined: Aug 2010
Posts: 698
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From: Stockholm Sweden
I have also looked on a little on the Richmond 6spd..
I found a setup wich gives me the following ratios.
1st = 3,28
2nd = 2,14
3rd = 1,57
4th = 1,24
5th = 1,00
6th = 0,76
This will give me a very usefull second gear and a low 1st, a nice 1,0 on 5th and a good overdrive on 6th.
However, there is a lot of gears..
Anyone got a 6spd in his car?
How is it to shift?
I found a setup wich gives me the following ratios.
1st = 3,28
2nd = 2,14
3rd = 1,57
4th = 1,24
5th = 1,00
6th = 0,76
This will give me a very usefull second gear and a low 1st, a nice 1,0 on 5th and a good overdrive on 6th.
However, there is a lot of gears..
Anyone got a 6spd in his car?
How is it to shift?
Last edited by RickyBerg; May 18, 2011 at 10:22 PM.
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I own the tko 600. I tried to figure out the best rear ratio. With a 2.87 first, I went with 3.55 rear gear. The tko .82 OD would be nice with 3.36
I've driven a 2.20 first gear before M tranny and taking off is not very good
I've driven a 2.20 first gear before M tranny and taking off is not very good
Last edited by gkull; May 19, 2011 at 10:50 AM.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I am running a T56 6 speed from an 06 GTO. Ratios are
1st 2.97
2nd 2.07
3rd 1.43
4th 1.00
5th .84
6th .57
I am running a 3.70 rear. I like the gear spread over the TKO 500 I was running. 5th gear is more useable and you don't get the big rpm drop. 6th gear is definitly a highway gear for 65+ mph. 3000 rpm in 6th nets you 110 mph. 2000 rpm is about 74 mph. 1st 4 gears are excellent for acceleration and 5th and 6th are good for cruising the roads. The T56 is no picnic to get into a C3 though but it can be done. It is big and heavy but it shifts very slick and the gate is very tight.
1st 2.97
2nd 2.07
3rd 1.43
4th 1.00
5th .84
6th .57
I am running a 3.70 rear. I like the gear spread over the TKO 500 I was running. 5th gear is more useable and you don't get the big rpm drop. 6th gear is definitly a highway gear for 65+ mph. 3000 rpm in 6th nets you 110 mph.
2000 rpm is about 74 mph. 1st 4 gears are excellent for acceleration and 5th and 6th are good for cruising the roads. The T56 is no picnic to get into a C3 though but it can be done. It is big and heavy but it shifts very slick and the gate is very tight.
Thread Starter
Pro
Joined: Aug 2010
Posts: 698
Likes: 8
From: Stockholm Sweden
I am running a T56 6 speed from an 06 GTO. Ratios are
1st 2.97
2nd 2.07
3rd 1.43
4th 1.00
5th .84
6th .57
I am running a 3.70 rear. I like the gear spread over the TKO 500 I was running. 5th gear is more useable and you don't get the big rpm drop. 6th gear is definitly a highway gear for 65+ mph. 3000 rpm in 6th nets you 110 mph. 2000 rpm is about 74 mph. 1st 4 gears are excellent for acceleration and 5th and 6th are good for cruising the roads. The T56 is no picnic to get into a C3 though but it can be done. It is big and heavy but it shifts very slick and the gate is very tight.
1st 2.97
2nd 2.07
3rd 1.43
4th 1.00
5th .84
6th .57
I am running a 3.70 rear. I like the gear spread over the TKO 500 I was running. 5th gear is more useable and you don't get the big rpm drop. 6th gear is definitly a highway gear for 65+ mph. 3000 rpm in 6th nets you 110 mph.
2000 rpm is about 74 mph. 1st 4 gears are excellent for acceleration and 5th and 6th are good for cruising the roads. The T56 is no picnic to get into a C3 though but it can be done. It is big and heavy but it shifts very slick and the gate is very tight. Im a bit afraid that its easy to get it in wrong gear when "speedshifting" (comparing with my 4spd).
Is that a problem or do you get used to it?
Thread Starter
Pro
Joined: Aug 2010
Posts: 698
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From: Stockholm Sweden
Yea the 2,20 is not for fast launching..
Maybe the 6spd Richmond a mentioned abowe is a good one then, With that one i get both the "launch-gear" and a usable second gear for tight corners..
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Not at all. The T56 takes very well to "speed" shifting. I am not easy on this transmission. I find it better shifting than the TKO 500 I had in my car. It is a short throw on the shifter and very positive on the shifts. The most difficult shift on any Shifter is the 2 to 3 shift where you go up and over one gear. This is very easy with this transmission. Drive it a few times and it just falls into the correct gear.
Thread Starter
Pro
Joined: Aug 2010
Posts: 698
Likes: 8
From: Stockholm Sweden
Not at all. The T56 takes very well to "speed" shifting. I am not easy on this transmission. I find it better shifting than the TKO 500 I had in my car. It is a short throw on the shifter and very positive on the shifts. The most difficult shift on any Shifter is the 2 to 3 shift where you go up and over one gear. This is very easy with this transmission. Drive it a few times and it just falls into the correct gear.
Does the T56 has an ordernary "outside" lincage for the shifter or is it "internal" as for the TKO?
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
It is internal.
Look here for a picture of it. It is big.
http://ultimategto.com/cgi-bin/showc...005/05_00084_2
Look here for a picture of it. It is big.
http://ultimategto.com/cgi-bin/showc...005/05_00084_2
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
I've got the Richmond 6 speed behind an LS motor with 3.08 rear in my 68.
First thing you should know is that the trans is available with about a have dozen choices for 1st and 6th gear. You might try one with a 2.77 or 3.04 1st. 6th will depend on your engines torque and how much hiway cruising you do. But the list is here:
http://www.richmondgear.com/07pdfs/RG21.pdf
It shifts a little notchier compared to an internal shift, but is much better than the old Muncie shifter.
Other advantages, you keep yor bell housing clutch, Z bar linkage, driveshaft, shifter location. If you buy the 67 hurst 4 speed shifter, it even looks like the old Muncie from inside the car.
The only mod was to the trans mount, it has to be a little lower.
Pic from inside the car.
First thing you should know is that the trans is available with about a have dozen choices for 1st and 6th gear. You might try one with a 2.77 or 3.04 1st. 6th will depend on your engines torque and how much hiway cruising you do. But the list is here:
http://www.richmondgear.com/07pdfs/RG21.pdf
It shifts a little notchier compared to an internal shift, but is much better than the old Muncie shifter.
Other advantages, you keep yor bell housing clutch, Z bar linkage, driveshaft, shifter location. If you buy the 67 hurst 4 speed shifter, it even looks like the old Muncie from inside the car.
The only mod was to the trans mount, it has to be a little lower.
Pic from inside the car.
I have also looked on a little on the Richmond 6spd..
I found a setup wich gives me the following ratios.
1st = 3,28
2nd = 2,14
3rd = 1,57
4th = 1,24
5th = 1,00
6th = 0,76
This will give me a very usefull second gear and a low 1st, a nice 1,0 on 5th and a good overdrive on 6th.
However, there is a lot of gears..
Anyone got a 6spd in his car?
How is it to shift?
I found a setup wich gives me the following ratios.
1st = 3,28
2nd = 2,14
3rd = 1,57
4th = 1,24
5th = 1,00
6th = 0,76
This will give me a very usefull second gear and a low 1st, a nice 1,0 on 5th and a good overdrive on 6th.
However, there is a lot of gears..
Anyone got a 6spd in his car?
How is it to shift?
Drifting
Joined: Jan 2006
Posts: 1,832
Likes: 38
From: Cedar,BC
The 06 GTO T56 will have an LS compatible input shaft and bellhousing,you will have to change them and I think the front plate of the transmission to use it with an older LT1 or SBC.I have been offerered a LT1 T56 setup,but can't decide if I should also move up to a LSX motor as well...
Last edited by tfi racing; May 19, 2011 at 11:37 AM.
Thread Starter
Pro
Joined: Aug 2010
Posts: 698
Likes: 8
From: Stockholm Sweden
I've got the Richmond 6 speed behind an LS motor with 3.08 rear in my 68.
First thing you should know is that the trans is available with about a have dozen choices for 1st and 6th gear. You might try one with a 2.77 or 3.04 1st. 6th will depend on your engines torque and how much hiway cruising you do.
First thing you should know is that the trans is available with about a have dozen choices for 1st and 6th gear. You might try one with a 2.77 or 3.04 1st. 6th will depend on your engines torque and how much hiway cruising you do.
So with the Richmond i basically can chose any gearing i want at 1st gear!
That sounds just fine to me.
//Ricky.