overdriven 4th in Muncie
Thread Starter
Instructor
Joined: Jun 2004
Posts: 162
Likes: 1
From: Johnsburg IL
overdriven 4th in Muncie
Curious if anyone has changed gears in their Muncie to have 4th gear ratio of .87
Seems like an economical fix to get better driveability without the cost of a 5 or 6 speed conversion.
If you have done, was it worth it? What rear ratio are you using? What rpm do you see at 70 mph?
link: http://www.riversidegear.com/categor...oduct-166.html
As always, your responses greatly appreciated
Steven
Seems like an economical fix to get better driveability without the cost of a 5 or 6 speed conversion.
If you have done, was it worth it? What rear ratio are you using? What rpm do you see at 70 mph?
link: http://www.riversidegear.com/categor...oduct-166.html
As always, your responses greatly appreciated
Steven
Racer
Joined: Jan 2004
Posts: 428
Likes: 2
From: Everfrost Second Life
Team Owner
Joined: Nov 2004
Posts: 20,709
Likes: 25
From: Sorrento Italy
Curious if anyone has changed gears in their Muncie to have 4th gear ratio of .87
Seems like an economical fix to get better driveability without the cost of a 5 or 6 speed conversion.
If you have done, was it worth it? What rear ratio are you using? What rpm do you see at 70 mph?
link: http://www.riversidegear.com/categor...oduct-166.html
As always, your responses greatly appreciated
Steven
Seems like an economical fix to get better driveability without the cost of a 5 or 6 speed conversion.
If you have done, was it worth it? What rear ratio are you using? What rpm do you see at 70 mph?
link: http://www.riversidegear.com/categor...oduct-166.html
As always, your responses greatly appreciated
Steven
Advanced
Joined: May 2003
Posts: 72
Likes: 5
From: Wilmington DE
Fourth gear is straight through and cannot be changed. What they do is change third gear to a 0.86 overdrive, so you shift 1-2-4-3. Supposedly you can flip the lever on the side cover of the transmission upside down and retain the standard "H" pattern, though I haven't tried this. This gives a bigger than normal spread between second and the new third, which is the old fourth. 0.86 is the biggest overdrive gear that will fit in the case.
I am considering this also and am interested in hearing comments from anyone who has done it.
I am considering this also and am interested in hearing comments from anyone who has done it.
Thread Starter
Instructor
Joined: Jun 2004
Posts: 162
Likes: 1
From: Johnsburg IL
Thanks for replies.
The final can't be lower than .87 or there would be too much gap between 3-4. There is also an issue with how big of a gear will fit in the case. They actually put the higher gear in place of where 3rd normally goes to fit then adjust the shifter to work so the pattern stays the same as original.
You can do with a 22 as well but have to replace one of the shafts for another $200.
I think I am going to do it since these guys will instal / rebuild m21 with the gears for about $800 including shipping which seems like an inexpensive medium. I have a strong 383 so I am not worried about the slightly higher 1st. They sticking with a 373 which will still allow for decent start. his would not appear to be something for the guy wanting to race though but would allow a little rubber to be burned.
Thanks
The final can't be lower than .87 or there would be too much gap between 3-4. There is also an issue with how big of a gear will fit in the case. They actually put the higher gear in place of where 3rd normally goes to fit then adjust the shifter to work so the pattern stays the same as original.
You can do with a 22 as well but have to replace one of the shafts for another $200.
I think I am going to do it since these guys will instal / rebuild m21 with the gears for about $800 including shipping which seems like an inexpensive medium. I have a strong 383 so I am not worried about the slightly higher 1st. They sticking with a 373 which will still allow for decent start. his would not appear to be something for the guy wanting to race though but would allow a little rubber to be burned.
Thanks
Le Mans Master
Joined: Jan 2006
Posts: 8,319
Likes: 7
From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
Hey thats better than the old 3 speeds 
3 Speed Manual M13
2.42:1
1.61:1
1.00:1
From the link
1st gear 2.20:1,
2nd gear 2.37:1,
3rd is 1 to 1,
4th position becomes .87
3 Speed Manual M13
2.42:1
1.61:1
1.00:1
From the link
1st gear 2.20:1,
2nd gear 2.37:1,
3rd is 1 to 1,
4th position becomes .87
Last edited by sweethence; Jan 15, 2008 at 03:56 PM.
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From: Melbourne, Fla. 6 months- New Middletown, Ohio 6 months
Le Mans Master
Joined: Jan 2006
Posts: 8,319
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From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
Thread Starter
Instructor
Joined: Jun 2004
Posts: 162
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From: Johnsburg IL
7T1 That is kinda what I was thinking. Would I be better off changing rear end to 355's from 373's? I don't know what the impact is on rmp's at highway speed though. Would it be the same gain of 13%?
I don't spend that much time on the highway but with 373's, 75 mph is no fun. I just can't bring myself to spend several thousand for a three or four time a year spin on the highway. Last note, there is another guy building 4 speeds with the following ratios which seem like they would be more driveable:
1st gear is, 2.199 to 1
2nd gear is, 1.506 to 1
3rd gear is, 1.000 to 1
4th gear is, 0.859 to 1
I don't spend that much time on the highway but with 373's, 75 mph is no fun. I just can't bring myself to spend several thousand for a three or four time a year spin on the highway. Last note, there is another guy building 4 speeds with the following ratios which seem like they would be more driveable:
1st gear is, 2.199 to 1
2nd gear is, 1.506 to 1
3rd gear is, 1.000 to 1
4th gear is, 0.859 to 1
Pro
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From: Melbourne, Fla. 6 months- New Middletown, Ohio 6 months
Team Owner
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From: Crossville TN
If that 4-speed does exist, colorado1967, it would be just the ticket. With a .86 final ratio, it would be like you had a 3.20:1 rear end instead of your 3.73 [not a lot different than my 3.08 and thm400]. It runs a bit under 3000 rpm at 70mph, and is not uncomfortable there. Still not much of a "gas saver".
Melting Slicks
Joined: Jan 2006
Posts: 3,028
Likes: 2
From: North NJ
I would consider a substitute differential until I could save up the coin for a 6spd. But the only differentials that can handle good power aren't cheap. Then it negates the fix.
I turn 70mph @ 3500 and need to fill up the tank every 45 minutes. Not fun on the wallet, but let me tell you, stomp on the go-pedal at 70mph and the needle climbs quickly.
but not as quickly as the wallet jumps out the window 
Next winter I'm going to keep my eye out for a viper 6spd conversion.
I turn 70mph @ 3500 and need to fill up the tank every 45 minutes. Not fun on the wallet, but let me tell you, stomp on the go-pedal at 70mph and the needle climbs quickly.
but not as quickly as the wallet jumps out the window Next winter I'm going to keep my eye out for a viper 6spd conversion.
Race Director
Joined: Jan 2001
Posts: 16,221
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From: Matthews NC
Fourth gear is straight through and cannot be changed. What they do is change third gear to a 0.86 overdrive, so you shift 1-2-4-3. Supposedly you can flip the lever on the side cover of the transmission upside down and retain the standard "H" pattern, though I haven't tried this. This gives a bigger than normal spread between second and the new third, which is the old fourth. 0.86 is the biggest overdrive gear that will fit in the case.
I am considering this also and am interested in hearing comments from anyone who has done it.
I am considering this also and am interested in hearing comments from anyone who has done it.
I've heard the same thing.
Racer
Joined: Jan 2004
Posts: 428
Likes: 2
From: Everfrost Second Life
Take the time to search and read old posts in regards to this. I've answered many questions related to this gearset.
There is no "supposively" on switching the lever upside down to achieve this. It works and has been done on OD transmissions of this sort offered by GM, Ford and Mopar for many years.
and again.... Autogear made the set. NOT RIVERSIDE! They are a reseller.
There is no "supposively" on switching the lever upside down to achieve this. It works and has been done on OD transmissions of this sort offered by GM, Ford and Mopar for many years.
and again.... Autogear made the set. NOT RIVERSIDE! They are a reseller.
Advanced
Joined: May 2003
Posts: 72
Likes: 5
From: Wilmington DE
By "supposedly", I didn't mean that I didn't know if it would work. What I meant was that I don't know if there is room in the tunnel on a Corvette to put the linkage on that way. Have you done this on a Corvette?
Thread Starter
Instructor
Joined: Jun 2004
Posts: 162
Likes: 1
From: Johnsburg IL
If that 4-speed does exist, colorado1967, it would be just the ticket. With a .86 final ratio, it would be like you had a 3.20:1 rear end instead of your 3.73 [not a lot different than my 3.08 and thm400]. It runs a bit under 3000 rpm at 70mph, and is not uncomfortable there. Still not much of a "gas saver".
Thanks for all of the feedback and I am not out to save any gas, just trying to get a little more comfort during the very occasional hwy spin. I don't drive enough to justify droping in a 6 or even 5 speed. I would rather save the money for a new project.
Steven