Overdrive Manual Transmission: Is it worth it?
01-30-2018, 02:22 PM
#21
Le Mans Master
I'll be swapping my TH-400 for a TKO 600 .82 close ratio 5 speed, with either 3.08 or 3.36 rear gears behind my 496.
It will be pleasant to drive around town and highway cruising speed will be nice.
I found the SST kits are very complete and the quality of the parts included seems better that the rest.
It is pricey so I'm saving my pennies.
It will be pleasant to drive around town and highway cruising speed will be nice.
I found the SST kits are very complete and the quality of the parts included seems better that the rest.
It is pricey so I'm saving my pennies.
01-30-2018, 05:51 PM
#24
Instructor
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I have a 1974 with a 396 and a 3:55 rear. I've thought hard about doing a 5 or six speed conversion. But I don't drive the car all that much so it would be hard to justify the expense. The other part that has held me back is that I think the car would lose its identity to some extent. It's funny, I drove a 1965 Corvette as a daily driver back in the late 70's, it had a muncie 4 speed and a 3:73 rear and it never bothered me. But after years of driving 6 speed Corvettes the four speed now seems like it needs more gears. So after much consideration I decided to keep it old school and live with the high RPMs on the highway for now. Who knows, I may have a change of heart in the future.
01-30-2018, 06:51 PM
#25
Race Director
If you don't plan to take longer trips or use it for weekend get away's then it probably would not be a good investment.
01-30-2018, 07:09 PM
#26
Le Mans Master
I'd do whatever result in you driving more miles in the car, this year. If it makes the difference between driving to Bowling Green vs. just driving locally, by all means do it. But beware of losing a driving season over a drawn-out transmission swap.
I find myself reaching for 5th a lot (a leftover habit from my Sunfire), but given the traffic I typically encounter, I can't justify a swap right now. I also wouldn't want to double my investment in my car with a single mod.
So my 4-speed works for me for now, given my situation. If I blow up the transmission, though, I'd splurge on the replacement. That doesn't stop me from trolling Craigslist for deals.
I find myself reaching for 5th a lot (a leftover habit from my Sunfire), but given the traffic I typically encounter, I can't justify a swap right now. I also wouldn't want to double my investment in my car with a single mod.
So my 4-speed works for me for now, given my situation. If I blow up the transmission, though, I'd splurge on the replacement. That doesn't stop me from trolling Craigslist for deals.
01-30-2018, 08:02 PM
#27
Drifting
If you are looking for financial justification it is not there, but neither is owning a 35 to 50 year old C3 in the first place.
01-30-2018, 08:57 PM
#28
Team Owner
Member Since: Jan 2007
Location: Southern Cal Ca
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St. Jude Donor '22
I recently had to put my vette in daily driver service.
imagine my surprise at getting 12-13 mpg.
last time i used it like this, it was pre alcohol and
traffic did not average 70plus.
when i did use it as a driver 15-16mpg town was about right.
sad thing is i have a 200 4r waiting on me to do a rebuild and slide it in the car.
imagine my surprise at getting 12-13 mpg.
last time i used it like this, it was pre alcohol and
traffic did not average 70plus.
when i did use it as a driver 15-16mpg town was about right.
sad thing is i have a 200 4r waiting on me to do a rebuild and slide it in the car.
01-30-2018, 09:09 PM
#29
Race Director
I have a 71 with a 5 speed and a 72 all stock. The 72 has a 3:36 rear the 71 has a 3:55 rear.
The difference in driving the cars is outstanding. The 71 can cruse comfortably at 75 to 80 all day with no engine noise. The 71 is at 2000 rpm at 80. Comfortable cruising. The 72 is winding out at 3000 rpm.
The comfort with the lower engine noise and less vibration is very nice.
The 5 speed also gives a lower 1st gear so leaving the light is better.
The wear and tear on the engine is reduced by 40% due to the amount of the overdrive .6 .
I do get about 8 more miles to the gallon, which does add up.
Yes do it, but keep the original. I used the SST / Silver Sport kit so I did not have to cut the drive shaft.
The difference in driving the cars is outstanding. The 71 can cruse comfortably at 75 to 80 all day with no engine noise. The 71 is at 2000 rpm at 80. Comfortable cruising. The 72 is winding out at 3000 rpm.
The comfort with the lower engine noise and less vibration is very nice.
The 5 speed also gives a lower 1st gear so leaving the light is better.
The wear and tear on the engine is reduced by 40% due to the amount of the overdrive .6 .
I do get about 8 more miles to the gallon, which does add up.
Yes do it, but keep the original. I used the SST / Silver Sport kit so I did not have to cut the drive shaft.
01-30-2018, 10:43 PM
#30
Worth it? Probably not. I put in a Richmond 6 speed with 0.62 overdrive about 20 years ago. It sure is a lot more pleasant since it has 4.11's.
Worth it. Doubt it. In the long run, 20 years later, it doesn't matter that it costs too much for the amount of miles driven.
BUT - it sure is a lot more pleasant and fun to drive.
Worth it. Doubt it. In the long run, 20 years later, it doesn't matter that it costs too much for the amount of miles driven.
BUT - it sure is a lot more pleasant and fun to drive.
Last edited by carriljc; 02-01-2018 at 09:31 PM.
01-30-2018, 10:59 PM
#31
01-30-2018, 11:02 PM
#32
Team Owner
I drive mine now, it's nice and runs great, but I asked myself if I would actually drive and enjoy it more if I had an overdrive, and my answer was yes.
If you don't plan to take longer trips or use it for weekend get away's then it probably would not be a good investment.
If you don't plan to take longer trips or use it for weekend get away's then it probably would not be a good investment.
I like my 4 speed because it's in the car right now, works great and I have thousands of $$ in my bank account for things that I really need.
Just say'in
01-30-2018, 11:36 PM
#33
Maybe
i got a used T56 when I converted from 350/350TH to LS1/T56 for $1100, another couple hundred for TO bearing and clutch. Couldn’t be happier-lower end gearing also lower for sea of the pants acceleration from stop and about 80 mph at about 2200 rpm on freeway. But understand those who don’t drive much not wanting to spend $$
01-31-2018, 07:04 AM
#34
Pro
No offense meant to the original poster - but threads like this will bring out a lot of different perspectives - to go back to the OP's stated questions:
Is it worth it?
That depends completely on what you want and what your priorities are.
If you prefer a stick, it will transform your car. It might be cheaper to sell your car and buy a 4-speed of that si what you prefer. If you want a C3 stick with OD, you will still need to do some sort of conversion.
For me, yes it was worth it, but I also needed to upgrade after losing my automatic. For some, no such justification is needed, and for others it would not be worthwhile. It just depends on your own priorities and personal tastes. It will probably never pay for itself, so it's not like an investment. Only you can decide if that is worth it.
If anyone has done the conversion what's the best easiest kit out there.
My vote is for SST, that is why I went with them. It's a complete kit, providing everything from the shifter, clutch, pedal mounting hardware, cross member adaptor (if needed), linkages as well as everything between the engine and the differential, and you get great support when you call.
As for difficulty, for me it was a 3-weekend project that I could do in my own garage. Not difficult, but somewhat time-consuming.
It also stands up to abuse. You don't need to scrounge parts stores or swap meets for parts - but its also expensive, so that also depends on your own priorities and personal tastes.
Is it reliable?
The SST kit is, can't speak for others.
Is it worth it?
That depends completely on what you want and what your priorities are.
If you prefer a stick, it will transform your car. It might be cheaper to sell your car and buy a 4-speed of that si what you prefer. If you want a C3 stick with OD, you will still need to do some sort of conversion.
For me, yes it was worth it, but I also needed to upgrade after losing my automatic. For some, no such justification is needed, and for others it would not be worthwhile. It just depends on your own priorities and personal tastes. It will probably never pay for itself, so it's not like an investment. Only you can decide if that is worth it.
If anyone has done the conversion what's the best easiest kit out there.
My vote is for SST, that is why I went with them. It's a complete kit, providing everything from the shifter, clutch, pedal mounting hardware, cross member adaptor (if needed), linkages as well as everything between the engine and the differential, and you get great support when you call.
As for difficulty, for me it was a 3-weekend project that I could do in my own garage. Not difficult, but somewhat time-consuming.
It also stands up to abuse. You don't need to scrounge parts stores or swap meets for parts - but its also expensive, so that also depends on your own priorities and personal tastes.
Is it reliable?
The SST kit is, can't speak for others.
01-31-2018, 05:13 PM
#35
Le Mans Master
I love my clunky Borg T-10 four speed....and it is part of the character of owning a classic car. If I wanted a modern car, I would buy one with all it worthless appeal. So if you try hard enough, you can modify all the cool character of our C3 Corvettes right out of it, and you could have just bought a new one. it would be a big mistake for me to every do that to my car.
But, there are simply is no disadvantages, or loss of character to the car by installing an OD transmission. Besides far better shift quality and a far stronger transmission, it just transforms the car into something more enjoyable to drive. Particularly in a state like Texas, which has many high speed highways. Speed limits of 70 to 80 mph are very tiring with a car without an OD, unless your car is equipped with a tall rear end gear ( which, of course, kills good acceleration). OD transmissions solve that problem.
Now, if you do mostly city driving, or are fine with a highway cruise speed of 55-60 mph, it may not be worth it.
It’s a personal choice.
01-31-2018, 05:46 PM
#36
Race Director
Just seems like an automotive oxymoron to own a C3 and have to go slower than everybody else... I just bought a T5. I have a lot to do to this car, now 1 more thing...
Last edited by derekderek; 01-31-2018 at 05:47 PM.
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AirBusPilot (01-31-2018)
01-31-2018, 06:07 PM
#37
I had the stock 3:36 ratio in my 73 for 13 years....Motor is a worked 350......Never had any complaints driving far....200-250 mile trips except for the stock uncomfortable seats,it was fine...
Than one day,boom !! rear end gears just broke apart.....Found a 3:70 complete unit.....Great for the streets, great......On the highway, not so great....The first 5-10 miles I'm like, this is ok.....After that it gets old sort of, especially interstate driving.....
Down the line if I keep my car I think I would definitely definitely switch to a five speed....
Than one day,boom !! rear end gears just broke apart.....Found a 3:70 complete unit.....Great for the streets, great......On the highway, not so great....The first 5-10 miles I'm like, this is ok.....After that it gets old sort of, especially interstate driving.....
Down the line if I keep my car I think I would definitely definitely switch to a five speed....
01-31-2018, 08:03 PM
#38
01-31-2018, 09:20 PM
#39
Race Director
For me the decision is simple. I'm doing a complete body off resto/mod to my 73 BB, TH400 3.36 rear gears. I'm stroking my 454 to 496 cu in, so my TH400 would need to be rebuilt or replaced with a transmission that will take the estimated 600 hp build. Swapping from auto to manual makes sense over trying to make an automatic and torque converter work with my engine mods and choice of cam shaft. When looking at the cost of rebuilding and upgrading my TH400 and a custom built torque converter the cost exceeds that of a TKO 600. Since the body will be off, the conversion will be a breeze and going with the SST kit, all the parts are high quality. Shifting my last hot rod with a TKO 600 wasn't really any different than shifting my old 70 SS Chevelle.
The great thing about this forum is we can all interject our own opinions and those all provide the OP information so he/she can make the choice that's best for them.
The opinions make for interesting reading and we can always learn something new.
The great thing about this forum is we can all interject our own opinions and those all provide the OP information so he/she can make the choice that's best for them.
The opinions make for interesting reading and we can always learn something new.
Last edited by OldCarBum; 01-31-2018 at 10:53 PM.
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Torqued Off (01-31-2018)
01-31-2018, 09:32 PM
#40
We all know this is a personal thing, so no right or wrong,....BUT, disadvantages of making this conversion include:
- cost - very expensive
- size - big old transmission fills the tunnel versus small Borg Muncie
- Many aftermarket improvements end up having a downside
- No more old school 4-speed feel....it now feels like a modern shifter, if I wanted that I would buy a modern Corvette....I don't want modern feel or character in my 77 Corvette
- hassle of all the necessary mods required
- No longer original in style or equipment
- Biggest of all....no more old school character...this is the #1 reason I am not interested.
Look, everybody who mods their car thinks they are doing the right thing, and they are, for themselves. That does not mean it is logical or smart, or any other definition. But quite often, people who make these mods seem to NEED to tell everybody else that they should do it on their car...or else you are a moron. My point in making comments is to not join the band wagon on every super duper mod, and try to provide a balance so readers can think about all sides.
I have modded motorcycles to the point they no longer are interesting to me anymore. I try not to let that happen again, and was the premise for which I rebuilt my 77. And I know if I put a 5 speed late model transmission in my car, I would like it less. Its that simple. Some of us like our old cars and motorcyles because they are old cars and motorcycles. If you want to make your car into something else,....go for it.
- cost - very expensive
- size - big old transmission fills the tunnel versus small Borg Muncie
- Many aftermarket improvements end up having a downside
- No more old school 4-speed feel....it now feels like a modern shifter, if I wanted that I would buy a modern Corvette....I don't want modern feel or character in my 77 Corvette
- hassle of all the necessary mods required
- No longer original in style or equipment
- Biggest of all....no more old school character...this is the #1 reason I am not interested.
Look, everybody who mods their car thinks they are doing the right thing, and they are, for themselves. That does not mean it is logical or smart, or any other definition. But quite often, people who make these mods seem to NEED to tell everybody else that they should do it on their car...or else you are a moron. My point in making comments is to not join the band wagon on every super duper mod, and try to provide a balance so readers can think about all sides.
I have modded motorcycles to the point they no longer are interesting to me anymore. I try not to let that happen again, and was the premise for which I rebuilt my 77. And I know if I put a 5 speed late model transmission in my car, I would like it less. Its that simple. Some of us like our old cars and motorcyles because they are old cars and motorcycles. If you want to make your car into something else,....go for it.
Same with my 81. In 82 they added a 700R, so my 700R is a mod, but nothing that can't be changed back. I drove it 6600 miles in 3 weeks this summer, and the car was comfortable/practical.
As for your list of disadvantages, they are all opinion. You don't need to justify an opinion. But disadvantages sounds factual, which your more sentimental than fact.
