auto vs manual tranny

For those who swapped one way or another, i want to hear your input. I want to do a tranny swap really soon and i want to know which is more worth my time and money

Application:

1972 Coupe with a 302 with approx 250-400 HP (never dynoed but it has to be within that range) currently have FMX open diff with a 28 in tire and 3.08.

Use:

I really want an OD tranny for freeway use, either a t-5 or a AOD with manual valve body. thinking of doing 3.55 or 3.73 with LSD for road racing and occasional autocross/ 1/8th mile drag, but mostly road racing and street use.

I would really love and appreciate any and all input. Still have time to save up but need to make a decision so i know what route i decide to take.

250-400 horsepower is a HUGE range. You certainly would not need a dyno to tell you which end of that range you are closest to.

For Manual, I'd go T-5 transmission with 3.5 rear end. If you want to stick with automatic, I'd seriously look into a 4R70W tranny with 3.7 rear end. If you don't want to go with electronically controlled transmission, then get a wide ratio AOD (uses gear set from the 4R70W)

Open differential will help keep you from fishtailing when accelerating thru a curve, but will lose traction when flooring it from a dead stop like a drag race.

Locking or limited slip differential will be better for off the line (like a drag race), but will be more prone to over-steer when accelerating thru a curve

If you're at the upper end of your horsepower range a stock AOD won't handle the power, you'll need to have one built. The weak point for an AOD is the hollow input shaft. A 4R70W will handle more power, and the electronic controller can be tuned for street or strip use.

Its such a wide range because the builder says its 450-500..I think its 350-400 and others think Its less than 250.

I want a manually controlled tranny because i road race it..with my open diff and 3.08 i have really bad oversteer every corner if i punch it, it jus spins for about 1-2 seconds before it catches on

Sounds like you should get the suspension sorted out before you start changing a major part of the drivetrain.

Look into a posi/traction lock rear differential, bigger front swaybar, install a rear swaybar, and maybe new shocks and even better tires if traction is a problem.

Do you have front disc brakes?

I hate automatic transmissions. They're boring. I suppose it depends what you want it for. As far as a manual, a T-5 is a pretty straight forward swap. A lot of places sell kits for this. I used the TKO-600 and their kit from Modern Driveline. I personally wouldn't use a T-5 for much more than 400hp. For a 302, I would go T-5 with a Pro-5.0 shifter (smooth shifts and shorter throw), 3.55 gears and a Torsen or TruTrac differential. That would be a great street/road race combo. As for 1/4 mile stuff, I think those that are serious about it tend to stick to an automatic for consistency.


I would square away the suspension first then brakes. My '68 has Global West upper/lower control arms and Total Control strut rods, Maier Racing 600# coils and 165# Race leaf springs, 1 1/8" front sway bar/ 3/4" rear, TKO-600 with 3.50:1 9in rear with a 393w stroker. Not bone jarring but firm. It's my daily driver. I'm planning the exact same for the '73 Mach-1. The only thing I would consider adding to my '68 is a torque arm.

Sounds like you should get the suspension sorted out before you start changing a major part of the drivetrain.

Look into a posi/traction lock rear differential, bigger front swaybar, install a rear swaybar, and maybe new shocks and even better tires if traction is a problem.

Do you have front disc brakes?

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600LB coils 195LB leafs 1 1/8" front sway bar 3/4" rear sway bar, subframe connectors. getting them installed as we speak hopefully done by saturday to test it out on the track. Shocks (front sensa-trac monroe and KYB gas-a-just rear) are ehhh and so are tires (falken zieks (225/45/18) in the front and lionharts in the rear (275/35/20). thats next on my list when they get worned out.

brakes are wilwood 4p

I hate automatic transmissions. They're boring. I suppose it depends what you want it for. As far as a manual, a T-5 is a pretty straight forward swap. A lot of places sell kits for this. I used the TKO-600 and their kit from Modern Driveline. I personally wouldn't use a T-5 for much more than 400hp. For a 302, I would go T-5 with a Pro-5.0 shifter (smooth shifts and shorter throw), 3.55 gears and a Torsen or TruTrac differential. That would be a great street/road race combo. As for 1/4 mile stuff, I think those that are serious about it tend to stick to an automatic for consistency.


I would square away the suspension first then brakes. My '68 has Global West upper/lower control arms and Total Control strut rods, Maier Racing 600# coils and 165# Race leaf springs, 1 1/8" front sway bar/ 3/4" rear, TKO-600 with 3.50:1 9in rear with a 393w stroker. Not bone jarring but firm. It's my daily driver. I'm planning the exact same for the '73 Mach-1. The only thing I would consider adding to my '68 is a torque arm.

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suspension is getting done. But i want a tranny for that OD. It kills on gas going to school. and if i went with a t-5 what would be a nice clutch for dual purpose?

I use to swear for manual transmission and use to think the automatics are for grannies. Well, I ain't granny, but the more powerfull the engines gets the more it needs to use the manual right. Try to shift TKO600 from 2nd to 3rd gear while your engine is revving 7000 rpm, doable but not an easy task. Manual needs to be driven like it's stolen when hammering on the strip or track - you don't baby it. Manual transmission behind pumped up SBF/BBF makes you smile and gives you a healthy doze of testosterone. It's hard to beat in emotional way.

When it comes to consistancy on strip or the user friendliness the automatics are hard to beat. Plus you can stick your elbow out while cruising on town even with heavy traffic.

Take a look too the TH200 R4, they are light, they are small and they're good geared. Extreme Automatics makes adapters for SBF and for 429/460 engines. TH200 R4 can be made to withstand +1200 hp so no need worry about. Only bugger is that they're GM made...

Anyway I'll stick with the stick, but something to think about.

Yup..Love driving a manual...but counts where i am...I agree with Finmach...Alot of give and take with each...But for less hassle in town specially if you got alot of power..Auto is the king of in town driving..Being in southern Cali you mite have some heavy traffic and tall hills...I been stuck in some bad spots with a stick in seattle...And i swore i would never hit that town again with a stick!! i wasted so much clutch They got oil slick wet hills that are so steep at some stop lights in town..You feel like you are taking off in the space shuttle..Burning clutch then rubber and sliding back with cars right on your ass is not my idea of fun..lol

Heavy traffic and lots of stop and goes and tall hills?...Auto!!...Have rural driving or alot of long non clogged freeways.?.stick!! atleast for me..lol

i have a OEm c6 car and i drove it with a c6 for years. then i went to a tko600 the last 4 years and i love it however the HP and TQ limitation on them is horrible. plus, i had a .064 OD which the water my 521 stroker is built, it hates the low rpm cruising. the 600hp/tq thing is kind of weak for me and i've already surpassed that. i did made the tranny a little stronger but i'm still worried so i pulled the tranny.

with a TQ monster BBF stroker, 2.87 1st gear and 4.11 rear gear, lil 28 inch tall tires & 11 inches wide and a 4500rpms launch with a dumped clutch, that'll make you poop your pants and look at the sky for an entire 60ft.

therefore, i'm making decent amount of power with plans of 200 shot of nitrous i had to go another route again. i am going back to my c6 with a transbrake and it being rollerized. i am still in the process though. i need to wire cooling fan that sides in the factory muffler location, the transbrake with button activation.

all in all, if you ain't going to surpass 350hp then i'd do the t5 for it being cheaper. if you want stronger a tko600 is best. if you want a tko600 i have one available that's gone thru before this season.

suspension is getting done. But i want a tranny for that OD. It kills on gas going to school. and if i went with a t-5 what would be a nice clutch for dual purpose?

Call Modern Driveline and talk to Bruce. Ask about the dual Kevlar clutch. I run that on my 393w and have on my supercharged 393w in my '95. It will hold all the power you're going to throw at it and is very smooth and streetable.

I'm curious about those leaf springs you're using. I would like to know how it is on the street. I'm wondering if a bigger and heavier car (verses the '68) would want a little more spring.

For my '73 Mach-1, I'm running a 245/45-17 with plenty if room. You should be able to go a bit wider if you wanted.

suspension is getting done. But i want a tranny for that OD. It kills on gas going to school. and if i went with a t-5 what would be a nice clutch for dual purpose?

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Call Modern Driveline and talk to Bruce. Ask about the dual Kevlar clutch. I run that on my 393w and have on my supercharged 393w in my '95. It will hold all the power you're going to throw at it and is very smooth and streetable.

I'm curious about those leaf springs you're using. I would like to know how it is on the street. I'm wondering if a bigger and heavier car (verses the '68) would want a little more spring.

For my '73 Mach-1, I'm running a 245/45-17 with plenty if room. You should be able to go a bit wider if you wanted.

Definitely will let to know. Its those grab-a-trak 5 leaf rev eye leafs. Going to the track saturday to test out all my new components. I wanted to get some 245/40/18 but apparently ill rub since i lowered the car alot. But ill let you know how the new suspension upgrades go.

i have a OEm c6 car and i drove it with a c6 for years. then i went to a tko600 the last 4 years and i love it however the HP and TQ limitation on them is horrible. plus, i had a .064 OD which the water my 521 stroker is built, it hates the low rpm cruising. the 600hp/tq thing is kind of weak for me and i've already surpassed that. i did made the tranny a little stronger but i'm still worried so i pulled the tranny.

with a TQ monster BBF stroker, 2.87 1st gear and 4.11 rear gear, lil 28 inch tall tires & 11 inches wide and a 4500rpms launch with a dumped clutch, that'll make you poop your pants and look at the sky for an entire 60ft.

therefore, i'm making decent amount of power with plans of 200 shot of nitrous i had to go another route again. i am going back to my c6 with a transbrake and it being rollerized. i am still in the process though. i need to wire cooling fan that sides in the factory muffler location, the transbrake with button activation.

all in all, if you ain't going to surpass 350hp then i'd do the t5 for it being cheaper. if you want stronger a tko600 is best. if you want a tko600 i have one available that's gone thru before this season.

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hmmm how much are you looking to get for it? might not get it now. Need to save up for it

I use to swear for manual transmission and use to think the automatics are for grannies. Well, I ain't granny, but the more powerfull the engines gets the more it needs to use the manual right. Try to shift TKO600 from 2nd to 3rd gear while your engine is revving 7000 rpm, doable but not an easy task. Manual needs to be driven like it's stolen when hammering on the strip or track - you don't baby it. Manual transmission behind pumped up SBF/BBF makes you smile and gives you a healthy doze of testosterone. It's hard to beat in emotional way.

When it comes to consistancy on strip or the user friendliness the automatics are hard to beat. Plus you can stick your elbow out while cruising on town even with heavy traffic.

Take a look too the TH200 R4, they are light, they are small and they're good geared. Extreme Automatics makes adapters for SBF and for 429/460 engines. TH200 R4 can be made to withstand +1200 hp so no need worry about. Only bugger is that they're GM made...

Anyway I'll stick with the stick, but something to think about.

Click to expand...

Hmmm. it isnt exactly a DD but i do drive it as much as possible, and i started taking to road tracks. Not much of a drag racer but there is a local 1/8 that i will hit every full moon. Living in socal the traffic is horrible.

I use to swear for manual transmission and use to think the automatics are for grannies. Well, I ain't granny, but the more powerfull the engines gets the more it needs to use the manual right. Try to shift TKO600 from 2nd to 3rd gear while your engine is revving 7000 rpm, doable but not an easy task. Manual needs to be driven like it's stolen when hammering on the strip or track - you don't baby it. Manual transmission behind pumped up SBF/BBF makes you smile and gives you a healthy doze of testosterone. It's hard to beat in emotional way.

When it comes to consistancy on strip or the user friendliness the automatics are hard to beat. Plus you can stick your elbow out while cruising on town even with heavy traffic.

Take a look too the TH200 R4, they are light, they are small and they're good geared. Extreme Automatics makes adapters for SBF and for 429/460 engines. TH200 R4 can be made to withstand +1200 hp so no need worry about. Only bugger is that they're GM made...

Anyway I'll stick with the stick, but something to think about.

Click to expand...

Hmmm. it isnt exactly a DD but i do drive it as much as possible, and i started taking to road tracks. Not much of a drag racer but there is a local 1/8 that i will hit every full moon. Living in socal the traffic is horrible.

Yup..Love driving a manual...but counts where i am...I agree with Finmach...Alot of give and take with each...But for less hassle in town specially if you got alot of power..Auto is the king of in town driving..Being in southern Cali you mite have some heavy traffic and tall hills...I been stuck in some bad spots with a stick in seattle...And i swore i would never hit that town again with a stick!! i wasted so much clutch They got oil slick wet hills that are so steep at some stop lights in town..You feel like you are taking off in the space shuttle..Burning clutch then rubber and sliding back with cars right on your ass is not my idea of fun..lol

Heavy traffic and lots of stop and goes and tall hills?...Auto!!...Have rural driving or alot of long non clogged freeways.?.stick!! atleast for me..lol

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ya thats the thing that makes me not want a stick. The traffic is pretty bad. hills eh not to steep but there is lots of hills and the maintence of clutches will be burdensome since i do the upkeep of my car not my parents. and i want a clutch that will handle some abuse so when i track it it doesnt burn on me

As far as that cutch, I had good experiences with the dual Kevlar clutch from Modern driveline. It will easily handle 500+ rwhp. If you're concerned about it, the Kevlar/metallic clutch is another option. I tried that as well On my '95 GT. Since I live in California, I was concerned about emissions so I went small on the throttle body, MAF, and cam (still made 500rwhp). When I figured out I could go with a bit more cam, MAF, TB and boost, I was right under 600rwhp. On a daily driver, passed California emissions and all under 5500rpm. The Kevlar/metallic clutch was very streetable and very smooth.

hmm interesting. My motor doesnt make no 500 HP so its not the numbers im worried about, im more worried of dumping the clutch haha..where in cali?

I live in Sunnyvale (near San Jose). 40 miles south of SFO and 30 miles in from Santa Cruz.


I understand it's more clutch than you need. Just saying to have options. A lot of "road racer"/street cars around here use these clutches. The guys who actually makes the clutches is just a few miles from me. He makes them primarily for road racing.

I live in Sunnyvale (near San Jose). 40 miles south of SFO and 30 miles in from Santa Cruz.


I understand it's more clutch than you need. Just saying to have options. A lot of "road racer"/street cars around here use these clutches. The guys who actually makes the clutches is just a few miles from me. He makes them primarily for road racing.

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ohhhh man haha im done in socal. hmmm and roughly how many miles do they last? with normal driving haha


i guess another thing to ask is if the whole manual conversion worth it. Because right now i have an auto, so the conversion to stick will be costly and is it worth my investment?

Well, I didn't race at all. However, I did get on it a bit on the freeway and drove in traffic regularly. I would drive six miles to work, after work I would drive to my girlfriends after (25 miles) then drive home (30 miles). That was about 4 days a week. An easy 300+/- miles a week. Plus the occasional trip to Tahoe or the Beach. That clutch lasted easily 3-4 years.

dam ok haha thats a while. hmmm ok for the conversion what will i need?