[scott-462]

I have a 70 Lemans that currently has a worn out th350 in it. I've always wanted to swap a manual trans in it and have done some research. My engine is a 455 with around 450ish HP according to others, never dynod. From what I've found, the only manual trans that could handle the torque is an old Muncie, or something new like the tkx. The trans from say an 80's 5 speed are only rated for maybe 350tq, don't quote me. The apprx $4,200 for a TKX "kit" is hard to swallow. Throw in the extra stuff considering i currently have an automatic, and the price is just ridiculous and cant justify apprx 5-6k for a full conversion kit. This is just a street car, probably never see a sticky track. I currently have a 28" radial tire and with the automatic it just lights the tires from 30 mph and slower. I have double adjustable 4 link bars and a quick performance fabricated 9" rear diff. I hope to tune it in for better traction at launch. I guess the question is, how long would an 80's 5 speed hold up to over 500ftlb torque on the street, and is it even worth it. Also, any suggestions on a trans and pricing is welcome. Keep in mind I don't have a bellhousing, third pedal ect.

[unruhjonny]

I have found that the numbers are evenly divided between those who say the older Muncies are tougher vs the aluminum cased BW-ST10.

Other (read: transmissions with lower torque ratings) can live behind that engine, but you have to be intentional on how you drive it.

[bdk1976]

Tough to beat a 3 speed dearborn for strength/cost ratio if you can find a complete setup locally.

[unruhjonny]

ha!

I was going to suggest a three speed (because they can often be had for a small fraction of the cost of a four speed) - but I figured that might be too predictable of me

Just stay away from saginaw three speeds!

[tom s]

I was told by a tech at Richmond that the ratings have about a 20% fudge rating.I have been driving the 3.42 ST-10 which has a very low TQ rating in 2 diff 421 HO full size cars for many years with normal street tires and never broke one.If you want one to race than that stuff goes out the window.NASCAR years back used aI think a 2.64 high nickel gear and steel midplate ST-10.Hard to find. Tom

[Skip Fix]

One of my street racing buddies in the 70s like the 3 speeds -had a 455 in a 65 GTO. Healthy enough to grenade the clutch!

[sdbob]

If I wanted long term reliability 4spd, I check out Paul Cangailosi (spl) 4speeds. I spend $$ upfront to get convenience, not working on it. Just my 2cts.

[Dragncar]

I put a Ford Toploader in my GTO back in the 80s. Still have the stuff. Much tougher than any Muncie. You just have to to a little fab work on the shifter handle but mine came up in the stock console, worked great. Custom driveshaft needed.

[Sirrotica]

Troy beat me to the light..........

Since GM already made the Dearborn 3 speed adaptable by drilling both case patterns into the bellhousing, the Ford top loader 4 speed can be switched into the GM car with minimal adapting. Lots more strength in one of the top loader 4 speeds than any Muncie or Borg Warner transmission, but that strength comes with a weight penalty, The Ford offering is much heavier duty from the get go.

As far as early/late Muncies strength I would speak from experience that the 73 Grand Am 4 speed I owned was a much better strength wise than any of the earlier 64-72 Muncie equipped cars I owned. With mostly stock 389s and 400 engines, and street tires myself and friends trashed dozens of early Muncies.

The 73-74 Muncie equipped transmissions were designated as M20 HD had a fine splined input shaft same as the M 22 and the same output shaft size as a T400 has. Not exactly easy to locate used ones as they only were installed for 2 model years.

Pontiac didn't offer the Muncies in and 455 A body cars 73-74, only 400 cars. The engineers must have calculated that sidestepping the clutch on a 2 plus ton car with a 455 wasn't going to get through the warranty period.

Going from memory the 64-65 Muncies had a smaller diameter cluster gear shaft, and in 1966 it was increased I believe 1/8th of an inch to aid in deflection.

If I were looking to do this swap myself I'd likely try to get a later BW from some car such as a Trans Am. Other than main shaft roller bearings needing replaced under 50,000 miles they're usually trouble free, and are superior to early BW transmissions as far as strength. In the 70s when I owned my garage the only problems I saw on the late BW was the roller bearings wearing prematurely, causing whine while driving. Cure was to replace the roller bearings and you were back in business.

For brute strength in an older transmission the Ford top loader would win.

I have zero experience with the late model stuff, or the after market 5-6 speeds. so I can't comment.

Myself if I wanted 4 forward gears behind a 455 it will be a 4L80E and bonus of .75 OD in 4th, likely it will outlast the engine with no broken parts, but it can be expensive depending upon how you attack the conversion.

[RocktimusPryme]

While I am not saying you cant beat $5k, I would be willing to bet than any manual swap is likely going to be more expensive in either money time or effort than you calculate it will be at the start. You'll either spend a lot of time trying to be thrifty, or you will start buying some trick parts (Like American Powertrain's new clutch pedal kits) to save some effort and make it expensive. This is not me tellig you not to chase your three pedal dreams. Just go into it with your eyes open is all.

I would agree of the vintage 4 speeds the Top Loader is likely the tougest. But its probably marginal compared to the big output shaft muncies or ST10s. My dad is fond of saying he can make any manual trans last because he doesnt flog them. My Dad is also the most boring person on the planet so hes probably right. So if you arent going to beat on it, you couldnt probably even get away with a T5 and get the advantage of OD.

When I was putting together the manual swap for my 66 Fairlane gasser project, I got universally told to not bother with any of the vintage units. Go straight to a T56 and dont look back. And I do mean everyone in the manual trans world I talked to. Granted, we are talking about double the power, and sticky tires, but there was not a single builder who was willing to put their name behind a Toploader in that car and say they thought it would survive a season.

[AG]

Originally Posted by Dragncar

I put a Ford Toploader in my GTO back in the 80s. Still have the stuff. Much tougher than any Muncie. You just have to to a little fab work on the shifter handle but mine came up in the stock console, worked great. Custom driveshaft needed.

What input yoke does the 3 speed toploader use?

[unruhjonny]

Pontiac source toploader three speeds for 1969 & prior high power applications;
Those transmissions used the TH350 output shaft - and they had the added benifit of using (iirc) a GM bellhousing side bolt pattern.

The funny non-GM transmssion in a GM application is the Dodge overdriven four speed used in trucks...

[mgarblik]

Also agree that a Ford Top Loader is stronger than anything from Muncie or BW. Just look at the physical size of the gears and all the internal parts. Heavier yes. But really tough. The only thing really nice about the Muncie and Super T10 is the light weight and the fact that they can be torn down and rebuilt with a hammer, screwdriver, punch, a couple wrenches and 1 good pair of snap ring pliers.

[Dragncar]

Originally Posted by AG

What input yoke does the 3 speed toploader use?

I ran a small block Top Loader 4 speed out of a 65 Mustang. The input shaft just needed to be turned down by a machine shop to fit our throw out bearing.
And you use a crank pilot bushing, not a bearing and have the machine shop bore it to fit the Ford input shaft.
It all worked really well. Used the Ford transmission yoke and ran a adapter U joint.
Ran a Lakewood bellhousing, 30lb steel flywheel, Borg and Beck Long pressure plate and clutch from McLeod. Used a TransDapt bellhousing/transmission adapter plate.

[bdk1976]

Dearborn 3 speed = 10 spline input, 28 spline output (uses different output yoke than TH350/Muncie), driveshaft length same as Muncie/ST300/TH350

Need to use bellhousing with dual bolt pattern

[besserspat]

Just my 2 cents, but in a 70s Lemans I would prefer a 4 speed manual than 3 speed. Nothing wrong with 3 speed I had a bunch in Jeep, trucks and older cars but I just find 4 speeds more fun to drive.

Find a good used BW ST 10 with a 2.64 first , q hurst shifter and bellhousing that can be had for like 1000 $ if you shop a little.

It would give the car additionnal value, and make it more fun to drive. If you are worried about strenght get a used iron case and mid plate for it and youll have a very tough transmission.

Peter

[Dragncar]

Oh, used a GM 11" style pressure plate and a Ford style clutch.
If was pretty bullet proof. I pounded that set up and never hurt a thing. Had 12" tires, Ford 9" with 3.90 N case posi and a Alston 3 link so it would hook too.

[mgarblik]

Originally Posted by besserspat

Just my 2 cents, but in a 70s Lemans I would prefer a 4 speed manual than 3 speed. Nothing wrong with 3 speed I had a bunch in Jeep, trucks and older cars but I just find 4 speeds more fun to drive.

Find a good used BW ST 10 with a 2.64 first , q hurst shifter and bellhousing that can be had for like 1000 $ if you shop a little.

It would give the car additionnal value, and make it more fun to drive. If you are worried about strenght get a used iron case and mid plate for it and youll have a very tough transmission.

Peter

Using all GM parts, I would agree that would be a pretty strong set up. ST 10 with those upgrades makes for a nice driving combination. E Larson has had good success with that combo in drag racing and currently in a road race application.

[goa484]

Originally Posted by scott-462

I guess the question is, how long would an 80's 5 speed hold up to over 500ftlb torque on the street, and is it even worth it. Also, any suggestions on a trans and pricing is welcome. Keep in mind I don't have a bellhousing, third pedal ect.

If I remember correctly, somebody a few years back on this forum did a swap with a 80s 5 speed and it was kinda of a debacle. Not sure how it worked out for him in the long run but may be worth a search. Franks Pontiac parts has a used set of pedals but Ive had luck with repo too. Not cheap, but if you want hydraulic clutch, I recommend the Malwood setup. I switched from stock to that about 5 years ago and have had no issues.

[Formulajones]

There isn't much that most would consider affordable about a classic muscle car. Taking an auto and doing a full stick conversion, even if you're resourceful and spend time finding good used parts (good luck) you'll still spend $2-$3000 easily. Finding a usable Muncie that hopefully won't need much more than a basic rebuild (good luck) is still going to set you back $1000-$1500 for the trans alone, around here anyway.

Everyone's idea of affordable is vastly different but honestly $3000 is a drop in the bucket for a job like that. I'd just go for a 5 speed conversion with everything delivered to your door step and save the aggravation