Classic Mustangs (Tech) Technical discussions about the Mustangs of yester-year.

Which Toploader.. or is there something better?

Old 03-03-2017, 06:03 PM
  #1  
BKKSW
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Default Which Toploader.. or is there something better?

For a street/track based 66 coupe with a max of 400hp, what manual transmission would you choose and why?

I have a line on a top loader which was the 4 speed of the day, casting number Casting no. C4AR-7006A. A 1964 model but I'm not clear if it's aluminum like 65-68 Mustang toploaders, or cast. Or how much weight difference there is. a 10 Spline input shaft. The Tail stock number is C4ZR-7A040-A, 13 3/4" long and 28 spline output shaft.

Will this work in a 66? Anyone know if it's wide or narrow ratio?

Any help is greatly appreciated.
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Old 03-03-2017, 09:15 PM
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guitarman376
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Wide ratio is the way to go for any street car if you ask me, that way you can have a numerically lower rear end and still have some ooomph at lower speeds. '64 toploaders were different from all other years and for that reason I recommend not using a '64. 65-68 toploaders were not aluminum, not sure where you got that from. There may have been some special ones or something but 99.9% were iron.
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Old 03-03-2017, 09:35 PM
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some cars got aluminum case T10s, but I believe toploaders are all cast iron.

To see which specific toploader that is, you need the ID tag info. Then you can check on David Kee's toploader website to figure out where it came from, close/wide ratio, etc.

Keep in mind that a toploader from a full-size or pickup won't work due to tailshaft differences. Also, I believe '64 used a weird bell housing bolt pattern, which causes problems with bell housing selection.

I stumbled on a close-ratio toploader w/Hurst shifter a while back that turned out to be in excellent condition. Swapped it in place of the original 3sp and I absolutely love it. I definitely need to re-gear to make up for the tall first, but it's a blast to drive. No good for drag racing, though.
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Old 03-03-2017, 09:36 PM
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Originally Posted by guitarman376
Wide ratio is the way to go for any street car if you ask me, that way you can have a numerically lower rear end and still have some ooomph at lower speeds. '64 toploaders were different from all other years and for that reason I recommend not using a '64. 65-68 toploaders were not aluminum, not sure where you got that from. There may have been some special ones or something but 99.9% were iron.
Interesting. In the past.. very distant high school days past, I owned both a 65 2+2 K with an aluminum toploader and a GT350 with the exact same trans.. I assumed and shouldn't have. Gets you every time. I was never sure if they were narrow or wide.

Why wouldn't you use the 64? Was it dimensions, quality, design?

The casting number on the trans is: C4AR-7006A and the tail stock is: C4ZR-7A040-A. The input shaft is 10 splines.

Thanks, any information helps.

Last edited by BKKSW; 03-03-2017 at 09:39 PM.
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Old 03-03-2017, 09:45 PM
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Originally Posted by Starfury
some cars got aluminum case T10s, but I believe toploaders are all cast iron.

To see which specific toploader that is, you need the ID tag info. Then you can check on David Kee's toploader website to figure out where it came from, close/wide ratio, etc.

Keep in mind that a toploader from a full-size or pickup won't work due to tailshaft differences. Also, I believe '64 used a weird bell housing bolt pattern, which causes problems with bell housing selection.

I stumbled on a close-ratio toploader w/Hurst shifter a while back that turned out to be in excellent condition. Swapped it in place of the original 3sp and I absolutely love it. I definitely need to re-gear to make up for the tall first, but it's a blast to drive. No good for drag racing, though.

I'm pretty sure the tail housing is the correct one for a mustang.. maybe it came from a Falcon? Why is your transmission not good for drag racing? Seems a close ratio would be idea for racing.. at least track type racing. Not sure about drag racing.
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Old 03-03-2017, 11:15 PM
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The 64 toploader has a narrow rectangular bolt pattern where it mates to the bell housing. The early trans makes it difficult to find a bell housing to mate to. Are you sure the alum transmissions weren't T10's? There are several different tailshaft configurations including big cars like Galaxies.
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Old 03-03-2017, 11:29 PM
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Originally Posted by barstowpo
The 64 toploader has a narrow rectangular bolt pattern where it mates to the bell housing. The early trans makes it difficult to find a bell housing to mate to. Are you sure the alum transmissions weren't T10's? There are several different tailshaft configurations including big cars like Galaxies.
Thanks. That could have saved me from a big mistake.

They could have been T-10's.. people said they were top-loaders and I never heard of a t-10 in a K or a GT350.. but maybe. Or I was just wrong in thinking they were aluminum vs. cast iron.
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Old 03-04-2017, 12:45 AM
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I believe Shelby asked for aluminum T10s in earlier GT350s for road racing. Not quite as durable as a toploader, but a hell of a lot lighter.

Close ratio models are fantastic for road racing, letting you keep the engine right at the peak power sweet spot, but the gear spacing is too close for drag racing, or even most people's idea of street driving. Wide ratio models let you take better advantage of a wide power band, and on the street they'll give you better oomph off the line.
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Old 03-04-2017, 01:15 AM
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Originally Posted by Starfury
I believe Shelby asked for aluminum T10s in earlier GT350s for road racing. Not quite as durable as a toploader, but a hell of a lot lighter.

Close ratio models are fantastic for road racing, letting you keep the engine right at the peak power sweet spot, but the gear spacing is too close for drag racing, or even most people's idea of street driving. Wide ratio models let you take better advantage of a wide power band, and on the street they'll give you better oomph off the line.
Thanks. Good information. U can see what you're saying about drag racing. You want more powerband per shift, the same reason you want a 7000 redline vs. a 6000..
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Old 03-04-2017, 11:02 AM
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Toploaders are very rugged. The early aluminum T10 didn't hold up and T10's are somewhat weaker in general. You can tell a T10 by the side plate. The internals load into the trans from the side. Toploaders load from on top. Unless you drive like I do, either trans will probably work for you. Just make sure you get one that fits your car. Check out David Kee online. He can supply complete transmissions or any parts you might need.
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