4-speed transmission parts 128 -> X1/9 ?

4-speed transmission parts 128 -> X1/9 ?

Joined: January 7th, 2006, 8:59 am

July 28th, 2008, 11:50 am #1


Hi all,

I have a Hoelscher-built 4-speed with 4.08 gears in my X, so I don't really need a new transmission.

But I really want the longer 3.67 gears.

A guy here says he has a NOS 128 transmission with those gears for sale (don't know price yet). I am sure he wants a good price, so I am wondering how much of the parts in that transmission I could use.

Can I just swap the final drive over and keep the rest of the transmission as NOS spares for my current transmission?

Does the shorter 4th gear of 128 transmission automatically come with the final drive or can I keep the longer 4th gear? ( I obviously don't know much about transmissions).


Ulix
http://www.mirafiori.com/~ulix/x19
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Matt Brannon - Midwest-X19.com
Matt Brannon - Midwest-X19.com

July 28th, 2008, 1:20 pm #2

Hey Ulix,

The R&P / final drive will be a straight swap.
You might not be able to use much else though.

The 128 transmissions used the "ring"-style synchronizers on 1st and 2nd
gear as opposed to the "cone" style on X boxes.

I am not sure off the top of my head whether the tooth counts
on the 128 are the same or not for 1st - 4th, which will dictate
whether the input shaft, 3rd or 4th are applicable...

I need to do some research...

-M

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Joined: January 7th, 2006, 8:59 am

July 28th, 2008, 2:03 pm #3


Thanks Matt!

AFAIK, the 128 has a 4th gear that is slightly shorter than 1:1, while the X has one that is slightly taller than 1:1.

Probably due to the fact that the X has a higher top speed because of superior aerodynamics.


Ulix
http://www.mirafiori.com/~ulix/x19
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Joined: August 29th, 2005, 1:53 am

July 28th, 2008, 2:05 pm #4

Hi all,

I have a Hoelscher-built 4-speed with 4.08 gears in my X, so I don't really need a new transmission.

But I really want the longer 3.67 gears.

A guy here says he has a NOS 128 transmission with those gears for sale (don't know price yet). I am sure he wants a good price, so I am wondering how much of the parts in that transmission I could use.

Can I just swap the final drive over and keep the rest of the transmission as NOS spares for my current transmission?

Does the shorter 4th gear of 128 transmission automatically come with the final drive or can I keep the longer 4th gear? ( I obviously don't know much about transmissions).


Ulix
http://www.mirafiori.com/~ulix/x19
Ulix, Matt is correct, the ring and pinion shaft can be swapped independant of the gearset. And the 128 R&P will bolt right in. You can transplant your existing gearset right on to the 128 pinion shaft.

As Matt noted, the early 128s had the Porsche type synchros on all four gears. Later 128s had the blocker ring type synchros on 1st and 2nd, just as the X1/9 does. When that change was made I can't say.

Steve
1x5
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Joined: January 7th, 2006, 8:59 am

July 28th, 2008, 2:10 pm #5


Thanks Steve!

Does that mean that if it had the blocker style synchros I should buy it since the gear set would be identical to mine except for the 4th gear? Or does the different ratio make everything different?

Which parts would be different?

Thanks, Ulix


Ulix
http://www.mirafiori.com/~ulix/x19
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Joined: August 29th, 2005, 1:53 am

July 28th, 2008, 2:47 pm #6

<<< Does that mean that if it had the blocker style synchros I should buy it since the gear set would be identical to mine except for the 4th gear? >>>

I can't say because I don't know that much about 128 ratios. I can only say that I know the later 128s used the blocker rings on 1st and 2nd. I am pretty sure that the 128SL used the X1/9 gearset entirely. But it has been years since I built an SL unit and can't say for sure.

<<< Or does the different ratio make everything different? >>>

If any single ratio is different then the input shaft dictates which ratio set you can use with it. So if only 4th gear is different then you can't use the input shaft or 4th gear but the others can be. That is assuming it uses the blocker rings on 1st/2nd.





Steve
1x5
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Steve Cecchele
Steve Cecchele

July 29th, 2008, 9:35 am #7

4 speed 128 uses a different syncro setup on 1 /2 as noted in previous posts. 128 (post 75ish) have the X19 cone type syncros on 1 and 2, but the syncro ring size on 3 and 4 is smaller than the later X19 style.

Reverse gear sliding hub is also different from early (pre 77) to late (post 77)

I don't think there would be much you could use from a 128 gearset (unless you wanted to go backwards in syncro sizing)

Change the R&P to the taller set and keep the gear spacing as per X19.

SteveC

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Courtney Waters
Courtney Waters

July 29th, 2008, 11:33 pm #8

<<< Does that mean that if it had the blocker style synchros I should buy it since the gear set would be identical to mine except for the 4th gear? >>>

I can't say because I don't know that much about 128 ratios. I can only say that I know the later 128s used the blocker rings on 1st and 2nd. I am pretty sure that the 128SL used the X1/9 gearset entirely. But it has been years since I built an SL unit and can't say for sure.

<<< Or does the different ratio make everything different? >>>

If any single ratio is different then the input shaft dictates which ratio set you can use with it. So if only 4th gear is different then you can't use the input shaft or 4th gear but the others can be. That is assuming it uses the blocker rings on 1st/2nd.





Steve
1x5
That gearset should coincide with the different synchro setup. Yugo 4-speeds have the same ratio as well. The 128 gearset has a more even spread between gears, or so I'm told. I just donated a couple of late 'boxes to some friends for their race X effort for that reason.

Per the factory North America 128 manual (early gearbox):

first - 3.583:1
second - 2.235:1
third - 1.454:1
fourth - 1.042:1
rev - 3.714:1

final drive 4.077:1

Wagon final drive 4.416:1
* we discussed this at OR08 and it was brought up that some mid-70s sedans may have been fitted with the wagon 'box to overcome the loss of power due to the de-tuning and emissions gear to pass smog.

Per Haynes Chapter 13 Supplement:
"All models manufactured in the latter part of 1976 are fitted with a revised synchromesh and a higher final drive ratio (3.76:1)."

Per the factory North America 128 Sport L Specifications and Data manual:

final drive 4.416:1
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