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Transmission overall lengths

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Old May 15, 2018 | 05:41 PM
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Will Colon Jr's Avatar
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Transmission overall lengths

Hi everyone. I’m having some trouble finding the right transmission for my swap. I’m installing an 88 convertible 13b n/a into an 87 samurai. I’m trying to keep it 4x4. Does any knows which transmission will fit my n/a engine but at the same time shortens the distance from the block to the shifter or output shaft?
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Old May 15, 2018 | 09:49 PM
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All, repeat ALL, pre RX-8 N/A manual transmissions are the same length. From 1991 back to the early 1970s. Even the 3 speed automatics are the same length as that.

Shifter position changed a lot, though. FC RX-7 (what you have) had the shifter the furthest back. FB RX-7 (1981-1985) had it an inch or so more forward. SA RX-7 (1978-1980) and RX-2/3/4/5 had the shifter about six inches forward of that, sprouting from the case itself and not on an external housing.
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Old May 16, 2018 | 08:01 PM
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Ok. So I will need to look for one of the RX2/3/4/5 in order to create enough clearance. Now I just need to find one of those witch I bet will be a job by itself. Lol.
Thanks so much for the information. I truly appreciate it. Next will be finding a front mount cover so I can get things rolling
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Old May 16, 2018 | 09:11 PM
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It would be way easier to find an SA transmission than any pre RX-7 trans. The older units had really crap syncros.

Bear in mind too that there were at least five different pre-RX-7 variants, but they all generally had the same shifter placement.
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Old May 17, 2018 | 11:27 AM
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Just for reference:



81-85 transmission on left, 79-80 Transmission on right
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Old May 17, 2018 | 04:26 PM
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Originally Posted by peejay
It would be way easier to find an SA transmission than any pre RX-7 trans. The older units had really crap syncros.

Bear in mind too that there were at least five different pre-RX-7 variants, but they all generally had the same shifter placement.
You have a valid point there. I will look for an SA instead.
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Old May 17, 2018 | 04:28 PM
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Originally Posted by Richard Miller
Just for reference:



81-85 transmission on left, 79-80 Transmission on right
Thanks a lot for the picture, this is more than enough clearence for the swap. Got to find a buyer for my FC transmission.
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Old May 19, 2018 | 09:06 AM
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Hold off on selling the s4 tranny.

If you are trying to get the right position of the shifter for your swap. You may be able to modify the remote shifter on the s4 to work for you.

All the remote shifters mount to the tail stock with four bolts. There is a rod that passes into the tranny to do the shifting.
If you cut the first 2 holes off the remote shifter you can then mount the remote shifter closer to the tranny. The rod needs to be shortened and drilled for a split pin.

As mentioned the location of the shifter varies between transmissions. Much of this is done with changesmto the location of those 4 bolt holes. Different combinations of tranny's and remote shifters gets you different locations of the shifter relative to the output shaft.

So for example to mount the 13bt and tIi tranny into my rx3 I used the sa remote shifter with the first 2 bolts cut off. The rod and its tube was cut. To get clearance for the reverse spring on the remote shift I remove a mount for the remote on the tail stock.

The work involves opening up the tranny. And there are minor variations that are not apparent so good planning is involved. A good drill press helps to redrill the rod, but none of it rocket science. I found much help on this site to complete the modification.

I think the s4 tranny would hold up better than the sa. That said there are some variations in gear ratios if that's important to your build.
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Old May 19, 2018 | 07:08 PM
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Originally Posted by EDSRX3
Hold off on selling the s4 tranny.

If you are trying to get the right position of the shifter for your swap. You may be able to modify the remote shifter on the s4 to work for you.

All the remote shifters mount to the tail stock with four bolts. There is a rod that passes into the tranny to do the shifting.
If you cut the first 2 holes off the remote shifter you can then mount the remote shifter closer to the tranny. The rod needs to be shortened and drilled for a split pin.

As mentioned the location of the shifter varies between transmissions. Much of this is done with changesmto the location of those 4 bolt holes. Different combinations of tranny's and remote shifters gets you different locations of the shifter relative to the output shaft.

So for example to mount the 13bt and tIi tranny into my rx3 I used the sa remote shifter with the first 2 bolts cut off. The rod and its tube was cut. To get clearance for the reverse spring on the remote shift I remove a mount for the remote on the tail stock.

The work involves opening up the tranny. And there are minor variations that are not apparent so good planning is involved. A good drill press helps to redrill the rod, but none of it rocket science. I found much help on this site to complete the modification.

I think the s4 tranny would hold up better than the sa. That said there are some variations in gear ratios if that's important to your build.
Intersting. I been contemplating at the remote mount since I seen the trans for the first time but was not sure if it was possible. I think I might save me the money and try that first. I’m not concern about the gears ratio. Maybe at a later time thanks for the info.
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