Druken

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WackyRotary

I can't advice about the 79-80 tranny or S5. Never seen one actually to compare. But a 81-85 5spd can be compatible with S4 n/a for sure by removing the tail housing and swapping.

79rx_7

Can anyone tell me if the 79-80 tranny is different from 81-85. I realy want to swap to a S4 or S5 GXL tranny which has the best gearing for fuel economy I think

Stock 79 gears: 3.647 - 2.218 - 1.433 - 1.00 - 0.825
S4 or S5 GXL : 3.476 - 2.002 - 1.366 - 1.00 - 0.697

This tranny only came on the second gen 87-91 GXL

Rogue_Wulff

The trans will physically fit, with a couple minor issues.
1. The shifter is about 4" further rearward on the FC (86-91) trans compared to an SA (79-80) trans. The FB (81-85) trans shifter is about 2" rearward of the SA. This will require modding the floorboard and console.
2. The trans mount is different on the FC trans. You will either need to obtain an FB tailshaft housing, or fabricate a custom crossmember to mount the trans.

Felgar

Quick question for the guys who've done this...

When removing the S4 tailhousing, how did you seperate the housing from the front of the tranny without removing the block from the end of the shift rod?

For my S3 tailhousing the block was just held on by a bolt so I took it off then slid the housing over the shift rod. But the S4 block is held with a roll pin which is a problem esspecially with the tranny half taken apart. Any ideas?

(if I punch the roll pin through it looks there might not be enough room in that little enclosure, and I was also unable to verify that the shift rod is drilled all the way through)

renns

Felgar,

I just disassembled one a few days back, and it punches out no problem. The FSM shows it clearly as well.

Jeff20B

iTrader: (13)

So you just tap it all the way through?

renns

Jeff,

If you remove the other bits as shown, you can knock it straight through. Also, check you PM's

Jeff20B

iTrader: (13)

So it's a little more complicated than the FB bolt type, but is doable. Thanks!

trochoid

iTrader: (6)

The pin is not hard to knock out, but the orientaition must be right to get enough clearance to push the rool pin all the way out. If not, the pin hits the wall and stops. Flat bottom drift works well, a pointed on jambs the pin.

Felgar

Yup, understood. Thanks guys.

caddy83

I need an SE tranny but very difficult to find. Parts for rebuilt are not all available. Who can post up the most recent write up to install a 2nd gen non turbo tranny into a 1st gen SE. Turbo 2 tranny to much modification. Need a simple 2nd gen swap. Anyone in the Los Angeles Area done this swap. Need help. Thanks

Rx-7Doctor

iTrader: (13)

You are looking at the thread that answers your question. The S4 Non-turbo transmission with the listed tail shaft swap is a direct bolt in. Remove old transmission, perform swap and install.

Is their other information that you need besides this?

The S5 non-turbo transmission is not a direct bolt in.

caddy83

Thanks RX Doctor? S4 non turbo trannies are from what exact years of a 2nd gen. rx7. These trannies are readily available, correct? Where can I have an S4 tranny rebuilt? Or an 85 SE tranny rebuilt near Cerritos, CA. Who can do this modification for me(L.A, CA area). Any recommendations of an affortable rotary mechanic.

trochoid

iTrader: (6)

S4, 86-88. Parts between the SA and any 2nd gen tranny are not compatible, parts from the S5 are not compatable with the S4, when swaping tail housings. What may be confusing people is the terminology The tail housing is the rear 1/3 of the tranny case/body. The shifter housing is the part that bolts on the top of the FB and newer tailhousings, which is the part that positions the shifter location. Section 7A of the FSM has a complete teardown and rebuild guide for trannys. I suggest that all those asking questions read and familiarize yourselves with that section.