5 Speed With Weird Ratios

[KenFirch]

I finally got a lead on a 5 speed, which has been sitting on the shelf since the mid 90's at a Sacramento manual trans business .  Went to look at it, appeared to have a close ratio tail housing.  Did a quick check of the 1st and 5th gear ratios by marking shafts and turning, not too accurate.  Estimated 5th was .773, and first was 3.6, which I thought odd.  They recently replaced the seals since it was sitting for so long, and came with 1 year warranty.  They unfortunately painted it gray, ugggh.  Anyway, decided to buy it.

It looks like like a typical close ratio tail shaft housing, no dust shield, bottom speedo bolt, one rear tab, reverse lockout plate.  Its does have the oil filler plug on the left side of the case instead of the normal right side.  I put a degree wheel on the input shaft to try to get more accurate ratio calcs, with 2 output shaft turns:

• 1st - 3.6 (2590º / 720º) probably 3.59)
• 2nd - 2.25 (1620º / 720º)
• 3rd - 1.42 (1022º / 720º)
• 5th - .81 (585º / 720º)

So, it looks like it has the 72-74 4 speed ratios, which is fine with me since I still have the 3.364 diff.  Can the 4 speed gear set be used in a 5 speed case?

And a .81 5th, I didn't know that was even possible.  That's right in the middle of what I was expecting, .773 or .864.  Actually .81 my be perfect.

Anyway, anybody have any thoughts on how this tranny came together?

Thanks, Ken

[Zed Head]

The starter position seems high.  I think that might be for a V6, like a 300ZX.  Edit - The shifter would be different though.  Not sure what you have there.  

People do swap front cases, 280ZX front case on 300ZX gear set, after some relatively minor modifications.  But it will only bolt to an L6 in the wrong, tilted, orientation.

Here's an 83 280ZX followed by the 88 300ZX.  Notice how smooth the case is also.

Edited January 4 by Zed Head

[Zed Head]

I found an old picture of an 83 280ZX front case next to a 1985 300ZX case.  The V6 starter position is actually lower not higher.  Not sure what's going on with the FSM pictures above.  A picture from the front of the bolt pattern and drain slot might help ID it.  

Edited January 4 by Zed Head

[Zed Head]

P.s. There are also truck versions out there.  They differ in overall length.  You might measure yours and put the number out here.

[KenFirch]

Yeah, front view does look different.  Measures 30.5" overall, 29" to shifter centerline.  ZL71B is cast into side of main case.

Edited January 4 by KenFirch

[KenFirch]

I think I'll be returning this. I think it's a 200SX trans, somehow with a 280ZX tail shaft housing.

[Zed Head]

I happen to have the 1986 200SX manual.  It shows the older style shifter.  And similar ratios.  I had wondered if there was a four cylinder out there that might use it.    Good luck.

 

[SteveJ]

From searching for ZL71B#3, I would say that is a 720 transmission.

[KenFirch]

I returned tranny for a full refund.
You guys should never listen to me for any 240Z advice! [emoji23]

[SteveJ]

The 720 box isn't bad. I did find confirming information with your ratios, too.

https://www.zhome.com/ZCMnL/tech/GearRatios.html