What transmission is this?

[Milenko2121]

I've been trying to find a rebuild kit for my S14 transmission as I'm planning on doing an overhaul later in the year due to transmission whining at idle(goes away with clutch pressed in) it doesn't grind at all just noisy whine that started 6 months ago and hasn't changed since.

I am reading a lot of conflicting information online as to which kit I need to overhaul it.

I originally had the S13 transmission in my L28ET 280z (I had my bell housing machined to fit), but 1st and 2nd grinded so I purchased a used SR20DET transmission for $100, and was surprised when I popped it open.

I'm told all S13/S14 SR20DET transmissions are the same, but I have two in front of me that looked identical until I popped the bell housing off.

The gear ratios are the same on both
3.321
1.902
1.308
1.000
0.759

However, 3rd gear is physically larger in the S14 version and also has a much beefier shift fork.

I'd appreciate the help figuring this out, and also to possibly stop the "all S13/14 transmissions are the same" argument.

Thanks,
Mil

[Milenko2121]

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[Milenko2121]

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[Milenko2121]

round 2

[gaz_moose]

the one with open bearings is off a 180sx / silvia S13
the one with sealed bearings is off an s14 / s15

the s14 box will have syncro's for reverse where the s13 one will be more complex and probably have a chewed up reverse gear.

if its a late s14 / s15 box then it will have a 'trap door' setup on the centre plate whereas the s13 box will just have loads of holes allowing oil to slosh backwards when accelerating.

[Milenko2121]

Originally Posted by gaz_moose

the one with open bearings is off a 180sx / silvia S13
the one with sealed bearings is off an s14 / s15

the s14 box will have syncro's for reverse where the s13 one will be more complex and probably have a chewed up reverse gear.

if its a late s14 / s15 box then it will have a 'trap door' setup on the centre plate whereas the s13 box will just have loads of holes allowing oil to slosh backwards when accelerating.

Appreciate the help, thank you. I had been confused about this for a bit.