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240sx trans swap into 280z measurements and install pix


280zex

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What kind of welder did you get? 

 

I got an el-cheapo wire feed from Harbor Freight. My welding is ok on the flat spots, but them corners are not so well. It's definitely harder to do than the videos I seen on u-tube make it out to be.........

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YES!!! test drive completed and the Z runs great!! I like the lower 5th gear compared to my original 5 speed too.

 

Now to fab a new shifter boot as the original Z boot doesn't fit so well over the 240sx shifter...........

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I drove the Z to work for the freeway shake down test. All I can say is WOW!! The 240sx trans swap is the best considering I have the 3.90 rear diff. 2500rpm @ 60mph, thats down from 3100 rpm.

 

The stock sx shifter has to go. Its too tall for my Z as I dont have the center console, so the shifter knob sits about 8 inches high, and its a bit squishy feeling. It seems to be a 2 piece unit with the upper half connected to the lower half by some type of big rubber bushing/vibration dampening setup. I did find some after market short shifters with out that integral bushing. I also need to fab a new shifter boot, my original unit ripped on me and I get hot trans tunnel air blowing me in the face in 2nd and 4th gear ;-(

 

I highly recommend this trans swap!! The gears are butter smoothe and no more grinding going into reverse!

Edited by 280zex
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  • 3 weeks later...

I really want to do this swap as well. Highway driving for my Z is sometimes downright painful with the high rpms and all. Quick question, which years 240sx transmission are compatible with the 280z? I know 94 and 96 boxes are but not sure if all years are compatible.  Also did you get a rebuilt unit or just a used one? 

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I really want to do this swap as well. Highway driving for my Z is sometimes downright painful with the high rpms and all. Quick question, which years 240sx transmission are compatible with the 280z? I know 94 and 96 boxes are but not sure if all years are compatible.  Also did you get a rebuilt unit or just a used one? 

I have the 1990 240zx 5 speed, I paid 225$, and it came with some replacement parts. I then had that completely rebuilt as it is NEVER a good idea using a trans in unknown condition!!

 

Just about any 5 speed gear box for the KA engines will work, except for the 4x4 truck, unless your going for an awd z?? 

There is different gear ratios as well...... all you have to do is google "KA 5 speed" or "240sx 5 speed" there is plenty to read up on :wink:

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I really want to do this swap as well. Highway driving for my Z is sometimes downright painful with the high rpms and all. Quick question, which years 240sx transmission are compatible with the 280z? I know 94 and 96 boxes are but not sure if all years are compatible.  Also did you get a rebuilt unit or just a used one?

Any SX 5 speed will work, but they are not all created equal. Later years have thicker gears and a larger diameter mainshaft (documented in my 240SX install guide). Also, IIRC the SX box has a shorter fifth gear (higher revs) than the ZX 5 speeds. If you want to lower your cruising rpm, you have to look at the diff ratio and tire size as well.

 

Nigel

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Any SX 5 speed will work, but they are not all created equal. Later years have thicker gears and a larger diameter mainshaft (documented in my 240SX install guide). Also, IIRC the SX box has a shorter fifth gear (higher revs) than the ZX 5 speeds. If you want to lower your cruising rpm, you have to look at the diff ratio and tire size as well.

 

Nigel

your right about the rear gear set and tire size, and I forgot to mention what I am running. the fifth gear ratio of my new 240sx trans is 0.759 to 1 rotation.

The rear diff is 3.90 to 1 rotation and my tire travels 23 inches (225/50-15) per 1 full rotation, so in 5th gear 60mph is 2700 rpm. By the math my Z can spin the rear tires to 150mph in 5th gear turning 6500rpm

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225/50/15's are 24", unless you have 205's. Look into a b&m short shifter, they are reasonably priced and make a world of difference. 

I took the measurement in the driveway. I would add that my tires are worn out!! total distance was maybe 1/8 inch over 23 inches total distance per 1 full rotation. Tires are Champiro 225/50/15's, super soft rain tire. 30psi pressure. I was told they "might" last 20k miles at best, and that's what I got!

I did purchase the short shifter, however, the sealant that was used during re-assembly is NOT willing to let me remove the original shifter plate from the trans.... bummer!!!!!!!!!!!!

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