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1973 620 Transmission swap, f4w63 to 1982 280z na 5 speed

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In now at the moment: (healthy and running)

     Motor is L20b with 4speed F4w63


I will be getting a new:

     Drive shaft (shorter) (unless resolved by Question2 below)

     Modded rear transmission mount

     Motor mounts

     Gaskets and seals



     Q1:      Is everything else used from the f4w63? Clutch,fly, throw, bearing, speedo cable ect ect ect. 

     Q2:     Would a drive shaft from 1977 and up 620 with a 31 inch trans work instead of a new one? Q2-1: If not is.                        there one that will work?

     Q3:     Is it easier pulling out the motor and transmission OR just dropping the transmission and reinstalling?





     To reduce rpm at higher speeds.


Nothing ever goes to plan.



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Unless there is damage to them leave the motor mounts alone.



1/ The 5 speed bolts right up using your clutch but you must use your L16 release bearing collar or housing that holds the release bearing. The collar is intimately matched to the pressure plate and clutch so they must stay together. It's advisable to use a new bearing as they are hard to get to to replace later.


You can use your 4 speed clutch arm and the clutch slave cylinder on the zx 5 speed.


The shifter hole may need to be ovaled out slightly.


If you take the cross member off and rotate it 180 it might fit the 4 speed mount to the 5 speed. If you have a '77 get the cross member that holds the mount.


If you disconnect any clips and pull the old speedometer cable up into the engine compartment, you can run it down diagonally over the top of the transmission to the right rear side and there should be enough slack to fit. I've done this FS5W71B to F4W63 swap in a car and it does fit and work.


2/ YES! the front half of the 2 piece driveshaft is about 5.5" shorter for the longer 71B 4 or 5 speed on the '77. I would replace the U joints now while it is out


3/ Having only pulled/installed the transmission I can honestly say it was a bitch to do. If you get the truck high enough, have an overhead hoist and a way to adjust the level of the engine as it goes in I think together would be easier.



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Yes, sorry. What ever release collar you have right now has to stay with the clutch and pressure plate you have now.





As you can see they come in different heights. They are intimately mated to the height of your pressure plate so if one came with your 5 speed do not use it. These two do not have the release bearings on them. Always put new bearings on them when they are out and don't buy the cheapest. If this was a wiper blade it wouldn't matter but if you get a cheap one and it fails nest summer you have to pull your engine/transmission apart to get at it.



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Yes you can replace the clutch and PP but it must match what you have now.


Just the transmission. If it came with a slave cylinder or clutch arm, you can use those if you want. But if it came with a release bearing and collar do NOT use them.

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From Question 2


77 to 79 620 drive shafts.

Does it have to be from a single cab like mine or is all 77 to 79 620 have the same drive shafts lengths? assuming they came with the L20




Found answer in search:

The wheel base must be the same for driveshaft swap.



From Question 2


Can part of the drive shaft section be swapped between the longer and shorter and would the wheel base matter at that point? Meaning can part of a kingcab drive shaft section be swapped on my original?


Edited by FatDatSun
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The difference in driveshaft lengths between long and short wheelbases are all in the rear half of the two part driveshafts. The front half is the same for the '72-'73 4 speeds and the '74-'79 and up are shorter because of the longer transmissions but are all the same.


Does that make sense?


If putting a longer 5 speed into the earlier 4 speed truck just get the front half of a two part drive shaft from any '74-'79 truck KC/reg cab or long bed does not matter.

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  • 3 weeks later...

I have a 76 620 kc, l20b, 5spd dogleg. Did the input to output test.

It's the mid ratio. Clutch set is o.o marked 72 240z. The short time I drove it 2nd gear was a problem as in rough shifting into gear. All other gears were good. 

While backing up I got a kick in the clutch pedal and the tried out bearing started making noise.

A few pumps on the clutch temporarily stoped it.

On the way home it got louder and was making a burning smell.

After removing the engine/tranny in one piece noticed the clutch slave was leaking. Also found the driveshaft center bearing rubber ripped. The bearing itself just rotating and wobbling in the housing. 

Clutch is marked hp made in Korea.

It looks good.

Keep it or replace. 

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The 620 5 speed was not a dogleg. Doglegs have reverse above first like this...






Someone may have put one in but not a good idea as it's not strong enough for a truck.



The flywheel pressure plate bolt pattern determines what diameter clutch will bolt to it. The 240z and the L20B engine 620s both had 225mm pressure plates so yes a 240z clutch could be run on a truck.


Throw out or release bearing. They usually squeal when pedal is down and they are in use. When the pedal is up they aren't moving, or shouldn't be.


Smell could be slipping clutch burning. If you say looks good was the transmission full of oil???


The center bearing is inside the driveshaft and almost never goes bad. The rubber surround is another story, they always rot away. All you need is a new rubber. What I did temporarily, was wrap a one inch wide strip of conveyor belt (anything even rubber mat) round and round the driveshaft to build it up, then clamp it down. Worked so well I never did fix it. 



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F5W63A Dogleg. Smooth front case and 26" long



FS5W71B. Ribbed front case and bell housing. 31.5" long.

pre '80s 71B 5 speed



Here's wonderfully written article in the dime quarterly on how to ID your 510 transmission or any transmission you may come across, even has the automatics. I wish I knew half of what this guy knows about them.


















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Most accurate change is if you go a steady 50 MPH and have someone clock you or GPS it. I need what it reads when actual speed is 50. Double this give the error in %. Blue is 18 tooth. Just in case what is the tire size you're using?

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24 minutes ago, datzenmike said:

Most accurate change is if you go a steady 50 MPH and have someone clock you or GPS it. I need what it reads when actual speed is 50. Double this give the error in %. Blue is 18 tooth. Just in case what is the tire size you're using?

I've successfully done this with a chronograph watch, the higher end ones are pretty accurate. 

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