DIY Rebuilding your transmission

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I searched all over and never did find a DIY for rebuilding an S2000 transmission, and I needed to rebuild mine so I decided to go for it and what follows is my attempt to document my rebuild with lessons learned (this is my first transmission rebuild) Hopefully it will be helpful to someone else who is looking for a DIY for transmission rebuild.


Of course step one is to remove the transmission. Since you have to remove the transmission anyway now is a good time to replace the clutch kit/flywheel if necessary.

Special tools needed:
07746-0030100 DRIVER HANDLE ~$35

07746-0030300 ATCH, I.D. (30MM) ~$18

07746-0030400 ATCH, I.D. (35MM) ~$25

07965-SA50500 DIS TOOL E ~ $44

A shop press (got mine from Harbor Freight ~$130)
Large bearing separator ~$25
Bearing puller 2 jaw preferable (I have a 3 jaw puller, and made it work but would have been better I think with a 2 jaw puller) ~$20
Seal driver set ~$26
Hex bit set with 14mm bit in the set ~$13
Large metric socket set containing 36mm and 38mm sockets ~$30
Adapter set 3/4″ to 1/2″ drive for above sockets ~$4
Craftsman Circlip pliers ~$15
Hondabond high temp silicone liquid gasket 08718-0001 ~$9
2 3ft long pieces of heavy angle iron 2″X2″ from Home Depot ~$24 (the supports supplied with the shop press were not wide enough for the gears and all to fit through so I made my own)
Bench vise with at least 6″ wide opening and wood blocks for disassembling/reassembling countershaft.~$79 (I had to buy a new vise because the one I had would not open wide enough)

I did not rebuild the secondary shaft assembly as I was having no issues with it so I did not need the extra special tools that are required for it.

I did rebuild the rest of the transmission including all bearings (except for the ones in the secondary shaft assembly) and all synchro sets and seals and shift forks. Parts for the rebuild cost ~$1260

Total cost of rebuild: ~ $1798 which is about half the price for a new transmission or for that matter a shop rebuilt transmission. Yes you can find used transmissions everywhere for less than that, but you are buying a transmission that you don’t know the condition of and I for one would rather put my money toward something I know the condition of (new) than something that may fail on me sooner than it should. Plus the tools I can keep and use for other things too, or even to rebuild the transmission again someday.

Service manual is a must for this DIY.
This should only serve to complement the service manual, not replace it.
All work you do to your transmission is at your own risk…as it was with me.
If you do not have good mechanical skills you should not attempt this DIY. That being said, this is my first transmission rebuild ever, so if I can do it, so can most mechanically inclined individuals.

Follow the service manual and remove the secondary shaft assembly (pretty straight forward, remove bolt from shift arm, remove shift arm from shift rod, remove 8 12mm bolts from the secondary shaft assembly and off it comes.

You may have to take a flat bladed screwdriver holding it horizontally and put the tip under one of the “ears” on the casing and gently tap on the shaft of the screwdriver in an upward direction with a rubber mallet to break the seal. I recommend putting parts for each page of work in zip-lock bags to keep them separate from other parts to avoid confusion later on and to help keep from losing parts.
I did not disassemble the secondary shaft assembly as mentioned above so I skipped those steps.

Transmission housing removal:
Remove the oil pump drive gear and its shaft. Just pulls out.
Use a chisel and unbend the divet they made in the 29mm nut, don’t worry too much about damaging it as you should have a new one to replace it with when rebuilding.
Install the spline shaft holder as shown in service manual.
I used an air impact wrench and 38mm socket with 3/4 to 1/2″ adapter to remove the 29mm nut, set to clockwise because the 29mm nut is reverse threaded. Comes off quite easily that way.
Use bearing separator with bearing puller to remove the needle bearing above the secondary drive gear. Comes off without much difficulty.
Remove secondary drive gear with bearing puller, (this is where I wished I had the 2 jaw puller)
I didn’t remove the oil pump rotor or its plate no issues there so I left them installed.

Remove all the set screws and springs and steel balls and sensors from the transmission housing. I separated the springs/set screws/steel balls in ziplocks, one bag per side of the transmission. It makes it easier to figure out which size spring goes where later.

Remove the 14 12mm bolts from the transmission housing and screwdriver under the “ears” rubber mallet trick works here too.

I did not have to use the slide hammer to remove the bearing race in the next step because I am not replacing that bearing set (part of secondary shaft assembly) It did however fall out by itself while I was removing the 29mm nut with the impact wrench, so I had to reinstall it later on.
Remove the oil seal from the shift rod hole on the transmission housing. Pry with a screwdriver. Just pops out.
Use circlip pliers to remove the oil pump suction strainer. Mine was filthy and nearly clogged. I cleaned it with carb cleaner and blew it out with air. Much better now.
I did not remove the oil guide plate or shims in the next step.
Remove oil guide tube and magnet. Magnet had metallic sludge and fine metallic shavings on it.

Cleaned it with paper towel.

Remove the bolt holding the reverse shaft holder, then remove the reverse shaft holder, reverse shaft and its needle bearing, just pulls out.

Remove the bolt holding in the pin that holds the 1-2 shift levers. Remove the pin from the 1-2 shift levers just pull out once the bolt is removed. Then remove the 1-2 shift levers. You may have to shift them left or right to get clearance to remove them, then lift off of the clamp position and out.
Remove the spring pin holding the shift arm in position on the shift rod. I used a 4mm hex bit on a socket extension, worked great.
Pull out the shift rod.

Remove the shift arm, interlock, select return spring, and its stake pin.
Remove the 1-2 shift piece, just pulls out.
Now you will need the 14mm hex bit to remove the plug on the side of the clutch housing the gives access to the circlip that holds the countershaft ball bearing (and everything else) in place.
I turned the whole thing over upside down with the gears hanging in a 5 gallon bucket suspended by the circlip.
Use the circlip pliers (I found some at Sears that work perfect for this) to expand the circlip and gently bounce the assembly until the gears fall into the 5 gallon bucket (only falls about 3 or 4 “) Gravity works! Remove all the parts from the 5 gallon bucket (Main shaft, countershaft, shift forks, spring washer, reverse idler gear, thrust washer)

Remove the 3 bolts holding the release bearing guide and the release bearing guide.
Remove the oil seal from the clutch housing, I just used a screwdriver and a hammer, drive it out. Replacing it anyway.
The shift forks were worn beyond service limits,

and the synchros were worn too.

Mainshaft disassembly:
Use bearing separator and press to remove ball bearing above the 3rd gear.
Remove 3rd gear its needle bearing, distance collar, and its synchro and sleeve. Just pulls off.
Use bearing separator and press to remove 4th gear, 3rd/4th gear synchro hub and 4th gear synchro.
Remove needle bearing, distance collar, 5th gear, and its synchro.
Use bearing separator and press to remove 6th gear, 5th/6th synchro hub, synchros and needle bearing.
Use bearing separator and press to remove remaining ball bearing.

Mainshaft reassembly:
Using the exploded view on p.13-32 and synchro sleeve and hub reassembly on p13-51 of service manual, (when reassembling synchro hubs/sleeves make SURE that the longer teeth are not installed in the slots for the synchro tabs, it will allow you to, they should be installed in the only other place it will go where the longer teeth fit into the longer grooves of the sleeve.)
Support 2nd gear on plates that came with shop press and using the driver handle and 30mm attachment press on the ball bearing with thin edge of outer race facing 6th gear (which is to be installed on the other end of the shaft), then install 6th gear its needle bearing and synchro/spring.
Install the 5th/6th synchro hub and sleeve making sure to align the stops as pictured in step 3 p13-33 and taking note of which side of the sleeve faces up. Press the 5th/6th synchro hub with the driver handle. Make sure the synchro sleeve moves back and forth between 5th and 6th gears after pressing.
Install synchro spring/synchro and 5th gear with its needle bearing, then distance collar, 4th gear and its needle bearing, 4th gears synchro/spring.
Install the 3rd/4th gear synchro hub and sleeve making sure to align stops and taking note of which side of the sleeve faces up.
Press on the 3rd/4th gear synchro hub with the driver handle. Install 3rd gears synchro/spring, distance collar, 3rd gear and its needle bearing, making sure to align holes in 3rd gear with tabs on synchro hub.
Then press on the angular ball bearing with thin edge of outer race facing 3rd gear using the driver handle.

Counter shaft disassembly:
Needle bearing slides off of inner race, the using bearing separator and press remove inner race.
Use chisel and unbend the divet in the 27mm nut. This nut should also be replaced with a new one.
SECURELY clamp the countershaft on the 4th and 5th gears with wood blocks as shown in drawing p13-39 of service manual.
Remove the 27mm nut and washer using 36mm socket with 3/4 to 1/2″ adapter. I just used my air impact wrench to remove this nut set to counterclockwise (this one is normal threaded)
Then remove the ball bearing with bearing separator and press.
Rest of parts just pull off.

Countershaft reassembly:
Using exploded view on p13-41 and synchro sleeve and hub reassembly on p13-51 of service manual,
Install 2nd gear and its needle-bearing, friction damper with its tabs facing up, 2nd gears synchro/spring.
Install 1st/2nd synchro hub and sleeve making sure to align grooves on bottom with the tabs on friction damper and taking note of which side of the sleeve faces up.
Install 1st gear’s synchro/spring (and if AP1 install friction damper on 1st gear (not required on AP2 transmission)) Install 1st gear aligning holes in 1st gear with tabs on the synchro hub.
Install distance collar, reverse gear and its needle bearing. Install reverse synchro/spring, and then reverse synchro hub and sleeve taking note of which side of sleeve faces up.
Press on the ball bearing above reverse gear with driver handle and 30mm attachment.
SECURELY Clamp 4th and 5th gears in vise with wood blocks. Install the spring washer concave in and 27mm nut. Tighten to spec, 119ft-lbs. normal direction.
Use chisel and hammer to stake the locknut into groove on end of shaft.
On the other end of the shaft press on the inner race of the needle bearing using the driver handle and the 35mm attachment.

Transmission housing installation:
Use the seal driver of appropriate size to install oil seal to 4-4.5mm depth in transmission housing.

Install release bearing guide.

Transmission reassembly:
Orient the mainshaft and countershaft and shift fork assemblies

as shown in drawing on p13-56. I used two large zip ties to hold it all together during this step which made the seemingly impossible almost easy.

Install the 64mm shim, reverse idler gear thrust washer. Partially install the ziptied gears/forks so that mainshaft bearing enters its race giving room to install the reverse idler gear.
Using circlip pliers expand the circlip through the hole in casing allowing the assembly to drop into place. Make sure that circlip is properly seated in groove in bearing.

Make sure that you have installed the needle bearing on the inner race you have installed on the countershaft before continuing on……(experience talking here…lol)

Put some liquid gasket on the threads of the 34mm plug and install the plug using 14mm hex bit, torque to spec. 51ft-lbs. Install the 1-2 shift piece,then install the select return spring and interlock mechanism and pin per drawing. Make sure the select return spring ends are on proper sides of the pin.

Install the shift arm into the interlock and shift fork grooves.

Install the shift rod through the holes of the interlock mechanism and shift arm and insert the spring pin through the shift arm and shift rod. IMPORTANT: before pinning shift rod make sure that the shift rod is oriented where recessed hole at top of rod has internally threaded side facing toward gears and bare side (no threads for about 1/4″) facing out or what will be upwards when transmission is reinstalled.

Install the 1-2 shift levers (outer one first then inner one) making sure that stamped centers are closer together than ends as per drawing on p13-57. Insert pin through the 1-2 shift levers, you may have to shift the gears as necessary to get the 1-2 shift levers to align properly. The bolt will help drive the pin through the levers once aligned properly.
Install the reverse shaft needle bearing, reverse gear shaft, thrust washer, reverse shaft holder into reverse idler gear, then install the bolt with washer and torque to spec. 25ft-lbs
Install oil guide tube and magnet.
Install the oil pump strainer and suction guide with circlip.

Install the shift rod oil seal using just the driver handle from seal driver kit, fits perfectly.

Install the oil guide plate, shim and bearing outer race using appropriate sized seal driver and hammer.
Apply liquid gasket to edge of the transmission housing as shown on p.13-58
Install the transmission housing on the clutch casing.
Install all the bolts taking note of which holes get the longer bolts and torque to spec in order as shown on P13-59
Apply liquid gasket to threads of all set screws and insert steel balls into proper holes in transmission housing, take note of which size spring goes in which hole. Torque to spec. 16ft-lbs.
Install reverse switch with washer, torque to spec. 18ft-lbs.
On the other side of the transmission housing install the steel balls in their holes, take note of which size spring goes in which hole. Torque to spec. 16ft-lbs
Install VSS with “O” ring and torque its bolt to spec. 8.7ft-lbs
Install the 2 drain plugs with gaskets and torque to spec 29ft-lbs.
Install fill plug after filling (not yet) with fresh MTF of your choice. 33ft-lbs.

Install the secondary drive gear using the driver handle (I didn’t need the tool they spec for this).
Install the needle bearing above the secondary drive gear with the special tool 07965-SA50500. I did not use the bolt and nut spec’d until I had driven the needle bearing on most of the way to the secondary drive gear with a rubber mallet and the special tool, (the 14mmX1.5mmX40mm bolt size spec’d is too short to reach, should be at least 80mm long). When it was most of the way there I used the bolt to finish tightening the two together. Install the spring washer concave in and 29mm nut. Install the spline lock tool and torque to spec. in counterclockwise direction (nut is reverse threaded) 127ft-lbs This task is nearly impossible without some way of securing the transmission to allow you to torque it down. I used a small sheet of plywood under the transmission and strapped the transmission down to the plywood with ratcheting tie down strap then stood on plywood while torquing the nut. Worked great.

Use chisel to stake the nut into the groove on the end of the shaft. Install the oil pump gear and shaft. You may have to play with it a little to get the shaft to line up with the hole underneath and also with the oil pump gear so that the shaft goes all the way through and seats where it belongs. You will know when the shaft slides into place, the shaft length will be shorter standing above the oil pump gear. Shaft shown here at proper height:

Install “o” rings on the ends of the shift rod tube. and install on transmission housing, pops into place. Apply liquid gasket to the sealing surface between secondary shaft assembly and transmission housing. Making sure dowels are in place install the secondary shaft assembly onto the transmission housing. Taking note of which holes get the longer bolts. Torque all 8 of the bolts to spec. 20ft-lbs in order shown on p13-65.

Install the shift arm onto the shift rod with special bolt and spring washer concave in (now you see why it is important to make sure the correct side of shift rod faces up) torque to spec. 22ft-lbs. Install shift lever housing torque bolts to 7.2ft-lbs

You are basically done! Reinstall transmission and enjoy your new smooth shifting! Hope this helps someone.

Based on an original write up by ronnuke

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