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Thought I'd start a thread on my latest attempt to finally put in the RB25 tranny in my '89 GTS. For the longest time, I have been running an RB20 tranny first with my RB20DET, then with the blown, untunable RB25DE-T (no thanks to the guys who did my wiring at MEAN STREET, lol), and then the current RB25DET. Over the last few months, the RB20 tranny started to slowly slide into its grave and I found that I had a few blown syncros.
It was time for a tranny change and I went for an RB25 tranny (thanks, Ali, youre the best!!).
Ray (BigBlueR32) and Mike (belontay_typeM) have helped me do the tranny work and here is a brief rundown of the steps involved. I will try to upload some pics of the project for others to see as to what we did.......ignore Ray's pic of kicking back on a Canadian while we caught our breaths (I didnt do much...it was my friends who did all the work).
So, without further ado, here it goes:
SWAPPING AN RB25 TRANNY INTO AN R32 TO RUN WITH AN RB25DET
Tools needed:
1. A tool box with at least 5-6 extensions
2. C- clip removing tool.you can use a long nose pliers, but sharpen the ends a bit to catch the clip so you can remove it
3. A jack
4. Four (4) jack stands, OR a roll of carpeting to drive up on if you dont have a jack, so the front gains a bit of height.........this happened to us and we had run to Crappy Tire to get a sweet deal on a Jack and 2 jack stands, all for under $40....WOOT WOOT!!
5. An empty container to drain the tranny fluid
Steps involved:
1. Disconnect the battery
2. Using the 5/6 extensions, loosen the top screw of the starter from the engine bay. You need to do this, because you cannot easily reach this screw from under the car.
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3. Jack up the front of the car and slide the jack stands under the front control arms. We went around 1 ft plus.
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4. Repeat the jacking process for the rear. Having the car in the air really helps. Although it seems like a girl with her legs up in the air, there is enough room for a guy to slide under and still have the ability to get the tranny down.
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5. Loosen the 4 bolts on the rear differential that are holding the driveshaft in place. KEEP THE BOLTS and NUTS on the driveshaft rear flange - you dont want to lose them
6. While you're at it, it may be a good idea to get the exhaust piping out of the way. Unhook the rear muffler and unbolt any hooks holding the exhaust pipe in place. There are at least two sets of them - a couple are around a foot behind the front of the muffler, and the other COULD be a bracket attached to the tranny mount on the other end. If you dont have that, then dont worry about it.
Mike and Ray - I see RED
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7. The next step is to loosen the hanger bearing. It is a circular ring around a rubber bushing that has a bearing inside it. The circular ring around it has two holes on its edge. This is the part from which the hanger bearing is bolted on to the body. One of these is held thru a NUT with a washer and the other is held in place with a bolt. Loosen the bolt and the nut and the hanger bearing should come off loose.
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8. Pull the driveshaft out from the tail of the tranny. Put it aside. While being there, unbolt the engine mounts. You need to do this because when the driveshaft is removed and you are about to pull the tranny out, it will exert a lot of force on the crankshaft and having the engine just sitting on the motor mounts as fulcrum will help achieve the angle at which you can slide the tranny out.
9. Get in the car and remove the rubber surrounding the shifter. Remove the shifter knob. You will need to use a special tool to remove the C lip that holds the shift lever in place. Or you can use a sharpened long nosed pliers. After removing the C clip, you can pull the shift lever out. Put it away.
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10. Drain the tranny fluid into an empty container. Should be around 4 liters.
11. Disconnect the clutch slave cylinder and the speed sensor.
12. Now comes the kicker!! The tranny is bolted on to the flywheel by way of bolts. The top two bolts are called BITCH bolts, due to their FRIENDLY location and EASE of removal. Get to these bolts with the help of the long extension that you used before to get to the starter bolt. Once these are out of the way, proceed to unbolt the reast of the screws.
13. The tranny will come loose after all the bolts around the bell housing have been removed. Slowly pull it back. One way to do it is to use a jack to support the tail of the tranny, while you gently pull it back. Another is to use your chest as a cradle while you lie down under the tranny and wiggle it out.
14. The tranny is HEAVY, so gently bring it down and put it away.
15. Now if you need to do the clutch job as well, you need to have a way to somehow keep the crank pulley stationery while you loosen the bolts holding the clutch cover in place. One way to do it is to remove the rad and the fan to make room for a socket to slide into place and the hold the crank pulley bolt. We didnt do the clutch!!
16. Take the RB25 tranny and bring it under the car.
17. The driveshaft of the RB20 is NOT compatible with the RB25 tranny. The yoke is not wide enough to slide on to the tailshaft of the tranny, so you need an RB25 yoke. We also found that you also CANNOT use the RB25 driveshaft, because (a) it is too long, and (b) the hanger bearing on it has no points to be bolted onto the hinges in the middle. So your best bet is to (a) put an RB25 yoke on to the RB20 driveshaft, (b) shorten the RB25 driveshaft, or (c) get a one-piece driveshaft of the same length as the RB20 driveshaft with the RB25 yoke. I went with the first option, but I had to cut off the yoke along with around 2 inches of the pipe towards the front of the RB25 driveshaft. This was slid INTO the RB20 driveshaft and then welded to strength and balanced. This ensures that the final product would be strong and wont bend under load. Getting the driveshaft done cost me $130 plus tax.
Here is a pic of what it looks like when installed - notice the slight gap between the tranny tailshaft and the yoke? You need it to have a bit of a play, so when the car goes over bumps and the wheels move up and down, the driveshaft has room to move forward or backward a tad (not too much).
18. We had to power arm the tranny while holding its tail under a jack. Its a pain becuase the Rb25 tranny looks like an RB20 tranny that has been stung by a bee. Its swollen from the middle and so leave less room for you to reach the bolts even with the extensions. But it CAN be done, as we discovered and Ray did it. You will have to lift the tranny as straight as possible, until the input shaft slides in thru the clutch plate and flywheel. Once that is done, you can let go, as that will hold the tranny in place. Get out from under the car and take a breather, have a smoke, or a beer, whatever you want.
You're gonna need some willpower to do the next step.
RB20 Baby tranny
RB25 Pregnant tranny
18. Get to the BITCH bolts first. Due to a lack of direct visual contact with these two bolts, especially if you are doing it under no light as we were, you will have to FEEL your way to them.
19. Bolt the tranny back by tightening the screws around the bellhousing. Alternate between them to ensure a more even tightening.
20. Bolt the engine back onto the motor mounts.
21. Assuming you have the right driveshaft, reinsert the yoke into the tailshaft, reconnect the hanger bearing to the hinges, and tighten the other end of the driveshaft to the rear diff.
22. Reconnect the clutch slave cylinder. Don't forget to bleed it to make sure there are no air pockets in it. Otherwise, when you press the clutch, it will stay down and not return up as if its an ex who doesn't want to come back home.
23. Readjust the clutch to your preferred settings
24. You CANNOT use the speed sensor of the RB25 since its electronic and RB20 uses a mechanical system. You need to get the one for the GTR. There is an info thread on this subject elsewhere.
25. Refill the tranny. You can do it by either unbolting thew filler screw on the side or thru the shifter hole. I prefer the latter, since its easier and we dont need to prove our manliness anymore by doing it under the car
. As a proof, see Ray's manly pic of showing the Canadian bottle its true place.......get your minds out of the gutter!!
26. Put the shift lever back in place and then hold it in place by sliding in the C clip. The clip will keep it where it belongs.
That should pretty much do it. Bring the car down, remove the jacks, start the car and go for a drive. You may feel that the RB25 shift lever's throw is a bit less than that of the RB. I felt it that way, but for the reverse, I had to throw it quite a bit to the right and then back.
I hope that I have covered the essence of the tranny swap. If there is something else left out, please feel free to suggest and add.
It was time for a tranny change and I went for an RB25 tranny (thanks, Ali, youre the best!!).
Ray (BigBlueR32) and Mike (belontay_typeM) have helped me do the tranny work and here is a brief rundown of the steps involved. I will try to upload some pics of the project for others to see as to what we did.......ignore Ray's pic of kicking back on a Canadian while we caught our breaths (I didnt do much...it was my friends who did all the work).
So, without further ado, here it goes:
SWAPPING AN RB25 TRANNY INTO AN R32 TO RUN WITH AN RB25DET
Tools needed:
1. A tool box with at least 5-6 extensions
2. C- clip removing tool.you can use a long nose pliers, but sharpen the ends a bit to catch the clip so you can remove it
3. A jack
4. Four (4) jack stands, OR a roll of carpeting to drive up on if you dont have a jack, so the front gains a bit of height.........this happened to us and we had run to Crappy Tire to get a sweet deal on a Jack and 2 jack stands, all for under $40....WOOT WOOT!!
5. An empty container to drain the tranny fluid
Steps involved:
1. Disconnect the battery
2. Using the 5/6 extensions, loosen the top screw of the starter from the engine bay. You need to do this, because you cannot easily reach this screw from under the car.
[IMG]
[/IMG]3. Jack up the front of the car and slide the jack stands under the front control arms. We went around 1 ft plus.
[IMG]
[/IMG]4. Repeat the jacking process for the rear. Having the car in the air really helps. Although it seems like a girl with her legs up in the air, there is enough room for a guy to slide under and still have the ability to get the tranny down.
[IMG]
[/IMG]5. Loosen the 4 bolts on the rear differential that are holding the driveshaft in place. KEEP THE BOLTS and NUTS on the driveshaft rear flange - you dont want to lose them
6. While you're at it, it may be a good idea to get the exhaust piping out of the way. Unhook the rear muffler and unbolt any hooks holding the exhaust pipe in place. There are at least two sets of them - a couple are around a foot behind the front of the muffler, and the other COULD be a bracket attached to the tranny mount on the other end. If you dont have that, then dont worry about it.
Mike and Ray - I see RED
[IMG]
[/IMG]7. The next step is to loosen the hanger bearing. It is a circular ring around a rubber bushing that has a bearing inside it. The circular ring around it has two holes on its edge. This is the part from which the hanger bearing is bolted on to the body. One of these is held thru a NUT with a washer and the other is held in place with a bolt. Loosen the bolt and the nut and the hanger bearing should come off loose.
[IMG]
[/IMG]8. Pull the driveshaft out from the tail of the tranny. Put it aside. While being there, unbolt the engine mounts. You need to do this because when the driveshaft is removed and you are about to pull the tranny out, it will exert a lot of force on the crankshaft and having the engine just sitting on the motor mounts as fulcrum will help achieve the angle at which you can slide the tranny out.
9. Get in the car and remove the rubber surrounding the shifter. Remove the shifter knob. You will need to use a special tool to remove the C lip that holds the shift lever in place. Or you can use a sharpened long nosed pliers. After removing the C clip, you can pull the shift lever out. Put it away.
[IMG]
[/IMG]10. Drain the tranny fluid into an empty container. Should be around 4 liters.
11. Disconnect the clutch slave cylinder and the speed sensor.
12. Now comes the kicker!! The tranny is bolted on to the flywheel by way of bolts. The top two bolts are called BITCH bolts, due to their FRIENDLY location and EASE of removal. Get to these bolts with the help of the long extension that you used before to get to the starter bolt. Once these are out of the way, proceed to unbolt the reast of the screws.
13. The tranny will come loose after all the bolts around the bell housing have been removed. Slowly pull it back. One way to do it is to use a jack to support the tail of the tranny, while you gently pull it back. Another is to use your chest as a cradle while you lie down under the tranny and wiggle it out.
14. The tranny is HEAVY, so gently bring it down and put it away.
15. Now if you need to do the clutch job as well, you need to have a way to somehow keep the crank pulley stationery while you loosen the bolts holding the clutch cover in place. One way to do it is to remove the rad and the fan to make room for a socket to slide into place and the hold the crank pulley bolt. We didnt do the clutch!!
16. Take the RB25 tranny and bring it under the car.
17. The driveshaft of the RB20 is NOT compatible with the RB25 tranny. The yoke is not wide enough to slide on to the tailshaft of the tranny, so you need an RB25 yoke. We also found that you also CANNOT use the RB25 driveshaft, because (a) it is too long, and (b) the hanger bearing on it has no points to be bolted onto the hinges in the middle. So your best bet is to (a) put an RB25 yoke on to the RB20 driveshaft, (b) shorten the RB25 driveshaft, or (c) get a one-piece driveshaft of the same length as the RB20 driveshaft with the RB25 yoke. I went with the first option, but I had to cut off the yoke along with around 2 inches of the pipe towards the front of the RB25 driveshaft. This was slid INTO the RB20 driveshaft and then welded to strength and balanced. This ensures that the final product would be strong and wont bend under load. Getting the driveshaft done cost me $130 plus tax.
Here is a pic of what it looks like when installed - notice the slight gap between the tranny tailshaft and the yoke? You need it to have a bit of a play, so when the car goes over bumps and the wheels move up and down, the driveshaft has room to move forward or backward a tad (not too much).
18. We had to power arm the tranny while holding its tail under a jack. Its a pain becuase the Rb25 tranny looks like an RB20 tranny that has been stung by a bee. Its swollen from the middle and so leave less room for you to reach the bolts even with the extensions. But it CAN be done, as we discovered and Ray did it. You will have to lift the tranny as straight as possible, until the input shaft slides in thru the clutch plate and flywheel. Once that is done, you can let go, as that will hold the tranny in place. Get out from under the car and take a breather, have a smoke, or a beer, whatever you want.
You're gonna need some willpower to do the next step.
RB20 Baby tranny
RB25 Pregnant tranny
18. Get to the BITCH bolts first. Due to a lack of direct visual contact with these two bolts, especially if you are doing it under no light as we were, you will have to FEEL your way to them.
19. Bolt the tranny back by tightening the screws around the bellhousing. Alternate between them to ensure a more even tightening.
20. Bolt the engine back onto the motor mounts.
21. Assuming you have the right driveshaft, reinsert the yoke into the tailshaft, reconnect the hanger bearing to the hinges, and tighten the other end of the driveshaft to the rear diff.
22. Reconnect the clutch slave cylinder. Don't forget to bleed it to make sure there are no air pockets in it. Otherwise, when you press the clutch, it will stay down and not return up as if its an ex who doesn't want to come back home.
23. Readjust the clutch to your preferred settings
24. You CANNOT use the speed sensor of the RB25 since its electronic and RB20 uses a mechanical system. You need to get the one for the GTR. There is an info thread on this subject elsewhere.
25. Refill the tranny. You can do it by either unbolting thew filler screw on the side or thru the shifter hole. I prefer the latter, since its easier and we dont need to prove our manliness anymore by doing it under the car
. As a proof, see Ray's manly pic of showing the Canadian bottle its true place.......get your minds out of the gutter!!26. Put the shift lever back in place and then hold it in place by sliding in the C clip. The clip will keep it where it belongs.
That should pretty much do it. Bring the car down, remove the jacks, start the car and go for a drive. You may feel that the RB25 shift lever's throw is a bit less than that of the RB. I felt it that way, but for the reverse, I had to throw it quite a bit to the right and then back.
I hope that I have covered the essence of the tranny swap. If there is something else left out, please feel free to suggest and add.
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