thisisnotphil1

Alright so ive done alot of searching and havent come across anything yet, but would anyone happen to know the length of an rb20 trans? Bellhousing to tailshaft casing. Heres the issue. The synchros went bad on my rb20 trans. i pulled the trans and put the rb20 bellhousing on a ka trans and its ready to go back in. When i get to school tonight i can measure but id like to be prepared if its not going to fit so i can figure something out. So what im asking is if anyone knows the length of an rb20 full trans compared to ka ka full trans? I have a one piece ka driveshaft so im hoping i shouldnt have any issue. If anyone has done this and can let me know before 6.30 est id be eternally grateful.

TougeSR20Kid

It should be the same I believe the rear half of the casing on the SR/KA/RB20/CA/etc trannies is the exact same and the only part that is different is the front half of the case with the bell housing

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thisisnotphil1

Alright so incase anyone is ever searching about this i have done all the necessary work for it to be known that you can do this but i personally want to steer people away from doing this.

There is alot of information saying that the ka/sr/rb20 trans are "exactly the same." Now i would like everyone to know that i am unfamiliar with the sr transmissions but from what i have researched, and also discovered on my own, the sr, ka, and rb20 trans are not the same internaly or externally. Gear ratios, exact same. Dimensions, not so much. With that being said it is possible to swap the bell housing from an rb20 onto a ka for it to fit an rb20 or rb25. I am only assuming this is also true for the sr.

Logically, it seems to be a good idea that if your rb trans is muffed up, you could just buy a ka trans, swap the bell housings and youre good to go. Unfortunatly, this is not true. For some reason, unkown to me at the moment, the trans shaft is longer in a ka than in the rb20. Assuming you didnt notice the length difference of the transmissions side by side, you will instantly notice the 4 inches, give or take, of distance where the shifter was supposed to be. 4 inches doesnt sound like alot, but it is quite alot of space. If you want to continue you must cut a hole to compensate. Or design some crazy ass shifter. Also, the ka shifter and rb20 shifter are NOT the same. So if you dont have a ka shifter, get one.

Another issue that comes from the extended tail shaft, is your driveshaft length. Do not plan on using your stock driveshaft. It will be around 7/8 to an inch too long. Again, 1 inch doesnt seem like alot. I personally could have gotten the driveshaft on, but i would run the risk of having the driveshaft smack into the trans case and destroying it.

So, in conclusion, it is possible to do the rb20 bell housing swap on a ka trans, but i wouldnt. There are enough s chassis out there that are all cut up and abused. If youre running an rb25 with an rb20 trans like i am, pay the extra money for an rb trans. I want to buy an rb25 trans but as you all know, alot of drifters are broke. I hope this helps for anyone who is searching around and stumbles across this post. Good luck

OrangeVirus1

So what you are saying is, if I use the actualy RB20 trans, I'm ok? but if I use the KA trans on the RB20 engine I'm fuxxored?

thisisnotphil1

WHAT...

Ok. If you have a messed up rb20 trans and think you can use a ka trans with an rb20 bell housing you can, but you might as well just buy another rb20 trans. It would cost around the same. There you go, the short version.

OrangeVirus1

Ok I was just reading this ( because I am doing the RB20 swap with a RB20 tranny ) and for a minute I thought you were talking about all those issues as if using the RB20 tranny. so What I was asking is that using the Actual RB20 trans +RB20 engine = alot less hassle than using RB20 engine + Ka trans

thisisnotphil1

Exactly.

The bell housing swap takes time, effort, and money. Buying another rb20 trans takes less time, less effort, but around the same amount. Depending on how much you can get a trans for.

OrangeVirus1

cool cool. so I should be set my RB20 trans is fine lol

thisisnotphil1

It never hurts to check and recheck. Especially fluids. Bought my motor and trans off a guy. Opened up the drain plug on the trans. Nothing came out. Added gear oil. First drive ever in the s13. Gear grinds between shifts and gear pop outs. Drained the fluid to do the bell housing swap and there was water in it. Idk how it got there. Idk when it go there. Unfortunatly i learned my lesson the hard way with the bellhousing swap but at least i can share my new knowledge with my fellow zilvians.

mpadill

Im sure you prob bought another trany but i just found out for rb20 trans you can use an 86.5-up s12 trans its exactly the same, there cheaper then buying a rb trans from an importer like for 500 bucks or higher at least in the states not sure for the rest of the world...just have to swap bellhousing..ka/sr trans work but unless you wanna cut the body, create custom shifter and custom drive shaft or move drivetrain ect... go really custom... there about 2inches longer on the tail side. thats the problem with that... Like said earlier I hope this helps for anyone who is searching around and stumbles across this post. Wish the best.

240Z28

does anyone know where I can find an rb20 trans?? I posted in the WTB section a couple times, but no one even looks at the posts

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