RB/KA bellhousing swap

[JCAP_Tuning]

A precaution to those that "think" that swapping bellhousings from KA to SR, RB to SR, etc. is simple, I have to let you know you have been misinformed.

On the NJ Turnpike last weekend on the way down to NC I broke the 5th gear sprocket off in the RB20 transmission on my s14. In addition, I find out later that I have no reverse gear and that 1st, 2nd and 3rd gears are grinding, so essentially I have 4th gear remaining to get me back to NC. Quite an interesting ride with my 4.36 final gear, running 4000 rpm at 70 mph the whole way home.

As soon as we get to Durham NC, we pull the RB transmission. Overnight Kyle Bennett (KA24detKyle) and I disassemble the RB20 trans and a KA transmission from a 1991 240sx and attempt to make a hybrid trans with KA internals, RB bellhousing and KA tailend.

(make sure the transmission is in neutral) First, you have to remove the bolts attaching the front cover behind the throwout bearing, this is well sealed and took some prying. Behind that a c-clip holds the main bearing in. The FSM calls for use of special tools (flathead screwdrivers and needle nose pliers, strategically placed) to pull the clip off.

Next, once that is all pulled there are bolts in the center attaching the tailend to the bellhousing and must be removed. Once all these bolts are removed, it is recommended to remove the shifter all bolts on that end (shifter cover and the two large bolts on each side of the shifter end which also have springs and pins on each side).The bellhousing and tailend are more than likely sealed very well and takes a few strikes with a rubber mallet, wood and hammer or your choice of demolition equipment.

Once everything does come apart, you will see that the internals all come out although all assembled can be misaligned. In order to reassembled correctly (FSM is very unclear just says you need to put the gears in neutral, but not how) you need to try and keep the gear levers from moving, otherwise you will have a time figuring out how to get them all back in neutral. The shifter fork according to the FSM needs to be removed taking the retaining pin you will see under the shifter. This is not necessary you can use the shifter fork from the other tailend.

You will need a lot of patience and time to do all of this correctly. However, to make a long story short, the KA internals are longer than the RB20 and in addition the tailend is as well. Although you can use a KA transmission internals for SR, you CANNOT use them to replace a RB20 transmission without modifying your driveshaft and using the Mckinney mounts as I did on my RB, the shifter will now be too far back using KA internals.

We first tried using RB bellhousing, KA internals and KA tailend, then attempted using RB bellhousing and tailshaft with just KA internals. All of these were too long and I ended up acquiring another RB20 transmission. Needless to say we wasted a whole night assembling at installing the hybrid transmission. The reason I used a RB20 transmission originally on my RB25 was because it was readily avaiable at the moment and that I was able to use the s14 driveshaft without modification.

[BoostFab]

good info, thanks! how did you broke the rb20 box?

[gani]

if you are using the stock skyline crossmember you will not have to get a driveshaft and the shifter will be at the same location as a ka. trick is just to use the bellhousing.

[Wulfgang]

I hate to say it... but I told you so. Search and you will find. I posted all of these measurements almost a year ago.

No, you cannot just switch the bellhousings. Get out your tape measure and make some measurements. No need to pull everything apart to see that there is no way to make this work, even with the stock R32 x-member.

Also, ProjectRB240sx confirmed that only a few of the internals are even swappable.

Forget about this swap, people!

[PROJECTRB240SX]

ACTUALLY IF YOU USE A KA24E TRANS PARTS IN A RB20 CASE EVERYTHING IS FINE. SAME LENGTH AS STOCK RB, STRONGER GEARS, MORE ABUNDANT PARTS, AND THE ONLY MOD YOU HAVE TO DO IS SHAVE THE NOTCH OFF THE FRONT BELLHOUSING. I'VE GOT A HYBRID SITTING HERE WITH ALL BRAND NEW KA INTERNALS ($875 WORTH TO BE EXACT).... DON'T KNOW WHAT TO DO WITH IT SEEING AS I HAVE A SBZ NOW AND NO RB240.

[PROJECTRB240SX]

OHH AND WHERE YOU CAME UP LONG IS YOU NEED TO SWITCH TO THE RB TAIL SHAFT IN ORDER TO USE THE RB TAIL HOUSING.

[accel junky]

^^Email sent to you PROJECTRB240SX

[Jayzeon]

i also have a ka24e sohc transmission and my rb transmission is not going into any gear but reverse. I was thinking of doing the bellhousing swap for my rb20 to the ka24e tailend. I was wondering if you could give me a more detailed discription on what steps to take.