RB26 6-SPD Swap?

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Lev_96_240sx
Posts: 577
Joined: Thu Nov 29, 2007 5:51 pm
Car: 96 240sx

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The RB26 transmission can be made to work. There was a guy on Zilvia that swapped an RB26 with the 6 speed transmission into an E30 BMW. He removed the t-case gears and cut off the extended portion, welded on a steel plate to seal up the hole. Now this guy is a mechanical engineer, if you have that kind of knowhow, you too can have the awd RB26 transmission.

Here is a link to the thread, it's an absolutely amazing build:

http://zilvia.net/f/tech-talk/....html

And here is the how-to:
ctnewman;1227749 wrote:here's today and yesterday's updates. I apologize for typos. More on this later...

Yesterday:

Added another brace to the crossmember. This triangulates the subframe and i am convinced it is now strong enough. My welding leaves much to be desired... I need to work on this much more...

Next, pulled the transmission back out of the car and unbolted the transfer case. I took everything out of it. This is what was left.



Then i went home.

Today:

Went to the shop after work. I taped off the bearings to avoid contamination and bolted the gutted transfer case back together. I then used the horizontal band saw and cut the output case off of the transfer case.





This step went remarkably smoothly. The result:



Next i mounted the transfer case on the milling table I was only able to get 2 mounting points, one of which was a bit "shady" but I hit it with a rubber mallet after i bolted it down, and it didn't budge. The tool in the mill is not the tool i used (i used a 2.5 inch facing tool) I used a level and shims to get the case mounted correctly. The location of the face didn't need to be that precise, so a level was fine:



Next, i made pass after pass on the part, taking off about .100 per pass. About an hour later I had a flat surface, about an inch shorter than the above picture. (sorry, no pic)

At some point during this, the tape over the bearings gave way and a ****-ton of aluminum chips made their way into the front bearing. I will try my best to get them out of there with a parts washer/ air gun, but i may need to suck it up and buy a new bearing. Meh, live and learn, I should have taken it out first, instead of trying to take the easy way out and "cover" it.

Also at some point during this, i somehow managed to crush my hand between the workpiece and the tooling. I had to pick bits of fingernail off the tooling. EW.



Now that the face was complete, i chucked up a drill and drilled (11) #21 holes X .9 deep along the perimeter of the face. Then using a hand tap, i tapped the holes to 10-32 thread. A hand tap was a bad idea, i should have used the mill to guide the tap, as one of the bolts went in slightly crooked, not a big deal, though. It is not terribly off. The hole that looks like it is "falling off" is intentionally placed there, as it was necessary to avoid an internal bolt.



All that was left was too make a cover. Since i had written down the X,Y locations of all the holes i had drilled in the case, it was relatively easy. I used a belt sander and the mill to make the outside perimeter, then after the holes and perimeter were complete, i made a few facing passes on the mating surface of the cover. Due to the fact that the cover was no longer in square, there was a tiinny bit of chatter on the final face, but nothing that wont be sealed with RTV or hondabond.

The finished cover and assembly:







Total time = 6 or 7 hours.Dollar amount saved (vs buying rb25 transmission) = $1500Weight difference = negligable

Now i just need to put it back together. Oh, I also plan on drilling a tapping a few holes on the cut-off portion of the tcase, then using a torque wrench to find out at what torque the threads strip, this will allow me to get a torque value to tighten the hardware to.

I will leave you with this picture:

Modified by Lev_96_240sx at 6:50 AM 2/4/2009


!Zar!
Posts: 254
Joined: Fri Apr 15, 2005 9:22 pm
Car: Countless.

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Kraelic wrote:I want a 6 speed mostly for highway cruising speed, but I want a vq and 350z transmission.
The six speed and the five speed have the SAME final drive.

If you want to change your cruising rpm's, then you need to change your ring and pinion on the diff.

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Hcraig13
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Joined: Mon Mar 03, 2008 5:09 pm
Car: 1992 240sx

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Free Post

I think you should put a mercedes 7 speed in it that would be way more cooler and easier

!Zar!
Posts: 254
Joined: Fri Apr 15, 2005 9:22 pm
Car: Countless.

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Thing that sucks is, in automatic mode it's a seven speed.

Yet the moment you put it into manual mode it only lets you go up to 6th.

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SullivanRacing06
Posts: 1974
Joined: Sat Apr 21, 2007 8:45 am
Car: r32 gtst, 06 350z, r32 gtr, rs4 steaga, 04 350z, f350/6bt
Location: Gainesville

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Kraelic wrote:Full Race R14.. working 2.6 and AWD in a S14... Very expensive, haven't heard of anyone else doing it.

RB20DET transmission uses the same driveshaft as the SR, but I don't know if you can take the rb20 bellhousing and put it on the SR 6speed. I do know neither transmission can hold rb26 power levels or potential.

I want a 6 speed mostly for highway cruising speed, but I want a vq and 350z transmission.
lol, how about no 6 spd rwd s body, sorry, if someone doubts me then go ahead and show me pics opf YOUR car that youve done this in!

i dont want oh my friend did, or i saw it at a car show crap, be realistic here, whos going to cvut a gertrag awd 6spd transmission to convert it to rwd for a s body usdm car! come on! if you swap a 26in your s body do a 25 transmission behind it, im oushing over 600whp on my rb28 using a new 25 transmission w no problems, remember sticky rear tires are the key to traction

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SullivanRacing06
Posts: 1974
Joined: Sat Apr 21, 2007 8:45 am
Car: r32 gtst, 06 350z, r32 gtr, rs4 steaga, 04 350z, f350/6bt
Location: Gainesville

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or stick with the s15 sr20 swap, having a 6 spd isnt gonna make your car worth ne thing more then a rb26 5 spd, sorry to break it you.

!Zar!
Posts: 254
Joined: Fri Apr 15, 2005 9:22 pm
Car: Countless.

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His best bet would be s14sr, or rb25.

Either that or LSx.

Honestly, I think OP just wants to have a 6speed just to have it.

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SullivanRacing06
Posts: 1974
Joined: Sat Apr 21, 2007 8:45 am
Car: r32 gtst, 06 350z, r32 gtr, rs4 steaga, 04 350z, f350/6bt
Location: Gainesville

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!Zar! wrote:His best bet would be s14sr, or rb25.

Either that or LSx.

Honestly, I think OP just wants to have a 6speed just to have it.
lol yea itd be nice to say youve got a six speed, but sorry its only closer gear ratios, not like your gonna have allota extra to end by havin a six speed, make up for that in investing in a super 70 turbo on a sr or rb and youll spank the guys with the fancy weak 6 spds

cody180sx
Posts: 303
Joined: Sun Apr 22, 2007 2:54 pm
Car: s14 rb25det fully built 550whp coming soon

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also 1 less gear to shift to. gears are longer =less shifts= faster times


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