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View Full Version : SR20 Blacktop to RB20 gearbox?



deegee
22nd December 2010, 01:36 PM
First post!

Hey guys, sorry ive tried to search as best as I can - on here, nissansilvia and googled the hell outta it.

Currently starting a AE86 SR20 build and am about to source the engine. I have just read up on mating a SR20 with an RB20 box to almost keep factory holes in the floor but came across a comment in my searches that this cannot be done with a blacktop?

As i know people swap their blacktop 6 speeds for a S13/14 5 speeds I couldn't see why not?

I was hoping someone in the know could shed some light on this for me?

Any help greatly appreciated,
DeeG

matt99
22nd December 2010, 02:07 PM
I dont see why the blacktop would be any different.

But yes, SR20, with SR Bellhousing on a RB20/30 box will put the shifter almost smack band where the stock shifter goes.

I just used all SR20 items and moved the hole back a bit, doesnt feel to bad, it just involved a bit of cutting obviously.

Skylar
22nd December 2010, 03:50 PM
Yeah man, same same.

The blocks are different between S13 and S14 (not sure if S13 blacktop is S14 block or not) but it's dumb shit like the upper left oil pump/timing cover bolt is about 15mm further out on S14 and the water pump has an extra hole for water pump, or maybe just moved around.

deegee
22nd December 2010, 04:41 PM
I think i might actually have answered this myself just now...

As the process is using the SR bell housing and bolting that to the RB20 gearbox...

Can anyone confirm that with the 6spd that when separating the bell housing from the 6spd gearbox this bell housing will mate with the RB20 box as i think thats where the issue may be...

sundee
22nd December 2010, 05:45 PM
dont quote me, might want to do some research, but i was under the impression that the Rb20 box was similiar strenght to the SR box.
thats why most guys go Rb25 or VQ30 box's

Skylar
22nd December 2010, 08:24 PM
Yeah, same gearset. Kouki S14 is the best of the W71C's due to the gate centre section but it's more oil control than gear strength. The good thing about RB20DE/DET/25DE gearbox is that the output shaft is shorter than on CA/SR trans. so it brings the shifter forward by 5cm. oh and a R34 20DE/25DE is newer than S13/14 gearboxes so better chance of getting a good nick one.

and it's VG30(Z32) gearbox not VQ30(don't think VQ30 came manual). Z31 VG30 trans. is W71C.

deegee
22nd December 2010, 08:42 PM
dont quote me, might want to do some research, but i was under the impression that the Rb20 box was similiar strenght to the SR box.
thats why most guys go Rb25 or VQ30 box's

As far as I can find this is true.

But i'm doing this for shifter location, not strength. The RB box will be plenty strong enough... Only be around 200kw mark...

Skylar
23rd December 2010, 02:51 AM
Woah, totally missed your post deegee. Yeah, your issue is in using the wrong front housing. S15/mx5/is200 6 speeds are aisin units bolted onto different engines with different bellhousings and are nothing like the Nissan W71C series. You need a S13/14 front housing.

Not that I know a lot about them but isn't the problem the 6 speed one little circlip?

sundee
23rd December 2010, 09:34 AM
Yeah VG30, my bad... some guy does a kit to use the VG30 box, looks neat to.

H8CHIR6KU
23rd December 2010, 10:52 PM
yeah man you need s13/14 sr20 bellhousing.
s15 6 speed is different box altogether.
then its just a matter of split and fit.

and yeah the shifter does sit forward abit. i found it to be alot better especially when using the standard handbrake.

deegee
24th December 2010, 03:00 PM
No worries,

Thanks guys appreciated!

No point in getting a front cut for me then :)

Just have to find the body which is proving difficult, wish me luck ha!

DeeG