RB20/25 RWD Transmission Q's - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Not You · 10-21-2010, 11:20 AM

I need to know the differences between the two as far as gearset length and shifter placement. I planned to use an RB20 mission on my SR for the simple fact that the gearset is shorter then the SR and puts the shifter forward more by about 3''. However I am having trouble finding one locally and all that keeps poping up are 25 missions. So basically, what are the differences between the two gearsets. Length, gearing, etc. And if anyone could take a side by side picture of both you might have laying in your garage that would be AWESOME. Thanks

Not You · 10-21-2010, 07:31 PM

So I've gotten a couple of people saying that the 25 missions are longer and have different splined output shafts. Can anyone verify this please?

Sileighty_85 · 10-21-2010, 07:37 PM

RB20/KA/SR trannys are basically the same, front Bell housings can be swapped
RB25/VG tranny internals are similar front bellhousings can be swapped but rear section is different so shifter and Driveshaft need to be custom or modified.

RB25 tranny output shaft is bigger than the KA/SR and RB20

Not You · 10-21-2010, 08:02 PM

Hmm, so your saying 25 missions have longer input shafts then 20? What all is needed to swap bells on a 20 missions to use on an SR, just some elbow grease and RTV? The only reason I want this RB20 mission is because of the fact that the gearset is shorter then KA/25/SR

Sileighty_85 · 10-21-2010, 08:10 PM

RB25 Tranny is bigger ans beefier.

you want a shorter Gear ratio or a shorter transmission.

IIRC the RB20 is the same length as the KA/SR.

Not You · 10-21-2010, 08:29 PM

Shorter transmission. Im going SR86 and would rather not cut shit.
RB20 mission

SR mission.

Sileighty_85 · 10-21-2010, 08:36 PM

interesting, I too will be doing a SR86 after i finish my S14,

I really dont think the RB20 tranny is shorter but i could be wrong

I plan on going a different rout by making a custom shifter hopfully enough room to move it back to the stock location

Not You · 10-21-2010, 08:45 PM

If you mean cutting the shifter and doing something like this.

You will still need to cut a hole. All doing this does is help with clearance with the shifter and e-brake.
Stock shifter hole

Cut for SR mission

Not You · 10-21-2010, 08:57 PM

Also the transmissions out of D21 pickups/Pathfinders (FS5R30) are shorter by roughly 6" and can be adapter to SR bell. So that's my second option.

Sileighty_85 · 10-21-2010, 09:01 PM

Something like that shifter but more aggressive

Mines already prepped for the SR,

10-21-2010, 11:20 AM	#1
Not You Leaky Injector Join Date: Sep 2009 Location: FailIDA Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	RB20/25 RWD Transmission Q's I need to know the differences between the two as far as gearset length and shifter placement. I planned to use an RB20 mission on my SR for the simple fact that the gearset is shorter then the SR and puts the shifter forward more by about 3''. However I am having trouble finding one locally and all that keeps poping up are 25 missions. So basically, what are the differences between the two gearsets. Length, gearing, etc. And if anyone could take a side by side picture of both you might have laying in your garage that would be AWESOME. Thanks

10-21-2010, 07:37 PM	#3
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	RB20/KA/SR trannys are basically the same, front Bell housings can be swapped RB25/VG tranny internals are similar front bellhousings can be swapped but rear section is different so shifter and Driveshaft need to be custom or modified. RB25 tranny output shaft is bigger than the KA/SR and RB20 __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

10-21-2010, 08:10 PM	#5
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	RB25 Tranny is bigger ans beefier. you want a shorter Gear ratio or a shorter transmission. IIRC the RB20 is the same length as the KA/SR. __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

10-21-2010, 08:36 PM	#7
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	interesting, I too will be doing a SR86 after i finish my S14, I really dont think the RB20 tranny is shorter but i could be wrong I plan on going a different rout by making a custom shifter hopfully enough room to move it back to the stock location __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

10-21-2010, 09:01 PM	#10
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	Something like that shifter but more aggressive Mines already prepped for the SR, __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

10-21-2010, 07:31 PM	#2
Not You Leaky Injector Join Date: Sep 2009 Location: FailIDA Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	So I've gotten a couple of people saying that the 25 missions are longer and have different splined output shafts. Can anyone verify this please?

10-21-2010, 08:02 PM	#4
Not You Leaky Injector Join Date: Sep 2009 Location: FailIDA Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	Hmm, so your saying 25 missions have longer input shafts then 20? What all is needed to swap bells on a 20 missions to use on an SR, just some elbow grease and RTV? The only reason I want this RB20 mission is because of the fact that the gearset is shorter then KA/25/SR

10-21-2010, 08:29 PM	#6
Not You Leaky Injector Join Date: Sep 2009 Location: FailIDA Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	Shorter transmission. Im going SR86 and would rather not cut shit. RB20 mission SR mission.

10-21-2010, 08:45 PM	#8
Not You Leaky Injector Join Date: Sep 2009 Location: FailIDA Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	If you mean cutting the shifter and doing something like this. You will still need to cut a hole. All doing this does is help with clearance with the shifter and e-brake. Stock shifter hole Cut for SR mission

10-21-2010, 08:57 PM	#9
Not You Leaky Injector Join Date: Sep 2009 Location: FailIDA Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	Also the transmissions out of D21 pickups/Pathfinders (FS5R30) are shorter by roughly 6" and can be adapter to SR bell. So that's my second option.