Quick engine and gearbox question

Rob · Post by **Rob** » Mon Dec 12, 2005 6:24 pm

I have recently purchased a Subaru 1985 L series Rx conversion

i am getting an engine rebuild and replacing the gear box

Since i am running an Rx engine What gear should i put into the car L series or Rx gear box

I am new this so i dont really know

Cheers

steve_rising_sun · Post by **steve_rising_sun** » Mon Dec 12, 2005 9:16 pm

Carbie box has a better low range
Steve

Rob · Post by **Rob** » Tue Dec 13, 2005 6:17 pm

oh ok cool

i need more info..

BlackMale · Post by **BlackMale** » Tue Dec 13, 2005 6:28 pm

Depend on what you want it for. If it has had a FULL RX conversion the you should have the 3.7 LSD and you will need to use a 3.7 gear box.
The other comon set up is 3.9. The RX box and L box have different size stub axles and drive shaft sizes (i think that its 23 or 25... some1 will post 4 u). Neither box is any stronger then any other if thats the kinda think that you were after.

AndrewT · Post by **AndrewT** » Wed Dec 14, 2005 9:30 am

The gearboxes from the standard MPFI L series also have the larger splines, might be a cheaper option rather than a genuine RX one, and as Jaffa says no weaker or stronger.

LTurbo · Post by **LTurbo** » Wed Dec 14, 2005 11:19 am

Correct Jaffa, Most boxes are 23 spline while the RX box is 25 spline. The actual boxes may be no different in strength, but I think the 25 spline drive shafts are slightly bigger and therefore stronger?

Rob · Post by **Rob** » Wed Dec 14, 2005 5:57 pm

So i should put a Rx 3.7 Gear box in then?

Fang · Post by **Fang** » Wed Dec 14, 2005 6:15 pm

Do MPFI boxes have 25 splines too? Same as RX?

If you want to offroad, the normal 4WD Dual Range box (23 spline) is a goer. The "Lo" on these box is better suited for 4WDing. Make sure you find a 3.7 version of this box if that is what you need.

Otherwise you can just use an RX 3.7 Box (25 spline)