q's about tj boxs

[silver6pac]

hi guys just got a few questions, im currently installing some 4.10 diff gears into my tj and it is a 6 speed manual but later down the track im looking at installing a auto box for some crawling. now if i installed a tj auto box what size rubber to make it correct ratios with the 4.10s? or am i better off out sourcing another box like a commodore box or something similar? any help would be good, cheers

[fil]

You have a few choices, you could use a tj 3speed auto, these have no overdrive though, which will increase your rpm at highway speeds. You could use the tj 4 SPF from the '03 on models, it is overdrive, but it is controlled by the PCM, so I'm not sure what you will run into there. And you could use the AW4 from and xj, also overdrive and electronically controlled, but use a TCU separate to the PCM. I have done a couple manual to auto conversions and a 3rd to 4spd auto conversion using the xj trans, easy enough to do. If you search the JP magazine archive, they have done the T700 (commodore trans) conversion before. I have priced it up, albeit a while ago from the Australian supplier and came to 2k almost, for adaptors and such, then you need to find a trans for the swap, not to mention drive shaft mods and shifter, cross member, oil cooler ect,ect. Easiest would be the 3 speed, but can you live with no overdrive?....

[silver6pac]

You have a few choices, you could use a tj 3speed auto, these have no overdrive though, which will increase your rpm at highway speeds. You could use the tj 4 SPF from the '03 on models, it is overdrive, but it is controlled by the PCM, so I'm not sure what you will run into there. And you could use the AW4 from and xj, also overdrive and electronically controlled, but use a TCU separate to the PCM. I have done a couple manual to auto conversions and a 3rd to 4spd auto conversion using the xj trans, easy enough to do. If you search the JP magazine archive, they have done the T700 (commodore trans) conversion before. I have priced it up, albeit a while ago from the Australian supplier and came to 2k almost, for adaptors and such, then you need to find a trans for the swap, not to mention drive shaft mods and shifter, cross member, oil cooler ect,ect. Easiest would be the 3 speed, but can you live with no overdrive?....

cheers for that, im not too worried for overdrive as the tj is only used to go off road as i have business cars and the missus car so its just to play with. if i went the 3 or 4 speed what size diff gears did they come with factory? as i have 4.10s in and im looking to see what size rubber i could use with this combo?

[wes]

Early autos (3 speed) have 3.07 diffs. Later autos (4 speed) are 3.73.

3 speed with 4.10 and 33" tyres is a good combo.

[silver6pac]

Early autos (3 speed) have 3.07 diffs. Later autos (4 speed) are 3.73.

3 speed with 4.10 and 33" tyres is a good combo.

awesome, i was hoping that was going to be the answer. how strong are the 3 speeds?

[silver6pac]

if i go the 3 speed box am i able to use the tj spedd cable or will i have to use the other one?