31" tyres on td sj

[d_r_1989]

Thinking about some 31 " kingpin Trekkers for my sj to replace my 235/75/15 insa turbo Saharas.
How much difference will it make to gearing and the wear on bearings etc? I already have 32mm spacers and samurai axles so the wear on components is already increased.

Worth it or not?

[ScottieJ]

31s should be fine with the torque of the derv....as long as they fit.

How much lift do you have?

31s are the perfect size for a lifted sj.

[d_r_1989]

Ok great! It's about 6" of lift at a guess. Spoa with hd springs to compensate for the engine. Also my next question is about transfer boxes. I was led to believe my transfer box was a 410 but it doesn't have a drum brake on, instead the cables go to the back like a conventional car. I'm thinking this is a sammy transfer box? Do I need to change this for the wheels or Infact in general?

[donkeychomp]

My old 413 lost all it's oomph when I put 31" tyres on it. Wish I had a 410 transfer box to put in! Not sure if having a diesel engine will change anything but I would certainly want the 410 box.

[ScottieJ]

It could be a 410 Tcase that has just had the handbrake drum removed.

Only way to tell is to put it in low and count the turns of the input compared to the output. 2.5 input to 1 turn of the output and it's a 410tbox.

[d_r_1989]

It would make sense for it to be a Sammy one as its not very low in low box, hills in 2nd can only be done with abit of a run up.

What effect will the 410 box have on speed as with it being a derv its already at a disadvantage only revving to 4300. It gets used about 60/40 off to on road. Mainly driving to lanes and sites etc.

I do happen to have another sj with what I believe to be 410 running gear so I wipl check and possibly swap it all over.

[twiss]

You would lose a bit of your top end probably, but not a huge amount

[d_r_1989]

My main concern is the revs at about 50mph cos there's not much room for a rad big enough to keep these diesels cool. As it is now I can just potter enough to keep out of the turbo at 50 but any more throttle and it boosts and gets very warm. Might be better now it's abit cooler to be fair though.

[Boyes]

My main concern is the revs at about 50mph cos there's not much room for a rad big enough to keep these diesels cool. As it is now I can just potter enough to keep out of the turbo at 50 but any more throttle and it boosts and gets very warm. Might be better now it's abit cooler to be fair though.

You should be fine, i have the 1.9 Straight diesel in my Sj runs fine on 31's gearing is abit low but I was suprised when I did 50 down the motorway without revving it's nuts off (don't have a rev gauge for the derv)

For cooling i have an electric fan on a switch, that I leave on all the time to help and my temp gauge hardly moved, never had any problems even when off roading (revving it to get up a hill for 10 mins) I run a clio DCI radiator.

How do you find the gear selection in your Sj?

[d_r_1989]

My gearing at the minute feels pretty low but I think thats cos of the diesel engine. Again no rev counter but top speed is 70/75 at the governor. I do like how the gearing is now, will trundle along in 5th at 30 but not up any gradients.

But I do have a bad whine (think its transfer box) and if a 410 box is better overall then I might change to this to accommodate the bigger wheels, at the minute im on 29"