gearing for RRC Auto

[ukmudmaster]

Been offered some 33"x12, 1/2"x 15" Khumo tyres for my RRC 3.9 Auto. I know I will have to something with the gearing, but what?
Does a Defender transfer fit onto a ZF 4 speed?
Any ideas welcome,
Thanks,
Dave

[paulmmc]

I ran 33x12.5x15 on a standard series 3 for abour 3 years with no problems at all, cruised faster and lost some acceleration but nothing to worry about, still regularly did some hard stuff off road. My main concern was damaging the half-shafts but never became a problem.
Obviously the turning circle becomes even worse and needed to modify the wheel arches, personally i wouln't have thought a 3.9 V8 would notice the difference drive-wise.

[dod51e]

I run 255 85 16's (about 33") with no problem on a 3.9 RRC.  As stated the turning cicle suffers abit (not that it was great in the first place!!).  Slight reduction in acceleration but nothing to worry about..... 2" lift sorts most clearance issues.

[Bowie]

Gearing and autobox changes will be all to pot tbh, making it very unpleasant to drive on the road. Changing the transfer box to a defender 1.4 item restores it to about stock gearing, and it drives SOOOOO much better again -I have not long ago done this swap and it transformed the vehicle.

Low range is unaffected of course, but a set of lower ratio ring and pinions would sort this out, and you wouldn't need to change transfer box of course ;)

[hairyasswelder]

Gearing and autobox changes will be all to pot tbh, making it very unpleasant to drive on the road. Changing the transfer box to a defender 1.4 item restores it to about stock gearing, and it drives SOOOOO much better again -I have not long ago done this swap and it transformed the vehicle.

Low range is unaffected of course, but a set of lower ratio ring and pinions would sort this out, and you wouldn't need to change transfer box of course ;)

Mine is similar with 265 insa turbo's (33") and loses all power up hills at cruising speed, just below 60.  I have a defender t-box with a broken centre diff.  would it be possible to build a hybrid t-box.

Mine is a V8 3.5 ZF auto with manual diff lock, lt230??

[Range Rover Blues]

Steve, i don't think you can atke the guts out of a Borg-Warner to rebuild a LT230, but other than the gears all LT230s are the same.

Mudmaster, yes the LT230 and Borg-Warner are interchangeable

[ukmudmaster]

Thanks RRB, the tyres I went after were too much money in the end, so will stay with 235/85/16s.
Got to spend some dosh now on the diffs so tyres go to the back of the list,
Thanks anyway
Dave

[hairyasswelder]

Steve, i don't think you can atke the guts out of a Borg-Warner to rebuild a LT230, but other than the gears all LT230s are the same.

Dont think I got the borg warner viscous t-box, never really looked  :lol: its a 3.5 with the manual diff lock so just assumed it was an LT230  :oops: looks like I'd best have a better look  :-o

Stripped the defender t-box and it has broke the two shafts for the planetary gears in the centre diff.  might repair it if I get the time  ;)

Mudmaster... sorry to hijack your thread but it is the same topic  :oops:

[Bowie]

Thanks RRB, the tyres I went after were too much money in the end, so will stay with 235/85/16s.
Got to spend some dosh now on the diffs so tyres go to the back of the list,
Thanks anyway
Dave

If you are spending money on diffs, think about swapping to lower ratio ring/pinion at the same time, for future tyre size upgrades :)

[Range Rover Blues]

Dont think I got the borg warner viscous t-box, never really looked  :lol: its a 3.5 with the manual diff lock so just assumed it was an LT230  :oops: looks like I'd best have a better look  :-o

Sorry Steve, I just assumed yours was the same as mine.  If it's got manual diff lock it's an LT230 then and you can canibalise it to rebuild the Deafener box.