Orgasmic Farmer Posted September 14, 2006 Share Posted September 14, 2006 Right, second weekend running my mate has blown his rear diff in the 90 due to running 35" tyres. He now has an ARB to install so hopefully this will now stop BUT the last time it blew all we had to hand for repairs was an old series front axle. KNowing them to be "rover" type diffs we stripped it out and managed to rebuild the broken 90 diff using the pin out of the series diff and the undamaged planetary gears from the diff broken the week earlier. So now to the point of my ramble. While the diffs were apart we got to thinking about ratios. The 90 diff has a 3.54 ratio and the series one is 4.7. Normally when fitting 35" tyres you can get 4.11 R&Ps from Ashcrofts or the like to get back to "normal gearing". Looking at Ashcrofts site they also sell these 4.7 spacer rings So am I right in thinking that for £36 we can use the 4.7 R&Ps from a pair of series diffs on the 90 carriers (or ARB) to give a much lower set of gear ratios over standard, even considering 35" tyres. I appriciate that high ratio would be lower too (though a disco transfer box could cure this?) but thats not important in what is essentially a pure offroad truck. Someone tell me it really is that simple. Or am I missing something here (just wondering why this isn't common practice) Quote Link to comment Share on other sites More sharing options...
LR90 Posted September 14, 2006 Share Posted September 14, 2006 Yes, quite correct, but if you get past the first punch you'll be lucky. Believe me I tried it. I'm now running a KAM 4.75 with the ARB and if I thought I could save my pennies and keep using 4.7s I would have Quote Link to comment Share on other sites More sharing options...
SeriousIIa Posted September 14, 2006 Share Posted September 14, 2006 4.7 series diff's are soft like applepie, I've got lots off them lying around to prove it. You'll strip the ring gear in no time...... Cheers bowy Quote Link to comment Share on other sites More sharing options...
Orgasmic Farmer Posted September 14, 2006 Author Share Posted September 14, 2006 i see a pattern forming.... did wonder why the practice was not more widespread. Ah well, back to the drawing board. M Quote Link to comment Share on other sites More sharing options...
Steve 90 Posted September 14, 2006 Share Posted September 14, 2006 Well mine are at ascroft now for 4.1's, Kris should have thrown his diffs on the pallet with mine and had a pair of C&P's and lockers fitted. We could have split the postage! Quote Link to comment Share on other sites More sharing options...
will_warne Posted September 15, 2006 Share Posted September 15, 2006 Standard series diffs are made of Chocolate that's been left in the sun too long. I've been there done that and managed to strip the teeth on open diffs using 33" tyres with 50 bhp. My advice is stay away from that ratio on Rover axles; if you want to go that low go for Salisburys. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted September 15, 2006 Share Posted September 15, 2006 Land Rover seemed to get around the problem of weak diffs on Series vehicles by fitting halfshafts that were weaker. I once saw a rear halfshaft snap on a S3 SWB 2.25 diesel when it drove over a kerb Quote Link to comment Share on other sites More sharing options...
Guest diesel_jim Posted September 15, 2006 Share Posted September 15, 2006 Land Rover seemed to get around the problem of weak diffs on Series vehicles by fitting halfshafts that were weaker. I once saw a rear halfshaft snap on a S3 SWB 2.25 diesel when it drove over a kerb i'm not amazed that the shaft broke driving over the kerb, i'm amazed that the 2.25 diesel had enough power to get it over said kerb!! Quote Link to comment Share on other sites More sharing options...
BogMonster Posted September 15, 2006 Share Posted September 15, 2006 It was going down over the kerb Jim Quote Link to comment Share on other sites More sharing options...
will_warne Posted September 15, 2006 Share Posted September 15, 2006 Actually I reckon front shafts are better than most coiler ones given how well Tonk's shafts stand up. Rears are toffee, though. Quote Link to comment Share on other sites More sharing options...
jules Posted September 15, 2006 Share Posted September 15, 2006 i'm not amazed that the shaft broke driving over the kerb, i'm amazed that the 2.25 diesel had enough power to get it over said kerb!! We run 4.75 kam with no trouble on a 4.2 V8 auto 90 perfect gearing on 35" the 90 would still cruse at 80 mph could do with ease 90mph but a little scary due to simex... I have twisted the shafts but that was due to showing of with the tect Dirctor of LR Aus in the truck doing donuts at brickyln farm.. B) The truck is under going a minor face lift after a minor off in Feb...you may have seen the video.. Quote Link to comment Share on other sites More sharing options...
TomG Posted September 15, 2006 Share Posted September 15, 2006 Jules, Am considering going to 4.75 diffs myself, what ratio of transfer box are you running? Quote Link to comment Share on other sites More sharing options...
Adrian Turner Posted September 15, 2006 Share Posted September 15, 2006 i see a pattern forming....did wonder why the practice was not more widespread. Ah well, back to the drawing board. M Blew front/back together in less than an hour They work fine in my class 1 running 7.50 dumper's but it weigh's the same as a bar of chocolate Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted September 16, 2006 Share Posted September 16, 2006 Ran four pinion converted 4.7's in my old hybrid never damaged one. Killed three LT95 Boxes when the Supercharged 4.6 was in there. Never broke a half shaft either. The four pinion units were built up from LR parts by Martin Lewis. I ran 35x12.50x16 BFG MT's and the vehicle weighed in at over three tonnes. Most breakage is down to driving style, fact, accept it or ignore it. Quote Link to comment Share on other sites More sharing options...
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