DAN82SED Posted September 24, 2011 Share Posted September 24, 2011 alright guys, since fitting 33" tyres to my disco is suffering with bad acceleration. Does anyone know if changing the diffs for defender 90 would help sort out the gearing. (if they fit?) i was hoping i could do it on the cheap buy buying second hand from ebay rather than new ones from Ascrofts Any advice would be helpful, ratios etc Cheers Dan Quote Link to comment Share on other sites More sharing options...
19MART82 Posted September 24, 2011 Share Posted September 24, 2011 the defender diffs are the same ratio as disco's its only the transfer box that are different ratio's,ashcroft do different ratio ring and pinions but there not cheap,a lot of people fit disco transfer boxes in there defenders to increase speed/mpg so dont think it would be worth fitting a defender one in your disco,if yours is a tdi try turning the fuel pump up slightly as this worked wonders on my 90 when i fitted 33" tyres,it gave it a lot more pull through the gears Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 24, 2011 Author Share Posted September 24, 2011 cheers 19mart82, it is a 300tdi already turned the fuel pump up (to the point it chucks out black smoke under load) also fitted an allisport uprated intercooler but still feels like it wants to stall when pull away from stationary. i had a 110 with the same setup and its acceleration/ power was really good any idea what ratio diffs i would need to have a happy medium between acceleration and motorway speeds? cheers Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted September 24, 2011 Share Posted September 24, 2011 If you think your Disco is bad Try 37 inch tyres Disco transfer box and towing an loaded up Arrows trailer. Not fun! I now have my gearing now sorted because low range was carp decending any half decent decents. 1.003:1 transfer box and 4.7 diffs. A Disco with 33's should be about right to be honest. Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 24, 2011 Author Share Posted September 24, 2011 cheers jai, think im going to try flushing my intercooler to see if that makes it any better. Its amazing how much difference there is between disco and defender Quote Link to comment Share on other sites More sharing options...
19MART82 Posted September 24, 2011 Share Posted September 24, 2011 cheers 19mart82, it is a 300tdi already turned the fuel pump up (to the point it chucks out black smoke under load) also fitted an allisport uprated intercooler but still feels like it wants to stall when pull away from stationary. i had a 110 with the same setup and its acceleration/ power was really good any idea what ratio diffs i would need to have a happy medium between acceleration and motorway speeds? cheers im not very mathamatical with anything like that but ashcrofts got a very handy ratio calculator which will help http://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html Quote Link to comment Share on other sites More sharing options...
scatt Posted September 24, 2011 Share Posted September 24, 2011 Swop the transfer box for a defender 1.4 ratio! It will be sound. I Run 35's on a disco with no problems. Transfer box made a big difference!! Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 24, 2011 Author Share Posted September 24, 2011 cheers scat, sounds good. gonna check out prices on tinternet for good used box Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 24, 2011 Author Share Posted September 24, 2011 scatt, what sort of motorway speed can it cruise at? Quote Link to comment Share on other sites More sharing options...
inaine Posted September 24, 2011 Share Posted September 24, 2011 1.4 defender transfer box will sort it Quote Link to comment Share on other sites More sharing options...
Off Road Toad Posted September 24, 2011 Share Posted September 24, 2011 Definately put a defender 1.4 transfer box on it, A disco on 33's with it's original 1.2 t/box will be absolutely hideous! Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted September 24, 2011 Share Posted September 24, 2011 My Brother runs his Disco on 235 85 R16 BFG All terrains about 32 inch measured dia (we all know how they differ from advertised 33's actually 31's and 35' are 33's etc) He runs a a 1.208 (I think) Borg Warner Transfer box and I must say the gearing is spot on having deiven it and other disco's and my 90 its great cruises at 65 all day long quite quiet nice. I would measure you actual tyre diameter before swapping and if you still think its sluggish then swop the box. Me I'd never go back. I have run through the minefield of gear ratios. A brief history below. Changed parts bit by bit depending on what parts came up at the right price to work towards final ideal ratio because of available cash buying a house etc so no real spare cash to buy what I needed. Firstly I had tal 750's with a 2.5na, very revy, Rover rear axle, Tall 750's with a 200tdi 1.4 very revy, Rover Rear axle Tall 750's with a disco 1.22 tranny box about right, Salisbury ~Cheap strength. 37 inch with a disco 1.22 tranny box well overgeared especially low range, Salisbury axle cheap strength, Decending Chaplegate low range was far too fast to be nice. I needed a lower low ratio I opted for 4.7 diffs to cure this being available cheap and having stuff kicking about helped no end aswell as an ebay purchase 2 axles for £1 salisbury rear Genuine 4.7:1 and front axle complete. 4.7 diffs Salisbury rear 1.22 tranny box far too revvy again When I put on the 33 inch tyres for a couple of local trialling comps 5 mile away I was sitting at 40mph because it was reving so hard and sounded horrendus above 45mph. Low range was great takes a bit of getting used to tho using 3rd gear to do some serious hill climbs! Now I managed to get a RR 3spd auto box and transfer box 1:003:1 at a reasonable price £50 but it was in Cornwall so Friday after work I take the mrs down to a travel lodge rock up at midnight and get up at 5.30 to hoof the box in the back of the car. The end result is lovley the gearing is spot on. my 90 is mainly std no sound proofing or much else and its not horrendus its not too bad at 75mph. Likewise 1st gear is fine for towing the sankey full of rubble. I'm quite happy with the end result. The only advice I can offer you is get it how you like it there is no correct ratio its whatever you feel is best and returns th efuel economy that you are happy with and expect. Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 25, 2011 Author Share Posted September 25, 2011 cheers jai, great info. fitting big tyres appears to open a big can of worms. glad i should be able to sort it without messing around with diff diff ratios Quote Link to comment Share on other sites More sharing options...
disco_al Posted September 26, 2011 Share Posted September 26, 2011 but still feels like it wants to stall when pull away from stationary sounds like you need to adujst the spring preload, and the stop screw. try http://www.legionlandrover.com/index.php?sec=31&id=12&tipo=Todos%20los%20modelos about 13 up from the bottom for the proper tuning details i retuned the pump on my old one, following the proper bosch tuning instructions, and it made a hell of a difference to the acceleration. that was with a full width intercooler, and 235/85 tyres, running standard boost. you can of course alter the boost slightly on a 300tdi, but it's advisable to have an EGT fitted. Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 26, 2011 Author Share Posted September 26, 2011 cheers Disco, just finished reading your link. A+ Bit of information overload but i think i understood. Might have to read it a couple more times before tacking it. The prevoius owner had it tuned and has some sort of a valve fitted to the side of the intake manifold, any ideas what its for (im guessing boost) sorry for bad picks but its a bit dark outside cheers, Dan Quote Link to comment Share on other sites More sharing options...
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