Thread: D2 Final Drive Ratios Dilemma

Fyi: No D2s came out with a DPF, EU3s had a catalytic converter.

Get a remap and change the exhaust. Air filter won't make any / much difference. Search for an old Tombie post on getting more out of your TD5. Flashable ECU is most probably better as it can be remapped easier. TD5alive seems to be the go now; although other ecu nap providers are around.

Put an auto in it, more torque at take off and stall speed allows the Turbo to spool up quicker, no brainer, Regards Frank.

Originally Posted by kitto

Hello all.

Long time reader here, but my first actual post for help. Been a member for almost a year now and owned my D2 for the same time.

I'm very cluey and good with cars so i've been able to find out all the info i need for the most part by searching.

However, i have a final drive ratios dilemma...

Vehicle is used for towing (2.5T) and for 4x4 use. I'll feed as much info as i can.

Current vehicle status;

245/70/16s Fitted when normally driving and towing. 285/75/16s fitted when 4x4ing.
Manual TD5 D2a
EGR Blanked
DPF cat removed, factory exhaust
NOT tuned (to my knowledge) - NNN re mappable ECU
3" rear lift
2" front lift
Snorkel

Future modifications to improve response and power:

Better air filter
Centre muffler delete
Remap
If at absolute necessary, VNT turbo upgrade

I find driving the vehicle normally is fine, quite gutsy once on boost but an absolute pig off boost in first or second gear. I find that in 5th @ 110kmh the engine is revving just too high and out of the peak torque range @ around 2,700RPM. Now with a remap, there will be more power and torque available down lower hence me wanting the engine to rev less at 110.

When towing i find that 1st gear is just a pain to get the thing off the line until its on boost. Hill start's are challenging to say the least and the clutch cops it. I have tried the start in low range and then shift into high range on the fly. But no matter how i try and nicely change from low range to high range whilst moving, the TC feels like its about to drop all of its cogs - no synromesh. Diagram says its ok to change from L to H range under 8kmh. It may just be that my TC is almost very dead and does require replacement, but personally i'd prefer not to change the TC ratios on the fly.

So, this leaves me wanting effectively a shorter first gear for towing and in fact 4x4ing with 33" mud tyres. The TD5 R380 already has a 3.692:1 first gear ratio which is a little higher than the V8 R380, no other options available to replace first gear with a higher ratio unit.

So to effectively change first gear ratio to be shorter, i'd be wanting to change High range ratio in the TC to a defender 1.413:1. However that effects all gears in H range and i actually want the engine revving less, especially in 4th and 5th at 110. Same thing goes for diff ratios, which i'm honestly trying to avoid.

I am almost to the point of having to replace the R380 and the TC as they are both on their last legs with 270,000kms on them. The gearbox synchros are badly worn, 5th gear howls (the lovely 5th gear support bearing failure) and the transfer case has more oil on the outside than on the inside thanks to the lovely intermediate shaft leak. I'm currently planning on a replacing both with Ashcroft items, with the R380 having the upgraded 5th bearing support and also the longer V8 R380 5th gear installed. This will drop the rev's slightly in 5th at 110.

Under / Over drives. I've found that Under or Over drive units can be fitted to the LT230, but is there a manufacturer that does a unit that is a combination of both Under drive and Over drive?

When towing, i try very hard to avoid 5th, but do find myself using it at 110 when on very flat road, when i approach an incline, i change back to 4th. If i could find an overdrive unit, i could simply stay in fourth and flick between the direct drive in the OD unit, or going into OD when on the flat to avoid using 5th gear at all.

Sorry this has rambled on ridiculously long... I was trying to keep it short.

I guess my question is, what have some of you done with your gearing, Honestly i'd prefer to set the gearing up so that with normal tyres are on, its comfortable to come off the line with a big load, but also have the engine working at a reasonable speed at 100 - 110kmh.

Your input is appreciated - or maybe i've opened a debate?

Cheers, Dan.

Stick a MXA 5R Isuzu gearbox in 4.987- 1 first 5th at 0.728 1.003 TC gears .Gives a low first for hill starts a 5th gear you can tow with and low cruising revs and when you see the light you have the conversion half done

AM

Originally Posted by Tank

Put an auto in it, more torque at take off and stall speed allows the Turbo to spool up quicker, no brainer, Regards Frank.

God no.

Thanks for the replies.

Well it seems that doing an exhaust upgrade and then a remap is the way to go before changing ratios etc. Hmm

Maybe defender transfer gears but you will lose any top end speed

If you want to get a new turbo I suggest you read this thread.

http://www.aulro.com/afvb/verandah/2...o-release.html

I am going to order one of these plus the remap. If you just want to do a remap, TD5 inside are probably as good as any.

Jose really knows the Td5.

How heavy is the vehicle? Also don't forget the td5 is only 2.5litres and yes first gear ratio coupled with the 1.22 high range is too high for hill starting with a bit of weight attached imo. You are trying to move at lwast 5 tons when you are towing if you have the 2.5t hanging off tge back...When you say 110 at 2700 that sounds a little high. Should be around 2450 or so. (2250 @ 100).

Jc