OK, here's my problem. I run 285's daily, and 34" Swampers on the trail. I recently extended my radius arms to accomodate the Swampers without having to trim my rear doors, etc. So now, I plan on moving up to 315's for my daily use.

Now, the problem at hand. 4.10's or 4.75's? I may have a lead on a set of very low mileage 4.75's for a very good price. Or should I stick with 4.10's?

Remember, this is my daily use vehicle, so I don't want to be screaming down the highway at 3K RPM at 60 mph. Whaddya think?

Greg - speed kills.

You know what to do :flipoff2:

What are your trails like?
Do you the experience pucker factor on a regular basis?
Do you use your brakes more than the skinny pedal?

hehe Ok. The trails around here vary alot. Can be anything from flat mud to steep slippery or dry rock, to fallen logs. Yes, I've found myself using my brakes alot to keep my speed slow on the trails.

I know I'm under-geared right now because I'm still running the stock 3.54's. I just don't want to over-gear myself for highway driving. Right now, I'm only turning 2K at 65+. But, it's a slug around town and I'm constantly shifting down into third in traffic.

I've heard about the possibility of the 4.75's not being as strong, but I honestly feel that for my style of driving, that shouldn't be an issue. I just want to avoid putting in something that I'll regret later.

Originally posted by Greg Davis
hehe Ok. The trails around here vary alot. Can be anything from flat mud to steep slippery or dry rock, to fallen logs. Yes, I've found myself using my brakes alot to keep my speed slow on the trails.

I know I'm under-geared right now because I'm still running the stock 3.54's. I just don't want to over-gear myself for highway driving. Right now, I'm only turning 2K at 65+. But, it's a slug around town and I'm constantly shifting down into third in traffic.

I've heard about the possibility of the 4.75's not being as strong, but I honestly feel that for my style of driving, that shouldn't be an issue. I just want to avoid putting in something that I'll regret later.

That is exactly why I haven't put them in. We don't have a lot of mud here, and so far I haven't gotten out of hand using the pinion brake on decents.

I would be interested in your results if you go with 4.75s. I think since you have a stronger motor, if you can put up with the decents, you should leave it alone or go 4.10

j

Originally posted by redrangie


That is exactly why I haven't put them in. We don't have a lot of mud here, and so far I haven't gotten out of hand using the pinion brake on decents.

I would be interested in your results if you go with 4.75s. I think since you have a stronger motor, if you can put up with the decents, you should leave it alone or go 4.10

j

:confused: :confused: :confused:

Originally posted by RockRover


:confused: :confused: :confused:

What's so fawking confusing?

I don't mind using the brakes for descents, and I haven't run out of gearing off road yet.

He has about 60 more ponies than a 3.9. That should help on the freeway.

4.75's will kill his final ratio if you ask me on the freeway. It's all about the engine braking he needs though.

j

Here's what I know now. With 35's and 4.10's my speedo is dead on. So one would assume when taking into consideration my tire size versus a truck with stock gears and tires, that my effective crawl is stock. Thus at 3000 RPM in low range gear 1, my truck travels as fast as a stock truck at 3000 RPM in low range gear 1.

So given that if you want a better crawl go with 4.75's. It won't be that bad on the highway. My truck still runs 80 MPH no problem, as long as it isn't uphill, but that's another story.

Ever since CT went up to 4.1's in his 90 [with 33's and 35's on] he hasn't stopped raving about the difference.....

I guess thats a pretty good recommendation...






But god its boring :flipoff2: :flipoff2: :flipoff2:

I personally whent another way, I have a defender 90 running 36 tires (Swamper Q78-16). I'm not certain what type of truck you have, but if you have an LT-230, there is another option.

I whent with the Maxidrive RC kit, 30% lower low ration, Almost equivalent to 4.75, while doing this change, I also changed the T-case high ratio from 1.22 to 1.41, almost equivalent to 4.10.

So, with stock diff, i have 4.10 on th highway and 4.75 in the trail for around the same price. The change is fairly easy to do yourself if your a bit of a mechanic.

I think it was one of the best changes i've done to the D90.

Im thinking 411 and underdrive. best of both worlds but cost is so much of an issue.

btw.. 97 d1..35x12.50 untested on the trail as of yet, so maybe i am talking out my butt.

I'm liking Ric7D90's idea.

I'm doing a similar thing with the LT-95 that's in the Series One. I already have the lowest low range I can have, but I'm going to put the higher ratio high range gears in it this weekend. Hopefully it'll help top speed and mileage. Where did you get your gearsets Rick?

Rick's gearing choice on his LT-230 is what I'm contemplating now for the CC. I'd like a lower low range and 90mph at 3000rpm's isn't fast enough for me. :flipoff2:

Nobody hold your breath, but someone somewhere will come up with a unit that is an underdrive and an overdrive in the same bolt-in package. It's been in the works for quite a while, but may hit reality here in the next year or so.

Oh yeah, and welcome newbies! :flipoff2: :flipoff2: :flipoff2:

And I another way.

Fitted hirange gears from early auto to my lt230 case.
from stock 1.192-1 to 1.003-1.

this dropped the engine revs heaps.

then I fited 4.3 diffs.

perfect

now just want md low range gears as well
Regards
Michael.

the 4.75s will allow you to use ALL 5 gears in your transmission. Otherwaise, with the 3.54s or the 4.1s, you'll still be using the first 3.

I was astonished that 4th Low with Series 4.7s and 32" rubber was the IDEAL gear for a slippery, long hill-climb, and when I get my 4.75s from GBR in a couple of weeks, and my 36" SX, I'm sure that I'll have a better chance of relieving 1st and 2nd in some cases...

Someone was arguing that that was an important point to consider when in a comp...not sure who it was...

Then again...Greg knows he needs 4.1s...don't ya?
:D

Maxi-drive in Australia put the package together for me, I have to avoid buying in the US because of the exchange rate with canada.

I think the higher ratio gears are stock rovers parts bought from the dealer in Australia, I could have bought those in Canada, but to fit the RC Kit, Maxidrive has to modify the intermediate gear. Some LT-230 are also around with these ratios, but they seem to be hard to find and probably from non V8 vehicule.

Another solution is to go with 4.10 or 4.75 diffs and go the other way with the High range, from 1.22 to 1.0(Or something like that, I know it exists, sorry for the imprecision) You would need to work out the numbers, I havent checked it out. This would be more expensive and give close to the same results.

But if you were to go with 4.10 or 4.75 with th RC Kit and proper high range, you would have incredible low range.

Thanks for the welcome, I've been watching for a while and finally decide to jump in.

I guess I should have stated what vehicle I have. It's a '00 DII. I have a line on the 4.75's for a pretty good deal, and they have less than 1K on them. The overdrive isn't reccommended for the DII for some reason (I hear that alot!), so I don't know if that's even an option for me.

Yeah, the 4.75's with the high range gears from the early 3spd LT230 would be nice.:)

Man, I know what a pig my 5 speed is with 32's and stock ratios, I can only imagine how bad yours is. I wouldn't want to get any where near the continental divide with that thing.

Let's see, you can go 4.11's for about $800 if you do the install/setup yourself. What's the LT230RC kit cost ? $2 grand USD ?? Hmmmmmm, that's easy.

Lot's of people are running 4.11's in Discos - clean and simple.

keith
:usa:

OK. I made an offer on the 4.75's, so if that goes through, I'll need the high range set from the '83/'84 LT230 that was mated to the 3spd auto, right? Where would be my best source for the high range gears? And what should I expect to pay for them?

I've always had this little spreadsheet I use for estimating gear/tire/speed/rpm so he's what the computer tells me.

315/75/16 is about 34.5" tall, I'll use 34" for a more realisic number.

High range is 1.2:1 (is it in the Disco 2?)
Overdrive is 0.77:1

4.11 @ 70 = 2629 rpm
4.11 @ 80 = 3005 rpm

4.75 @ 70 = 3039 rpm
4.75 @ 80 = 3473 rpm

With a 1:1 high range

4.11 @ 70 = 2191 rpm
4.11 @ 80 = 2504 rpm

4.75 @ 70 = 2532 rpm
4.75 @ 80 = 2894 rpm

I run Ashcroft 4.1s and a 1.192 transfer case, on 33's it is fine on the highway - with 35's it is overgeared a little but not dramatic. Speed limit here is 100km (about 60 mph) anyway.
Offroad it could do with further reduction IMHO and the maxidrive crawler gears would be a great combo.

Originally posted by ric7d90
I whent with the Maxidrive RC kit, 30% lower low ration, Almost equivalent to 4.75, while doing this change, I also changed the T-case high ratio from 1.22 to 1.41, almost equivalent to 4.10.



The MD RC kit uses straight cut teeth on the gears. How much noicier are they in real life?

Ask Rich Hills. He has them and likes them, but his wife says they are loud enough to be irritating.

Billster

OK. I made an offer on the 4.75's, so if that goes through, I'll need the high range set from the '83/'84 LT230 that was mated to the 3spd auto, right? Where would be my best source for the high range gears? And what should I expect to pay for them?

You should probably get a new (exchange) case. I almost bought a couple of them used but for various reasons the deals fell through.

The LT230R which has the 1.003 high, has different bearings than the LT230T/Q/SE and I am not sure the gear sets are interchangable because of this.

Ron

Greg,

My 33" TSL's are damn near or larger than a lot of tires considered to be 34's or 35's out there. I have 4.10's in my Disco, the rest of the drive train is stock. I think it works out just fine. Sure it would be nice to have the low range a bit lower, but I can always upgrade later.

Since you are doing the 4.75's right off the bat, you are creating quite the project for yourself to get back on the highway. I think you should go with the 4.10's to see how you like it. Then, play with the other gears later to get a lower low range if you think you need it, which I doubt you will.

Tom

I have changed my disco to 1.4 high range with md crawler gears low range. With 255/85r16 tyres this seems the perfect combo.

There is know noticable gear noise in high range but they do whine in low range a bit, but I have a tdi to drown out the noise.

I have a friend who has the 1.003 high range gears in an LT230T so it is definitely possible, but bits are easy to get in Oz.

John D

So, consensus is straight cut gears only whine noticeably when loaded in low gear? I can live with that.

Mine is a Td5, slightly more refined than the Tdi200, but I wouldn't call it quite, especially not since I pulled the main muffler.

Well, it seems that I may have missed my opportunity on the 4.75's. But you guys have given me alot to think about.

For another questions, what makes all of the different LT230's (R, Q, etc) different from one another. I have a DII, so I think mine's a Q (but I'm not sure). Are they interchangeable? Reason I ask is a friend has a spare 230 that I could build up without taking my rig off the road. But would it bolt in to my DII?

When the whining start to bother you, it's time to switch to high range. ;)

Originally posted by wilsby


The MD RC kit uses straight cut teeth on the gears. How much noicier are they in real life?

I have only recently installed the MD RC kit in my 89 RR. I was initially shocked with the increase in noise, i was worried we had stuffed something up with the install! It does only whine though under load and you do get used to it. Alternatively, pump up the radio or just more right foot so the exhuast drowns it out! :)

As far as off-road performance is concerned, it's awesome. I went from manual to auto at the same time and had to change my low range gearing to compensate for this (engine braking).
Shame my compression is stuffed and it hasn't helped too much yet!
The control with an auto and low gearing is awesome, it drives up obsticles easily which would have been quite difficult with the manual due to clutch control. Every thing can be taken at a much slower speed.
BTW, i have 3.54 r&p and 1.42 in the transfer case. With 33's this is pretty close to stock on road - speedo is spot on!