Maxi Drive 49% low range gear set

[uninformed]

I was at Maxi-drive today. Mal now has these available, a low range gear set giving a 49% reduction over stock. For the lt230 transfer case.

original low range 19/40 tooth count = 2.10:1 \ Low
30% MD low range 20/55 tooth count = 2.75:1 } Gear
49% MD low range 23/72 tooth count = 3.13:1 / Ratio

Defender transfer case 26/41 tooth count = 1.58:1 Primary Reduction


total transfer case = original 3.32:1
30% MD 4.34:1
49% MD 4.94:1

Manufactured from EN39B, case hardend and shot peened. Cost will be approximately $100-$200 more than the 30% MD low range gear set.
cheers, serg

PS i'm just passing this infomation on as a customer and friend of Mal's.Maxi-drive do not have a web site.

[ISUZUROVER]

Interesting... Doesn't look like it fits inside the case though? Does the case need to be modified?

[uninformed]

hey ben, you are correct. a small amount has to be removed. Mal has these in his "Side Winder" he used an angle grinder. "carefully" were his words.
cheers, serg

[landy_man]

yeah... looks like a very tight fit with a lot of the casing needing to be removed...
what would this do to the strength of the casing ??

looks like the walls would be paper thin....

[dirtydisco2]

The gear is 184mm dia. compared to 181mm for the 30%'s so a touch more clearancing is needed. He says that the thinnest part ends up a thumbnail sized area about 3mm thick in the indented area of the t-case.

[Bush65]

I like my 30% reduction gears.

Had to grind some of the internal bosses (where bolts screw in) and a good bit from the selector shaft.

I would say that the gear could not be much larger OD than for the 30% reduction because there is not much more that can be ground from the selector shaft.

EN39B is probably the best available material for high strength gears, but a bitch to machine.

[will_warne]

Ashcroft now do an 80% reduction kit although high range has to be 1.22. There's virtually no work to do to the case either. If you go down this route he'll also sell you 4.11 r&ps for half price!

He's also putting the finishing touchs to a 40% reduction with a 1.41 high range.

[uninformed]

will, i was on there site yesterday and didn't see anything. can you give us more details. ie; materials used, gear design, gear width, tooth count etc.
cheers, serg

[will_warne]

Serg, i can't give tooth count but I can tell you its a complete new gearset, not just low range. They started by looking for the low range they wanted (5.95 ) and working backwards.

Material is the same as DII gears, they're using the Q gear technology to help keep noise in low range down.

I'm not sure if the kits commertailly available yet. The 10 week test period must be just about over now so I don't think it'll be long (ie weeks) before its commertially available. I've driven a truck fitted wit them and it is low!

[ISUZUROVER]

Serg, i can't give tooth count but I can tell you its a complete new gearset, not just low range. They started by looking for the low range they wanted (5.95 ) and working backwards.

Material is the same as DII gears, they're using the Q gear technology to help keep noise in low range down.

I'm not sure if the kits commertailly available yet. The 10 week test period must be just about over now so I don't think it'll be long (ie weeks) before its commertially available. I've driven a truck fitted wit them and it is low!

I don't know how they manage it without a complete re-engineering of the case with relocated shafts. Any info?

[uninformed]

does this mean the gears are helical cut? whats the opinion of you guys(john,bill ,ben sam etc) straight v helical
if they use the 1.2:1 high and an 80% low will there be too much difference between ranges?
cheers, serg

[will_warne]

Isuzu, sorry, I've not got any other details. Dave Ashcroft's been keeping quiet about the exact size of the gears. He's a cleaver guy and it took him quite a while to make it work.

Serg, IIRC, helical gears are quieter and should be stronger. As far as high / low overlap goes: 5th low is about the same as 1st high.

[rick130]

Dave has posted on here a few times, (can't remember his handle)
Maybe Will can encourage him to give us all an insight ?

[HSV Rangie]

ashtrans
I think

Michael.

[landy_man]

perhaps a PM from the moderator is in order nudge nudge HSV...
would be very interested to find more info on this 80% reduction...
I cant see how 5th Low will be equivalent to 1st High... but will wait and see

[rick130]

to put you all out of your misery, I just emailed Dave Ashcroft, and asked him to post any news direct to the forum.

[ashtrans]

Hi,

to clarify a couple of things :

we are busily working away on many new products for the 'Rock Crawling' and 'Challenge' vehicles,

we have 2 new products which will allow lower gearing for the LT 230 transfer case,

we will not be making a 40% lower ratio set,

we will be releasing full details on these 2 new products on 6/6/5 on both our web site and in the LRO Mag July issue,

look forward to discussing any queries on these soon,

[RUFF]

Hi,

to clarify a couple of things :

we are busily working away on many new products for the 'Rock Crawling' and 'Challenge' vehicles,

we have 2 new products which will allow lower gearing for the LT 230 transfer case,

we will not be making a 40% lower ratio set,

we will be releasing full details on these 2 new products on 6/6/5 on both our web site and in the LRO Mag July issue,

look forward to discussing any queries on these soon,

So what about this 80% Lower ratio set??? Im about to by Mals 49% kit and am curious about this 80% Kit?

[RUFF]

Actually at 49% im concerned about the strength of the Output shafts. How do you think they are going to stand up to an 80% reduction?

[GRIMACE]

Actually at 49% im concerned about the strength of the Output shafts. How do you think they are going to stand up to an 80% reduction?

they wont Tony

[ashtrans]

How do you think they are going to stand up to an 80% reduction?

all OK in testing

[ashtrans]

Actually at 49% im concerned about the strength of the Output shafts. How do you think they are going to stand up to an 80% reduction?

they wont Tony

I think you are assuming we are getting this reduction the same way Maxidrive does,

you assume wrong,

[RUFF]

How do you think they are going to stand up to an 80% reduction?

all OK in testing

Its just i have seen a rear output shaft break in a 3.3-1 ratio gear set. This was in a 1400kg buggy. And this is similar to what im looking to fit them into.

Now there may have been other reasons as to why the output shaft broke but it still concerns me a little.

[RUFF]

Actually at 49% im concerned about the strength of the Output shafts. How do you think they are going to stand up to an 80% reduction?

they wont Tony

I think you are assuming we are getting this reduction the same way Maxidrive does,

you assume wrong,

Unless you are getting the reduction after the output shafts then i can see why someone would assume that the Output shafts will not handle it. It doesnt make any difference how you are getting the reduction if its before the output shafts. Its still going to put a lot more stress on the output shafts.

[ashtrans]

Actually at 49% im concerned about the strength of the Output shafts. How do you think they are going to stand up to an 80% reduction?

they wont Tony

I think you are assuming we are getting this reduction the same way Maxidrive does,

you assume wrong,

Unless you are getting the reduction after the output shafts then i can see why someone would assume that the Output shafts will not handle it. It doesnt make any difference how you are getting the reduction if its before the output shafts. Its still going to put a lot more stress on the output shafts.

OK, I understand this theory but in practice it doesn't happen, when we were selling the underdrive, this is a further 2.69 reduction on top of the stock low ratio in the LT 230, some people said this equates to 2.69 more stress on the halfshafts so they will pop immeadiatly, didn't happen, if anything they broke less drivetrain parts as you could crawl with control and no longer needed speed to get momentum.

We rebuild over 1000 LT 230's a year and I don't think I have seen a broken output shaft , not to say it never happens but not a common fault,

[GRIMACE]

sounds very interesting keep us all posted

[wilsby]

Planetary gear reduction in the Ashcroft unit?

Dave, give us a hint...

[Bush65]

does this mean the gears are helical cut? whats the opinion of you guys(john,bill ,ben sam etc) straight v helical
if they use the 1.2:1 high and an 80% low will there be too much difference between ranges?
cheers, serg

For same size, material etc, helical gears are stronger and quieter than spur gears. I would say that Mal has changed other details so as not to compromise the strength with spur gears.

Helical gears produce side forces. For that reason, Mal would probably have to make a complete new intermediate gear (more cost) if he made his reduction gears with helical teeth.

[uninformed]

thanks john now for a simple question why are they quieter and stronger????????
serg

[wilsby]

Quieter because they engage and disengage gradually. Not the noice producing immediate engagement along the full length of a straigth cog. I guess it is the lack of this shockload that helps them survive, too.