Page 3 of 8

Re: low range gears

Posted: 19 Sep 2017 22:10
by Mystical_Beast
40 % of my business is the manufacture of gears for various industries.
The biggest obstacle to manufacturing the reduction box gear sets would be batch quantity.

Again one would want an agreement on a specific reduction percentage that would suit everybody, in the hope to obtain some economies of scale.

Further, its not a matter of just cutting the gears, as the tooth profile would have to be ground to eliminate backlash and to ensure silent operation as well as longevity.
There would be a couple of processes involved before final product, starting with correct material selection as well as specific heat treatment process.

Ideally I would want to do a spectrograph analysis of the material used to establish if an equivalent alloy is readily available.
My suspicion is that is would be superior to OEM transfer box gears due to higher torque loading.

Finally, the best possible route would be to have the complete set and reverse engineer it, a fancy term for copying.

Further, having looked at the assembly, I would be able to offer the rebuild of the transfer case including the relevant machining required for a professional conversion.

In looking at what is involved I guestimate around R 15 to R 20000.00 excluding the building of the box.
The building/assembly and testing of the box including machining of the casing would probably add another R 5000.00
Any incorrect meshing of the gears will result in premature failure.

My gut feel would be around 10 units to make it around pricing indicated.
5 units would probably push the pricing up to around R 25000.00
If someone is able to lay their hands on a set of the actual reduction gears I would be able to do a proper analysis and costing.

The above however is probably pretty close to upper range as to what it would end up being.
Timing would be around 6 weeks to manufacture, however would suggest a proto-type is made first for testing.

If one were to make 20 to 30 sets the pricing would probably halve.
Marks 4wd would specifically cost their products at a point which discourages one from going down the line of manufacturing your own, whilst still making a reasonable profit. Our exchange rate however provides a bit of room to look at it.

In all honesty though one would need at least five sets to make it worth while to investigate.

Re: low range gears

Posted: 19 Sep 2017 22:55
by hugejp


Re: low range gears

Posted: 20 Sep 2017 00:19
by davidvdm
How much space is in that box for gear changes. I ask this as the Hardbody crawler gear kit for the TX10 TC, includes instructions to grind part of the inside of the casing away, to make space for the larger gearset to fit in the box. Or has this already been tested by the likes of Marks?

I ran some figures and get a fairly nice crawl speed of 28 meters per minute on 35s at a TC low range of 4.2 with diff ration of 4.88. The downside of course, is that you are now stuck with only that low range ratio, although you can get back to your normal 1st gear LR speed somewhere between 2nd and 3rd gears. These are speeds calculated at 700RPM which I assume is engine idle.

At 3000RPM in 5th gear, you will have just under 500 meters per minute, or 30km/h.

Figures are rough estimates, and based on the Hardbody gearbox, and diff ratios, with TC ratio a combination of the TX10 (2.02) and T100L (2.074) TC's.
If someone can post the Patrols ratios, I can run the figures more accurately at RPM's you may feel more relevant, and what crawl speeds you would like.

Re: low range gears

Posted: 20 Sep 2017 09:11
by Bre
The TX12A in the Patrol is also 2.02 David

Re: low range gears

Posted: 20 Sep 2017 09:18
by hugejp
I am doing a gearbox swop on my diesel, the swop includes the transfer case.

I would be happy to lend you the old transfer for R&D

Re: low range gears

Posted: 20 Sep 2017 12:05
by Mystical_Beast

Not sure who your post is directed too..

If you have a transfer box that one can open, it will be as good as 90 % for analysis and costing.

The reduction box would have a larger output gear, dependant on reduction ratio and therefore more teeth, but it will at least provide an indication if it is worth looking at locally.

I would have something to work with .to provide costing

Re: low range gears

Posted: 20 Sep 2017 12:09
by hugejp
I am happy to let you open it!

As soon as my swop is done, I have been contemplating importing gears for while now so if this helps get a local option I am all in!!!


Re: low range gears

Posted: 20 Sep 2017 12:19
by Mystical_Beast
That will be great

I could let our factory look at it, I will do material analysis on the gears, just to check that its not some exotic that we would not ordinarily use.

Normally material would be EN36B Case Hardened, I’d like to confirm.

Other Option are a High Chrome Nickel Steel like EN 19 which I feel would be better.
This you can harden the core to create toughness and then finally do a fairly deep plasma ion nitride on the surface for hardness, which will last forever.

I don’t like case hardening small tooth profiles as a rule as you can only provide a shallow case, but it may be suitable.

Would like to see what the original gears are made of and what hardness they are.

That will point the way ..

Re: low range gears

Posted: 20 Sep 2017 22:10
by davidvdm
Bre wrote:The TX12A in the Patrol is also 2.02 David
Thanks Bre. Can someone give me gear ratios 1st - 5th gears, and diff ratio as well. What size tyres are most people running. I am guessing 33's

What ratio would the guys be looking at for the new crawler gearing.

My question is still, crawler gears are nice, but does it work all the time? Will it not be too low for some obstacles.

Re: low range gears

Posted: 20 Sep 2017 23:00
by SJC
Ek sien die "reduction/low range gears" wat marks4wd verkoop is as volg:
24% - 2.484:1 Reduction
43% - 2.86:1 Reduction
85% - 3.743:1 Reduction
Ek neem aan dat indien die ratio te laag is sal mens 2de in plaas van 1ste gebruik, of 3de in plaas van 2de? :think:

Patrol diff ratios:
GQ 2.8 Diesel = 4.625:1
GQ 3.0 Petrol = 4.11:1
GQ 4.2 Petrol auto = 3.9:1
GQ 4.2 Petrol manual = 4.11:1 or 3.9:1
GQ 4.2 Diesel = 4.11:1
GU 2.8 Diesel = 4.625:1
GU 3.0 Turbo diesel auto = 4.375:1
GU 3.0 Turbo diesel manual= 4.11:1
GU 4.2 Diesel = 4.11:1
GU 4.2 Turbo diesel (wagon) = 3.9:1
GU 4.2 Turbo diesel (ute) = 4.11:1
GU 4.5 Petrol = 4.11:1
GU 4.8 Petrol manual = 4.375:1
GU 4.8 Petrol auto = 3.54:1

Patrol transmission/gear ratios:
specs.jpg (72.46 KiB) Viewed 1134 times