[yeda]

[yeda]

I should have added, I'd prefer not to go the automatically transmission, as then the speed control varies a lot.

[tanshi]

for lower gearing in an SJ410, try and pick up some, lj80, 4.5:1 diff gears, or lj50 4.8:1.. or even carry van, 5.1:1 diffs

none of the diffgears you have mentioned above will fit in an sj410 diff and they are larger.

[TryHard]

Idea Get SJ70 Transfercase Fit 6.5s is best bet i think 8 to 1 Transgears are hard to find dont think they make them anymore ?? I would think 6.5's first gear would be slow enuf for u

[tanshi]

depending on what model of sj410 you have, the transfer gears may or may not fit. if its a transfer case with a 4x4 switch they will but other wise they won't

[TryHard]

tanshi wrote:

depending on what model of sj410 you have, the transfer gears may or may not fit. if its a transfer case with a 4x4 switch they will but other wise they won't

get whole new box ?.. im almost positve that 6.5s would be low enuf to do the job going any lower is just plane stupid and requires alot of work are u installing hand throttle cable or cruse control type thing ? ..

[BlueSuzy]

Get original size tyres

or 6.5gears in a 1.3 transfer with 4wd light. Will be slow enough even with large tyres. (33"s) The difference is amazing.

The larger load will be fine. You wont be hardcore 4wding it?

[TryHard]

BlueSuzy wrote:

Get original size tyres

or 6.5gears in a 1.3 transfer with 4wd light. Will be slow enough even with large tyres. (33"s) The difference is amazing.

The larger load will be fine. You wont be hardcore 4wding it?

x2

[tanshi]

LJ diffs would be a whole heap cheeper than swapping the transfer and buying crawlers.
Finding them might be harder however.

[BlueSuzy]

budget 1k max FOR: a transfer case sourced local, 6.5 gears landed from usa, and you fit the gears if your mech minded

[TryHard]

1k for stock transcase ? i think not u can get a transcase with 6.5s from usa for that ...

http://www.lowrangeoffroad.com/index.ph ... cases.html

[BlueSuzy]

TryHard wrote:

1k for stock transcase ? i think not u can get a transcase with 6.5s from usa for that ...

http://www.lowrangeoffroad.com/index.ph ... cases.html

Read again. maybe i worded it wrong. 6.5's, local case, owner fitted, 1kmax

Shipping is not going to cost $65 for a whole case. Unlike just a gearset. Shipping the whole case will cost 200+

[TryHard]

BlueSuzy wrote:

TryHard wrote:

1k for stock transcase ? i think not u can get a transcase with 6.5s from usa for that ...

http://www.lowrangeoffroad.com/index.ph ... cases.html

Read again. maybe i worded it wrong. 6.5's, local case, owner fitted, 1kmax

Shipping is not going to cost $65 for a whole case. Unlike just a gearset. Shipping the whole case will cost 200+

ah i thats what i thought u ment lol yerp thats what i would do ..

[303zuke]

yeda wrote:

The vehicle is an SJ40 (1986 model, 970cc engine F10A I believe, 4spd manual)

As far as I know, the gearing is stock. I believe the stock information for the vehicle is this:

Diff ratios:

SJ40 1981-1987 4.11:1
SJ50 1984-1989 3.9 :1
SJ70 1989-1998 3.7 :1

So I am 4.11 to 1.

I've found alternate diff gears on the web, something called nitro or yukon gears?, eg:
http://www.lowrangeoffroad.com/index.ph ... gears.html

This would offer gear ratios of:
4.57 to 1, hence 11% slower speed overall
5.38 to 1, hence 31% slower speed overall


I've also found alternative transfer case gearing, something like this (although I haven't confirmed it's correct for my vehicle):

Gear Set Comparison Chart
Gear Set 4.16:1 Gears 4.9:1 Gears 5.14:1 Gears 6.4:1 Gears 6.5:1 Gears
Low Range Reduction 84% 115% 127% 181% 187%
High Range Reduction 12% 16% 18.3% 17% 20%


What I'd like to know is,
- what's the recommended way to reduce the speed of the vehicle from a reliability perspective?
- Diffs have the least impact upstream of the diff, but give the smallest reduction
- I'd think transfer case gears put more strain on the driveshafts and diffs, but a 2nd box is probably worse
?
- Have I got the options wrong? It's a bit hard to understand if the US based stuff will fit a 1.0l setup.

Your 1986 SJ40 is called a Type 3 and already has the type of transfer case suited for the reduction gear sets. However, the calculations you have quoted for the extra reduction apply to fitting those gears to a 1.3 transfer. Your transfer already has lower ratios than that, so for example fitting 4.16 gears will give you 0% change in Hi range and about 63% lower Low. Also, all of the gear sets except the 6.5s require the re-use of one of the gears from a 1.3 case which you will need to source.

Some good news, your gearbox is the type that will accept the internal gears from a 1.3 5 speed. Although the 5th gear is not what you're really looking for, this will reduce your 1st gear ratio from 3.163 to 3.652, a drop of about 15%. That equates to you fitting the 4.556 LJ80 diff gears. 2nd, 3rd and 4th are still the same ratios, plus you get a 5th of 0.795.

Of course, you can fit any or all of the combinations of gearbox, transfer and diffs completely independantly of each other or all together for combinations of reduction. Best outcome for reliability would be 5 speed gears (3.652 1st) x 6.5 transfer x 5.125 Super Carry diffs for a 122:1 crawl ratio, a 272% increase over stock. (but do carry spare axle shafts and learn how to change Uni Joints! )

[Gwagensteve]

I think the best option is just to put 6.5 gears in your transfer.

At idle, with everything else stock, I get 1.23km/h in first low, so about 1300rpm or so for 2km/h.

I think that's plenty low enough for your application.

My own car is geared much lower than this, and I'm travelling at <1.0km/h at idle, but it makes 1st low pretty much useless - even for travel at very low speed, revs are just too high, so I end up in 2nd or 3rd low at idle.

Steve.

[Teracis]

Gwagensteve wrote:

I think the best option is just to put 6.5 gears in your transfer.

At idle, with everything else stock, I get 1.23km/h in first low, so about 1300rpm or so for 2km/h.

I think that's plenty low enough for your application.

My own car is geared much lower than this, and I'm travelling at <1.0km/h at idle, but it makes 1st low pretty much useless - even for travel at very low speed, revs are just too high, so I end up in 2nd or 3rd low at idle.

Steve.

What gearing do you run in your zook?
Also, that volvo gearbox thing sounds ridiculously good, don't think the transfer would enjoy that kind of treatment though!

EDIT: Oh and OP, if I were you I'd go the 6.5's in the transfer case, once you've done it you'll understand it's pretty much exactly what you're trying to achieve, also as suggested, maybe rig up some sort of hand throttle cruise control for that thing!

[alien]

all this talk of gearing when fitting smaller tyres would be a way easier option to begin with =)

[Gwagensteve]

Teracis wrote:

What gearing do you run in your zook?
Also, that volvo gearbox thing sounds ridiculously good, don't think the transfer would enjoy that kind of treatment though!

EDIT: Oh and OP, if I were you I'd go the 6.5's in the transfer case, once you've done it you'll understand it's pretty much exactly what you're trying to achieve, also as suggested, maybe rig up some sort of hand throttle cruise control for that thing!

660cc 5 speed gearbox - 3.6:1 first gear (or something) 6.4 case, 5.12 gears - 120:1 or so.

Steve

Ps its easy to make a hand throttle with an old school frame-mounted bicycle gear shifter, mounted on the gear lever.

[Ben_Sierra]

alien wrote:

all this talk of gearing when fitting smaller tyres would be a way easier option to begin with =)

Funnily, that was my first thought too...

[Teracis]

Ben_Sierra wrote:

alien wrote:

all this talk of gearing when fitting smaller tyres would be a way easier option to begin with =)

Funnily, that was my first thought too...

Depends if he's got the smaller tyres and or he'll still get where he wants to go with smaller tyres on!

[ajsr]

buying 4 tyres is probably more expensive than a trans gearset from lowrange

[alien]

narrrr just go down the local tyre shop - tons of people swap their tyres with 50% or more tread on them. a cheap set can't be far away, possibly even on rims if you're really lucky.

[BlueSuzy]

alien wrote:

all this talk of gearing when fitting smaller tyres would be a way easier option to begin with =)

Funny i already said this

[alien]

BlueSuzy wrote:

alien wrote:

all this talk of gearing when fitting smaller tyres would be a way easier option to begin with =)

Funny i already said this

nuh -uh don't go there girlfriend. *click click*

[BlueSuzy]

[yeda]

Firstly, I'd like to thank all for the information. It helps a lot.

To clarify,
- I don't know exactly what it means to have a case with a 4wd switch on it? My dash does have a 4wd light in green, the t-case has a lever to shift, and the pattern is a J, with 2 high at the top right, 4 high in the middle right, and 4 low on the left.
- If this is the transfer case with a switch, then transfer case gear swaps for the 1.3 would fit (almost. see below).

- Also, the diffs in the SJ410 are a smaller size, anything for the sj413, eg the 5.38 from the web won't fit.

- I'm not using anything to do hand throttle cable yet. I just use the bush mechanic method - turn the idle speed of the engine up a bit so it won't stall when rolling.
- I have considered fitting a working tacho so I can properly relate the engine speed to ground speed, but haven't done it yet

- Am I doing hardcore four wheel driving? I don't think so. I'll be spending most time on flat ground, I've just got surface rock to get over now and then, and pulling a trailer over that at slow speed. To and from base of operations should be on level ground, on a track, with only minor potholes.



So, the options are:

(tanshi) - use existing diff cases, use
- lj80 diff gears for 4.5:1
- lj50 diff gears for 4.8:1
- carry diff gears for 5.1:1
- the existing diff cases are not compatible with the 5.38 or 4.37 (yukon and nitro) gears I've found so far.

(TryHard) - replace current transfer case with SJ70 transfer case:
- Then 6.5:1 and 8:1 gears can be used
- 6.5:1 is probably slow enough

(tanshi) - If the transfer case is with a switch, I can already use these transfer case gears


(Bluesuzy) - Return to original sized tyres?

(303zuke) - The transfer case is a 'type 3' and is compatible with the reduction gears, however, it will need one gear from a 1.3 transfer case.
- Also, the reduction rate won't be as high, as the type 3 case already has lower range gears.
- a 1.3 5-speed manual can provide 15% drop in first gear speed


(Gwagensteve) - 6.5 to 1 in the transfer case in his application allows 1.23km/hr in first low at idle, and ~1300rpm for 2km/hr
- transfer case gearing is a better option than feeding higher torque into the case to begin with.

Observations:

- Feeding high torques into the transfer case is bad, and will result in:
- Possibly damaged axles,
- Uni joints and shafts getting damaged

- This suggest to me that the 2nd gearbox solution might give problems down the track.


- Reducing loading into the transfer case would involve:
- higher gearing inside the case
- smaller diameter tyres
- higher diff gearing
- lower first gear gearing (in the gearbox upstream)
- not towing a heavy trailer
- not taking the car extreme four wheel driving

- Reducing the tyre diameter is not a preferred option for me as:
- I only have the non-stock wide tyres and rims
- The car is light enough, and the tyres wide enough, that the car goes over the terrain without too much damage (my patrol churns up mud in the same conditions)
- The wheel diameter is larger than stock, which makes driving over rocks less abrupt in the cabin, and to my spraying gear

- Reducing the diff ratio:
- Basically, look for carry crown gear and pinion will give a high ratio

- Reducing the transfer case gear:
- I have the right transfer case that could take 6.5:1 gears as a changeover, but I'd need a gear from the 1.3 case.

- Reducing first gear:
- I have a carry 4 speed gearbox (sourced from a wrecker). Apparently that also has the lower first gear (as the 5 speed does) that I could sub in.

Conclusions;
- The diff method first seems easiest, as long as I can find parts.
- The transfer case is doable, with an extra gear.
- The gearbox 1st gear is doable with donor bits
- A second gearbox is the least desirable for durability.


Questions
- It is implied that sj413 diffs are bigger. Does this mean better?
- 303zuke - could you describe the gear needed from the 1.3 case? Or will it be easier to work out once I have the case open.
- I assume the carry is 2wd. Would there be an issue fitting carry crown and pinion gear in both the front and rear diffs? I'd prefer 4wd capability is preserved.
- Anyone with a 6.5 have to upgrade the mounting of their transfer case?

[303zuke]

yeda wrote:

To clarify,
- I don't know exactly what it means to have a case with a 4wd switch on it?
- If this is the transfer case with a switch, then transfer case gear swaps for the 1.3 would fit (almost. see below).

So, the options are:

(303zuke) - The transfer case is a 'type 3' and is compatible with the reduction gears, however, it will need one gear from a 1.3 transfer case.
- Also, the reduction rate won't be as high, as the type 3 case already has lower range gears.
- a 1.3 5-speed manual can provide 15% drop in first gear speed

Questions
- 303zuke - could you describe the gear needed from the 1.3 case? Or will it be easier to work out once I have the case open.
- I assume the carry is 2wd. Would there be an issue fitting carry crown and pinion gear in both the front and rear diffs? I'd prefer 4wd capability is preserved.

Yes, your transfer case is the type with a light switch, which is the type that accepts the aftermarket reduction gear sets. You will not need to source an SJ70 Transfer Case to fit the lower ratio gears. It is your model of SJ410 that is a "Type 3", not your Transfer Case.

The 5.125 diff gears are from a SUPER CARRY (SK410 '84-'87), not the Carry (ST80 or ST90). Yes, you will need two sets (from 2 vehicles) as these are a 2wd and only have one diff per vehicle. The gearbox gears also need to be from the SK410 and not an ST80/90 to fit inside your gear box. ST80/90 use an earlier design of g/box in common with the LJ50/LJ80 and Type 1 and 2 SJ410.

The diagram that I attached of the transfer gear ratios is colour coded. The gears from the 1.0 transfer are RED, 1.3 Transfer are GREEN. You can see that the 1.3 Low Range Output Gear (wlth 56 teeth) is re-used with the 4.16, 4.9 and 5.14 ratios. The 4.16 gears were the first form of gears made and were done by welding two halves from the 1.0 and 1.3 gearsets to form a hybrid gearset using gears from both boxes. Nowadays, all Idler gears are cut from new billet.