Series transer to series transfer double up/under drive

[Nick B]

Now I know Sam O has said how to do this but I just spent forever trying to find it but to no avail.

What needs to be done to use a series transfer case as an under drive!

Love to know so I can save it on my computer and then try it.

Thanks in advance!

Nick

[Strange Rover]

I had an idea to do something with a LT230 transfer and a late model viscous transfer (cause its got a planetry reduction).

For a series box you can buy a overdrive that hangs out the back of the transfer - fairy overdrive or something its called. Tyr to find out about it and you can see how you can put a reduction/overdrive at the rear of the transfer.

Sam

[Strange Rover]

Doing something cutome like this wouldnt be easy to do cause you are talking about modifying mainshafts ETC and it can get expensive. There is basically no cheap way around getting lower gearing.

Sam

[Nick B]

Thanks for the reply mate. Things like that are made a bit cheaper because my mate Landy lad who visits here has a lathe he he. And I will be getting one for work soon to, so here come the series mods.

Basically I want have normal gearing plus some serious underdrive.

I will be slowly restoring and moding a series 1 88" and puting series 3 diffs with front and rear maxi drives and running 33inch mongrels. as I am trying to do it all on the cheap. (the maxi's are second hand through a mate just have to trick/bribe them.

But thanks again for the reply I shall downloads the schematics for the airy over and under drives.

[modman]

i think fairy only made overdrives.
i have heard of a guy (bill) who put dana transfer gears into a fairy overdrive case.
this bolted behind the series transfer became the underdrive.
busted overdrives are very cheap, you only need the case i guess??
good luck,
david

[ISUZUROVER]

Overdrives were made by:

Fairey (noisy and not very strong)
Toro (much quieter and much larger sump - but less common)
Santana (LR Spain - unavailable here, but very good)
Rocky Mountain (New $$$ - just on the market - don't know if available here yet).

None of these use planetary gear sets (except RM) and you would need to machine your own gear sets which probably wouldn't fit in the case. You also need a hob and a lot of other gear besides a lathe for gear cutting.

Since you are only running 33's, the cheapest and easiest option would be to get Suffix B SII low range and intermediate gears. This will keep the high range the same but give you 49:1 1st low instead of 40:1. I pull 33's fine with this gearing in a LWB 2.25 Diesel.

[modman]

stock dana transfer gears will fit into overdrive cases.
i have seen crawler boxes done this way on series transfer cases and
also on the back of a lt95. not sure what overdrive is used on the lt 95 though??
both trucks were wheeled with lockers and 36" tyres very very hard all round melbourne.
nam might have seen these boxes before at offroad rover.

david

[N*A*M]

yeah bill told me about these underdrives
he's out of the country at the moment but i can get more info when he comes back

[Adam]

more info would be great.... im very interested in this

[modman]

like nam said, might have to wait till bill is home to ge more (solid) info.
maybe post it on pirate and see what happens??
david.

[Adam]

Bill home yet?

[daddylonglegs]

Hi gents, Bill here. i will try to give you a brief rundown on what is involved in making up a crawler gearbox that fits to the pto aperture on Landrover series tranfercases and 4 speed LT95 tranfercases also.
The parts you will need are, an old Fairey overdrive to suit your particular transfer. This must have an input shaft and adaptor gear that is in good condition in the male and female spline area. You will also need to source the bolt on two speed high low range planetary gearbox from a Borg Warner Quadratrac transfercase as used on automatic Jeep wagoneers, Cherokees, CJ7's etc from circa 1980's If you plan on stealing one, these vehicles can be identified by having a rear diff that is offset to the right whereas non Quadratrac models have a centred rear diff. The only partts of the old overdrive you will use are, part of the gear case from the flange forward.
The adaptor gear, the input shaft and the cylindrical output gear. and some needle thrust and roller bearings.
the fairey input shaft is cut and resplined to engage with the female spline of the Quadratrac input gear. The Fairey cylindrical output gear is modified by grinding the teeth off the small helical gear at one end, and welding on the course splined dog from the old Quadratrac out put gear.
An aluminium adapter and blanking plate will need to be machined up to bolt the planetary unit to the Landy pto aperture. I have only performed this conversion twice. on a series 2a tranfercase and an Lt95 and I worked out the dimensions as I went along, so unfortunately i didn't make drawings. They have proven to be very strong with hard use over the years. I had to replace the roller bearing with a bronze bush on the adaptor gear due to brinelling as the planetary unit spends most of its life in high range. This brinelling also occurs on standard Fairey overdrives if overdrive is not engaged regularly. This conversion will not suit lt95's with the large handbrake assembly. you must adapt the smaller handbrake from a series i,2 or 3 or the early Rangerover 4spd. It could possibly also be adapted to the later Lt230 transfer case but as there are no dead overdrives around for these it would be more complicated and expensive.
The low range ratio in the planetary unit is 2.57:1 when this is combined with the LT95 gearbox and 3.54 diffs it yeilds an overall ratio in low low 1st gear of around 127:1 . Standard low 1st is around 48:1.
My own series 2a LandRover fitted with a D series Ford truck gearbox, suffix b tranfercase, crawlerbox, 3.54:1 diffs and 1:56:1 hub reduction in the portals yields an overall ratio in deep reduction 1st gear of 278:1.
Most people would think this ratio is unusable, but with lockers, good tyres, lots of ground clearance and gobs of axle articulation I have used this ratio to good effect on many occaisions.
Because the company that I was involved with "Off Road Rover" is no more. and I no longer possess the machining facilities that I once had, my assistance with this conversion unfortunately is limited to advice.
I have seen a similar pto mounted crawler box on a landcruiser transfercase in the showroom of Marks 4WD adaptors. It apears to be a coventional Mainshaft Layshaft (non planetary}design. They do not appear to like Rovers too much over there, so I am not sure how easy it would be to persuade them to adapt the crawler for rovers.
Incidently, I had heard that Ashcrofts crawler unit was withdrawn from the market because they were having too many warranty claims, not because of low sales volume. Ashcroft is not a volume oufit and one or two units per month would probably have been enough for them.
Regards Bill.

[modman]

bill, how do you run a pto winch and the crawler box on your series transfer??
i plan on using the series transfer case my self with a pto winch but would ultimately like a crawler box as well.
david.

[ISUZUROVER]

bill, how do you run a pto winch and the crawler box on your series transfer??
i plan on using the series transfer case my self with a pto winch but would ultimately like a crawler box as well.
david.

Would be difficult. There is a model of series fairey that has a splined section under the rear cover plate to run a pto, but I think they are only available in the UK. I think there was also a PTO adaptor that bolts on instead of the T-case rear cover plate and runs off the intermediate transfer gear bot that really interferes with ground clearance.

The crawler sounds great. Now I need to find the necessary parts...

Do you still have the problems with the fairey inner spur gear (on the gearbox mainshaft) that wears out all the time??? How does the series T-case hold up? any shaft breakages? do the intermediate gear bearings die faster?

[DiscoDino]

hey Bill,

Welcome to the board

Remember when I called you from Germany and had discussed a doubler kit like the Toyota Guys run? I've floated this idea over the board(s) and it got sunk pretty quick by some of the top mechanically oriented guys...

Any chance that can actually see the light of day? I am CERTAIN that many people will be willing to pay <300$ for a 1" thick adapter to slap in a seconf LT230 transfer case and, if necessary, run a D90 rear shaft for the 100" trucks...

Your thoughts...

Nadim

[red90]

Hey Bill, I see Mr. Ashcroft has reponded to your accusation over at PBB... LOL

http://www.pirate4x4.com/forum/showthread.php?t=250708

[daddylonglegs]

My apologies to David Ashcroft. I did not mean to cast doubt on the quality of your workmanship. I am fully aware of the fine work that you do and the varios products that you manufacture. A couple of aquaintences made enquiries about about purchasing two of your crawler units about a year ago and was told about the warranty issues.
I agree that they would be expensive and time consuming to manufacture from scratch. Have you considered making one based on the design principals of the Fairey overdrive but much stronger and with reduction gearing instead by using readymade gears such as Landrover transfercase gears for example. that should in theory make them more economical and feasable to produce.
Nadim and others. I think the doubler system as is common in the States is only practical if you use a cut down through drive transer case such as a spicer model 20 in front of your existing landrover transfer case.
the amount of work and reengineering involved would be immense and you would probably be better off adapting a toyota Hilux high-low box to the front of your Landy case.
Modman and IsuzuRover. The Quadratrac panetary unit has a length of splined shaft protuding from the rear bearing. I made up an adapter plate and dog and fitted a modified Thomas pto drop box to it to drive the winch.
As i said in my previous post, the only parts of the Fairey overdrive I reuse are a cut down input shaft and a reworked output gear to adapt to the Quadratrac, so the problems of gears wearing out does not apply here.
the problem of the splines on the mainshaft adaptor gear and input shaft wearing away was addressed by drilling the shaft and grinding radiul oilways on both components, as well as removing the inner oil seal from the output gear.
The LandRover series 2 tranfer case has stood up very well . but then again I am running very low diff ratios which reduces the strain further up the line. Regards Bill

[ISUZUROVER]

Sorry Bill if I caused any problems posting your reply over there. There were some people on PBB who were interested.

[slorocco]

There used to be a very detailed thread somewhere with lot's of pics but I can't seem to find it. Can anyone give me a pointer to the right place? Thanks.

Hi gents, Bill here. i will try to give you a brief rundown on what is involved in making up a crawler gearbox that fits to the pto aperture on Landrover series tranfercases and 4 speed LT95 tranfercases also.
The parts you will need are, an old Fairey overdrive to suit your particular transfer. This must have an input shaft and adaptor gear that is in good condition in the male and female spline area. You will also need to source the bolt on two speed high low range planetary gearbox from a Borg Warner Quadratrac transfercase as used on automatic Jeep wagoneers, Cherokees, CJ7's etc from circa 1980's If you plan on stealing one, these vehicles can be identified by having a rear diff that is offset to the right whereas non Quadratrac models have a centred rear diff. The only partts of the old overdrive you will use are, part of the gear case from the flange forward.
The adaptor gear, the input shaft and the cylindrical output gear. and some needle thrust and roller bearings.
the fairey input shaft is cut and resplined to engage with the female spline of the Quadratrac input gear. The Fairey cylindrical output gear is modified by grinding the teeth off the small helical gear at one end, and welding on the course splined dog from the old Quadratrac out put gear.
An aluminium adapter and blanking plate will need to be machined up to bolt the planetary unit to the Landy pto aperture. I have only performed this conversion twice. on a series 2a tranfercase and an Lt95 and I worked out the dimensions as I went along, so unfortunately i didn't make drawings. They have proven to be very strong with hard use over the years. I had to replace the roller bearing with a bronze bush on the adaptor gear due to brinelling as the planetary unit spends most of its life in high range. This brinelling also occurs on standard Fairey overdrives if overdrive is not engaged regularly. This conversion will not suit lt95's with the large handbrake assembly. you must adapt the smaller handbrake from a series i,2 or 3 or the early Rangerover 4spd. It could possibly also be adapted to the later Lt230 transfer case but as there are no dead overdrives around for these it would be more complicated and expensive.
The low range ratio in the planetary unit is 2.57:1 when this is combined with the LT95 gearbox and 3.54 diffs it yeilds an overall ratio in low low 1st gear of around 127:1 . Standard low 1st is around 48:1.
My own series 2a LandRover fitted with a D series Ford truck gearbox, suffix b tranfercase, crawlerbox, 3.54:1 diffs and 1:56:1 hub reduction in the portals yields an overall ratio in deep reduction 1st gear of 278:1.
Most people would think this ratio is unusable, but with lockers, good tyres, lots of ground clearance and gobs of axle articulation I have used this ratio to good effect on many occaisions.
Because the company that I was involved with "Off Road Rover" is no more. and I no longer possess the machining facilities that I once had, my assistance with this conversion unfortunately is limited to advice.
I have seen a similar pto mounted crawler box on a landcruiser transfercase in the showroom of Marks 4WD adaptors. It apears to be a coventional Mainshaft Layshaft (non planetary}design. They do not appear to like Rovers too much over there, so I am not sure how easy it would be to persuade them to adapt the crawler for rovers.
Incidently, I had heard that Ashcrofts crawler unit was withdrawn from the market because they were having too many warranty claims, not because of low sales volume. Ashcroft is not a volume oufit and one or two units per month would probably have been enough for them.
Regards Bill.

[Bush65]

There used to be a very detailed thread somewhere with lot's of pics but I can't seem to find it. Can anyone give me a pointer to the right place? Thanks.

I can remember it and the pics, but I can't remember what forum it was on. Probably here on Outers, but may have been or Pirate. Unfortunately if it was here, then because it was at the time when pics were kept on the server, those pics were deleted a few years back.

[Michele]

I'm quite sure I have all the pics



Just need to check all my tech folders on DVDs...it might take a while!

[red90]

This is the thread that had the photos: http://carl.outerlimits4x4.com/viewtopi ... c&start=60" onclick="window.open(this.href);return false; All OL photos were lost one day. If Michele finds a copy, probably best to put back on that thread.

[Michele]

I'll give it a try as soon as I have a chance, I've been carried away a bit recently

[ISUZUROVER]

I'll give it a try as soon as I have a chance, I've been carried away a bit recently

Since when do you drink coffee???

Looking forward to the pics. Thanks in advance Michele.

[Michele]

Correct Ben, I'm supposed not to drink it
But over the last years something has changed and sometimes I force myself to have some when I hit the bottom
I tried Red Bull and Monster but no effect...

Next time you'll be here (COUGH!) we'll go to the best microbrewery in Milan, they have very good stuff