o/d or ashcroft trick transfer box???

[richardthestag]

Hi All

My dad has a 68 IIa SWB and wants to improve the gearing. Apparently 55mph balls out and going deaf is not good for him. I have been looking at o/d converstions which seem to be readily available etc through e-bay but a bit on the pricey side when compared to an Ashcroft recon transfer box with trick internals.

http://www.ashcroft-transmissions.co.uk/part_35.html

I heard that overdrive units are a bit on the fragile side, is this true? I guess that they cannot be tested off the car and that only a full strip down will identify any problems? However on the plus side they look pretty easy to fit?

Has anybody got any advise / experience of tranfer box vs overdrive that could help us?

p.s. did a transferbox change on my RRC a couple of years back and although it was heavy it was pretty straighforwards so again I am guessing that the series IIa shouldn't be that different.

I am also trying to pursuade him to buy freewheel hubs to cut down a bit on the road noise / fuel consumption. Are they any good?

Cheers

Richard

[jimfoo]

If you are in a hilly area, an OD is better, but if you will be driving flatter roads, I think the Ashcroft is the way to go unless you have a suffix b low range gear in a later box. I think the Roverdrive is probably the best OD out there right now, though if you could find a Santana, they are very well built. The input splines are what usually wear out on the OD's. Free wheel hubs do save gas.

Hi All

My dad has a 68 IIa SWB and wants to improve the gearing. Apparently 55mph balls out and going deaf is not good for him. I have been looking at o/d converstions which seem to be readily available etc through e-bay but a bit on the pricey side when compared to an Ashcroft recon transfer box with trick internals.

http://www.ashcroft-transmissions.co.uk/part_35.html

I heard that overdrive units are a bit on the fragile side, is this true? I guess that they cannot be tested off the car and that only a full strip down will identify any problems? However on the plus side they look pretty easy to fit?

Has anybody got any advise / experience of tranfer box vs overdrive that could help us?

p.s. did a transferbox change on my RRC a couple of years back and although it was heavy it was pretty straighforwards so again I am guessing that the series IIa shouldn't be that different.

I am also trying to pursuade him to buy freewheel hubs to cut down a bit on the road noise / fuel consumption. Are they any good?

Cheers

Richard

[CR88]

Hi,

O/D is more flexible, I know one SIIA LWB with the ashcroft transfer gear kit. The owner isn't totally pleased with it, because all gears raise their final ratio. Sometimes uphill the engine isn't enough. But after a while he get used to the new final ratio.

I have O/D and I'm happy with it, probably is more iffy then the solution that ashcroft have, but for the moment is working well.

Regards,

[Jon White]

What are you using it for primarily??

FWH are horrible things - I took mine off and threw them away years ago.

There are other options - taller tyres, 3.54 diffs, 5 speed gearbox etc.

Do you ever use low ratio or is it a pure road going machine?

Jon

[FridgeFreezer]

I reckon Range rover diffs would be the best option if it's not used much off-road and you don't have too many steep hills. They will raise all the gearing, cost less than an OD and won't whine like an OD.

Mind you, if it's a stock 88 then just fitting slightly larger tyres such as 7.50's would raise the gearing about 10-15%.

Don't bother with hubs, they are rubbish (they leak, they are a weak point, they are inconvenient) and frankly I don't think they make any noticeable impact on fuel economy.

[Mark]

I have/had both the overdrive in my diesel IIA and the high ratio transfer box in our lightweight.

You don't mention what engine you are running. My personal opinion is that unless you have uprated your engine then the overdrive will do a much better job.

Our 2.25 petrol lightweight had a stage II performance kit from ACR (SU carb, manifold, head exhaust, revvy cam etc) and I still found that the gears were a bit on the tall side with the ashcroft high ratio kit. I was running 235/85-16s (same as 750's diameter wise). The kit was designed for V8 converted series trucks orignally.

The Diesel IIa has a fairey overdrive, and it does exactly what it should - gives you an extra gear on top of 4th. It also gives a gear on top of 3rd too, which is useful when towing or fully loaded.

Both the Overdrive and High ratio t-box kit do not affect the low range of the vehicle (unless you choose to, in the case of the o/d). However, if you feel that having low range affected is not a bad thing, than have you thought about swapping diffs?

The standard series diffs are 4.7 10 spline, so fitting a set of 3.54 10-spline diffs ups the gearing in all gears, high and low range. Again, I would have thought that you would need to have a bit more power available to you to go down this route, but it would likley be cheaper than either of the others.

hth

Mark

[jimfoo]

Only crappy or poorly maintained FWH's leak oil. American vehicles have had them for years, and if they were as bad as some say, they would have never lasted. They reduce wear on the front end driveline components, and they DO increase mileage and power. As soon as I get to the first hill, I immediately know if they are locked or not as I have quite a noticeable decrease in speed if they are locked. Some say your front propshaft will get trashed if you drive around with them unlocked, which is rubbish. I have owned 4wd's since I could first drive 27 years ago, and all my vehicles had FWH's and none ate front propshafts.

If you are worried about oil leaks, better sell your Landy. As far as a weak point, I have never busted one of them despite breaking 4 or 5 front halfshafts. I have on occasion dented them so they don't engage quite as easily, but a hammer fixes that.

[bill van snorkle]

Anything that permanently raises the gearing on a series Landrover be it diff ratios or high ratio transfercase will have a significant and detrimental affect on gearbox reliability and reduces the overall usefulness of the truck.

I am currently looking after a friends series 3 swb to which amongst other things I have fitted a 200 tdi, Warner T98 gearbox and Ashcroft type transfercase conversion with 4.7:1 diffs. IMO the over 30% step up in high range that the transfercase gives is too high and if it wasn't for the very low first gear of the T98 the truck would be incapable of pulling the hair off my balding head. I originally fitted the high ratio transfercase to the original 2 1/4 deisel and series 3 gearbox prior to fitting the 200 TDi and T98 but the truck really struggled to move away on anything but level ground. Because the gearbox had to work harder with much more frequent use of the indirect gears, gearbox reliability was very poor indeed., requiring regular rebuilds.

For the alterations to a regular transfercase that is required to transform it into a high ratio one there is no technical reason why a 1:1 ratio couldn't be made available,(only one new gear required) and IMO would have been a better proposition.

On the subject of free wheel hubs, I have tried Warn, AVM, Selectro, MAP, Fairey and PowerLock brands and have yet to find one that I could not break, even with 10 spline front axles. I've never detected an improvement in fuel economy, but the reduced vibration at cruising speed was a positive thing.

bill.

[tacr2man]

The o/d option is probably best with a standard engine, and with the better lubricating oils (synthetic) now available will be reliable for a high mileage.

I have fitted them, and used them in RR, 6cyl S3, and diesel 2a both with standard 2.25 and leyland 3.8 .

As for FWH the only time I broke one in normal use was trying to tow with 2a running at 4.5 tons broke rear halfshaft, so tried running front wheel drive only to get home .

They make a marked difference in winter when using low powered engine (2.25 diesel) between acceleration and just being able to increase speed

[rtbarton]

Bill - is this true For the alterations to a regular transfercase that is required to transform it into a high ratio one there is no technical reason why a 1:1 ratio couldn't be made available,(only one new gear required)

To alter the ratio, the new gear will be a different size to the one it replaces, therefore it wouldn't mesh properly with the idler gear? You'd have to replace them as a pair??

I find the FW hubs do make a difference, but you probably use the extra power liberated to drive faster so you won't notice any increase in economy.

[Phil Hancock]

I did speak with Ashcrofts once about a series 1:1 transfer box, the reason for not doing it was that with the input and output shaft centers being fixed and then moving the idler center position to get the correct mesh on all the gears it ended up with the idler not being able to pass thro the middle as normal, the idler had to be moved around the output shaft as the input gear needed to be bigger so that it matched the output. Result worn/failing idler bearings = idler jamming into the meshing input/output gears so locking up the transfer case. More power = more jamming action.

Now wouldnt that be fun at 70mph on the motorway?

[bill van snorkle]

I did speak with Ashcrofts once about a series 1:1 transfer box, the reason for not doing it was that with the input and output shaft centers being fixed and then moving the idler center position to get the correct mesh on all the gears it ended up with the idler not being able to pass thro the middle as normal, the idler had to be moved around the output shaft as the input gear needed to be bigger so that it matched the output. Result worn/failing idler bearings = idler jamming into the meshing input/output gears so locking up the transfer case. More power = more jamming action.

Now wouldnt that be fun at 70mph on the motorway?

It is true with the ''clover leaf'' placement of the gears that if the intermediate (idler) gear bearings failed completely the intermediate gear would tend to get wedged into a smaller gap by the mainshaft and output gear,This would require that the bearing separators disintegrated thus allowing all the rollers to gather together on one side to permit gear deflection. but since the adoption of plastic bearing cages over 30 years ago I haven't seen a failure of that nature. Anyway this hasn't stopped virtually every other manufacturer of transfercases in the world including Toyota,Nissan,Spicer etc etc from persisting with thie cloverleaf design, and I've never heard of any of these vehicles having a serious high speed transfercase related incident. I'd expect that the small baby teeth on the series gears would merely strip if such a bearing failure were to occurr anyway.

Bill.

[bill van snorkle]

Bill - is this true For the alterations to a regular transfercase that is required to transform it into a high ratio one there is no technical reason why a 1:1 ratio couldn't be made available,(only one new gear required)

To alter the ratio, the new gear will be a different size to the one it replaces, therefore it wouldn't mesh properly with the idler gear? You'd have to replace them as a pair??

See Phils post above for an explaination of how it could be done. The only new gear that would be required is the mainshaft gear which would be identical to what Ashcroft supplies for the higher ratio conversion.

It should be pointed out to anyone with series 1 or 2 vehicles with suffix A or B main gearboxes that fitting a high ratio transfercase to these boxes will significantly raise the overall low range ratio in addition to high range. The low range ratio in the t/case goes from 2.88:1 to 2.35;1 and overall ratio in low 1st will go from 40.6:1 to just over 33:1 and reverse would be very poor indeed.

bill.

[rtbarton]

See Phils post above for an explaination of how it could be done. The only new gear that would be required is the mainshaft gear which would be identical to what Ashcroft supplies for the higher ratio conversion.

I thought that might be the case - change the mainshaft gear and move the idler gear if I read Phil's post correctly.

[bill van snorkle]

I've just been out in the shed and placed 2 high gear wheels and an intermediate gear together in a cloverleaf mesh pattern and it would appear that the offset is not much, so the wedging forces of a transfercase modified in this manner may in fact as Ashcroft said be quite high in comparison to Toyotas etc.

Of course another way of acheiving a 1:1 ratio whilst keeping all the shaft centres in a straight line is to weld up or plug all the gearbox to transfercase mounting holes and redrill them the 6mm or so further to the left side.At first glance at least, there appears to be enough room on the transfercase mounting surface to do this. This will require a new PTO coverplate with an offset bearing, but that is no biggie.

Bill.

[rtbarton]

I've just been out in the shed and placed 2 high gear wheels and an intermediate gear together in a cloverleaf mesh pattern and it would appear that the offset is not much, so the wedging forces of a transfercase modified in this manner may in fact as Ashcroft said be quite high in comparison to Toyotas etc.

Of course another way of acheiving a 1:1 ratio whilst keeping all the shaft centres in a straight line is to weld up or plug all the gearbox to transfercase mounting holes and redrill them the 6mm or so further to the left side.At first glance at least, there appears to be enough room on the transfercase mounting surface to do this. This will require a new PTO coverplate with an offset bearing, but that is no biggie.

Bill.

Crafty. Would there be enough room to fit new studs 6mm to the left on the rear of the T-case to take the original PTO hole cover?

[bill van snorkle]

Crafty. Would there be enough room to fit new studs 6mm to the left on the rear of the T-case to take the original PTO hole cover?

No I dont think there is quite enough room, and the spigot diameter of the PTO cover plate would then need to be reduced by 12mm to move it over 6mm. I think compared to welding up the original intermediate shaft hole, reboring and spot facing it in the new location, plus supplying 3 new gears verses relocating the transfercase mounting holes, making a new pto coverplate, plus supplying one new gear, there wouldn't be much in it cost wise.

Note that this idea would probably only work on pre suffix D transmissions because the front hole on the transfercase is rough cast, large diameter and plays no part in centreing the gearbox and transfercase. Centreing is done by 2 dowel pins. The front hole on suffix D transmissions is machined concentric and registers with the gearbox mainshaft rear bearing carrier, so moving the transfercase 6mm offcentre would require the front hole to be clearanced and centreing effected by the earlier dowel pin method.

bill.

[Gremlin]

Hi all, i had manged to make a 1.1 series case when i flanged it to the lt77 5 speed, in simple terms, all i did was use the bottom output gear of another tc and put it as the input gear. i offset the flange for the lt77 and made another offset pto cover. It worked fine for some years untill i had input spline issues due to lack of lube (just like any early lt77 + lt230) The whole thing has been replaced by an lt77 and an lt230 with a 1.003 ratio now.

Grem

[Gareth Dickens]

So you are all telling me that a std s3 xfer case in high range is a reduction box. I always assumed it was a 1 to 1 ratio. Since I am now fitting the F250 xfer case (that is 1 to 1) I should have an improved top speed. Only issue is I'm running a 3 speed auto box and I hope my first gear low range has adequate reduction as the F250 xfer case only has about a 1.75 to reduction.

So what is the reduction in high range on a s3 xfer case?

[Phil Hancock]

1.148:1

[bill van snorkle]

So you are all telling me that a std s3 xfer case in high range is a reduction box. I always assumed it was a 1 to 1 ratio. Since I am now fitting the F250 xfer case (that is 1 to 1) I should have an improved top speed. Only issue is I'm running a 3 speed auto box and I hope my first gear low range has adequate reduction as the F250 xfer case only has about a 1.75 to reduction.

So what is the reduction in high range on a s3 xfer case?

I think the low range ratio ofthe Np205 transfercase on f250's is 1.96:1. should be ok with the 2;1 stall ratio of the torque convertor and 4.7:1 diffs. An extra large oil cooler for the autobox maybe worthwhile if you do a lot of heavy towing orrock crawling.

Bill.

[Gareth Dickens]

I think the low range ratio ofthe Np205 transfercase on f250's is 1.96:1. should be ok with the 2;1 stall ratio of the torque convertor and 4.7:1 diffs. An extra large oil cooler for the autobox maybe worthwhile if you do a lot of heavy towing orrock crawling.

Bill.

Yep allready located a 32 line oil cooler and will run a fan on it. Will run the fan from one of my engines many fan switches (still through it's own relay) or do you think I should fit it's own. Going to install it in the fan stream of my big engine fan as well.

Does this sound sufficient?

[richardthestag]

Crikey that is a whole lot of advise, many thanks indeed..

So standard engine, lots of offroading (though not competatively) and many steep hills near where he lives (north devon) shouts overdrive then?

If so do I chance my luck with an e-bay job or is there a more guaranteed source for reliable units? If I do end up with a snotter what are rebuild costs like?

Thanks again for all the advise

Richard

[FridgeFreezer]

Tricky one, 2nd hand ones are cheap enough so it's down to how much you trust any given seller.

Rock Mountain make a Roverdrive for series which is supposed to be better than the old fairey ones, and the fairey ones are still in production, but for the price of either of them brand new you could buy an LT77/R380 and LT230 and 2WD kit and have 5-speeds, much stronger transmission and a choice of transfer box ratios, plus a lower low box.

Fitting would be a bit more of a faff but if I had the best part of £1k to spend I wouldn't be buggering about with Series bits.