Overdrive or transfer box upgrade

[Stewart]

Hi all I'm new to the forum and this is my first post so here we go.

I've got a 1983 series3 109 ex MOD 1 ton. I'm wanting to get a few more mpg and am considering an overdrive or an Ashcroft transfer box. I don't want to swap the diffs. There dosent look to be much difference in cost between the two.

Has any one got any views on this or any experiences with the ashcroft transfer box.

Thanks.

[Les Henson]

I had a 109 with the Fairey Overdrive on it. You can only use it in 3/4 gear, but it's supposed to save quite a bit in fuel. I never could accellerate whilst the O/D was engaged unless I was on a downslope, so it was more of a cruising gear than anything else. A higher range transfer case would be better as you just have higher gearing.

Les.

[bill van snorkle]

I fitted a 30% transfercase upgrade to a friends 88'' 2.25 deisel a couple of years back. In high range it wouldn't pull the skin off a rice pudding. the truck barely had enough accelleration to get out of its own way,and due to the necessary frequent use of the indirect gears it ate gearboxes with regular frequency. Those issues were addressed when I fitted a 200 TDI engine and a Ford F250 gearbox to it. Unfortunately the high gear wheel in the modified transfercase has softer dog teeth than standard gears and a very pronounced taper has worn on the sides of these teeth causing the transfercase to pop out of high range occasionally, despite my best efforts upon initial assembly to ensure maximum engagement of the teeth in high range. I must stress that this transfercase was purchased in Australia, not from Ashcrofts, and may well have been modified and supplied by another of several companies that performed this type of work at that time . My local vendor isn't prepared to tell me who his supplier is.

Bill.

[Stewart]

I fitted a 30% transfercase upgrade to a friends 88'' 2.25 deisel a couple of years back. In high range it wouldn't pull the skin off a rice pudding. the truck barely had enough accelleration to get out of its own way,and due to the necessary frequent use of the indirect gears it ate gearboxes with regular frequency. Those issues were addressed when I fitted a 200 TDI engine and a Ford F250 gearbox to it. Unfortunately the high gear wheel in the modified transfercase has softer dog teeth than standard gears and a very pronounced taper has worn on the sides of these teeth causing the transfercase to pop out of high range occasionally, despite my best efforts upon initial assembly to ensure maximum engagement of the teeth in high range. I must stress that this transfercase was purchased in Australia, not from Ashcrofts, and may well have been modified and supplied by another of several companies that performed this type of work at that time . My local vendor isn't prepared to tell me who his supplier is.

Bill.

Hi Bill

So Im probally better of with an overdrive then, at least I know ill be able to pull of normally without the overdrive engaged.

[simonb]

Hi Bill

So Im probally better of with an overdrive then, at least I know ill be able to pull of normally without the overdrive engaged.

The normal way of using an overdrive in a series, is to reach the desired speed in 4th gear, then engage overdrive to reduce revs and improve mpg. You won't get much mpg improvement if you try to use overdrive top for acceleration.

If you have a diesel 2.25 in a 109", you may find that the engine won't pull the higher gearing if the vehicle is fully loaded.... Petrol 2.25 should cope ok..

[101nut]

I had a 109 with the Fairey Overdrive on it. You can only use it in 3/4 gear, but it's supposed to save quite a bit in fuel.

On a V8 the quoted figure with the overdrive fitted shows under 1mpg saving ... better for saving wear, tear and your eardrums than fuel.

AndyG

[Steve_M]

I have the Ashcroft extended ratios on my lightweight (2.25 petrol) as well as a few other engine mods from ACR but I haven't driven a standard series to compare it with. I don't worry too much about the mpg but it does give me a higher cruising speed or a more relaxed drive at a lower speed and makes the vehicle more usable if you intend to drive any distance . However as would be expected you do have to change down earlier when climbing long hills etc, also I suspect it would be far from ideal if you are planning on towing anything heavy. It is also still accelerates faster than my friend's diesel series 3.

Steve

[bill van snorkle]

Hi Bill

So Im probally better of with an overdrive then, at least I know ill be able to pull of normally without the overdrive engaged.

It's very difficult for me to recommend an overdrive because I think they (the Fairey or Superwinch ones at least) are carp, and should have been redesigned 20 odd years ago.

The following may have been pointed out by other members on previous threads,but it may be worth repeating here for other members with early series LandRovers. Over here the advertising blurb for the high ratio transfercase conversion states that low range gear ratio remains unaffected. Whilst this is true when fitted to series 2a and 3 vehicles, owners of series 1 and 2 vehicles with original main gearboxes should note that your low range ratio will change from 2.88:1 to 2.35:1 and your overall ratio in low range 1st gear will change from 40.6:1 to around 33:1. This has a serious affect on pulling power and offroad hill climbing ability.

Bill.