19J and Series gearing

Looking at rebuilding my old 19J engine to put in the 109, which was originally a 2 1/4 diesel. I know the 19J isn't a very common conversion for a series 3, probably more from its reputation than anything else. But it's quieter than a tdi, cheaper to rebuild and just looks more suited to the engine bay.

Based on how the 90 used to drive (rumbling along at 60 most of the time) with standard series 3 gearing it will be quite under-geared, with top speed limited more by engine revs than lack of grunt. So I can see three options at the moment:

1. Raise the overall gearing, either with a high-ratio transfer box from Ashcroft or 3.54 diffs. The Ashcroft kit is probably easier and won't affect the low range gearing or the speedo. But there's a big jump between 3rd and 4th gear which may be troublesome and give the feeling of it being over-geared. Though I don't plan to do much heavy towing with it as it will be a pickup, so loads can go in the back.
2. Fit an overdrive. Trouble is the cost of a Roamerdrive and the durability/noise/rarity concerns with the old Fairey units. But then you do basically get six usable gears as opposed to four- I expect '3rd and a half' would be useful on occasion as well as the overdrive fourth.
3. Fit a 5-speed LT77 or R380 gearbox. But this gives rise to further issues due to the extra length.

Anyone got a 19J in a series? How do you find the overall gearing?

3.54 diffs are a cheap solution. But do impact low speed crawl if you like to off road.

There is a gap between 3rd and 4th. You just have to hang on to 3rd a bit longer.

The biggest problem is people and perceptions. Seems that they want 4th gear low enough to pottle as 25-30mph, yet also allow them to cruise at 65-70mph at low revs.

Physically this is impossible for a single gear to achieve.

The Ashcroft high range is probably the best solution all round.


I have 3.54 diffs in my 88 Tdi at the moment. But when I get chance I’d like to fit a Fairy overdrive that I have and return it to 4.7 diffs.

So it looks like the overdrive is most useful in taking out the gap between 3rd and 4th, but the high ratio kit (basically overdrive all the time in all gears?) is the best alternative. Maybe I'll keep an eye out for an overdrive at the right price in the meantime.

The 19j has only some 20 more horses than the series 10j, although the torque's is about a third more. Wether it is worth changing the gearing [ other than an overdrive ] in a 109 would depend on the type of use the vehicle is expected to have. I would try it with the 19j as is then see where to go from there.

To be honest, I'm not expecting to see much 'heavy' use with the 109- more for general bumbling about and for transporting bulky stuff that won't fit in a focus estate or messy stuff that I can just lob in the back without worrying. I do a bit of towing for the scouts but I'd probably use the focus for that too as it's got 17 more horses than the 109 will have.

FlyingPete said:

To be honest, I'm not expecting to see much 'heavy' use with the 109- more for general bumbling about and for transporting bulky stuff that won't fit in a focus estate or messy stuff that I can just lob in the back without worrying. I do a bit of towing for the scouts but I'd probably use the focus for that too as it's got 17 more horses than the 109 will have.

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id try the 3.54 diff ,ive had them and thought it made the truck drive like it should have

Sometimes I forget to take it out of overdrive, first 3 gears its hardly noticeable but you do fall into the hole between 3rd and 4th.

Trundling around town the standard gearing works really well and allows me to be comfortably in 4th in 30 limits, I guess thats going to be 3rd with a higher ratio box or 3.54 diffs, not the end of the world, just different.

Use the ashcroft ratio calculator to explore the options, I found it very helpful to compare choices. I run the 3.3l Perkins - only 63 hp but loads of torque. From that I would say 65-70 hp would pull around 60-65 mph so you can work the revs and ratios back from that. I run 3.54 diffs, and OD and 32 1/2 inch wheels (235/85/16) The 235/85 are about 10% bigger than the 205s which is close to the same as an OD. Mine already had the 3.54 diffs but was undergeared so I changed to the larger tyres which really helped but 3/4 is very wide so I fitted the OD (e-bay) and I now use it to split 3rd on hills as well as in top. This gives a usable 6 fwd gears and I find I really need that as the Perkins is really only good to 3000 revs and not happy above 2500. Current gearing is 2000 at 60 which seem to return around 30mpg on a run. I'm getting good at the 3 /3+OD/4/4+OD gear sequence but its easy to forget to come out of OD. Another benfit of this is that on an S2A the whole sequence is with syncho. The only real downside is a very high reverse, even in low range, tick over in Low reverse is a brisk walk. Low 1st is OK and if fully loaded or on a steep hill I would pull away in low range then switch to high once rolling. I would favour and OD over the high ratio box every time because there's no substitute for the extra 2 gears (3+OD and 4+OD), I regualry drive from Slough to Bath and can do 90% of the trip just on 4 and 4+OD which makes for easy (it relative) driving. OD was £225 and parts to fix it around £220 3 years ago. Its done around 5000 miles with no problems - oil is clean and never needed a top up (unlike everything else!)

I've spotted a couple of overdrives for sale- what's the main difference between Fairey and Toro units as they appear to be about the same?

Fairey overdrives seem to have a reputation for being noisy and unreliable- I guess it's a case of keeping on top of the oil level to stop premature wear, and not overtorqueing it by using 1st/2nd+OD.

The Toro is very similar to the Fairey but has a better input spline design and larger oil capacity. The problem with the Toro is spares, spares availability for the Fairey is now good but I don't know how much is interchangable. In good condition the Faireys don't make that much noise, they can whine a bit (mine does off load) but they reduce engine noise a lot so its a trade off. The Roamerdrive is probably the best bet if you have the budget as its a better design (epicyclic and shared oil) otherwise you have to decide between rebuilt units, as used but working and duff/as-seen. Prices vary a lot. My choice is as-seen on the basis that you will probably want to strip it anyway and some of the so called "rebuilt" units have turned out to be poorly done. Parts are reasonble :
http://www.onlinegearboxparts.com/product-category/land-rover-fairey-overdrive/
But notice there are no gears so these must be in good conidition.