Series 111 gearing ?

[Landowner]

We have just put a 2.5 n/a Defender diesel in a petrol Series three

As expected top speed is now about 45 mph with everything shaking to destruction.

Will fitting 3.4 Defender diffs (10 spline) be a direct replacement and by how much can we expect the gearing to be raised (cant do the maths )

thanks

Pete

[Jon White]

Yes it's a bolt in swap.

You'll find it will kill your acceleration completely. 2.5 naturally gasping was never a good engine, and won't pull the skin off a rice pudding.....

It'll change the gearing by about 30%

Jon

[Landowner]

Yes it's a bolt in swap.

You'll find it will kill your acceleration completely. 2.5 naturally gasping was never a good engine, and won't pull the skin off a rice pudding.....

It'll change the gearing by about 30%

Jon

Acceleration at the moment is set off in second then straight into top

No in between I'm afraid, the Defender was ok with the engine and diffs up to about 40 but struggle after that, only local with it so hope its ok. Thanks for info

Pete

[David Sparkes]

Ashcroft Transmissions do a Ratio Calculator It always tends to ask questions you don't know the answer to, 'because I haven't changed that', but feed it good food and it will give out good data. Understanding the data in 'real life' terms is another matter :-)

HTH

[Landowner]

Ashcroft Transmissions do a Ratio Calculator It always tends to ask questions you don't know the answer to, 'because I haven't changed that', but feed it good food and it will give out good data. Understanding the data in 'real life' terms is another matter :-)

HTH

Higher diffs will make for more space between the gears so progressively more mph in each gear, be happy with sixty flat out so as can drive at 45

The defender would go 70 downhill and wasn't too bad normal driving so a bit lower geared that that should be prefect for the 2.5......hopefully.

Can I change front diff by taking Spheres out a bit, or just pulling drive shafts like a defender, never done a series

[BSF]

A Fairy overdrive would be a lot easier to fit and that will give an extra 27% as well as eight usable forward ratios (well, a few less as the lower ones are not much use).

Alternatively, but probably a bit late for you, put a 200 Tdi in without the turbo; My 109 with that engine and the overdrive does an easy 60 MPH

[Phil Hancock]

We have just put a 2.5 n/a Defender diesel in a petrol Series three

As expected top speed is now about 45 mph with everything shaking to destruction.

Will fitting 3.4 Defender diffs (10 spline) be a direct replacement and by how much can we expect the gearing to be raised (cant do the maths )

thanks

Pete

Only does 45mph? what gearbox have you got? If this in a 109" i would not recomend fitting 3.54 diffs, i had an 88" with 3.54 diffs and it was ok for solo running about but a nightmare for trailer work needing low box to get moving on uphill starts. A series with a Rover diesel on 7.50 x 16 tyres runs at 65mph @ 4000rpm.

[Landowner]

Only does 45mph? what gearbox have you got? If this in a 109" i would not recomend fitting 3.54 diffs, i had an 88" with 3.54 diffs and it was ok for solo running about but a nightmare for trailer work needing low box to get moving on uphill starts. A series with a Rover diesel on 7.50 x 16 tyres runs at 65mph @ 4000rpm.

It was an 88 petrol and we stuck a 2.5 diesel in it. Cant get 50mph cause it sounds like its going to explode.

Its a good engine just too low geared

[DaveSIIA]

As noted above, it should run to 60+ on standard series gearing if the engine is set up correctly. Only doing 40 in a Defender and struggling beyond may indicate that all is not well. The 2.5 N/A diesel is not the quietest of engines, but should haul a 110 up to a noisy 70+mph in 5th.

[discomikey]

A Fairy overdrive would be a lot easier to fit and that will give an extra 27% as well as eight usable forward ratios (well, a few less as the lower ones are not much use).

Alternatively, but probably a bit late for you, put a 200 Tdi in without the turbo; My 109 with that engine and the overdrive does an easy 60 MPH

you should only ever use an overdrive in 3rd and 4th HI box.

they will explode if you load them up in a lower gear as they are quite fragile.

if you can afford one they are great. but the diffs should suffice as the gearing overall will still be lower than the defender the engine came out of.

[BSF]

<you should only ever use an overdrive in 3rd and 4th HI box.

they will explode if you load them up in a lower gear as they are quite fragile.>

Not sure I fully agree with this. Granted using a lot of torque in 2nd will not do the overdrive any good and there is no point in 1st, but if you are gentle with it in 2nd it copes. 3rd High is a really useful towing gear. You will forget to change the overdrive down occasionally anyway (I do and it hasn't "exploded" yet)

As for High Ratio, since the overdrive is upstream from the High/Low ratio box, 3rd low will put no more torque through the overdrive than 3rd high, although I can't think why I would want to do that.

The answer is mechanical sympathy

[Phil Hancock]

It sounds to me like the main problem is the driver not being used to the sound of a diesel.

[Snagger]

Pulling away in second and running out of performance at 45mph suggests you have on-standard gearing, like lower ratio diffs or a 1-ton transfer box. Performance with a good 12J should not be that dissimilar to a 2.25 petrol.

You do have the correct engine mounts? You can use the SIII diesel mounts to good effect, or the Defender mounts, but SIII petrol mounts are too small and will allow the engine to shake all over the place.

[Jon White]

A Fairy overdrive would be a lot easier to fit and that will give an extra 27% as well as eight usable forward ratios (well, a few less as the lower ones are not much use).

Alternatively, but probably a bit late for you, put a 200 Tdi in without the turbo; My 109 with that engine and the overdrive does an easy 60 MPH

I still cannot fathom out why anyone even considers fitting a 200tdi without the turbo........it's not hard to fit and make it all work, and I even go the opposite and tweek the boost and fueling up even more over stock.......

Jon

[FridgeFreezer]

Tonk's 88 had a 2.5NA in it running big tyres and that always went well enough, not sure I ever saw it going below 60mph on the dual carriageway!

[BSF]

<I still cannot fathom out why anyone even considers fitting a 200tdi without the turbo........it's not hard to fit and make it all work, and I even go the opposite and tweek the boost and fueling up even more over stock...….>

I think it is each to his own and at the risk of going off topic.

On one hand I have someone telling me that the overdrive is weak and will not take the torque and on the other someone telling me to increase the torque by using a turbo!

The reasons are as detailed in Glencoyne's excellent article, but to be brief:

A series Land Rover does not need that much power, if you do you need a Defender. I don't want to go faster and it goes better than the series engine.

The gearbox and overdrive gets an easier life and the engine will probably last for ever.

The halfshafts get an easier life

The exhaust is MUCH easier to invent.

No plumbing of the turbo

You don't need a fan.

Fuel Consumption is less.

And, in my case, the turboless 200 was already hanging on a hook in the workshop.

I have never regretted the decision, even towing a heavy trailer.

Niether have I regretted the disc brake conversion, which I regard as a must when towing in modern traffic.

The 2b that I am rebuilding does need the extra power, so it is getting a full fat 200 Tdi and I will accept the disadvantages that go with it.

But, as I say, each to his own.

"Stand by for incoming!" (in an American voice)

[discomikey]

I still cannot fathom out why anyone even considers fitting a 200tdi without the turbo........it's not hard to fit and make it all work, and I even go the opposite and tweek the boost and fueling up even more over stock.......

Jon

Here Here,

i would go as far as to say the Fairey overdrive copes well with the extra torque, even with 20psi boost and a lot of pump tweaks!

<I still cannot fathom out why anyone even considers fitting a 200tdi without the turbo........it's not hard to fit and make it all work, and I even go the opposite and tweek the boost and fueling up even more over stock...….>

I think it is each to his own and at the risk of going off topic.

On one hand I have someone telling me that the overdrive is weak and will not take the torque and on the other someone telling me to increase the torque by using a turbo!

The reasons are as detailed in Glencoyne's excellent article, but to be brief:

A series Land Rover does not need that much power, if you do you need a Defender. I don't want to go faster and it goes better than the series engine.

The gearbox and overdrive gets an easier life and the engine will probably last for ever.

The halfshafts get an easier life

The exhaust is MUCH easier to invent.

No plumbing of the turbo

You don't need a fan.

Fuel Consumption is less.

And, in my case, the turboless 200 was already hanging on a hook in the workshop.

I have never regretted the decision, even towing a heavy trailer.

Niether have I regretted the disc brake conversion, which I regard as a must when towing in modern traffic.

The 2b that I am rebuilding does need the extra power, so it is getting a full fat 200 Tdi and I will accept the disadvantages that go with it.

But, as I say, each to his own.

"Stand by for incoming!" (in an American voice)

I have known poeple with standard engines and 300DI engines (minus turbo) kill more series gearboxes than my full fat, fully tuned 200TDi,

the only thing is it chipped 2 teeth off 3rd on the layshaft as i let my friend drive and he was sidestepping the clutch in third whilst rolling to try to get it to kick out the back end.

that was before i b*****ked him and told him that it would go sideways just using smooth applications of torque.

its the same with racing starts, you can really launch a tuned 200TDi series off the line but you need to learn how. you dont just drop the clutch, you need to "pre load" the gearbox.

i did this on dry tarmac, and snapped a rear shaft without doing any damage to either gearbox, transfer box or overdrive! ( i was incredibly Mildly miffed off and there was only the tiniest of gaps to pull out into. and i was not in the mood to wait 10 more mins!!

so yes a gearbox and transferbox will cope. so will an overdrive. just keep the oil clean and i would reccommend a gearbox rebuild just to make sure everythings nice and tight and perfect. DO NOT use pattern parts though genuine is a must with gearbox bits!

[FridgeFreezer]

Your foot controls the torque / damage / mpg. I don't really care which engine anyone fits but let's not invent spurious reasons to mislead others.

There's loads of people running 200TDi's in Series (and many many running V8's before them) and no significant trail of gearbox destruction in their wake unless they're abused.

Fairey overdrives are not very robust devices, the manual does state they shouldn't be used in low gears even with the standard engine. The bigger problem these days is they're all quite old / whiny / leaky and spares are thinner on the ground. Likewise Series gearboxes, on a 30+ year old truck it's quite hard to say how many lives the gearbox has left, engine swap or not.

[Landowner]

Driver has been driving diesels since 1962

Took it up to fifty today and it was absolutely at the limit of its revs, putting defender diff in rear axle tonight to see if its any better, am I right in thinking that it will have a 1.6 transfer box? ( 1979 series three petrol )

No label on it unfortunately

[FridgeFreezer]

You haven't said what size tyres it's running?

[Landowner]

Standard skinny tyres

[BSF]

I notice no-one seems to have argued with "I'm happy with the power I've got" or "I already had a 200 without the turbo". The last is an overriding reason I'm sure you'll agree. I have a car to go fast in, I have Land Rovers for other reasons.

But seriously, I was answering Wabbit Jugglers comment <I still cannot fathom out why anyone even considers fitting a 200tdi without the turbo>, so I gave him my reasons.

There are quite a few people very happy with 200Di conversions to series Land Rovers (although seemingly not on this forum) and remember we were originally dealing with a 2.5 NA diesel conversion, which is generally considered an inferior engine in every way to the 200 with or without the blower.

For the third time, each to his own. Remember the old design principle, "Simplify, and add lightness".

[Snagger]

A standard Series transfer box has a high ratio of 1.15:1 - it's early 90s and 110s that had 1.6:1 because of their taller diffs, Defenders stepping up to 1.4:1 when they got more powerful engines..

I think the question about tyres was more to learn their diameter, not their width; if you're on 6.00s or 205/70s, then you'll not be going very fast, but will be 10% faster on 7.50s or 235/85s. They won't affect speedo readings, just the actual speed, and you need the correct speedo for the tyre size (all 109s had speedos calibrated for the bigger tyres, most 88s for the smaller).

[Landowner]

A standard Series transfer box has a high ratio of 1.15:1 - it's early 90s and 110s that had 1.6:1 because of their taller diffs, Defenders stepping up to 1.4:1 when they got more powerful engines..

I think the question about tyres was more to learn their diameter, not their width; if you're on 6.00s or 205/70s, then you'll not be going very fast, but will be 10% faster on 7.50s or 235/85s. They won't affect speedo readings, just the actual speed, and you need the correct speedo for the tyre size (all 109s had speedos calibrated for the bigger tyres, most 88s for the smaller).

Thanks for the info

Diff in and road tested, had it up to 55 without screaming too much and runs at 50 nicely, (speeds via sat nav)

Its on 6.00x16 tyres so maybe upgrade to a slightly larger size as long as it doesn't affect the pulling power too much

getting a defender diff for the front next

[FridgeFreezer]

6.00x16 are tiny, 7.50's were a "standard option", all LWB's came with them.