Hi folks.
Contemplating - for discussion - ways of lowering the overall gearing of the FL1 (in this case an L Series)

It would appear that these best way (if one wanted to do this ) would be to use the 1.8 K series gear kit and gearbox final drive unit in the TD box. (that is IF the 'U' - Up-rated) parts of the support bearings (and 'U' upgrades) etc for the TD box could be changed to support the K series - without losing the 'U' Status of the box. - in other words - adding the K series internals to a TDi Box and maintaining the 'U' status.

The K series gear set has the same gear ratios yet has an (apparently nice!) gearbox final drive ratio of 4.2:1 as opposed to 3.647 on the TD L series box. (please do not confuse this with rear DIFF ratios which are the same and nothing to do with this hypothesis
This is effectively a 14.1 % decrease of over all ratios which (in theory) should make a rather large increase in off road performance in 1st or reverse - yes, the ON ROAD performance will suffer slightly - but hey !
One of the biggest issues (to me) with the FL is the need to achieve lower gearing in off road use. - Should the 1.8K series gear kit fit in the TD (U) box (maintaining the 'U' spec - along with the 4.2:1 final drive - it could be a VERY interesting mod.

Any input appreciated.



Joe

I'll swap you my k1.8 box for the L box, it's a bit of a thrashy nightmare on the motorway!

It's a long time since I read up on the differences between the various PG1 specifications. However, my understanding was that the K and L Series (U) specs use different size shafts and/or bearing sets - so I would question whether the K spec final drive would fit in a L spec casing - or K spec gears would fit on L spec shafts. I've just done a search to find this....

http://www.mgf.ultimatemg.com/group1/info/Gearbox_numbers/index.htm

It says the differences in the U spec are...

• Bigger bearing fitted to upper end of input shaft

• Double bearing is fitted to the upper end of the Mainshaft

• Different spline for 5th gear.

• Longer and larger 35mm journal for lower mainshaft bearing with a bearing retainer plate and shot-peened gears.

So, it looks like the shafts are the same spec. I don't know if the last bit of 4th point implies the output shaft and final drive gears would be a different spec other than number of teeth (I would imagine not?), but it does look like you could swap the output shaft and final drive gears from the L (17/62) for the K (15/63).

Its sort of the wrong way you'd want to do it, but you could run larger tyres on-road to have the gearing back for more comfortable high speed motoring.

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Hi GG and Nodge (I knew I could rely on you guys !)
Many many thanks for the input. I have looked at the info you got GG and it seems in contradiction to RAVE - however - Microcat parts catalogue seems to confirm (mostly) the details from the MGF site.

So far - as far as I can ascertain from Microcat and Rave

GrumpyGel said:

• Bigger bearing fitted to upper end of input shaft

• Double bearing is fitted to the upper end of the Mainshaft

• Different spline for 5th gear.

• Longer and larger 35mm journal for lower mainshaft bearing with a bearing retainer plate and shot-peened gears.

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It would appear that the 'upper' refers to the 'rear end of the box' ie - with the box laid on the floor with the bell-housing down (if that makes sense ?)
Indeed, the bearing on the 'upper end.' of the MAINSHAFT (also referred to in this context as the INPUT shaft - both terms are used in Microcat and Rave for the same thing ) appears to be 28 x 75 on the petrol and 28 x 78 on the diesel. While the 'lower end' bearing is identical in ref to part numbers. - The shaft is a different part number - petrol to diesel' - however, that - theory, would not be changed.
There appears to be no 'double bearing' fitted to the input/mainshaft. It is the 'upper end of the OUTPUT shaft. In the K series it is still a double bearing (2 x ball bearings) in the L series it is 1 x Ball bearing and 1 x Roller bearing. The ball bearings appear to have differing part numbers and so far, I have found no actual sizes for these bearings.
By lower mainshaft - I presume they mean 'output shaft' This is the one with 'upper' double bearings - the 'lower' output shaft bearing (needle roller) is also a different part number.... Hmmmmm...
The final drive 'drive gear' is part of the output shaft so the output shaft would have to be changed to accommodate the final drive driven - gear (which is bolted on to the existing carrier unit.)

The different spline for 5th gear should not be an issue as 5th gear is still the same 'size / diameter / teeth' and no need (as far as I can see) to change the input / mainshaft at all
The 'Longer and larger 35mm journal for lower mainshaft bearing with a bearing retainer plate' - I believe - refers to the output shaft - not the input / mainshaft and is probably to do with the different dual bearings - I believe that is the journal that they mount to.

It would appear- at first glance - that the output shaft (which has final drive gear machined onto it as part of the assembly) is different in the bearing mounts and possibly journal sizes. That would tend to indicate that it may not be possible to swap them over - but.............. I am sure someone has done it at some point !. A larger 'journal size on the output shaft does not necessarily mean a greater diameter outside dimension of the bearing (but may do)

It would appear that the only things that need changing is the output shaft and the final drive outer driven gear (the large bolt on one.)
The 'K' shaft may have a smaller journal diameter (by the look of it) but still uses a roller bearing at the 'lower end' and 2 bearings at the upper end (2 x ball bearings on the K and 1 x Ball and 1 x roller on the diesel) - I would imagine it is quite possible to get the correct size inner and outer sizes and width size bearings to suite slightly different journal and case housing sizes.
What do you think oh gurus ?.. It would be bloody good if it could be done !. in fact - for where I live - a lot of the time (the majority) of 'on road' is 50 - 65 Km in fourth gear and in that 'band' the rpm is just dropping in and out of the 'turbo ideal band (around 2000 rpm) and that makes it slightly a pain to drive. with the 'lower final drive' it would have another 280 ish rpm at those speed which would keep it in ideal boost - and be far better off road.
I was also amazed to find out that this is the only vehicle I have ever owned that has a higher ratio reverse gear than first ! - in the past it has always been the other way around.. that would explain why I have a hell of a 'clutch smell' trauma when trying to reverse up the rather steep incline outside my door as opposed to driving up in first - which is ok....

Also love the idea of - if it can be done - and where there is a will there is usually a way (or in most cases - a relative ) that larger wheels / tyres could be used to revert the overall ratios if long distance on road cruising were contemplated. ! good call.

Joe

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Nodge68 said:

These are the U box bearing numbers.
The U box uses 78mm bearings in the input shaft whereas the K box uses a single 75mm bearing.
3/LJ28 Input shaft (inboard 78mm)
3/MJ28 Input shaft (outboard 78mm, not fitted to K box)
3LRJA25 Counter shaft roller bearing (outboard)
43/LJ25 Counter shaft top bearing 1LLRJ33 Countershaft roller bearing (inboard)
18/6208 x 2 Diff bearings
All bearings are made my RHP and steel caged are the best type to use.
It is very possible to build a hybrid K/U box, with minimal outlay

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Nice one Nodge ! - How theoretically would you propose to go about such ? - I note some of the bearings are actually plastic 'caged' - and also the bearings and journals of the output shaft appear to of differing sizes - are you proposing using the K output shaft with differing bearing sizes ? - I cannot see any other way as the final drive 'drive gear' is a machined part of the output shaft.
Thanks for the input
Joe

What would happen if you just slapped a K series gearbox in as it is? Assuming the bolt pattern is the same, it might be a bit weaker but there must be thousands of them around in dead Freelanders lying in the scrappies. If it breaks swap it out.

Alibro said:

What would happen if you just slapped a K series gearbox in as it is? Assuming the bolt pattern is the same, it might be a bit weaker but there must be thousands of them around in dead Freelanders lying in the scrappies. If it breaks swap it out.

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Hello Alibro mate , If I did that - I would have a huge huge worry issue lol
I am having the FL re-mapped (chipped) and will be looking at a realistic figure of 220 - 230 Ft Pounds torque. - the U series box is rated for (conservatively!) - (I believe) about 170 + .. whereas the non U are rated far far below.
So really a direct swap for a K series is not really feasible.
The removal of the CAT has made a dramatic difference to my L series. A chip replacement - I am doing it myself as far as the removal of the old - socketing the eproms - and replacement with EEproms - the hard work is being done by Kris at http://www.dieselpowered.co.uk/
We have conclusively determined that - against popular opinion ! - the MG ZR turbo is EXACTLY the same performance as the Free lander L series turbo.
The 'S' suffix on 1549 - means jack **** - it means that the turbo is an internally waste gated unit - nothing more !.
The turbine wheel and compressor wheel are exactly the same between the 100490 and the 100500. !
The A/R ratios are exactly the same - hence contrary to popular misinformation - the ZR turbo is NOT an upgrade for the FL L series .... 100%
The FL 1 td L series also HAS the 'sdi' injectors as standard - well - slight differences but virtually identical - so no increase in performance by adding either SDI injectors OR ZR turbo Compressor and core unit - totally wrong info !

The standard FL L series can easily be upped to about 225 torque - which I am aiming for... hence the gearbox has to be as strong as possible.
Joe

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Nodge68 said:

I'm sure you can use the U box casing with the K diff carrier and main shaft. This would need to be matched to the U bearings with sleeves if necessary. The gear cluster would be U box as I think it will all fit the K main shaft.

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Hi nodge - Do you mean the K series 'output shaft' ? as opposed to mainshaft ?
The 'diff carrier' surely (imho ?) would be the same - no need to be changed - only the bolt on driven large gear ?
Joe

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Lots of talk about different bearings - and I'm a bit lost!

However! The Input shaft stays as-is - only the Output shaft needs changes plus the driven Final Drive gear. The driven Final Drive gear looks to be a straight swap for the extra toothed K one - so no issues there. Which leaves only the Output shaft where things needs to be considered.

From what you say, the Output shaft has the Final Drive drive gear machined into it at birth - so presumably can not be changed. But, you're in luck because everything else on the 2 different shaft inside from the bearings on the K & L Output shafts are identical - so the whole K shaft can be used - so long as the bits it spins on (bearings) can be upgraded to the L spec. If they can, then it follows that they will fit in the L case. This is only true as well if what you say about the 5th gear splines only applies to the Input shaft and the Output shafts are identical.

So other than swapping the 62 tooth driven Final Drive driven gear for the 63 tooth one, it looks as though the "only" other thing you need to do is fit the L (U) spec bearings to the K Output shaft. This being the case, presumably you need to compare the width an internal diameter of the different bearings (@Nodge68 has provided the L (U) spec ones). Hopefully they'll be the same - but as I said initially, something tells me they are not, so the shaft will need to be machines to take the bearings. Hopefully the internal diameters are smaller on the U spec so you can simply have the shaft machines down to size rather than worrying about collars.

Interesting what you say about the driving characteristics of your L. Most of the time our's is running at the same 50-60kmh speeds - but around town. Here it is dead flat, straight roads and reasonable distances between stops (little congestion and spread out) - so you're maintaining a speed of 50 or 60. 50 is a no-no for 5th, I always try it, but always end up back in 4th - but its more than happy in 4th. It will hold 60 'OK' in 5th (1,500rpm), but you know if you need to accelerate - its definitely a case of "computer says NO". If you hit the smoke peddle at 60 in 4th though (2K rpm) - you will get that L Series cheek rippling acceleration.

The most enjoyable driving I've had out of the L Series has been when I've been towing our boat round the Queen Charlotte Drive. This is a hilly, super-twisty road up in the "Sounds" here in NZ. It just hits the sweet spot and I hardly need to change from 3rd - just feathering the accelerator and down to 2nd for the hairpins - its a really really wonderful drive

https://www.google.co.nz/maps/@-41.2708252,173.9565243,14z

Nodge68 said:

There are 3 shafts in the gearbox.
The input shaft takes the drive from the clutch, driving various gears to mesh with the main shaft.
The main shaft carries most of the gear cluster and the gear that feeds the modified ratios to the output shaft.
The output shaft is effectively the diff carrier, although on the Freelander there's no actual diff in there, just a spline to feed the power to the IRD.
That's the way I'd describe the gearbox shafts. They are much the same as an inline gearbox, just in a different configuration.

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That's interesting! I've never dismantled a PG1, only seen drawings/images. But I've seen reference to the Diff and wondered whether this was just a 'mounting' for an external diff - which is used to mount the IRD on Freelander or whether it is actually a Diff internal to the gearbox.

From what you are saying it is actually a diff internal to the PG1. This being the case, presumably in Freelander there is an "empty space" in the PG1 somewhere between the final drive and the output to the IRD. Perfect space of a couple of High/Low range gears maybe

OY! Joe, you great nonce.
Stop all this technical fancy talk, you sound like a right ponce.
Just stick bigger wheels on it. Job done
Mike

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Skinny Mike said:

OY! Joe, you great nonce.
Stop all this technical fancy talk, you sound like a right ponce.
Just stick bigger wheels on it. Job done
Mike

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That's the prob - Joe wants to go the other way (ohh nurse!) and get more turns of the smoke box per foot traveled. I'd think the Freelander would look a bit naff running wheels off a Mini!

Nodge68 said:

There are 3 shafts in the gearbox.
The input shaft takes the drive from the clutch, driving various gears to mesh with the main shaft.
The main shaft carries most of the gear cluster and the gear that feeds the modified ratios to the output shaft.
The output shaft is effectively the diff carrier, although on the Freelander there's no actual diff in there, just a spline to feed the power to the IRD.
That's the way I'd describe the gearbox shafts. They are much the same as an inline gearbox, just in a different configuration.

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Hi Nodge, Most of the problem when actually 'naming' the shafts in the gearbox when discussing them is the description and terms that LR use and the terms we are mostly familiar with from other (in my case mainly inline - rear wheel drive transmissions)
LR state 2 shafts - the input shaft (upper shaft as mounted in car) and the output shaft (lower shaft as mounted in car) The diff carrier (final drive carrier) is not referred to as a 'shaft' - as it is usually not referred to as a shaft in a final drive in 'normal diff'. (such as the FL rear diff)
Using this nomenclature is, sort of, contradictory to people who have worked on other 'normal type inline boxes where we have a separate input shaft connected to the main shaft with an extension rearwards through the case - the output shaft (which is actually part of the mainshaft and also a layshaft (countershaft).
It is a matter of the terms we use to describe the various parts.
Here is the LR description (below) -
If anything I would also consider calling the output shaft the mainshaft but that can also lead to even more confusion as there is no layshaft / coutershaft in the PG1 -the layshaft as used in a 'standard box'is effectively eliminated.
How confusing for us who were weened on in line transmissions eh ?
Joe

GrumpyGel said:

So other than swapping the 62 tooth driven Final Drive driven gear for the 63 tooth one, it looks as though the "only" other thing you need to do is fit the L (U) spec bearings to the K Output shaft. This being the case, presumably you need to compare the width an internal diameter of the different bearings (@Nodge68 has provided the L (U) spec ones). Hopefully they'll be the same - but as I said initially, something tells me they are not, so the shaft will need to be machines to take the bearings. Hopefully the internal diameters are smaller on the U spec so you can simply have the shaft machines down to size rather than worrying about collars.

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Hello GG, ta for the reply -It is interesting - that according to nodge's bearing numbers and also cross referencing with Micro cat that the K actually has the larger diameter Output shaft 'top' bearing - and seems to use a single bearing only - the bearing -
Designation: 4/MJ 28 ➀ CDU78L Petrol
Type: Deep groove ball bearings. Single row, without filling slot. Complete. (28X75X19).
As we can see (if all this cross referencing is ok) has a 28mm shaft journal size and an outer diameter of 75mm
Whereas the U series shaft runs 2 bearings in the same position - 1 ball and 1 roller.
The size as gathered from microcat and nodge's info and other cross referencing indicates -
FREELANDER 1 Rover Diesel PG1 Gearbox
Rover
Size :25 x 56 x 17
P Numbers -CDU79 CDU79L 43/LJ25 3/LRJA25
(haven't got a definitive size yet for the 2nd roller bearing on the U - the CDU80L - however, in theory it must be the same journal size Internal diameter and most likely the same outside diameter. (the case could be 'stepped' but highly unlikely)

This is interesting as the shaft journal size is decreased to 25mm on the U however it is lengthened (by extrapolation as 2 bearings are fitted in U but 1 as in the K) also the bearing outer diameter is decreased. to 56mm.
The single bearing 'length' on the K is 19mm and on the U is 2 of 17 mm (or certainly 1 of 17mm and another CDU80L that at this moment I have not got a measurement) - but if the same or similar it is likely to be 34 / 35 mm in total (which corresponds with point 4 in the link you first gave. The opposite end of the output shaft bearing / journal size appears to be identical on both and the bearing part number is the same.
So, it is not such a straight forward swap as one could not get the dual bearings onto the K shaft. presumably they changed to dual but 'smaller' bearings on the U to increase the strength.. hmmmm. interesting stuff ...

GrumpyGel said:

Interesting what you say about the driving characteristics of your L. Most of the time our's is running at the same 50-60kmh speeds - but around town. Here it is dead flat, straight roads and reasonable distances between stops (little congestion and spread out) - so you're maintaining a speed of 50 or 60. 50 is a no-no for 5th, I always try it, but always end up back in 4th - but its more than happy in 4th. It will hold 60 'OK' in 5th (1,500rpm), but you know if you need to accelerate - its definitely a case of "computer says NO". If you hit the smoke peddle at 60 in 4th though (2K rpm) - you will get that L Series cheek rippling acceleration.

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On the flat or 'flattish' mine is also fine - however we have a lot of hills around here - country roads that are up and down like a bride's nightie. at around 60 kph in 4th uphill you can just drop into the 'naughty' l series 'giggle band' s I call it and you so well describe above. which is ok but a tad annoying. - I may find that the remap alters this ? will have to wait and see. (I have an idea about that also (a cunning plan) but that is for another thread

GrumpyGel said:

The most enjoyable driving I've had out of the L Series has been when I've been towing our boat round the Queen Charlotte Drive. This is a hilly, super-twisty road up in the "Sounds" here in NZ. It just hits the sweet spot and I hardly need to change from 3rd - just feathering the accelerator and down to 2nd for the hairpins - its a really really wonderful drive

Click to expand...

Sounds superb and your pictures are excellent. Will have to get some posted of the view over the river Douro from the house as it is very similar to your fist excellent photo - what a lovely place mate.
/ramble off
Joe

Skinny Mike said:

OY! Joe, you great nonce.
Stop all this technical fancy talk, you sound like a right ponce.
Just stick bigger wheels on it. Job done
Mike

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Yo Mike - Ouch ! - I resemble that remark you old sod..
Joe