The Fordson Tractor Pages Forum

Hi

I have a new performance which doesn't have live drive and I want to know if I can take a live drive box and clutch out of one of my other fordsons and replace it as a straight swap. Will my back end on the new performance match or is there anything different. Has anyone done this? Thanks

What is the donor tractor?
Ford changed the gearing on the NP Super (from the Super) so as to allow higher engine revs to achieve the same ground travel speeds and PTO speeds. So if your donor tractor is a Power Major or a Super, you'd be changing the gearing.
Also, you'd be well advised to swap both clutch and flywheel ie keep the two together on both donor and recipient tractors.
I've got a single stage clutch NP Super. Just my personal opinion, but I don't get the need for the dual clutch, though I do see unnecessary complication, expense and potential catastrophic failure. Ask Brian.
Best, Adrian.

Hi Philip

Physically a flywheel, clutch, gearbox and PTO drive from a live drive Major/Power Major/earlier Super Major would bolt straight onto your NP engine and rear end , but there are many internal differences ( and some external differences) between the NP gearbox/PTO drive and that of the earlier models!!

Virtually the whole of the "New Performance" came from changing the PTO drive gears and ratios so that the engine speed at which 540 rpm at the PTO was achieved was increased from 1200 rpm to 1473 rpm (say 1500 rpm for simplicity) . This enabled far greater power to be delivered at the PTO at the standard 540 rpm speed ( a genuine 42 horsepower on the NP as opposed to barely 32 horsepower on the previous Super Major) . The engine speed of 1200 rpm had been originally chosen as it was the speed at which the engine delivered peak torque. This was fine in the 1950's for earlier implements such as mowers and combines which had low horsepower requirements, but was not enough for the later implements such as rotavators and forage harvesters! However an increased engine speed at 540 rpm PTO with the original gearbox and final drive ratios meant increased forward speeds, so the first change needed was to change the final drive diff ratio from 3.5:1 to 4.375:1, this brought the forward speeds back to as they originally were, the change from 3.5 to 4.375 is in direct ratio to the change in engine speeds from 1200 to 1500 rpm. Ford then made further changes to the actual gearbox ratios to make the spread of speeds better suited to PTO work,( I think they might have had the DB 990 in mind when doing this!), and every gear ratio except 5th was changed to achieve this better spread.

With increased power came the need to have stronger components and castings. Failure of the PTO drive casting had occasionally been experienced on Major/Power Major/ earlier Super Major tractors under conditions of constant extreme or surging load - the two lugs carrying the shaft for the intermediate gear would shear off allowing the gear to become loose which usually ended up damaging the PTO gears and bottom drive gears in the gearbox. Consequently the New Performance PTO drive casting was heavier and stronger and was about 40mm bigger in diameter where it met up to the underside of the gearbox - this is how to check for a genuine New Performance, people have been known to put hydraulic covers with the drop control valve on earlier tractors and re-paint them blue/grey and attempt to pass them off as NP in sales! I have seen more than one "Heinz 57" tractor cobbled up from various parts like this in vintage sales! This heavier PTO casting also meant that the main gearbox case was different and stronger than the earlier models, and the gearbox and PTO cases were not interchangeable with the previous models. The PTO gears themselves and the lower drive gears in the gearbox as well as being of different ratios had different hardening treatments to make them stronger. The PTO drive extension tube was increased in diameter by 1/8 inch. The PTO selector lever size was changed. The number of teeth on the hydraulic pump and drive gear on the PTO extension tube were changed to allow for the increased engine speeds encountered now.

The upshot of all this is that, if you fit an earlier live clutch, gearbox and PTO drive assembly to your NP, you will get "Old Performance" PTO capability and a set of completely screwed up forward travel ratios and speeds! The conversion to live PTO can be done and done quite easily by sourcing a flywheel, live clutch and NP gearbox and PTO drive assembly form a breaker, they appear quite regularly on Ebay, a number of NP Super Majors are being brought in from continental Europe at the moment for dismantling. This would be your best option.

One further thought - if this is for the NP Roadless that you have previously mentioned then the 12 inch diameter live clutch assembly with it's aluminium cover was not thought to be robust enough for this type of application and that is why you will have a single plate heavy duty clutch in it - beware of creating problems that the original makers avoided!

Yes it is for the roadless. I didn't know they were intentionally only making the single clutch versions into roadless due to the clutch build quality. If I've understood you that's what you mean.

Thanks.

I think I will leave it as is then as advised by you fine chaps.

a raised pto is more interesting then a live drive imho.