2nd gear always dies first.

Hi Andy

I had similar problems on my 88" 2a this was running a 2.5td with a fairy overdrive. Imo the main problem is that the gearboxes are only just up to the job of a 2.25 petrol engine so if you you put any extra grunt through them they fail remarkabley quickley.A bloke up the road from me who builds lots of them (supplies paddocks) will not warranty the box if an over drive is fitted or it is fitted to anything other than a standard engine. IIRC The later series 2a boxes were the strongest they made but no synchro on 2nd and saying that I went through 2 of them. The way I fixed mine in the end was to get a 110.

Hope this helps ( note my earlier post :-) )

Icky

The Series 3 gearbox was designed primarily for the 2.25 petrol engine. It copes with the six since the impulse from the individual cylinders is no more than on the four, but your engine is substantially higher torque than either, and also has much higher torque pulses than the engines the box was designed for. Your problem is that the engine is simply too powerful for the gearbox. The S3 gearbox is an all synchro development of the S2 box, which in turn is the S1 box with a few minor changes - and the S1 started life with a 1600cc engine of just over 50hp. But I understand the box was originally designed in 1932, when it was fitted to even lower power engines. JD

Thanks folks, well that seems pretty unanimous - the engine is too butch.

Oh well, now you've got me curious about later gearboxes. Don't go doing any major research but off your collective heads, are there any glaringly obvious issues.

Is there any similarity in length, bell-housing size and stud positioning or gearbox mount positions?

My biggest issue is with getting another engine/gearbox conversion plate made up.

It's on a 109 chassis with the detachable gearbox X-member if that helps. Cheers folks

If you have a look at the actual gears that do the 2nd gear work, you will see why they always wear out. In a IIa box, 2nd engages onto the

1st gear on the mainshaft to get drive along the mainshaft (2nd gear just idles on the mainshaft when out of gear) However there are only 11 protuding teeth on the 2nd gear, and 22 recieving teeth on the 1st gear, which engage as a dog clutch. Furthermore the teeth are only about 6mm wide or so. Consequently they wear out very quickly. The problem is less evident on SIII boxes as they have a synchromesh on 2nd, which means that you get less damage engaging the gear. Unfortunatly the gearbox is the same length, so there is no room to make the gears much bigger, so they still wear out, just not as fast. )

Your particular problem is that you have an engine which puts hell of a lot more torque through the gearbox. The Series gearbox is just not up to the job of handling much more than the power/torque output of a

2.25. It is an old design and despite the many, many modifications LR did over the 40 year life of the gearbox, it was never going to cope with anything bigger than the 2.25. Your only realistic option is to fit a later gearbox, from range-rover or defender.

Alex

Are you happy that the reconditioned boxes that you are using are fitted with new parts in the first/second synchro areas mentioned above by Alex?

I suspect that some (probably many) reconditioners are re-using parts which might survive their warranty period with the standard engines but have no chance with any engine with a greater output torque.

The long term solution lies with a different gearbox.

Sounds to me like the conversion plate is misaligned or off centre.

You can't really misalign the Fairey overdrive when fitting, but the gearbox mainshaft is not held as rigidly by the overdrive unit as the by the original rear bearing carrier where the overdrive now fits which will allow any run out of the mainshaft caused by a badly made conversion plate to be exaggerated and accelerate wear on second gear. (Run out on the input shaft will also affect the mainshaft behind it). Are you locking the mainshaft rear nut up properly on the overdrive adaptor?.

If the gearbox oil level is low the first and second gears may not dip in the oil but should still be lubricated by splash from the constant mesh. If it is losing all its oil in only a month then you have a serious leak which could run it dry and definitely needs sorting.

Have you yourself actually looked in the box to see what's worn and what isn't?. Series 3s are stronger boxes than series 2s but are weak on reverse (don't pull anything heavy backwards!).

A 200Tdi engine will fit straight to a series gearbox less one stud and a couple of holes drilling so it follows that an early 5 speed box off a

200Tdi will fit a series engine , or a conversion made to fit a series gearbox. Don't forget you will have to change the clutch driven plate though to fit the input shaft. The removable gearbox crossmember will be no good though, you will have to adapt the 5 speed crossmember or fabricate another and redrill the chassis.

Finally if the problem lies with the conversion then you will have to source another one anyway.

HTH Martin

It is certainly the case that 2nd is the one that jumps out of gear on my series.

In my experience the main failures are 2nd gear or the synchros on

3rd. Excepting early IIa boxes (A-B suffix) and early SIII boxes, where the layshaft bearings fail.

Alex