putting a IIa g/box in a series III

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putting a IIa g/box in a series III

Postby David V » Tue Oct 02, 2018 11:43 pm

Hi,

I'm new to the website though I have owned an airportable for almost 15 years. My question is this; has anyone put a series IIa gearbox into a series II FFR? I drive my truck pretty harshly and spend a lot of time off road. I am not happy with the reliability of a series III gearbox and have had several issues over the years. I feel like I'm repairing a manufacturing defect rather than wear and tear. Currently I cannot keep it in first gear on deceleration; which is not an issue on the flat but is extremely off putting on steep inclines where brakes will neither stop you or prevent you from leaving a trail. I have a late suffix (F) gearbox which on inspection, is far better designed and uses better materials for components. No synchro on 1st and 2nd is not such an issue as the series II second gear baulk ring is also giving trouble so I always double de-clutch into 2nd to prevent further issues. I am rebuilding the IIa box and I see an issue over the interface with the engine's flywheel. The series III has a 9.5" clutch and some series IIA's also but how do I know what I face? The IIa boxes came with no clutch or flywheel so I have nothing to compare to.

will the IIa pressure plate bolt up to a III flywheel?
is the gearbox input shaft compatible with the II flywheel?

Any help would be appreciated muchly,

David
David V
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Re: putting a IIa g/box in a series III

Postby FrogPart » Wed Oct 03, 2018 11:02 am

Yes, YES,,

However :) first - I cant. agree with your comparison (as is a common myth) regarding the superior strength of the S2A main box, i will not go into the reasons of this old chestnut, most I have forgotton as parted almost from S2A.

2nd. If you compare the S2A clutch release mechanism to the S3 , then the S3 looks a load of 'value engineering' £rap - true , however the S3 mechanism does work very well and in reality is just as good - as it should be.

3rd. Look at that S2A parts book for the actual clutch unit - complex, look at the S2A Rep. Op. manual all that time-consuming complex set-up , that is inferior to the S3 . What you need is the , let us say Borg & Beck (now the badge is owned by Firstline) hydrostatic diaphragm clutch unit, although a Valeo + odd other one is just as good , my pick is always as a rule a LUK,, WHAT YOU NEED IS a special unit , THE unit as far as I am aware only manufactured by B&B , although I think the last I used was under the label of AP Driveline Technologies (you need to know your clutch history). this clutch unit - THE only unit worth consideration has a special BLOCK thingie that locates in the bore of the diaphragm spring fingers - so you use the very strong (this is arguably the STRONG part) S2A clutch unit and associates all between the basic main S2A box and the standard rear flywheel S2a housing casting.

Most of my stuff is only in memory , busy , very busy just now - I would have to look in the odd vehicle log book of work done for more inf. (part number) of that clutch unit. The only person I suggest worth a conversation on this is Dom. at LR Series.

PS. A S3 ECM box is obviously a very good main-box, however - the most , most superior Series MB is the Suffix 'K' box made by Santana = period.. (Santana - who made the very last S3 MB's for Solihull (and then continued to supply the K as full new spares), Solihull had to devote their machine tools to the coiler gearbox(s) etc. + discontinuance of 109" & 88" production over 1 year - did not warrant UK manuf. also Santana needed the K for their own leafers that continued in production for years, such as their 109" station wagen along with Militar types , s.w. fitted with that 6 cylinder Series diesel (4 + 2 cast-on) and other thingies was getting heavier & heavier - this is the main & T gearbox test of strength.
And I thought it was a thermostat !
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Re: putting a IIa g/box in a series III

Postby FrogPart » Wed Oct 03, 2018 8:36 pm

https://www.paddockspares.com/571228bb- ... eline.html

This seems to be the cover , I have a note - Borg & Beck Type 9.1/2" & 9" D.S.

Can't remember what the abbr. D.S. means :? it seems as if it takes a 9.1/2" or 9" plate :?

The other thing I recall , some people have problems getting the correct stroke on the release , IIRC there is a early and a late mounting bracket for the clutch slave cylinder. ISTR - you need the late type otherwise you have to frig about with a non-standard length operating rod. Somewhere I have samples of both. With the S2A release - the archilles heel is part of the release mechanism - the design (crushed tube) of the X-shaft muff-coupling. LR Series stock a thick-wall (steam tube) improved type along with the required cheese head pins. You need to eliminate all wear/lost motion in this area & maintain them well greased. Get it well sorted and the diesel-spec. used on petrol does not require any additional leg strength - you would never notice.

---------------------

Needs more research on Part Nos. Turner Eng. list this one specifically for petrol.

https://www.turnerengineering.co.uk/571 ... 2x24827379

NB - you only get that centre triangle shaped block thinghy with a S2A ordered.
And I thought it was a thermostat !
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