Modified Minors

How's this?...

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Gerard

http://gerardsgarage.com/



Edited 1 time(s). Last edit at 2013-11-03 11:51 AM by pixelsmithusa.

Great, thank you.

If you have a 1098cc ribcase transmission, by far the easiest route is to have the 1275 flywheel re-drilled for the std 1098cc clutch .. you can also use the 1275 diaphragm clutch as long as you use the full assembly (all 3 pieces) and keep the standard original mechanical linkage .BUT the pedal is likely to require more effort due to the strong diaphragm of the 1275 clutch.. BTW..IF you have the full 1275 powertrain there are 2 ways to go:- hydraulic clutch conversion (avail from UK ) or fit the original l.h.d morris front trans cover ..the ones from 948cc cars will need two holes drilled in order for it to fit the ribcase trans...

The 948 cover has the wrong fork and fulcrum point on the cover to use with a rib case and 1098. They are not the same components used in 1098 series.

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Gerard

http://gerardsgarage.com/

I have been using mine for the last 5,000 miles with 1275, ribcage withe 948 front cover for left hand drive, diaphragm pressure plate and Spridget release bearing with the Morris Minor fork and mechanical linkage. So far all seems well.

correct..but it still works absolutely fine..(Critical issue likely the correct release lever to match front plate) :- I just removed a rib case that was attached to a 948 engine that still had its std 948 backplate..inside were a 1098cc clutch and flywheel...the old 948 gearbox LHD front plate had been re-drilled to fit the rib case.(dated april '63..C.R. box from an early 1098cc sprite/midget) . and it all worked just fine..with pedal feel as normal .. ( I fitted the car back to std spec 'smooth case' box and 948 flywheel and clutch..reason being it was a spectacularly sound and original early car with matching engine..the trans had been the ONLY modification from stock ..car a Feb '57 'tourer' that is now in Kansas with happy new owner ) I have now rebuilt the rib case box ..(had bad 1st and reverse..I had an NOS 22G76 laygear on hand as well as an NOS 1st gear hub assy) and deciding which engine to go with (have both 2" main 1098 and 1275 engines rebuilt and ready to fit the next project) I do have the correct rib case LHD morris front cover as well as a 1098 release lever and will probably use it rather then the re-drilled 948 front plate for which I might not have matching lever on shelf... basically...I'm finally getting to use up parts that Iv'e been dragging around for over 25 years...most of my time being spent on B series cars..

it works fine regardless of fulcrum point..the critical issue is matching the lever to cover.. the 948 front cover WITH 948 lever adapts to the rib case box with the addition of 2 new holes in cover to match the ribcase stud position. a mismatched lever to cover would cause problems for sure..

Philip :- how is the pedal pressure with 1275 clutch and 948 release mechanism ? reason I ask is my current stock 1098 has a very heavy clutch .(I believe due to the fact the clutch is old and worn..linkage is in good shape) and I recently owned a 948 with 1098 clutch and flywheel, ribcase box and 948 front plate and linkage...it worked very well..nice light pedal..and good 'feel'(I still have the clutch and flywheel assy..clutch had about 3,000 miles on it)
The leverage ratio is different on the 948 front plate compared to the rib case 1098 plate ..i948 has MORE leverage than the 1098 in which the pivot point is closer to outside of trans.. given this..a re-drilled to fit 948 front plate might function better with a 1275 diaphragm clutch. there certainly seem to be plenty of LHD 'smooth case' boxes still out there.

I feel it is totally normal, no strain whatsoever. Only problem is I am a truck driver, a semi truck clutch is extremely heavy, we learn real quick to shift without using it except to start and stop.

In practice..as long as one uses the matching release parts (ie..948 cover with 948 release arm..or rib case cover with rib case release arm)it works fine.. the 948 cover and release arm produces slightly lighter pedal than 1098 due to different (increased leverage..less movement) pivot point.. Iv'e discovered that old 1098 clutches can get VERY heavy to depress when old and worn ..with the clutches its critical to use the matching parts as an assembly..the relasse bearings are different depths on the actual cast housing ..948 most shallow ..1275 deepest..

I once tried to convert a Bug Eye 948 Sprite to a 1275 engine from a later model MG Midget. The problem we ran into was that the smooth case Sprite's male input shaft would not mate with the 1275 engine's female clutch splines. I had been told that it was a direct conversion. But, no way would they get together.

The solution was to use the 1275 Midget transmission. I did not want to use it because it needed an expensive rebuild and the smooth case original was in good condition. I could have changed the clutch friction plate but didn't believe that the 948 clutch would hold up to the greater torque of the 1275 engine.
All the frustration was worth it because the Bug Eye became quite a fast car after a few modifications to the engine for a little more power.

In spite of the time consuming nuisance..you have ended up with a much better and more durable power train..so ..all good.
In practice there are known differences between the smooth and rib case gearboxes..the 1st motion shafts are different lengths (presumably to compensate for the differing backplate thickness) but the spline pattern SHOULD be same ..I use old 1st motion shafts for clutch alignment...and am aware of 1 which does not fit the later clutch centres..so the spline may indeed have some minor differences.. I don't know for sure.. to the naked eye they look the same. Different spline profile may explain why a recent rib case conversion that recently went through my hands on a 948cc engine had a later 1098cc flywheel and clutch fitted.. does anyone know if the spline profiles are in fact different between smooth and rib case box's ? it seems they possibly are. ,

Does anyone know where to or who installs a seal in the front cover plate for a smoothcase LHD plate. most of the ones I've seen are 100. ++ plus core.

Has anyone put a 1098 transmission with 1098 shifting fork and front plate behind a 1275 motor, using a 1275 clutch disc, cover and release bearing, and had it work well??

diffrent secnario from Uk to USA :- the 1.3 marina was never exported here..nor were 'other' vehicles post '67 that used the 1275 'inline' engine.. the common 1275cc engine here is from Sprite/midget which was sported till late '74 afar which time, the A series was replaced by a triumph 1500 in the midget.. .. ... these have a small diameter diaphragm clutch.. the 1.3 marina has a bigger flywheel and choice of several clutch's that will fit.
The 948 clutch is not strong enough for anything more powerful than partially knackered 948.. and the 1098cc clutch does not fit directly to the midget flywheel..nor are flywheels interchangebale twixt 1098 and 1275 (more bolt holes on 1275 crank) this limits the easy 'bolt in' choice to the stock midget clutch .. or a 'different' (not readily available here ) style flywheel .. the good news is that the front plate which doubles as clutch pivot lf , for LHD Morris rib case box is now readily available from most UK suppliers.. along with the arm itself... many simply drilled their old 948 front plate to fit when converting to rib case box..