gearbox

[DaveTomo]

Giving a mate a hand to build a 200 engine,trying to get the gearbox right has turned into a right nightmare I'll give you the set up.New 200 casing with matching endplate,RIV rear hub bearing (went in a treat),original innocenti layshaft and sliding dog & wishbone from his previous engine and a LI 150 gearbox again from previous engine which when in the previous engine were superb.The rear hub bearing has been correctly torqued,the layshaft gone in with sliding dog,wishbone etc.gearbox put in (the right way- double and triple checked!) and the endplate which is matched to the casing.fitted the rear hub and all correctly torqued up to finalize the shimming.Thought it was going to be a hours work .......anyway 4 hours later still can't get the f*****g thing to shim,tried differnet endplates & shims.Get the thing shimmed up with in the given tolerances the gearbox will turn and then seems to bind,maybe the best way to describe it would be to say, if you had a circle it will turn 3/4 of the way then the last 1/4 it'll bind.Tried shims 1.9 to 2.8,could it be the rear hub bearing? The original matched endplate with a 2.0 shim will turn freely and the tolerance is just about within limits but you can move the first gear with your finger theres that much play,Obviously want to do this right and be with in the correct range.Any help/advice would be greatly appreciated

[WINTERMODEL150]

Hi,i think you've already answered your own problem by saying that with the old end plate fitted with a 2.0mm shim is within spec and all moves freely...you should be able to move first gear with your finger as it will be binding otherwise,the tolerance is 3-11 tho from the top of the shim to the underside of the endplate,make sure the xmas tree is fitted and the crownwheel centre nut is torqued up also fit the rear hub and tighten that correctly as well.

I've spent many hours fiddling around like this but you will get there i'm sure,just take time out and come back to it.


regards Dean.

[wack 63]

Firstly the 1st gear will have movement even when correctly shimmed,secondly have you hit the cluster after the end plate is fitted as doing so will sometimes free the gears off.The last one I had like your problem turned out to be a cracked tooth on the cluster that tightened the gears when revolving,worth a close inspection to rule it out.Also do the gears sit higher than the layshaft when fitted as if not ,shimming up correctly will not be possible.Another thing you could try is to fit endplate etc but without the gears to check the layshaft can turn freely first.

[Hotspur]

Check the sliding dog and wishbone. I had one like this, and the sliding dog was oval. It gave the same symptoms you describe "if you had a circle it will turn 3/4 of the way then the last 1/4 it'll bind" Took me ages to work it out !!!!

[Muppet]

What should the clearance between the layshaft and the internal face of the gears be, in metric measurement?

rebuilding my SX 150 engine V E R Y S L O W L Y and I thought I would do a thorough check while wating for other parts to arrive of all the clearances, but I cant find this in Stickys Bible.

[DaveTomo]

Sorted! Had another LI 150 gearbox,mate measured the difference and on the spare gearbox the 3rd gear was slightly thicker,put that in and hey presto problem solved.Both gearboxes original Innocenti but I suppose after 40+ years it had worn a little maybe,but as I say the first gearbox worked fine in the 150 casing the only difference being that in that it was a Casa rear hub bearing and in the new one a RIV so wether that made a difference?.I do love Lammys but sometimes they do give you tourettes :baddevil: