M20-M21 Selecting 1st problem

[Calum]

Hi all,I have an M20 4spd behind a 253 "standard issue" the one problem I have is it is hard to select 1st gear...all else is good,the box isn't noisy,the shifter isn't worn and is aligned well,rev+2nd 3rd and 4th go in perfect.It's just all aspects of selecting 1st is BAD meaning...from a standing start it's tight to get in "and or" it will be like i'm stuck locked between 1st and Reverse,the one way to get past this is to chuck her into 2nd then straight back into 1st and i'm away.When i'm on a roll to an intersection it's tight and GRINDS IN "if i'm lucky".So before I try a rebuild etc I thought it would be good to get a little feedback so I don't waste time and money,coz as I say apart from 1st it is a good thing. Thanks in advance for your feedback

[HK1837]

Sounds to me like the standard Aussie 4spd problem, circlip on the mainshaft on 1st gear busted or come loose. They fall to pieces and chew the mainshaft up under 1st gear. Means 1st doesn't spin freely on the mainshaft meaning it is harder for synchro and teeth to align.
May also be a flogged synchro ring too. In either case it will probably have to come apart
I'd also talk to a transmission shop to get 2nd and 3rd opinions!

[Calum]

Good "O" HK, after posting this thread I remembered that I have another M20 in storage SO I think it would be a good idea for me to start with that one(condition unknown) that way I won't screw up a "pretty good" box.So in a cupple of weeks I should know if the Unknown is OK or I have to drive the wife's KIA on weekends for a bit!!! at least with your input i'm not too worry that all's not lost just yet,but if i was to continue to drive the tonner as is,things would only get worse.Cheers Calbert

[SLR_dave]

Maybe also have a look at the linkages, paticularly the condition of the gromet on the reverse lever that the reverse push rod goes though.
If (e.g.) casual drivers have not understood that its a 'depress' box, it is easy enough to force it non depressed between first and reverse, thus wearing that gromet, and the detent plate (where fitted). Over time this can ceate a first/reverse lock, i.e.; possible to have both gears selected simulteaneously, and if nothing is done, over more time, similar useage can create a tendency for that to happen easily.

I'm not questioning HK here, he is probably right, but there is just a chance the problem is external. Maybe worth getting underneath it and watch what happens to the reverse lever as you get another person to try and simulate the situation? Can it be selected (or nearly selected) with first still engaged. Or, does the shift to first cuase the reverse lever to move just slightly toward engage.

[HK1837]

••Could easily be that too, that's why you should take it to a transmission shop for a second opinion.

[buck]

i must admit, my old man always told me when i was learning to drive to touch second gear first to get the synchro going on first, have always selected second and then first seems to go straight in, have to do this with my old ZF 5 speed from the 70s as its difficult to get into first when cold. could be a whole lot of bull, but seems to work for my m20 and zf box.
also very true about linkages and the circlip, nearly destroyed my m20 with a broken circlip on third gear, just got it in time before the bearing tore itself to bits.

[Calum]

Good onya fellas,yesterday after going through your suggestions I decided to start from the start again,After lifting up the boot on the gearstick I could see that as I headed for 1st the reverse gate does move ever so slightly with it as SLR_dave suggested. This morning I booked the old girl in to the local mechanic for Wednesday to put her up on the hoist with me in it so He can see exactly how the selectors are (condition+alighnment).and who knows what else will be spotted,will report back then. Ta for now...

[Calum]

OK good news and I feel just a little sillytoday I took the Tonner to the mechanic and once it was up on the hoist the old guy just grinn's and gets a can of CRC and the air-compressor blower nozzle then sets about cleaning out the build up of GRIT out of the linkage's moving parts and says "give it a go" WOW THAT'S IT,basically because the tonner gets driven along alot of sandstone roads including winter time GRIT had simply built-up and made the moving parts gum up.Now the funny thing is the shifter isn't firm any more,it's now sloppyStill better than a gearbox rebuild!! Once again thank's for your feed back/suggestions Byron,Dave and Buck.
Cheers Calbert