M21 Rebuild
#1 _Kevhaze_
Posted 28 January 2016 - 06:14 PM
I am in the process of rebuilding my M21 I got which I was told there was nothing wrong with it but was actually noisey in first and second😡. Now that I have got it apart it appears that my cluster gear and first gear both have some nice pitting so need replacing.
Who does everyone recommend getting the parts off?
Not sure yet why second gear was noisey at the moment as the needle rollers all looked fine.
It appears that the owner of the gearbox before me put a kit through it then found it was still noisey so sold it to me.... Bugger
Cheers Kev
#2
Posted 28 January 2016 - 09:15 PM
John Hall
02 98315772
Got some good parts for an M20 build last year.
Very helpful
#3
Posted 28 January 2016 - 09:34 PM
#4
Posted 29 January 2016 - 06:43 AM
I assume you means an Aussie 4spd, not a Saginaw or Muncie?
Kingswood Country sell new repro Aussie 4spd stuff.
Check the synchro teeth on 2nd gear to make sure it is still OK, and when you pull it apart check the mainshaft where 1st gear runs that it isn't buggered too. Whenever I've rebuilt Aussie 4spds in the past it is almost always a new cluster and 1st gear, and every second or third box will need a 2nd gear and/or a mainshaft. The input shafts are sometimes buggered too, check the case hardening on the inside where the needle rollers run, and the same on the mainshaft for the other side of the bearing.
#5 _Kevhaze_
Posted 29 January 2016 - 07:39 PM
I found Kingswood Country and ordered a first gear and new counter shaft so I should hopefully have it Monday or Tuesday, I am not sure on how the main shaft is but everything else looks good.
I do have pictures but I am unable to upload them at the moment.
The bit I am stumped on is where's the noise coming from on second gear?
When it's in 3rd or 4th it's great no noises at all.
Thanks guys for the details about J &VR transmissions, I will give him a call on Monday if I don't figure something out first
Cheers Kev
#6 _Kevhaze_
Posted 29 January 2016 - 07:43 PM
As you guys can tell it has some nasty pitting on first but all the other gears look great
Cheers Kev
#7
Posted 29 January 2016 - 08:10 PM
So my guess is you'll find the cluster back end case hardening is screwed as well as the teeth.
When you pull it apart you can check if the case hardening on the nose of the main shaft is OK also inside the input shaft. Once you pull 1st gear off the main shaft look for damage to the nose of 1st and to the slots that 1st spins on. The circlip that secures 1st can disintegrate and cause this damage. The best thing is to use a good quality circlip when rebuilding.
#8 _Kevhaze_
Posted 29 January 2016 - 08:29 PM
That is the case hardening wearing off. In 1st and 2nd more load is on that end of the cluster, and normally the bearing outer surface ( the cluster itself) is screwed at that end. 3rd puts more load on the other end of the cluster and 4th the cluster just spins as in 4th the input shaft is coupled to the main shaft.
So my guess is you'll find the cluster back end case hardening is screwed as well as the teeth.
When you pull it apart you can check if the case hardening on the nose of the main shaft is OK also inside the input shaft. Once you pull 1st gear off the main shaft look for damage to the nose of 1st and to the slots that 1st spins on. The circlip that secures 1st can disintegrate and cause this damage. The best thing is to use a good quality circlip when rebuilding.
Thanks mate, I thought it might just be first gear that's worn but the load on second might cause it to be noisey but I wasn't sure and thought I might ask some one with more experience with these gearboxes,
I just gotta steal a good pair of circlip plyers off my dad and I should be able to get first gear off for a better inspection
Cheers Kev
#9
Posted 30 January 2016 - 07:20 AM
Either 1st or second will be loading up that end of the cluster and it is that end that the inner surface case hardening is always shagged, so my guess is that is why its noisy in 1st and 2nd. Doesn't matter though as the cluster is buggered. Make sure you buy all new needle rollers and other bearings.
#10 _Kevhaze_
Posted 30 January 2016 - 01:14 PM
Cheers Kev
#11 _Kevhaze_
Posted 30 January 2016 - 07:03 PM
Cheers Kev
#12 _Kevhaze_
Posted 05 February 2016 - 01:10 PM
Took it for a little spin and no noises drove great actually. Now I just have to give it a good run out the road.
Thanks for all your help it was greatly appreciated
Cheers Kev
#13 _Doggies73_
Posted 31 March 2017 - 11:15 PM
#14
Posted 01 April 2017 - 04:16 PM
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