Tight crank bearing

Information relating to the Matchless G9 or AJS Model 20 500cc twin
theEagle
Posts: 16
Joined: Thu Jul 27, 2017 2:18 pm
Location: CHESHIRE UK

Re: Tight crank bearing

Post by theEagle »

Hi all. Sorry for lack of responsivness, jut other stuff to do and no time to test further yet.
I will try to fit it together using 4 hands (..? ;) tomorrow hopefully.
I am aware to just use teh rubber bands as a test and not for final mounting (yes, the bearings probably have sufficient leading angles to not need it..but still :).
CAnnot say 100% that it is not cam follower spindles...but it did fit ok without crankshaft and the wiggle movement described above seem to be centered around the bearing.

I report back when I have more feedback
Anders

Edited: had written camshaft instead of crankshaft .. made it even harder to understand..
Last edited by theEagle on Wed Aug 02, 2017 8:35 am, edited 1 time in total.
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Duncan
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Re: Tight crank bearing

Post by Duncan »

Hi Alan
surely the rollers hold themselves in place whist you assemble
The rollers in a used cage tend to fall back slightly when you are assembling just enough to make assembly a bit frustrating, agreed that the cam spindles can also complicate matters.
theEagle
Posts: 16
Joined: Thu Jul 27, 2017 2:18 pm
Location: CHESHIRE UK

Re: Tight crank bearing

Post by theEagle »

Hi,

Had time to look at it again. I did an attempt with sort of 3 hands...trying to fit on teh timing side cover and rotating the crankshaft a bit at the same time. It did not give a mm..
In all honesty I probably did not put all 150% into it as I am not convinced the problem lies there. However, I think I put in sufficient effort to be able to notice if that is the way forwards, but I am convinced now that it is not.

To check if it could be the cam follower spindles being bentt or something I actually tested putting the timing side case on turned 90deg. this means that the cam follower shafts/spindles is not in play at all. Still it got stuck on something, and the only thing in play in that position is teh bearing.

I will probably soon go ahead and just try to heat up the timing side a bit, assemble all cam stuff, add sealant and then just try to fit it together, hopefully not needing to much force with teh mallet.
(still open for some constructive criticism or alternative solutions.. )

As I think i will need to force the case onto the crank bearing i aim to use the mallet. Would it be another aidea to force it down using teh bolts that keeps the crank case togheter?

Cheers
Anders
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1608
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Location: ESSEX UK

Re: Tight crank bearing

Post by 1608 »

What is wrong with drawing the inner race and rollers off the shaft and trying it in the outer race whilst the outer race is still in situ. Its no trouble to replace the inner race etc. after you have established it is a good fit and just difficult to fit when re-assembled. Its less hassle than heating the timing side case and removing punch marks if not necessary.
My last word on the subject
alanengineer
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Location: KENT UK

Re: Tight crank bearing

Post by alanengineer »

Hi Anders

The way in which you describe joining the two halves with heat and a hammer will just end up in tears. Time to get someone who knows Matchless twins to have a play. You are missing something simple. (and so are we)
Jampot Rally in a few weeks, loads of 'experts' with free advice. Maybe worth the long journey
theEagle
Posts: 16
Joined: Thu Jul 27, 2017 2:18 pm
Location: CHESHIRE UK

Re: Tight crank bearing

Post by theEagle »

1608: I agree. However, it has been suggested to use a puller to pull it off, but with the puller I have found for resonable prices here it does not seem to be possible to get a good grip with the arms on the bearing? And I assume that i cannot grip on the rollers/rollercage? What is the correct approach to draw that bearing of the shaft?

alanengineer: Hmm yes, it is a risk.. And maybe I am to impatient..
It is to much of travel for this (yet) small project, even if i Really (!!) would like to go to that rally.. Here I have still not seen any jampot community accesible to ask.

Cheers
Anders
jack clegg
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Location: BUCKS UK

Re: Tight crank bearing

Post by jack clegg »

This is all very reminiscent of the trouble I had with the timing side roller on an Enfield Interceptor last year. Workshop manual advises to use string round the rollers to aid assembly. I had to fashion a gadget to allow string removal once engaged. The roller should enter the outer race cold. If it gets stuck then there is not enough internal bearing clearance. It is no use taking the inner race off the crank to try it in the outer race. The interference fit on the crank effects the internal clearance of the bearing, so you must check with bearing on the crank. I found that heating the timing case to 80 degrees-ish aided assembly, but once cold the bearing was trapped in the outer race. Once hot again it dropped out. Enfield also practiced the caulking/centre punch method of retaining the outer race & overdoing it can certainly close up the tolerance, but it may be only on the edge of the outer race, so once past the tight spot/lip, maybe OK. I would advise you try a test assembly with the timing case hot. If this thing was running OK before, it should go again. Thermal expansion is a wondrous magic to behold.
In my own struggle, I was supplied an incorrect CN type bearing. I fitted the outer. When hot, the inner race would fit OK. When cold It stuck. I well remember hearing the clonk in the oven when reheating the case as the inner dropped back out. I ended up relieving the interference fit in the outer case in order to use the CN bearing (should have been C3), then Loctite & caulking. I still found that heating the timing side case was a great aid to assembly. TTFN Jack
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G15 Roy
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Re: Tight crank bearing

Post by G15 Roy »

theEagle wrote:1608: I agree. However, it has been suggested to use a puller to pull it off, but with the puller I have found for resonable prices here it does not seem to be possible to get a good grip with the arms on the bearing? And I assume that i cannot grip on the rollers/rollercage? What is the correct approach to draw that bearing of the shaft?

alanengineer: Hmm yes, it is a risk.. And maybe I am to impatient..
It is to much of travel for this (yet) small project, even if i Really (!!) would like to go to that rally.. Here I have still not seen any jampot community accesible to ask.

Cheers
Anders
The best thing ship it to 1608 and it will be back together in no time at all. I sure John would not mind I Would even give him a hand. But of course you will need to join the club first.
Roy
theEagle
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Location: CHESHIRE UK

Re: Tight crank bearing

Post by theEagle »

Hi All,

Jack Clegg: Thank you for your input and experience! Yes heat is my friend :) but not friendly enough.. I tried "some" heat (some days ago) but it did not make it go on easy, but with some soft mallet use it got on a bit, sufficiently to get rather stuck as it cooled down... Yes, it moved quite freely before. And it is probably not a correct bearing... I did go for a try to fit it with heat ...see below

G15 Roy, and 1608, allanengineer, Duncan and all others given input: I hope you can forgive me for not following all advice and even make stupid choices... even if I know your experience is most likely 1000 fold of mine in this area. But for reasons of enthusiasm, time limits (last day of vacation. and i know this will still take yrs..) , impatience I just went ahead..... with a large chance for sorrows. What I do hope to avoid is to worsen the situation, but to in a cheap and quick(relative) way se if I can get to start the bike (aiming for within 6month-1.5 yrs..).
I did mount the cams and cam followers etc. I tested fitting and after a while got it right with the cam bushing fitting.I pre-prepared 4 studs to go on teh crank case to help pull it together. heated up the timing side a bit with a torch, smeared on (thinly)some gasket on tube. Managed to get teh timing side case on , and cams in bushes , to teh point it hangs on the bearing. Fitted teh studs and heated some more. Then i made some strikes with the mallet, tightend the studsnuts a bit in X order, hit with mallet , tightened the nuts slightly etc etc.. during the process the case "popped" or sounded like a short "krockk" every now and then , presumably as the bearing made small steps into the case. I felt teh cams being stuck but hoped it wold easy up when aligned. After a few minutes the faces met, I heated some more, made som mallet strikes in some sense to ease tension..?
Gasket sealant had flown out minimally around.
To my relief the cams moved smoothly.
Then i tried the crank shaft...stuck as a rock! (almost at tears, hearing teh words of alanengineer...) Damned!! I positioned teh engine properly and had a better grip and tried, stuck solid!! How the.... I shoudl have listened ...but on teh other hand I know I had to try ..sooner then later
After the first panic lay down, I agreed to give up (which would probably be for a couple of month to get strength and time..), then anger hit me and I thought "no damage in trying for all i have!!" so I took a good grip and it staretd to move..and in a turn or 2 it now moves quite freely, not extremely easy, but no problem moving, I guess the rollers was pressed sideways by the assembly? Now it feels good .

PLease let me know if you think could have induced any persisting damage ?
I know it will be hard to disassemble, but that I have done once before and it is doable
This also will allow me to continue with the rest as those smaller tasks will be easier to get time with.

I hope I have not made myself impossible by this approach as I Am sure i will ask for your guidance and input quite soon again!
AND I am VERY thankful for your input and ideas even if I did not follow/heed all of them I did consider them !!
Anders
raffles
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Re: Tight crank bearing

Post by raffles »

You have not mentioned the round paper gasket that fits between the crankcases on the oil filter tunnel. If you have indeed left this out
then you can expect a serious oil leak
Tony
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