ausmini :: View topic - Why you should put in Thrust washers correctly

I have just rebuilt my engine with a new cam and followers, and new pistons and bearings.

We put it all back together, and started it up fine. It had excellent oil pressure. We ran the cam in for about 25 minutes and then went to put it into gear to move it back into the garage. The engine stopped as soon as the cluch disengaged.

We tried a few times and exactly the same thing happened each time. If you had a few revs on then the engine would slow right down.

I did a quick search on Ausmini for similar symptoms and pretty quickly saw posts which said that a possible culprit was putting the thrust washers in backwards. We decided that it was better to be safe than sorry and pulled the engine back out, split the box off and popped off the centre main cap.

Sure enough the two halves of the washers which are in the actual block side of the crank had been put in backwards.

As you can see, the washers which are put under pressure by the clutch mechanism are fairly much rooted. The half which was put in backwards has been severely eroded and the stuff that came off has ripped into the bearing surface of the half that was correctly installed.

Hopefully it hasn't done too much damage apart from the washers themselves. The crank seems okay and I'll take off the oil pump and clean it to be sure.

Aah well, we live and learn.

Author:	Austin850 [ Sat Nov 27, 2010 2:51 pm ]
Post subject:	Why you should put in Thrust washers correctly
I have just rebuilt my engine with a new cam and followers, and new pistons and bearings. We put it all back together, and started it up fine. It had excellent oil pressure. We ran the cam in for about 25 minutes and then went to put it into gear to move it back into the garage. The engine stopped as soon as the cluch disengaged. We tried a few times and exactly the same thing happened each time. If you had a few revs on then the engine would slow right down. I did a quick search on Ausmini for similar symptoms and pretty quickly saw posts which said that a possible culprit was putting the thrust washers in backwards. We decided that it was better to be safe than sorry and pulled the engine back out, split the box off and popped off the centre main cap. Sure enough the two halves of the washers which are in the actual block side of the crank had been put in backwards. As you can see, the washers which are put under pressure by the clutch mechanism are fairly much rooted. The half which was put in backwards has been severely eroded and the stuff that came off has ripped into the bearing surface of the half that was correctly installed. Hopefully it hasn't done too much damage apart from the washers themselves. The crank seems okay and I'll take off the oil pump and clean it to be sure. Aah well, we live and learn.

Author:	MG Rocket [ Sat Nov 27, 2010 3:06 pm ]
Post subject:
That was close! At least you did the right thing.

Author:	Mick [ Sat Nov 27, 2010 3:16 pm ]
Post subject:
How is the crankshaft? Any damage to the crankshaft webs where the thrusts contact?

Author:	Austin850 [ Sat Nov 27, 2010 3:19 pm ]
Post subject:
Mick wrote: How is the crankshaft? Any damage to the crankshaft webs where the thrusts contact? I need to have a closer look to be sure but it initially looks okay. We took everything apart last night at my mate's place. I'll have a better look when I get back over there sometime during the week.

Author:	dodge [ Sat Nov 27, 2010 8:05 pm ]
Post subject:
i made sure i fitted mine the right way as i had to hand linish 2 tho of mine i think my finger tips lost 10 tho

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Why you should put in Thrust washers correctly https://www.ausmini.com/forums/viewtopic.php?f=2&t=67288	Page 1 of 2

Author:	9YaTaH [ Mon Nov 29, 2010 6:05 pm ]
Post subject:
Ouch feel your pain Sid...but thanks for sharing...maybe it will help someone else

Author:	Tspeed Jem [ Thu Dec 02, 2010 7:48 am ]
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9YaTaH wrote: Ouch feel your pain Sid...but thanks for sharing...maybe it will help someone else eerrr? Wrong 'S' Mick I think you ment to feel Simon's Pain Syd

Author:	Wombat [ Thu Dec 02, 2010 7:53 am ]
Post subject:
I'm glad now that GR put my block together

Author:	miniDave [ Fri Mar 02, 2012 8:11 pm ]
Post subject:	Re: Why you should put in Thrust washers correctly
Austin850 wrote: I have just rebuilt my engine with a new cam and followers, and new pistons and bearings. We put it all back together, and started it up fine. It had excellent oil pressure. We ran the cam in for about 25 minutes and then went to put it into gear to move it back into the garage. The engine stopped as soon as the cluch disengaged. We tried a few times and exactly the same thing happened each time. If you had a few revs on then the engine would slow right down. I did a quick search on Ausmini for similar symptoms and pretty quickly saw posts which said that a possible culprit was putting the thrust washers in backwards. We decided that it was better to be safe than sorry and pulled the engine back out, split the box off and popped off the centre main cap. Sure enough the two halves of the washers which are in the actual block side of the crank had been put in backwards. As you can see, the washers which are put under pressure by the clutch mechanism are fairly much rooted. The half which was put in backwards has been severely eroded and the stuff that came off has ripped into the bearing surface of the half that was correctly installed. Hopefully it hasn't done too much damage apart from the washers themselves. The crank seems okay and I'll take off the oil pump and clean it to be sure. Aah well, we live and learn. Older post I found but just wanted to get this bit right. The flat side fits against the block and the flat side of the cap while the 'channels' run the oil down the crank side? That is the 'copper' coloured side is the crank side?

Author:	simon k [ Fri Mar 02, 2012 8:16 pm ]
Post subject:	Re: Why you should put in Thrust washers correctly
miniDave wrote: Older post I found but just wanted to get this bit right. The flat side fits against the block and the flat side of the cap while the 'channels' run the oil down the crank side? That is the 'copper' coloured side is the crank side? that is correct

Author:	michaelb [ Fri Mar 02, 2012 8:24 pm ]
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Yes the soft copper side needs to bear against the moving crankshaft.

Author:	miniDave [ Fri Mar 02, 2012 8:39 pm ]
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OK thanks for that. One of the posts mentioned putting some bearing blue on the flat side to hold in place while assembling - is this a good idea?

Author:	simon k [ Fri Mar 02, 2012 8:53 pm ]
Post subject:
miniDave wrote: OK thanks for that. One of the posts mentioned putting some bearing blue on the flat side to hold in place while assembling - is this a good idea? have never felt the need for it

Author:	drmini in aust [ Fri Mar 02, 2012 9:57 pm ]
Post subject:
Drop the crank in, then slide the circular block half ones in and they will stay there. re the 2 cap half ones, you can hold their tabs with your fingers whilst you fit the cap on.

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Author:	Convertible Mini [ Sat Mar 03, 2012 5:09 am ]
Post subject:	Thrust washers
One thing that my old friend Jack Read (Miniman's dad) taught me years ago was. When building an engine especially a race engine when it comes to fitting thrust washers always use new ones with the correct clearance on the block side of the journal and on the cap side always either use a serviceable worn ones that have already been used or rub the new ones on a piece of very fine wet and dry paper to take some meat off to make them just sit there for the ride and to keep the block side one from spinning around. When crank Shaft starts flexing the first thing it will do is put side ways pressure on the cap side thrust washers, however if they are thinner it will not reach them as much and might save your engine. Thinking of this if you look at many new engines which have the thrust washers as part of the main bearing shell itself (one piece) they only have thrusts on the block side. I learnt a lot of things like this form my old friend Jack and I always think of him when putting an engine together.