| Author |
Message |
    
billv
Member
Username: billv
Post Number: 4
Registered: 06-2007
| | Posted on Tuesday, October 20, 2009 - 06:25 pm: | 
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Hi. Im reliably told I need to fit a thrust race to this and all motors. I cant find any evidence of a thrust race being fitted to this one.It appears to connect straight to the cluth. Nor can I find where it would bear on or fit near the motor. If I fit it after the cluth any movement(in the mounting) no mater how small would negate the load bearing actiity of the race. Further on examanimation of other bits and pieces of various small motors I cannot find evidence of bearings. I have seen the blaxland twin thrust set up. Is it possible that some smaller motors do without. help |
jb_castagnos
Senior Member
Username: jb_castagnos
Post Number: 486
Registered: 07-2002
| | Posted on Tuesday, October 20, 2009 - 08:42 pm: |
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What type bearings does your engine have, I'm not familiar with it. If it has tapered rollers or ball bearings you can get by, if it has babbitt it would be best to use a thrust. I've seen some of the antiques with internal roller thrust bearings. If you don't have room on the output shaft you could install one on the prop shaft with a mount to carry the thrust to the boat. |
todd_vidgen
Senior Member
Username: todd_vidgen
Post Number: 146
Registered: 03-2008
| | Posted on Tuesday, October 20, 2009 - 10:05 pm: |
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Some of the earlier Blaxlands used to use the face
of the web on the crank shaft big end throw against
a white metal bearing face that was part of the
main Babbitt bearing. But this had problems ,as the face's wore,the crank went forward in the case,which
in turn changed the timing ,stressed the con rod,
wore the reciprocating water pump,and eventually
the crank started to hit the crank case.(massive
case of big end knock) |
billv
Member
Username: billv
Post Number: 5
Registered: 06-2007
| | Posted on Thursday, October 22, 2009 - 12:19 am: |
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Thanks for the responses
As the bottom end seems tight I did not open it up but it appears to be white metal mains . The Clae has a chain drive to the maggy (prop shaft end) which sits behind a cast cover. There is no bearing behind the chain drive and the case has an oil seal which prohibits mounting a bearing against it. Thats one reason I suspect no thrust bearing. Mounting a thurst bearing on the prop shaft seperate to the motor would require, I think, a sliding shaft coupling to allow the shaft to bear on the mount rather than on the motor. No evidence of this either. Still thinking Bill V
Bill V |
laurie_d
New member
Username: laurie_d
Post Number: 3
Registered: 10-2009
| | Posted on Thursday, October 22, 2009 - 02:03 am: |
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My experience is that marine engines (with the makers' clutches or gearboxes) do not need thrust races. When using car engines or stationary engines in a boat a marine clutch or gearbox should be fitted (to include thrust issues) Otherwise, just don't use the boat often and be prepared for the wear and tear that thrust will give you (eg my uncle had a jeep engine with jeep g/box for years - he just didn't rev the motor too hard. Cheers |
puttputtputt
Member
Username: puttputtputt
Post Number: 6
Registered: 02-2009
| | Posted on Friday, October 23, 2009 - 08:36 am: |
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I'll offer three points of evidence that the old marine engines don't need thrust bearings.
1. My neighbour who is a professional boat restorer is quite clear that it's not needed. He has a pile of old St. Lawrences in his garage.
2. My own motor (VIM MOtor Co, Sandusky OH) has two little rings formed on the crank mains which would act as air seals and thrust bearings. When I got the motor, the bearings were a bit loose, but the thrust surfaces were as good as new.
3. I have original literature from Acadia Motors that describes in detail the installation procedure. They are very insistent on the need for secure mounting and perfect alignment, but they say nothing about a thrust bearing.
Don't worry, be happy, and make it go . . .
Puttputtputt |
billv
Member
Username: billv
Post Number: 6
Registered: 06-2007
| | Posted on Monday, October 26, 2009 - 01:05 am: |
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Thanks for all the responses Now I have a better picture
Bill V |
DickieGibbens
Visitor
| | Posted on Monday, October 26, 2009 - 10:09 am: |
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To add a cause for eliminating previously mentioned "Stress connecting rod," In 1991 I put into service a well worn 6HP 2cyl Lockwood Ash. I soon found the front crank pin worn from the crankshaft positioned too far forward, that is, with offsets installed, crankshaft in lathe, the journal indicated off centerline from the mains. Now my last step in assembly is determine cranksshaft end play and remove one half by positioning the thrust bearing. Some need the thrust bearing, some don't, |
miro
Senior Member
Username: miro
Post Number: 402
Registered: 11-2001
| | Posted on Tuesday, October 27, 2009 - 11:12 am: |
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Even on a small engine such as the copper jacket DisPro ( 3 HP at max, usually some of the horses have retired), there is a ball thrust bearing.
It's very tight fr space in that area of the engine installation , but it is essential, I think.
With heavier boats and more powerful engines, there's gotta be some way of getting the prop thrust into the hull other than the crank shaft.
miro |
