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[Andy B]

Thanks Mark

[aaronjb]

Speaking of.. I read recently one (well respected, if I'm remembering the source correctly) engine builder stating that plastigauge was as useful as a chocolate teapot, and the only way to measure bearing clearances properly was using a micrometer and bore gauge.

If I recall the procedure correctly it was; measure the main bearing shell with the bore gauge (after torquing down the cap), then measure the journal with the micrometer, zero the mic and then measure the bore gauge; that reading is then the clearance..

Wish I could remember where I read it now, whether it was in Barry Rabotnik's book or whether it was Mike Huddart.. the former being much less reliable than the latter!

[Kevin Wood]

Speaking of.. I read recently one (well respected, if I'm remembering the source correctly) engine builder stating that plastigauge was as useful as a chocolate teapot, and the only way to measure bearing clearances properly was using a micrometer and bore gauge.

If I recall the procedure correctly it was; measure the main bearing shell with the bore gauge (after torquing down the cap), then measure the journal with the micrometer, zero the mic and then measure the bore gauge; that reading is then the clearance..

Wish I could remember where I read it now, whether it was in Barry Rabotnik's book or whether it was Mike Huddart.. the former being much less reliable than the latter!

On those old yankee lumps you can measure the clearance with a tape measure, surely?

[aaronjb]

Nah.. If you can get your fingers between the journal & bearing it's worn, if you can't then it's good for another 200k..

[Kevin Wood]

Nah.. If you can get your fingers between the journal & bearing it's worn, if you can't then it's good for another 200k..

Makes sense. Too many damn 'nummers on the tape measure.

[Webby the Bear]

save posting a new thread.... ive been learning about thrust bearings.

am i right in thinking they are located along the main bearing journals in the block to locate the crankshaft laterally.... and that you can test it by pressing the clutch pedal and measuring forward crankshaft movement to see if theyre shot? well if thats the case how can you test it on an auto? and am i right in thinking that thrust bearings are poor on omegas? (just remember someone mentioning it

[henryd]

save posting a new thread.... ive been learning about thrust bearings.

am i right in thinking they are located along the main bearing journals in the block to locate the crankshaft laterally.... and that you can test it by pressing the clutch pedal and measuring forward crankshaft movement to see if theyre shot? well if thats the case how can you test it on an auto? and am i right in thinking that thrust bearings are poor on omegas? (just remember someone mentioning it

Clutch pedal will show you some of the play,better to grab the crank pulley and push/pull it in and out(engine off naturally  )

[Webby the Bear]

save posting a new thread.... ive been learning about thrust bearings.

am i right in thinking they are located along the main bearing journals in the block to locate the crankshaft laterally.... and that you can test it by pressing the clutch pedal and measuring forward crankshaft movement to see if theyre shot? well if thats the case how can you test it on an auto? and am i right in thinking that thrust bearings are poor on omegas? (just remember someone mentioning it

Clutch pedal will show you some of the play,better to grab the crank pulley and push/pull it in and out(engine off naturally  )

 

can you do that with an auto? i presume you can 

[Andy B]

save posting a new thread.... ive been learning about thrust bearings.

am i right in thinking they are located along the main bearing journals in the block to locate the crankshaft laterally.... and that you can test it by pressing the clutch pedal and measuring forward crankshaft movement to see if theyre shot?  .....

Pushing the clutch loads up the thrust bearing which is why it's not best practice to press the clutch as you start ...... however on lots of manual cars these days you have to press it to start the car

[Webby the Bear]

save posting a new thread.... ive been learning about thrust bearings.

am i right in thinking they are located along the main bearing journals in the block to locate the crankshaft laterally.... and that you can test it by pressing the clutch pedal and measuring forward crankshaft movement to see if theyre shot?  .....

Pushing the clutch loads up the thrust bearing which is why it's not best practice to press the clutch as you start ...... however on lots of manual cars these days you have to press it to start the car

i know about that. when i worked in edinburgh for a couple months the girls i work with were late. get a call at half 9 ''we cant start the hire car'' 

how much movement roughly would be acceptable? 

[Webby the Bear]

and presumably when we measure end float, this is what we're really testing?

[Andy B]

....
how much movement roughly would be acceptable?

Errr? Not sure really  There'll be limits quoted somewhere. It won't be that much because the thrust 'bearings' are only white metal  ..... like a main/big end.

[Andy B]

and presumably when we measure end float, this is what we're really testing?

yes 

[Webby the Bear]

got ya!!!! cheers andy. so basically just look at the end float tolerance and thats your thrust bearing test 

[Kevin Wood]

Thrust bearings are often incorporated into one of the main bearing shells, i.e. the inside of the shell forms the main bearing, and it has an additional thrust surface on either end of the bearing which runs between 2 faces machined on the crankshaft.

Haynes manual gives maximum crank endfloat for the V6 as 0.05-0.15mm.