Author Topic: timing bush  (Read 1001 times)

Offline shuswapkev

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timing bush
« on: 30.03. 2013 23:37 »

back to assembling an engine from stray parts...  1951 plunger a10 cases..

  looking for the thickness of the thrust flange on an a10 timing bush...
 i have made a new one using an oldie for a pattern...  but seems to be a bit thick as the cases wont close up...
 the original i had was a brass with babbit? liner...

the thrust face was .135 thick...i which on assembly seems to be near  .030 too thick...  thats just roughly measuring the space between the cases before it locks up solid...

  is there any spec sheets that give the dimensions of these and other parts???

i can easily turn this bush down to make all fit...but would be real nice to have an idea what it is originally supposed to be

Offline shuswapkev

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Re: timing bush
« Reply #1 on: 31.03. 2013 00:15 »
 looks like i have found the a65 specs...
 it shows the thrust face to be .0965...this would have the cases close up... and allow the shims to be put in

  i am wondering if the white metal may have picked up and redeposited on my old bush...and that may have account for the extra thickness???  my bush at its thickest place measured  .135... (the bush didnt come out of the cases i have)
 is there a tech sheet somewhere with the factory dimensions of parts like this...bushings..bearings...shafts..etc...

we are all buying "pattern" parts to fit 50-70 year machines...and would be a simple job to check the dimensions with what we have bought...taken out...against what is supposed to be...original....least then we would know...where the errors are coming up...and which one needs cutting..

maybe after 40 years or working on harleys...  life has  been too easy...all those dimensions and patterns are so easy to get...

  i,m hopin i just havent found the "right " page 

     put me onto it dudes...this cast iron bsa needs to live...and will...

Online bsa-bill

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Re: timing bush
« Reply #2 on: 31.03. 2013 11:14 »
Quote
and allow the shims to be put in

Hi shuswapkev

shims - what shims.
Now first things first are we talking about the same thing, the timing side crank shaft bush.
If so then any shims needed go between the drive side web of the crank and the bearing that sits there, after having the timing side bush line bored square to the crank you need to assemble the crank and cases without any shims, measure any end float, subtract 0.001" from the end float and what's left is the amount of shimming to go between the drive side bearing and crank web.
Your aiming for end float of  0.003" maximum
Not quite as easy as it is said and you may device other methods of measuring the end float, some people like to measure the bearing and leave it off while getting the end-float as it's easy to damage the bearing removing it.
If you have or funds allow then a dial gauge is a good.
All the best with it, 0.001" is ideal but anything less than 0.003" is good.

now your going to tell me it's another bush entirely ;)
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline shuswapkev

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Re: timing bush
« Reply #3 on: 31.03. 2013 14:53 »
bill

 thanks for the reply...  my question is...how thick is the thrust flange on the timing bush supposed to be????
 we are talking the same timing bush...
 my problem is finding the design dimensions to make up these parts...making the bush is easy as pie...inside and out dia...length and all
 where my problem is ...i was copying a stray timing bush..and after duplicating the thrust flange and assembling...i was .025 too thick to close up the cases...  easy enough to heat the cases drop out the bush and remove .028...which i did..and that allowed me a .002 shim...and now i have maybe .0005 endplay...  the lumpy thrust flange on the bush i was copying  was .135...??
 my problem is copying the parts i have...and using purchased "pattern" parts which generally dont fit for..whatever reason??
what is nice to know...is what the size is supposed to be,...that way i know that either my  "original" part has been altered or ...the pattern part is incorrect... and if you have that..you have the solution

most of my years are harley stuff...   i can get the dimensions on any of that back to 1910..and straightaway know what it was originall supposed to be
like when i had the small ends done on my bsa rods... the bloke asked me what the centre to center is...pushes the buttons...the machine measures from center of big end to centre of little...inserts the wrist pin..where it measures..the machine winds up and bores the hole to spec...and the pin to a 10 thousandth and perfectly square...made using an adjustable ream look like a rock on a stick...

another thing i found out tonight...of course maybe i am the last person to work this out... i had my cases grit blasted...and after that found all the little oil holes for the bushes..(the bushes were well in tolerance..)   anyway..no way to know how much grit is down those holes..as the bushes have a little slot turned in the circumference..out they all came and made new..
 how to line ream the cam shaft..??  bored the holes to size on my mill...but off far enough that tightening the cases..the cam jams up solid..
 BSA book ..says ... get a .746 reamer???  where you gonna get that???
well...i found an old chucking reamer about .750... i took a stone and in about 10 minutes had it down to .747.....tested on a few holes.. you beauty... success... and also..after the stoning...a worn out ream...cuts like gillette razor...and straight line thru all 3 bushes...
 yeah..these reamers come up on ebay all the time...cheap.. as well past any production work...

Online bsa-bill

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Re: timing bush
« Reply #4 on: 31.03. 2013 16:20 »
ah - now I see, thought you were talking about a bought in bush.
, sorry

I'm in and out the shed today, I think I have an old bush somewhere if I can lay my hands on it I'll give it a measure
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online trevinoz

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Re: timing bush
« Reply #5 on: 31.03. 2013 22:08 »
Kev,
       I measured a few old ones and they vary from 0.115" - 0.126". There was only one at the smallest measurement and the rest were all around the 0.125" mark.

Trev.

Offline shuswapkev

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Re: timing bush
« Reply #6 on: 01.04. 2013 07:42 »


 trev ... mate
       thanks heaps for that....  makes me feel a whole bunch better...now it works out that i am near to the size you mention...
  the one i have is white metal over brass......and pretty rough.. from long distant memory the engine it came out had a drive side roller bearing that didnt have sides...the rollers would slide right thru..and that likely was the cause of that engines demise...
but i collected those bits quite a few years ago...and at the time the parts had absolutly no significance... i just thought they didnt belong in the scrap metal
 with the unsupported rollers..likely the crank was banging back and forth...could have been picking up the white metal and piling it into one spot...
  as  my little refugee bush is a good .135 thick on near half of it...

my engine will have some anomolys...as the drive side case was in three pieces...  until my mate the  "amazing blaze..burn it and beat it" ran outta beer one day...and started looking around my shop for some way to pay for some more... and have to say..  that carton of 4xxx put another gold flash up on its wheels..well.... once i collected a few wheelbarrows of other stray parts...friends and ebay

  which brings me back to my original point...what size are all these "pattern"parts supposed to be...???
  i could have paid..$60-$80 and waited several weeks for a part that didnt fit anyway...

when i start knocking harley stuff apart...any parts can be measured and know right away...if motor co parts are good or...i need a chunk of iron, brass or ally  to get back to good...

 i assemble aj and matchy singles...now once i punch out the timing bush on those...i clamp it on the table and bore out the case..as almost all have cone shaped timing bushing holes...and then just make another bush...to my size...

  enough words...thanks heaps for the help ..... greatly appreciated

Online KiwiGF

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Re: timing bush
« Reply #7 on: 01.04. 2013 07:59 »
On pattern parts......its common to have one off timing side main bushes made as quite commonly the housing is over size  so an over size bush is the best solution, i had a steel outer made with a bronze liner but people use solid bronze mian bushes with no probelms, its a well covered topic on the forum as getting this bush right is crucial to long engine

I also had one off cam shaft bushes made for the reason, i had those line reamed as i had mismatched cases so  the drive side bush was made offset by circa 010"
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Offline shuswapkev

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Re: timing bush
« Reply #8 on: 01.04. 2013 13:21 »
kiwi

 thanks for the reply

 making the parts is easy as... if you have the sizes...parts will just roll off...the machines...
 the stuff i end up with generally needs parts made to correct the damage...( generally the reason i ended up with the part)
 seemms i spend more time working out a dimension than i do making the part

 but what i,l lookin for is the sizes...the timing side worked itself out... ended up with a .002 shim and .0005 endplay...

 cam bushes...i,m using .092 for the thrust face???  thats what the average of my rubbish bushes gives me...

also the same for the gearbox bushes... thrust face again...

Offline Goldy

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Re: timing bush
« Reply #9 on: 01.04. 2013 14:00 »
You might find service sheet 702 useful it gives bush and shaft dimensions
It's in the data section
All the best Goldy
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing