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Timing side crank bushing
#809377 05/18/20 10:46 pm
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Can i replace the timing side bushing myself or will it need to go to a machine shop? If i get a standard bushing will it need machined? My original bushing measures in spec but has some light grooves on the inside of the bushing. The crankshaft looks new and is also in spec. Should have .002 clearance in the original bushing. I had RO DY Machine check the crank for any cracks and turn the rod journals .010. Thanks for any info

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Re: Timing side crank bushing
RUSS TILLEY #809396 05/19/20 12:15 am
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Clearance should be .0015" with .003" largest acceptable. The new bush will need to be linehoned to size. The .0015 is very important. Too small won't allow adequate oil in bushing and too large causes a loss of oil pressure.


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
Re: Timing side crank bushing
RUSS TILLEY #809473 05/19/20 2:39 pm
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CBS list the std bushing at 1.501id. My crank measures 1.4995. That will give .0015 clearance. If the bushing needs to be linehoned looks like it would be out of spec. I can not find the procedure for removing and installing a new bushing. Does anyone know of a machine shop that has done this job that is close to Zanesville Ohio. Any information will be appreciated. Thanks

Last edited by RUSS TILLEY; 05/19/20 2:41 pm.
Re: Timing side crank bushing
RUSS TILLEY #809476 05/19/20 2:51 pm
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If you have the required 1.5 thou and just a few lines then I would leave it as is, the lines will not lose you oil pressure.

The original bush is very good, made by Vandervell, some of the replacements are of dubious materials.

The lines come from dirt in the oil, fit an oil filter in the return line and change the oil regularly and no extra lines.

2 members like this: Ignoramus, gavin eisler
Re: Timing side crank bushing
RUSS TILLEY #809487 05/19/20 3:52 pm
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Originally Posted by RUSS TILLEY
CBS list the std bushing at 1.501id. My crank measures 1.4995. That will give .0015 clearance. If the bushing needs to be linehoned looks like it would be out of spec. I can not find the procedure for removing and installing a new bushing. Does anyone know of a machine shop that has done this job that is close to Zanesville Ohio. Any information will be appreciated. Thanks
When installing the bushing, the ID will become smaller.


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
Re: Timing side crank bushing
RUSS TILLEY #809548 05/20/20 1:51 am
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Assemble the crank into the cases with no rods etc.
If you can get larger than a 2 thou feeler gauge into the journal/bush the bearing
needs to be replaced.
As Kommando says, a few lines are no problem plus fit a filter.

The chances are if you have the cases measured there will be fractional offset on the 2 main bearings,
this means that they should be line bored with a new bush fitted. Many run for many thousands of miles
without this ever being corrected. Its up to you. Blokes like Ed V can do the job if you decide to go down
that route.

Re: Timing side crank bushing
RUSS TILLEY #809582 05/20/20 12:07 pm
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I second the advice of Kommando and Nick. It is easy to go backwards with this issue! PRT

Re: Timing side crank bushing
NickL #809585 05/20/20 12:19 pm
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[quote=NickL]Assemble the crank into the cases with no rods etc.
If you can get larger than a 2 thou feeler gauge into the journal/bush the bearing
needs to be replaced.


Not an accurate way to measure that clearance. Would be great if it was.


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
Re: Timing side crank bushing
RUSS TILLEY #809615 05/20/20 2:56 pm
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The only alignment points for the case halves are the bush, one dowel pin and the cylinder joint. The clearance of the dowel pin in the opposite case half is usually more than the clearance of the bush on the crank. So even if you have the bush align bored there is little chance the case can be replaced over the crank in exactly the same place. It is important to get the bush and the bearing in the drive side installed square to the case so when the timing side is placed over the crank it is the crank that is aligning the case laterally and the cylinder joint aligning it around the crank.

Re: Timing side crank bushing
RUSS TILLEY #810674 Yesterday at 11:44 PM
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Many things to consider here..

I would personally invest in a micrometer and a bore gauge

Measuring the interference fit on the OD of the bushing is important - you do not want the bushing to spin..

Also make sure the hole is round (no tapers, damage, etc)

As Beach stated, .0015" is where you want to be, but I feel that the bushing material also dictates what clearacne you should run as not all bushing materials are the same

Just my 2cents


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