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Allan G, JER.Hill, KevRasen, NickL, Stuart Kirk
Total Likes: 7
Original Post (Thread Starter)
#838503 01/30/2021 8:27 AM
by Phil R
Phil R
I've been experiencing some difficulty lately with finding a shop that I trust to line ream the timing side bush on a "70 Lightning. This has got me to considering possible alternatives, to wit: adjustable reamers with pilots.

It appears that a suitably sized reamer is available to cover the necessary dimensions, this journal is on the 2nd regrind. Since I don't have any experience with these type reamers I'm hesitant to jump right in without first seeking some advise/insight from someone who may have already been there.

Questions arise such as:
1) if set up with a mic, will they (adj. reamers) hold true when used for fairly precision jobs like the timing side bush?

2) If a suitable "donut" is machined to fill the roller bearing outer race on the drive side (or perhaps use the roller bearing inner race
itself) to act as an end point for a pilot, can the bush then be hand reamed to the appropriate dimension with any expectation of
required accuracy?

Seems feasible but then again theory and reality often clash.

This bike had oil pressure problems ( unheard of regarding A65"s grin ) and after exhaustive efforts with OPRV's (both types), various oil weights, gauge readout locations, etc. a final teardown revealed uneven wear in the bush (approximately 80 mi on the engine). Bad job on the original line bore...?
Crankshaft possibly tweaked and wobbling....? Questions, Questions.
Any thoughts or information regarding the above are highly appreciated.

Liked Replies
#839216 Feb 6th a 07:50 AM
by JER.Hill

I might as well add my tuppence worth. I'd say if you timing bush is shot, then for the time and cost involved, I'd recommend upgrading to the needle/ball end-feed for the timing side.
I agree with Nick that it has to be machined correctly, but when done it all fits together straight off every time. And as you pointed out the Brg run's on the inner race and NOT on the actual crankshaft, plus, once fitted unlikely to wear out in your lifetime.

Pre 67 engines do require a little weld on the crankcase to bring the oil-way transfer to the inner timing case if going for the integral system. Again I'll agree with Nick in that its not a good idea to weld on the timing cover due to the potential chances of distortion, however its easy to make a seal carrier block which can be bolted or held in place with modern metal adhesives, the plus side in end-feeding the crank is that you have gained at least an extra 25% oil supply to the big-ends which wasn't available with the bush. So your old oil pump is good to go, I'm assuming it's been rebuilt correctly.

As for the EI, well I'll leave that to better qualified people to comment on. But I think it'll be something else that will break or fall off when you're out on your "Old Crate" that will stop you getting home. Sorry Nick couldn't resist steeling your description.

In advance, sorry if I've hurt anyones feelings.

2 members like this
#839251 Feb 6th a 07:53 PM
by John Healy
John Healy
But as I mentioned early in this thread Ed V is the only shop doing it in the U.S. that I’m aware of and he’s got a fair back log of engines awaiting that conversion.

Ed does great work, but so does Frank Deihl. Frank has been doing them for years. Classic Cycle Works Georgetown SC [email protected]

A lot of people who fit new timing side bushings finish sizing the bushing so as little material has to be removed from the crankshaft. They bore/ream hole until it cleans up and then have the crankshaft ground to give it the required .001" to .0015" clearance. They don't grind the shaft first and then size the hole. It is far easier to grind the shaft accurately as it is to ream/bore the bearing in the case. Also you only have to remove only the amount required from the crankshaft, and not go in increments of .010". There is no law that you have to go in .010" increments.
1 member likes this
#838661 Jan 31st a 06:25 PM
by Ignoramus
Originally Posted by gunner
Have a look at this YouTube video - Here which shows one way to line bore the timing side bush.

Note that careful measurements are made with the cases assembled to check the drive side housing is concentric, then the drive side is removed and the timing side is also checked for concentricity.

By using a mill with the cases bolted down the result should be that the timing side bush is perfectly concentric with the drive side once bored.

There are other ways to do this but using a solid mill seems best.

Yes that is the right way as long as you are completely confident that the split face and the outer face are dead parallel the look of the gear the guy in the vid has i would say he didnt miss that point.

However the question i ask is "is it necessary and why is it necessary? "

back in the day all you did was get an undersize bush and grind the crank to specified sizes and shove the new bush in and guess what it worked.

The internet has turned this whole thing into some kind of back art!

People go on incessantly about "line boring or align reaming" which by the way are totally different operations, and few seem to be able to explain what they involve, For those who think u can support a reamer from the ball/roller bearing and it will magically make the reamer line up the bush , you cant! ...if you don't believe me just put the crank into the bearing and see how much lateral movement there is over that distance, A reamer will follow the hole , the only way to make a hole "shift over a bit" is with a single point cutter ..

it is only necessary to do the milling thing as per vid if the bush hole has become oval or hammered out of round or if the cases have slightly warped by 50 years of hot cold cycles , but generally they haven't perceivably "shifted" ....other that that , well ya know.... racing guys shouldnt bother cause they are going to blow the things up any how ,


I dropped a rod on my A10 on the timing side it blew that side of the case to bits, i didnt lose my case numbers a VERY GOOD THING!

MAN did the experts in the club have a fielded telling me what i had to do if (as i did) i got a half case ( obviously from another motor) and fitted that . you MUST GET IT LINE BORED ETC .........i told them i would if it was necessary . IT wasnt! ....i made a new bushing to match the crank (which unbelievably was still ok) and with a bit of careful hand fitting reassembled it ........the bottom end is perfect. 5k miles and counting

I did not spend thousands and wait 6 month for some prema donna to do it.

man that ecercise shut a few mouths, fact is BSA did a very good job on making therir cases uniform and doweling insures alignment

but having said all that i would advise someone who isnt an engineer to just go with the latest trend and get it done , finding someone will be the hard part as will paying for it , doing that sort of work takes skill and a lot of gear and i dont grudge what they charge for a second ...its the lengly wait i object to.and if you get a comedian they will stuff it up big time

Just saying ....but ive only been a fitter turner for 40 years so what would i know?

now i will sit back and wait to be howled down hahhaha ive got sore figures after that lengthily post with probably no one will read anyhow ROFLMFAO
1 member likes this
#839877 Feb 13th a 03:58 AM
by BSA_WM20
PB is too hard IMHO
I always prefer LG 2 or 85-5-5-5
Which al almost as strong and has the added avantage of the lead lubricating the bush should the oil pressure fail.
1 member likes this
#840096 Feb 15th a 12:31 PM
by BSA_WM20
I think it was Trev from Newcastle ( TrevinOZ ) does LG2 sleeves shrunk back into the original steel outer which should work even better but is too much fiddleing around for me to attempt .
Thought he may have chimed in but perhaps not as he is a pre-unit twin man so may have skipped this thread.
The only other thig to mention is LG2 comes in two forms,
'Continiously cast solid & extruded tube.
For this application the extrude is by far the better material to use due to finer grain size & beter grain orientation .

LG2 is a universal bearing material.
We used to make at least 1 pour ( approx 6 ton ) a week as SFI .
the only place I would use something different is for valve guides because you want the guide to be harder than the valve stem in which case a phos bronze would be the go, and a leaded phos bronze even better .

And yes Ignoramus is correct about machining,
high speeds with negative / neutral rake
Hand scrapes beautifully if you have some old worn out files that need to be repurposed & the skills to use them.

And that should be WAS a metallurgist, been 40 years since I wore a dust coat .
I find myself needing to whip out the ASM handbooks a bit more often these days.
But yes it is good to be in agreement for a change.

As for the warnings about solid bushes, they should all be fine.
The big problem is most copper based bearing materials look very much the same so it is difficult to tell exactly what materail they are made from visually.
I got some bushes for the M20's box decades ago that were actully cast then machined ( badly ) to ( almost ) size.
A cast bush is highly likely to crack radially and then of course crumble away and I have a feeling that the warnings may have come from that happening.
These things are what you would expect to find unbranded for sale on evil pay or ammo-zone very cheap .
As a rule a good supplier will be able to tell you exctly what alloy the bushes they are selling are made from.
If not go some where else, and by exactly I mean LG 1, or 2 or 3 ( etc ) PB 1, 2 ( same thing ) .
For the USA it should be a 3 or 4 number material code.
If they just say "bronze " then walk away .
1 member likes this
#840144 Feb 15th a 07:02 PM
by kommando
Originally Posted by Stuart Kirk
Steel backed split piston pin bushes are used in diesel engines.

How would one of those work for a T/S bush on a bsa? They come un-sized with about .015" for machining.

This is of course assuming there is one of the right size.

These would be VP10 as a Vandervell made Bush or SY if a Glacier bush. Chemically the same, Vandervell cast on steel, Glacier sintered onto steel. Difficulty is finding the right sized bush, Perkins or Cummins would be a good start. The same bronze is used by most steel backed bronze bush makers. Just stay clear of modern car engines which are lead free and the bronze suffers.

Glacier Industrial Bearings do SY bushes in imperial sizes.
1 member likes this
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