Author Topic: Timing side bush - again !  (Read 2207 times)

Online Brian

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Timing side bush - again !
« on: 22.02. 2010 06:55 »
I know this subject has been gone over a million times but has anyone ever worked out just what material to make them out of ?

I am going to get a length of metal and make my own. Now I am not going to go into the subject of one piece or sleeved steel, mine will be one piece.

I have narrowed it down to two different metals. Both bronze alloys, one being lead/phosphor/bronze (SAE660) and the other lead/tin/bronze (SAE66). Both of these are very similar with the percentages of whats in them but one with tin and the other phosphorous.

I am fairly confident that either will do the job but one may be slightly better than the other. I am quite prepared if necessary to pull the motor down after 10,000 miles or so and measure everything to see how its going.

As has been said here before, machine shops always grind the journals in .010" increments but this is totally unecessary as usually 3 or 4 thou will clean up the crank. I intend to get the two cranks I have to do ground just enough to clean the journal and then make the bush to suit.

If anyone has made one themselves and done a few thousand miles on it I would be keen to hear how its going.

Offline jimmy

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Re: Timing side bush - again !
« Reply #1 on: 22.02. 2010 12:11 »
G`day Brian,
                       I have bushed my A7 with phosphor bronze but have only done a few hundred miles. Like you I got the shaft ground down the mininum amount to true it, I chose  phosphor bronze as it should be harder wearing than plain bronze and readily available. I bushed the steel outer and did it as original, have also done my A10 but goodness knows when that will run. I made an extended reamer guide and reamed the bush and was very happy with the result.
 I did a lot of umming and ahhing but in the end it came down to what bronze was readily available.

regards JIm
1961 Shooting Star on the road   1951 Golden Flash on the bench

Online A10Boy

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Re: Timing side bush - again !
« Reply #2 on: 22.02. 2010 13:19 »
Brian

I had one made by Mike from sae 660, its been fitted a year or so and is doing well. Mike makes them for all models and sells on ebay if you're interested and will make yours to suit. Its a really well made bit of kit.

http://cgi.ebay.co.uk/BSA-C15-B40-crankshaft-bearing-bush-SOLID-LEAD-BRONZE_W0QQitemZ320491006067QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item4a9ec0a873

Regards
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Andy

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Offline beezalex

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Re: Timing side bush - again !
« Reply #3 on: 22.02. 2010 15:21 »
I've had good results with 660.  Never used 66, though.
Alex

Too many BSA's


Online Brian

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Re: Timing side bush - again !
« Reply #4 on: 22.02. 2010 22:35 »
Thanks guys,

I am fairly sure I will use the SAE660. After doing as much research as I can it seems to be the one to use plus most of the ones on the market at the moment seem to be made from SAE660.

This is one of those things that when you start researching it gets more confusing. There are literally dozens of different metals available for bushing and some of them only have minor percentages of difference with their composition, very hard to work out which is best for a particular application.

I have found a company here in Aus that can supply these metals in bar form so I will ring them today and see what I can get.

Brian.

Offline muskrat

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Re: Timing side bush - again !
« Reply #5 on: 23.02. 2010 08:15 »
G'day Brian,
                660 is the go. Before I went roller I had one made and raced for a few years with very little wear.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline BSA_54A10

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Re: Timing side bush - again !
« Reply #6 on: 23.02. 2010 08:23 »
You should be able to get 88:10:2 or 85:5:5:5 leaded gunmetal in a heavy walled extruded tube sold under the name of "Guardshaft" ( actually I think it is Gardshaft ) .
Any way it is the ideal material for rebushing you mains with.
Not as hard as phos  or Al bronze so it won't grind against the journal.
The lead makes it self lubricating should it overheat due to an oil failure ( again protecting your crank )
It machines freely to a very fine finish.
Make it slightly oversize, fit it in the old steel backing ,then into the cases , now here is the trick, ream almost to size then finish off with a hone. The honed surface retains oil much better than a reamed surface and the fit should be a light press ( with you hand) fit , some call this a "stiff finger".
It will bed in in no time flat ( first 5 minutes ) and give you a long service life.
Bike Beesa
Trevor

Online Brian

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Re: Timing side bush - again !
« Reply #7 on: 23.02. 2010 09:04 »
Hi Trev,

The leaded gunmetal is called LG2 and as you say is 85-5-5-5, thats 85% copper, 5% lead, 5% tin and 5% zinc. The SAE660 is 85-7-7-3, 85%copper, 7% lead 7% tin and 3% zinc. Both have almost negligable amounts of aluminium and phosphorous. The company I have been researching with is Flocast in Vic, you may well know it. There recommendation is to use the 660 for bushings and the LG2 for things like pump and valve bodies. Its a bit of a toss up either way but the 660 seems to be the one most choose for bushes.

The argument over a solid bush or a lined steel one can go either way. Ian Croft at C@D's in the UK says they have only ever had two failures with timing side bushes they have sold and both were steel lined ones, they will only sell solid ones now. SRM say the same and will only sell solid ones. Obviously it can be argued that the lined steel ones where not fitted correctly etc. There seem to be plenty of A10's running with solid bushes that have not caused any trouble. I think it is a case of either would be fine if fitted correctly.

Brian.

Online Brian

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Re: Timing side bush - again !
« Reply #8 on: 24.02. 2010 04:03 »
A bit of an update for anyone interested.

I ended up getting a lump of LG2, leaded gunmetal 85-5-5-5. After a few phone calls and discussions with the company I was dealing with they tell me they no longer make SAE660 as it has been superceded with LG2 !

To make it even more confusing there doesnt appear to be an industry standard for this stuff so the composition varies between manufacturers. For example the LG2 I bought has a composition of 85-5-5-5 but two other companies I called call their version with the same composition SAE660 so I guess it depends on who you ask as to wether I have LG2 or SAE660.

I bought a 305mm length with a OD of 50mm and a ID of 25mm, I should be able to get ten bushes out of it. Cost me $118 Aust so about $12 per bush compared to about $80 to buy one and get it posted to Aus.

Trev, (BSA_54A10) I like your suggestion of honing to the final size and will do this.

Its all a big learning curve, but good fun.

Online RichardL

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Re: Timing side bush - again !
« Reply #9 on: 24.02. 2010 06:41 »
Brian,

This whole discussion of the bronzes is very interesting. I am lucky enough to have a copy of the American Society of Metals Handbook, so I tried a little research. First, I wonder if the bar you got is cast or wrought. In castings, it appears that the name for 85-5-5-5 is "Leaded Red Brass", while 83-7-7-3 is "High Lead Tin Bronze".

The following paragraphs in the sleeve bearing section were interesting:

TIN BRONZES

   The bearing bronzes are substantially alloys of copper, with from 5 to 20 % Sn, and a small percentage of residual phosphorus - phosphorus remaining after deoxidation of the alloys with 10 to 15% phosphor copper. These alloys are sometimes referred to as "phosphor bronzes".
   When 2 to 6% Zn is used instead of of phosphorus, the alloy is quite generally referred to as "gun metal" (also, as Government bronze, composition G, admiralty bronze, or zinc bronze).


I don't know if any of this is news to you, but it was interesting to me in following the thread of your topic.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Brian

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Re: Timing side bush - again !
« Reply #10 on: 24.02. 2010 07:23 »
Interesting reading Richard, one of the articles I came across also refered to it as red brass. Its nearly impossible to understand it all, like I said different companies class their products differently so just how you know for sure what you have is beyond me.

I am confident that the material I have bought will do the job, and after a few thousand miles I will know one way or the other !

The bar I bought is centrifigaly cast.

Brian.

Offline BSA_54A10

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Re: Timing side bush - again !
« Reply #11 on: 27.02. 2010 23:11 »
There are literally thousands of variations on the specs of Leaded Gunmetals.
According to the Aust standards the major alloying elements are = or - 0.5 % each.
When I was at Simms we used to make over 50 different variations on 3 fives the big difference is in the amount and tollerances for the major impurities like Chrome, Iron, Arsnic , Antiminomy & Aluminium .
Most of it is made from recycled plumbers brass, so you pick up a fair bit of chrome & iron.
The chrome is a grain modifier so yields a really fine grain direct from the cast ( good ) while iron tends to make it hot short, not so good.
We were a it unique as we used to actually determine the copper content which can be as low as 80% .
The specifications give a maximum & mimimum amount of each alloying element and a maximum level for each of the common impurities with the balance being copper.
Copper alloys have a long history of developement and use which preceede the understanding of the metallurgy of the alloys so the actual definition of Brasses vs Bronzes is very muddy so modern terminology is based around the microstructure and all alloying elements are measured against the amount of zinc that would produce the same ( or very similar) structure or cause a particular phase to appear.
They are given what we call a Zinc Equivalence.
Now that metallography is a common tool we have come to understand that you can achieve the exact same microstructure from a very wide and diverse alloying regeime.
Because we used to utilize the alloys before we understood them and in particular the effect of minor impurities, commercial companies gave particular specific alloy combinations names like "Admirality Bronze" or "Muntz metal" ( there are about 5 Muntz's ) or even "Gunmetal" ( what they used to cast bronze muzzle loading cannons out of )
   
Bike Beesa
Trevor