re-sleeve T/S bushing

[coater87]

 Guys,

 I was working on turning a new T/S bushing, when the thought hit me about re-using the original metal cage- and just turning the sleeve inside. Now I noticed this is pinned to stop it from rotating.

 My questions are, is re-using the metal cage a do-able idea (or a good idea at all), and if so how do you remove the pin from the cage without doing damage to the outer housing?

 Anyone actually ever do this, or know of someone who did?

 Thank you,
Lee

[muskrat]

G'day Lee,
              a friend of mine bored the bush out 15thou and coated it with white metal, then reamed it to suit his 2thou under crank. This was 20 years ago and it is still in service.
Cheers.

[trevinoz]

Lee, the dowel, or pin, will push out and can be reused.
Trev.

[coater87]

 Thanks Trev and Muskrat,

 I am going to give this a try and I will let everyone know the out come. Hopefully it works well as it would save a bit on the bronze and quite a bit on the time needed to turn a full bush.

 Lee

[Josh Cox]

Coater,

I have had exactly that just done, took the old bush ( metal outer copper inner ) to a machinist, he machined out the old centre and replaced it with a shiney new piece of PB, make sure you loctite the new inner inplace. (this guy has done lots of these, he reckons the pinning is not required).

Leave plenty of material there so you can later ream to the crank OD after crank grinding.

[coater87]

 Guys,

 That went pretty well. I had a little trouble removing the old bushing, but the pin popped right out- I just had to find it afterward.

 I turned the insert from LB, I made it 1/2 thousandth oversize. I heated the cage, used a little lock tite, and will reuse the pin. Probably over kill, but this is the first time I have done this and want to be sure its OK. I had my reamer resized, it will never ream 1.5 inches again, but it will ream any size T/S bushing comfortably.

 I still have to drill for the oil and pin, but I left .040 for reaming later. Its a lot and will take some time, but I have no idea how square the bushing will go back into the case. Now I just have to make a guide for the drive side, and ream till my arm falls off.

Lee

[orabanda]

Hey Coater87,
Good work; well done!
Just a suggestion; don't use that reamer on your bush!
The process will not be accurate enough. I am pretty sure that by the time you have reamed it enough for the crankshaft to rotate freely through 360 degrees, there will be too much clearance between the bush and the journal. Also the surface finish will only be average.

I suggest you (literally) drop the bush in the crankcase half (after heating crankcase in mum's oven to 250 C). Then, find a machinist with a borer, and request that he clocks off the machined bore for outer race for the LH (primary side) bearing.

Then he should machine your bush to give 0.0015" clearance on the timing side journal, and it will be hunky-dory!

Make sure:

He doesn't clock off the crankcase half mating face (the crankcase bearings might not have been machined at 90 degrees to this face)
The timing side crankcase journal has been ground  and linished in a crankcase grinder beforehand.
 Regards,
Richard

[coater87]

 Hi Richard,

 I would think that turning a guide bush for the drive side (that fits the reamer), bolting the cases together and then reaming would get me to where I need to go. I have found a complete lack of help from local machine shops, most of these guys are high production and seam unwilling to except one small job like this. I live in a foundry area, and I guess that should be expected.

 I have found in the past that I can greatly increase the finish using an expandable reamer. I make quite a mess, but it works well. To remove the harmonics (which cause the chatter), I first pack the cutting end of the reamer in very thick grease, then I wrap the whole mess with wax paper. The finish will be a mirror of the grind, and if done very slow feed/speed, its a very nice finish.

 And if worse came to worst, I can always remove the bushing, rebuild it and send it off. I would like to give this a try though first. A lot of my own enjoyment with this type of project is doing the maximum amount of the work myself and making things and doing the machining are part that too me.

 Heck, I even feel guilty I had to have the crank ground by someone else- but that type of equipment is beyond my budget, and space. Besides, how many cranks would you have to grind to make it worthwhile!

 Lee

[A10Boy]

Theres a chap in the UK who will make a LEAD bronze one piece bush for about £38, I got one and had it fitted at T&L Engineering.

I got his number if anyone wants it.

Andy

[nigeldtr]

Lee,

As I mentioned, I would like to do the same, how did you get on?

[BSA_54A10]

It is not a difficult job even for the home machinist to do.
Just be careful which material you use for the new lining.
We had a long and exhaustive discussion a while ago about suitable alternatives.
I very, very , very strongly recommend 85,5,5,5 leadded gunmetal.
Phos bronze is way too hard and I regard it as playing Russian Roulette with your journal.
Let the oil pressure drop and it will be toast.
Ditto for Al bronze.

As for making a complete new one piece bush from LC or LB , not a good idea, as neither have sufficient rigidity or strength,
Phos bronze dose have the ncessary strength but as already stated I consider it too " unforgving" to be a realistic alternative the the leadded bronzes or gunmetals

[RichardL]

Trevor,

A question. If the oil pressure was to drop to the point of no film on the T/S bush, wouldn't the left-side big end have left the building long since?

Richard L.

[A10Boy]

Both probably.

As for making a complete new one piece bush from LC or LB , not a good idea, as neither have sufficient rigidity or strength

Have you any calculations on this or is this just opinion?

I would imagine the forces at say 120mph, which would be around 8,000 rpm, must be huge?

[nigeldtr]

From what I can remember, it does not take much oil pressure to keep the crankshaft afloat even at high speed and loading. Provided oil gets into the crank, the centrifugal forces while push any oil out to the big ends with a huge pressure so again provided there is oil pressure at the main journal, things will work, perhaps not optimally from a stress and cooling perspective but there will be lubrication. Unless I am mistaken, (please correct me if I am wrong) the killer for white metal is heat and/or direct friction - running dry from cold after standing for 2 weeks etc. I don't have the materials experience but I would tend to a solid one piece Phos/Bronze bush simply because of the above problems. However, I am equally happy to try as recommended. I will probably only ride 2000 miles a year so what every I do should hopefully outlast me

Nigel

[A10Boy]

I just don't like the idea of inserts even if they are glued and screwed. You hear horror stories of them turning and cutting the oil supply.