2 3/4 bronze big end bearing material spec.

[Dave@NZ]

Hi,

Can someone please confirm the material specification used for making big end bearings on 2 3/4 engine, there is a very good article here..
https://www.douglasmotorcycles.net/index.php?topic=3376.msg12753#msg12753

Since the article is a few years old just thought best check that Colphos 90 is still the ideal material to use. 

Thanks in advance
David.

[cardan]

Difficult to source bronze in my home town, so I doubt I could easily get "Colphos 90". I use PB1 without problem.

Leon

[Chris (Sprinter)]

hello,

I have found Pb1 to be perfectly suitable in big end bushes that I have machined including Levis and Alldays. Although, i have yet to machine a bronze bush for a Douglas.

Chris

[Dave@NZ]

Hi,
 Thanks for the response Leon and Chris the crank shaft is at the reconditioners and they are requiring the material spec prior to starting work making new shells.
We have two options now and can find out what is available to use.
David.

[cardan]

Hi David,

They might offer LG2: it is OK but I'm told PB1 is better so that's what I use. They are the only two grade of bronze I've come across here in Adelaide.

Leon

[Dave@NZ]

Thanks for the advice Leon,
I will find out this week if they have PB1 or Colphos available available if not I will have some sent over from the UK not keen to use an un-tested material incase of failure.

David.

[joeis6]

hello I am interested in this discussion because I am presently undertaking this job, and I would like to know what is the current thinking with regards to the big end bolts. It is obvious they must be well locked, some I have seen have been soldered , most seem to be split then splayed, even then there is a lot of evidence that these bolts fail at least on my three sets of cases wheresome show damage where this has happened several times?

[Dave@NZ]

Hi joeis6,
The big end bolts and nuts are new from the Douglas club I an not sure what the reconditioners will do there in regards to locking them most likely will hacksaw a slot and splay them open like the ones removed. Possibly the ones you had that were cracked had been reused a few times, have you made your big end shells or is it still to do.
David. 

[Ian]

The bolts I got from the Douglas club were pre-split and have worked well

[Dave@NZ]

Hi Ian,
Yes you are correct I have reviewed the photos of the new parts, it has been a while since I last seen them they are languishing in at the reconditioners.
Dave.

[joeis6]

hello Dave  I am in Lincoln are you anywhere near?  I have not made my bearings yet I will search out some pb1 for that. I have been cleaning up the crank with fine sandpaper to remove the oval takes some time and much caution, but the results are measureable a few more hours and I shall be there.

[Dave@NZ]

Hi,
 Yes not far just the other side of the Waimakariri river, I have sent you an email with contact number, sound like you are going well fixing your crankshaft.
Dave.