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General => Douglas Motorcycles - General Discussion => Topic started by: Dave@NZ on 16 Aug 2013 at 03:36

Title: 2 3/4 bronze big end bearing material spec.
Post by: Dave@NZ on 16 Aug 2013 at 03:36
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.
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: cardan on 17 Aug 2013 at 09:32

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

Leon
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: Chris (Sprinter) on 17 Aug 2013 at 22:43
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
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: Dave@NZ on 18 Aug 2013 at 08:59
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.
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: cardan on 18 Aug 2013 at 09:08

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
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: Dave@NZ on 18 Aug 2013 at 10:01
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.
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: joeis6 on 19 Aug 2013 at 10:40
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?
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: Dave@NZ on 21 Aug 2013 at 05:39
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. 
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: Ian on 21 Aug 2013 at 08:45
The bolts I got from the Douglas club were pre-split and have worked well
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: Dave@NZ on 21 Aug 2013 at 09:15
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.

(https://www.douglasmotorcycles.net/aa-files/images/dave@nz/2014/bronze-big-end-bearing-material-spec-900.JPG)
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: joeis6 on 21 Aug 2013 at 21:19
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.
Title: Re: 2 3/4 bronze big end bearing material spec.
Post by: Dave@NZ on 22 Aug 2013 at 08:46
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.