Author Topic: The next project.  (Read 4455 times)

0 Members and 1 Guest are viewing this topic.

Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #50 on: August 12, 2018, 10:10:40 PM »
Ok so this morning I took my very sore head out to the shed to take stock. The back shock is probably done for also, pitted shaft and the nitrogen canister has been vibrating against the broken bracket on the frame. The linkage is good now with all new bearings so one step forward as they say.

Sent from my SM-A520F using Tapatalk


Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #51 on: August 12, 2018, 11:57:02 PM »
Hi to all
Can any one explane Yamaha part numbers for me. I am looking at 490 swing arms on CMS to see if any
cross over, as I see it the first three numbers or letters are the modle but after that if the following
numbers are the same does this meen it's the same part ?

Cheers Rich.

Offline Devondan

  • Yama-God
  • ******
  • Posts: 2297
Re: The next project.
« Reply #52 on: August 13, 2018, 04:28:16 AM »
Generally they used the same part numbers for each part the key difference was the model numbers at the front, so a 1W3 1234 would NOT be fthe same as a 4V5 1234. 

A number of the American parts websites like partzilla have a function that lets you see what other bikes the part was fitted to.

As I recall the first year of the YZ 490 could be fitted with the YZ 465 swinging arm ( complete with shock, chain adjusters etc) there?s a few of those conversions racing in the Twinshock class down here - direct link monoshock is permitted so long as it?s aircooled and has a drum brake.

Like this one http://www.facebook.com/groups/253236531428956/permalink/1650124195073509/

Hope that helps a bit!
IT  400D - Trail riding
74 Montesa Cappra - Racing
YZ250 H - Racing
Norton ES2 500 trials
Norton 250 Jubilee - Road
Norton 350 Navigator (in boxes)
Norton 350 Single M50 (in boxes)

Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #53 on: August 13, 2018, 06:36:21 AM »
Cheers for that Dan
Sort of makes sence from what I have beem looking at.
My YZ is a1984 it has a more upright shock set up so I dont think
that will work.
Partziller nex then.

Rich

Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #54 on: August 21, 2018, 07:26:03 PM »
Hi to all
Just a quick update on the YZ progress. I have found another swing arm from an 83 490. As far as I can tell the yz250 and 490 had the same arm from 83 to 85. It wasn't a lot of money so if it's wrong it won't break the bank. I spent a few hours sorting the wheat from the chaff as far as wheels are concerned, I have two good back and one good front hub. After Dave's thread on getting older I have been thinking what will I do when my body won't any more.
Then it struck me I have a nice collection of vintage rim clamps to play with. Can't decide if I should do them up or keep the original patina

Rich.


Sent from my SM-A520F using Tapatalk


Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #55 on: August 21, 2018, 07:43:45 PM »
After stripping wheels I gave Sids wheels a shout, he was very helpful
So he will be building the new ones.
Thanks Dave for that lead. So this is where I am at so far hopefully swing arm and wheels and forks sorted.
But I still need
Back shock every bolt in the bike
Including Linkage bolts
Sort out the rusty frame
Sort out the kick start
Modify the steerer tube to fit the YZ head stock
So should be up and running in a couple of weeks 🤣

Rich.

Sent from my SM-A520F using Tapatalk


Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #56 on: August 21, 2018, 07:55:49 PM »
Oh yeah and engine mounts

Rich

Sent from my SM-A520F using Tapatalk


Offline wayne61

  • Yama-God
  • ******
  • Posts: 1498
Re: The next project.
« Reply #57 on: August 21, 2018, 11:33:03 PM »
Aluminum is a polar opposite. Very rigid when heat treated and is unpredictable on time to failure. It's called fatigue cycle and aluminum has none. It can break on the first flex/return cycle.

Your friends at Boeing, and my colleagues at Airbus might suggest that aluminium (extra i for the Europeans  :) ) does have fatigue capability.
Lots of Aluminium A/C structure flying happily every day  :)
We do quite a lot of analysis to determine fatigue lives and demonstrate that structures meet design service goals.
There is much test evidence to confirm the predictability.
We know how many cycles a component can react between a detectable crack (L-det) to it propagating to a critical length (L-Crit)
Our basic analysis always assumes an undetectable crack at the most critical feature.

In fact, if a component fails on the first load cycle it is a static load (strength) failure, not a fatigue failure.

Most of our time these days is spent optimising our structure until fatigue becomes the limiting factor.
Of course, the move to carbon composites has made a difference, huge fatigue capability with the wattle and daub black metal.
But what material science gives us in fatigue performance, it takes away with thermal issues (differing co-efficients of linear expansion) and good old galvanic corrosion.


Regarding material choice for frame repair, engineering, like life is full of compromises.
Ideally the repair should be in OEM spec material, I guess this is the 4130 CroMo.
The original design would have used the properties of this material to size it appropriately for its requirement.
This sizing would have been done to include a safety margin.
The margin is evident because despite the frame in question being significantly corroded it has not yet failed.
The advantage of CroMo of mild steel is better material properties at the same net section area. ie you can use a lighter thinner CroMo to do the same job as mild steel.
If you're not concerned about the weight, a thicker walled mild steel tube would be strong enough.
I would err to the side of caution as I don't have the material specs, but if you could find a mild steel tube that was twice the wall thickness of the OEM tube I think it would be conservative enough.


I may have typed too much  ;D ;D
Go soothingly on the grease mud, as there lurks the skid demon.

GRIP AND RIP CRAIG AND CHRISSO!!!

Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #58 on: August 22, 2018, 12:58:58 AM »
Interesting stuff the plan was to go CDS as the tube is loaded in compression and the load it carries is me and the seat. The tube was ordered a while back and the delivery charge was shocking but it hasn't turned up so I may cancel the order and hunt some more.

Rich.

Sent from my SM-A520F using Tapatalk


Offline Bigusdickus

  • Yama-Hero
  • ****
  • Posts: 266
Re: The next project.
« Reply #59 on: August 22, 2018, 03:07:23 AM »
Hi to all
Good news this evening when I got in, the swing arm has arrived. There is two very subtle diferences
between the two firstly the block that prevents the box section from compressing is welded in on the 83 but glued in on
the 84, after looking at yz swing arms for a while I have found some that are  held in by two screws. The second I am fairly sure is a manufacturing variation, the chain guide hanger is 3mm further foward on the 83. It looks like 250 and 490
from 83 to 85 have pretty much the same swing arm, so made it a bit easier to find one. The last two pictures show
how much the bad bearing had eaten the swing arm.

Rich.