Operation: Battle Panda or: Getting the Airhead Ready for 2up Adventure - Page 2

igormortis · 02-01-2012, 05:26 PM

Brakes are being mulled over at the moment. I have a few solutions for a 320mm disc. I’m comparing options right now to see which is the most practical.

Steve, I may take you up on that offer of help, since you’ve cut your springs before...

I took the fork springs out today and did some approximate measurements.

Length is 505mm and the spring rate looks close to 4.2N/mm using the bathroom scale method (!).
I need to decrease travel from 300mm to the BMW’s 225mm, so 75mm needs to come off the spring.
A 430mm spring is 0.85 of the original length, so the original rate divided by 0.85 gives me the new rate...(?)

Am I right? This would give me a theoretical 4.9N/mm spring rate. Higher than the standard BMW rate (4.7 I believe) and higher again than a KTM 950 Adventure (I’ve read 4.8).

This seems like a good starting point for little to no cost, and would help me determine if I’m in the right range.

Box'a'bits · 02-01-2012, 05:51 PM

Quote:

Originally Posted by igormortis

Steve, I may take you up on that offer of help, since you’ve cut your springs before...

I took the fork springs out today and did some approximate measurements.

Length is 505mm and the spring rate looks close to 4.2N/mm using the bathroom scale method (!).
I need to decrease travel from 300mm to the BMW’s 225mm, so 75mm needs to come off the spring.
A 430mm spring is 0.85 of the original length, so the original rate divided by 0.85 gives me the new rate...(?)

Am I right? This would give me a theoretical 4.9N/mm spring rate. Higher than the standard BMW rate (4.7 I believe) and higher again than a KTM 950 Adventure (I’ve read 4.8).

This seems like a good starting point for little to no cost, and would help me determine if I’m in the right range.

Yes, that is the short cut for determining spring rate. Close approximate. I also tried to get spring rate calculators to check. These came out with a slightl;y different result (higher). Standard BMW spring rate is 0.48kgs/mm.

Your thinking is the same as I applied, & I am happy with the resultant spring rate. Your nm would equate to approx 0.43/kg/mm (start) & 0.51kg/mm (finish), with the resulting spring rate slightly firmer than what you have now. Good given the expected use.

When you cut the springs, mark where you want the sping to end & come back one spring turn. That will leave enough spring so that you can bend the surplus down, to create the new flats (effectively one turn of the spring).

Heat the ends of the spring to remove the temper (propane / butane torch will do it) & that turn down, either with a pair of pliers, or by compressing against some wood. Then grind the new flats on once you are happy with the bends.

I'm on leave at present, so am happy to pop around if you want a hand.

igormortis · 02-13-2012, 12:00 AM

I’ve cut my fork springs and disassembled the fork internals. As soon as I get some spacers made up I’ll see if I can successfully re-assemble them!

In the meantime, I pulled out my perfectly good R100R muffler...

...and cut it up:

Padmei · 02-15-2012, 09:46 PM

Coooooome on you slack bastard.

igormortis · 02-16-2012, 01:21 AM

Quote:

Originally Posted by Padmei

Coooooome on you slack bastard.

Yeah, I know. I could show you pics of scraping paint off the house, but that wouldn’t be too exciting...

igormortis · 02-16-2012, 10:32 PM

See... Progress, but not the kind you hope for in this thread.

Box'a'bits · 02-16-2012, 10:44 PM

Quote:

Originally Posted by igormortis

See... Progress, but not the kind you hope for in this thread.

That looks good. Want to come around & burn some paint at my place?

advNZer? · 02-20-2012, 12:39 AM

Quote:

Originally Posted by igormortis

See... Progress, but not the kind you hope for in this thread.

jeepers i need to do that too how come you have lost the eaves soffit cladding?

igormortis · 02-20-2012, 12:45 PM

Quote:

Originally Posted by advNZer?

jeepers i need to do that too how come you have lost the eaves soffit cladding?

Had to pull them off - rotten!

Padmei · 02-20-2012, 03:22 PM

Quote:

Originally Posted by igormortis

Had to pull them off - rotten!

Nows the time to put up those outside lites - The roof space is a bugger on those old houoses & there is usually a top plate erstricting access to the soffit.

igormortis · 03-04-2012, 09:40 PM

Not much to report due to house jobs. I did get some tools for the steering head bearings though, and they work great. If anyone local wants me to loan them out, let me know. They turn a potential clusterf*ck into a 5 minute job.

Box'a'bits · 03-12-2012, 12:58 AM

Quote:

Originally Posted by igormortis

I did get some tools for the steering head bearings though, and they work great. If anyone local wants me to loan them out, let me know. They turn a potential clusterf*ck into a 5 minute job.

Did you also get the 48mm seal fork seal driver?

igormortis · 03-12-2012, 01:30 AM

No, I didn’t. Was gonna follow your lead on that one.

Box'a'bits · 03-12-2012, 01:36 AM

Quote:

Originally Posted by igormortis

No, I didn’t. Was gonna follow your lead on that one.

Hmmm. Because I need to replace the fork bushes AGAIN, I may splurge. Watch this space. Need to get Gus up & running before RRRR

Mark_S · 03-12-2012, 03:00 AM

Quote:

Originally Posted by Box'a'bits

Hmmm. Because I need to replace the fork bushes AGAIN,

wtf?
did the missalignment of the forks with the duff axle eat the bushes?

For what its worth Proride just did a full service on my wr forks for $220 incl seals, oil etc which I thought was pretty reasonable.

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02-01-2012, 05:26 PM	#16
igormortis ^OP Beastly Adventurer Joined: Dec 2006 Location: Wellington, New Zealand Oddometer: 1,082	Brakes are being mulled over at the moment. I have a few solutions for a 320mm disc. I’m comparing options right now to see which is the most practical. Steve, I may take you up on that offer of help, since you’ve cut your springs before... I took the fork springs out today and did some approximate measurements. Length is 505mm and the spring rate looks close to 4.2N/mm using the bathroom scale method (!). I need to decrease travel from 300mm to the BMW’s 225mm, so 75mm needs to come off the spring. A 430mm spring is 0.85 of the original length, so the original rate divided by 0.85 gives me the new rate...(?) Am I right? This would give me a theoretical 4.9N/mm spring rate. Higher than the standard BMW rate (4.7 I believe) and higher again than a KTM 950 Adventure (I’ve read 4.8). This seems like a good starting point for little to no cost, and would help me determine if I’m in the right range.

02-13-2012, 12:00 AM	#18
igormortis ^OP Beastly Adventurer Joined: Dec 2006 Location: Wellington, New Zealand Oddometer: 1,082	I’ve cut my fork springs and disassembled the fork internals. As soon as I get some spacers made up I’ll see if I can successfully re-assemble them! In the meantime, I pulled out my perfectly good R100R muffler... ...and cut it up:

02-15-2012, 09:46 PM	#19
Padmei enamoured Joined: Mar 2008 Location: Nelson New Zealand Oddometer: 2,486	Coooooome on you slack bastard.

02-16-2012, 10:32 PM	#21
igormortis ^OP Beastly Adventurer Joined: Dec 2006 Location: Wellington, New Zealand Oddometer: 1,082	See... Progress, but not the kind you hope for in this thread.

03-04-2012, 09:40 PM	#26
igormortis ^OP Beastly Adventurer Joined: Dec 2006 Location: Wellington, New Zealand Oddometer: 1,082	Not much to report due to house jobs. I did get some tools for the steering head bearings though, and they work great. If anyone local wants me to loan them out, let me know. They turn a potential clusterf*ck into a 5 minute job.

03-12-2012, 01:30 AM	#28
igormortis ^OP Beastly Adventurer Joined: Dec 2006 Location: Wellington, New Zealand Oddometer: 1,082	No, I didn’t. Was gonna follow your lead on that one.