Help me with some rear shocks.

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KiwiBacon
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Help me with some rear shocks.

Postby KiwiBacon » Tue May 20, 2008 7:19 pm

Hey guys, as mentioned elsewhere recently, I'm planning to build myself a light trailer and I'm looking at motorbike rear coilover shocks for it.

I'm looking for info on the overall length (eye to eye), stroke and spring rates on common dirt bikes. Hopefully I can find something common enough to pull a matched (not shagged) pair from a wrecker somewhere.

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85BJ73
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Re: Help me with some rear shocks.

Postby 85BJ73 » Wed May 21, 2008 9:08 am

Try the Hagon website, they will give you the standard eye to eye lengths. Keep away from mudbug and farmbike shocks, the will be too light, go for some off, say a PE/IT/XR500, they are of better quality than the farmbike stuff.
If you get stuck, gimme a call at work, 06 345 3462, I work for a bike shop, and can help you with second hand stuff....also some ATV shocks are worth considering too. Have you got a length in mind? If so, lemme know, and I will see what I can find.
Shane
No matter the problem, the answer is always give it more gas.......
Modded 1985 Landcruiser, semi restrained nutter behind wheel.

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tpft
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Re: Help me with some rear shocks.

Postby tpft » Wed May 21, 2008 9:21 am

i,d say shocks from a twin shock road or dirt bike would just collaspe, only meant to carry rider and passenger say
100 or 150 kgs of direct weight, single shocks may work alright but a expensive way of doing it, plus designed to work with linkages, ktms pds would work as designed to mount direct but huge cost

just normal car shocks and springs be lot better.
95 Safari on brg 33,s/ 4age e class zuk (old faithfull)/ d class rig under construction.

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KiwiBacon
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Re: Help me with some rear shocks.

Postby KiwiBacon » Wed May 21, 2008 9:42 am

tpft wrote:i,d say shocks from a twin shock road or dirt bike would just collaspe, only meant to carry rider and passenger say


I'm looking for monoshocks (but a pair, essentially two bikes worth of rear shocks) and my trailer won't have 12" of wheel travel so the rates should work out reasonably well. But leverage ratios and mounting won't be known for some time yet.
Info on XR500 type shocks is what I'm looking for.

The Hagon site had an application guide, but it only lists price and part numbers. Sadly not length, stroke and spring rates. But thanks for the link.

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tpft
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Re: Help me with some rear shocks.

Postby tpft » Wed May 21, 2008 9:59 am

xr 500 shocks would be way too light.
u say u looking for monoshocks? hagon xr 500 are twin shock?

vmx guys used up all good xr 500 spares
95 Safari on brg 33,s/ 4age e class zuk (old faithfull)/ d class rig under construction.

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KiwiBacon
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Re: Help me with some rear shocks.

Postby KiwiBacon » Wed May 21, 2008 10:10 am

tpft wrote:xr 500 shocks would be way too light.
u say u looking for monoshocks? hagon xr 500 are twin shock?

vmx guys used up all good xr 500 spares


Unless you go back to the 80's, these XR500's are all prolink monoshock.
http://www.bikepics.com/honda/xr500/

An XR500 with a rider onboard has what, 150kg on the back wheel with most of a foot of travel?
Reducing the leverage by half means you can support 300kg at 1/3 sag with 6" of travel.
One of these on each side and that can take 600kg easily.

That's plenty for this application.

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tpft
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Re: Help me with some rear shocks.

Postby tpft » Wed May 21, 2008 10:34 am

ok u are talking mono and are willing to spend 800+ on a new hagon
reducing leverage by half?
so u are going to run a linkage or just a arm.

i guess u think that it will provide better offroad performance, which because a spring is a spring means u think the dampening off a offroad bike shock is better suited?
by removing the linkage, dampening rate is shot to shit.
can,t honestly see where the advantage to this over normal car spring and shock absorber

i have built plenty of the bikes over the years, owned a bike wreckers and have put bike shocks on everything from
airplanes to drag covettes to offroaders etc.

maybe u are thinking cheaper way to get a good shock, chaces of turning up 1 xr 500 prolink shock, let alone two pretty slim.
i,ve got 2 whitepower husky shocks, if u are totally convinced i,d do for a couple hundred each
95 Safari on brg 33,s/ 4age e class zuk (old faithfull)/ d class rig under construction.

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KiwiBacon
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Re: Help me with some rear shocks.

Postby KiwiBacon » Wed May 21, 2008 10:47 am

tpft wrote:ok u are talking mono and are willing to spend 800+ on a new hagon
reducing leverage by half?
so u are going to run a linkage or just a arm.

i guess u think that it will provide better offroad performance, which because a spring is a spring means u think the dampening off a offroad bike shock is better suited?
by removing the linkage, dampening rate is shot to shit.
can,t honestly see where the advantage to this over normal car spring and shock absorber

i have built plenty of the bikes over the years, owned a bike wreckers and have put bike shocks on everything from
airplanes to drag covettes to offroaders etc.

maybe u are thinking cheaper way to get a good shock, chaces of turning up 1 xr 500 prolink shock, let alone two pretty slim.
i,ve got 2 whitepower husky shocks, if u are totally convinced i,d do for a couple hundred each


The avantages over car shocks.
Motorbike shocks are often externally adjustable (preload, rebound etc), they're more compact, they're rebuildable and revalvable. The springs are also avaialable in different rates.
With a car strut you get what you're given, they look like crap, the spring rates, damper rates and the mounting points are all wrong for this application.

Shock linkages don't change the damper rates, they only change the speed ratio from wheel to damper.

I'm not looking to buy shocks right now, I'm not looking for people who know nothing about my project to tell me it won't work, I'm looking for measurements of shock length, stroke and spring-rates.

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tpft
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Re: Help me with some rear shocks.

Postby tpft » Wed May 21, 2008 10:58 am

it won,t work
95 Safari on brg 33,s/ 4age e class zuk (old faithfull)/ d class rig under construction.

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KiwiBacon
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Re: Help me with some rear shocks.

Postby KiwiBacon » Wed May 21, 2008 11:18 am

tpft wrote:it won,t work


Thanks professor.

If you want to sell me some shocks in the future, it would greatly increase your chances if you could provide some of the information I'm after.
If you'd prefer to play the nay-sayer and provide nothing useful, then your chances of selling anything aren't particularly good.

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tpft
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Re: Help me with some rear shocks.

Postby tpft » Wed May 21, 2008 12:36 pm

whatever, was only trying to help.
spring rates are dependant on linkages, i.e xr 200 about twice as heavy as xr 250, xl 250 a lot heavier again.
if u prepared or have knowlodege to re-valve shim stack, swapping springs will prob be needed anyway

eye to eye can,t help u with on xr 500 as don,t have one in stock
xr 600 390mm roughly eye to eye (still in bike) around 65mm travel.
spring rates foir varoius bikes avail on net http://www.4strokes.com/tech/honda/sprngrts.asp
std xr around 9.8
myself, using swingarm and linkages into design, makes it work better
i built something similair into a offroader.
don,t want to sell u shit
want any more help, perhaps stop being such a ahole
95 Safari on brg 33,s/ 4age e class zuk (old faithfull)/ d class rig under construction.

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KiwiBacon
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Re: Help me with some rear shocks.

Postby KiwiBacon » Wed May 21, 2008 6:17 pm

tpft wrote:want any more help, perhaps stop being such a ahole


Asking for information, having questions ignored and being told "it won't work" has that effect on people. :roll:

Yes I revalve shocks, I am well aware of the effect linkages have in translating spring-rates to wheel-rates (I'm repeating myself here). I am a mechanical engineer and I earn my living designing among other things, linkages.
Suspension is a hobby and the core of a business I own. But it's not centred around motorbikes which is why I asked for some basic shock sizes.

Thank you for the link, if you'd provided that earlier instead of telling me "it'll collapse", "it won't work", "xr500 shocks will be way too light" and "I've got two shocks to sell" then I'd be thinking quite highly of you right now.

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tpft
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Re: Help me with some rear shocks.

Postby tpft » Wed May 21, 2008 8:25 pm

KiwiBacon wrote:
tpft wrote:want any more help, perhaps stop being such a ahole


Asking for information, having questions ignored and being told "it won't work" has that effect on people. :roll:

.

whats the point of the specs when it won,t work ?
prob looking at wrong end of the machine, air is free.
remove linkage equation, still plenty of clickers to play with
twin chamber cartridge yadda yadda
easy to add another seal ,shorten etc etc etc.
poor mans fox shock
but then its a trailer????

professor bored now :roll:
95 Safari on brg 33,s/ 4age e class zuk (old faithfull)/ d class rig under construction.

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KiwiBacon
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Re: Help me with some rear shocks.

Postby KiwiBacon » Wed May 21, 2008 8:37 pm

tpft wrote:whats the point of the specs when it won,t work ?

:roll:

tpft wrote:prob looking at wrong end of the machine, air is free.


Considered those breifly, but too much hassle to get a similar result and I prefer coils over air.

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