ar in glasgow, scotland

[lgingell]

Hi guys

I bought my ar in december 2008.

I use it to race in the scottish enduro championship, hare and hounds scrambles and twin shock moto cross rounds.

I also ride a BMW R1100RT, Honda Hornet CB 250 FX, Honda CB 500 W.

I drive a Volvo 850 T5.

My full time job is a lecturer of motorcycle maintenance at motherwell college.

Part time, i run my own workshop.

Please feel free to get in touch if you would like to discuss anything.

thank you
leonard

[fallenmikethebike]

Hi Leonard, welcome to the site, and yes, you have struck straight at the ARs Achilles heal, primarily, it,s thought, because, the AR was just so much better than the "Fashion" item it was retailed as.
Any way, you sound like your on the case with getting her sorted, good luck, and results.
Mike

[knackeredMk1]

There is a lot of information on this site about the suspension issues you are facing. Try doing searches and look under 'What fits What' in Technical section.

Basically it boils down to buying replacement foks from a CR125 and getting your shock revalved and resprung.

[Jonorow]

or change the shock for a cr125 91 with stiffer spring and possibly longer dogbones.
I have just had the bump stop replaed on my converstion and bought a stiffer spring, so cant fully condone this action yet but initial reports were very good around the motocross track i use.
what i can say is the cr125 fork conversion is much better and easier to accomplish.
Good luck with you bik andi hope you will bring much more help to the forum.
Jon

[lgingell]

Hi

Thanks for suggesting the cr 125 shock.

I have had lots of shocks measured up, but none as old as a 91.

It looks in the pictures as if it may fit.

Do you have one on your bike? Is your bike a MRK3?

Did you make any mods to shock or bike to get it to fit?

What spring rate are you using? standard for a cr 125 is around 50 n/mm, but i need 105 n / mm on the crm.

Thanks for the help
leonard

[Jonorow]

ther are a few mods to the shock. First, get it serviced! probably either hasn't been done for a while or has never been done. second is to reposition the bottom bolt hole and tap a new thread. cant remember off hand but i think it does say on the post how much you need to shorten it by.
the shock wil end up about 1 inch longer than standard, wwich cn be taken up with longer dogbones (108 instead of 100mm)
The spring ona cr125 is 4.8kg but i have gone for 5.2 as the standard was too soft and was botoming out to much ( I destroyed the bumpstop!) I have only refitted the shock today and wont get chance to give it a thrashing around the motocross track to find out how much of a diference it has made.

[Jonorow]

oh I forgot to mention thatonce you have done all this to the chock, you then need to modify the link to take the new lower bearing for the CR shock. This will involve grinding or milling the edges down and boring out the hole. Might be an idea to track down a spare link!

[lgingell]

Hi Jonorow

what you said about actually fitting the shock makes sense.

I havnt yet found any other shocks that were the same length or stroke, so the extra length is one concideration.

I also havnt found any other shocks with the same width bottom mount (except cr80 which isnt suitable) so modyfiying the linkage is another concideration.

I am not suprised that the bump stop was smashed to bits! It must have been bottoming out really hard!

Im not convinced yet that 5.5 kg will be the correct spring rate for you. It depends on the linkage used, standard spring rate, rider weight and machine weight.

Do you know what the standard spring rate for the mrk3 is?

The standard spring i removed from my CRM 250 ar w (1998) was a 80 n / mm (8kg). I tried a 90, and am now using a 105n/mm.

I have a part book for the ar, but it doesnt cover the older crms, so i cant check if shock / linkage part numbers are same unfortunatly.

One of the best ways to establish correct spring rate is to compare the static sag (no rider) race sag (with rider) and spring preload measurments.

Do you know how much sag and preload you are using?

I would recomend 27 mm static sag, 95 mm race sag.

Preload on the spring should be 2-15mm. If you have reading outside these you are probably using the wrong spring rate.

I assume that you tried the 4.8 spring, and now have fitted a 5.2 - but havnt riden it yet? is that correct?

If the linkage on the mrk 3 is same / similer to the ar i would guess that you would need a spring much stiffer than 52 n/ mm.

If the linkage has a different leverage ratio than the ar it might work.

Time ( and a measuring tape) will tell.

Please let me know how you get on.

P.S if you want to sell your mrk 3 shock let me know!

[woolley]

Has James May moved to Scotland

Wool

[lgingell]

ha ha lol - guilty as charged!

no buy serisously, i am definetly an anorak, but thats what makes me a good motorcycle technician!

ask yourself who would you rather work on your bike?

someone who knows how things work, and cares, or someone who doesnt care or know how the bike should be put together?

[knackeredMk1]

I've just writen a long reasoned arguement about why this won't work without a lot of time and money, but the Forum has thrown a wobbly and dumped it into cyberspace. (Probably with some justification ).

Call me a 'Party Pooper' but respringing and adjusting the damping seems the most effective way forward. On the other hand it is leaps like this that keep the knowledge of the site expanding and part of me hopes I'm wrong.

Link to the work so far - viewtopic.php?f=4&t=4527&st=0&sk=t&sd=a ... k&start=15

[SkidMark]

Has James May moved to Scotland

Wool

[knackeredMk1]

With regards to rear suspension - AR has 10mm more travel than Mk3 (According to Honda AR Factbook). Suspect this is due to length of shock

[Jonorow]

Hi Guys, leondard, I have a long list to reply but wrote it the old fasioned way first to gater my thougts and will type it in later, but i wanted to update evryone on my shock.
I wish i hadn't started! the spring is till too soft. the originalspring must have been around 5.2 and not 4.8 and standard. I set the race sagto 100mm and ended up with 0mm static sag!! BUGGER thats a waste of £80 , might have to sell some of these springs fo some cash to keep this going.
so not sure now what spring to get? probably a 5.7 but not as far as a 6.0
your thoughts gents?
Jon

[knackeredMk1]

Have done some research - apparently stock AR spring is 7.5 There is an option for 6.5.

This looks the wrong way round but apparently it is the case.