Cagiva/Aprilia suspension triangles

Technical stuff specific to the Raptor 1000

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Boofhead
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Cagiva/Aprilia suspension triangles

Post by Boofhead » Thu Oct 10, 2019 11:51 am

G'day everyone,

I have finally got my bike back on the road with the GSXR legs and Aprilia rear… yay :D . I’ve also thrown in a Bitubo shock into the mix (which is a nice looking bit of kit) to finish off the suspension.

However all nice and rosie this sounds, I have an issue with the rear suspension, it’s hard as a rock. Either the spring is too stiff or the triangle ratios aren’t correct.

One of the guys from my local bike shop, who is an ex HRC factory rider and bike mechanic, has made it much better by adjusting the dampening etc and it is he who is questioning the triangle ratios as the spring rate is set to my weight and should be ok.
He will check the spring rate when I give him the info from Bitubo to see if the spring is correct. Sag is good after the adjustments.

I have used the Cagiva triangles, which most people seem to have used from the photos I’ve seen.
I also have the Aprilia triangles which some people have also used. Are they better?

I have drawn a basic model of all the Cagiva suspension pivot points with autocad, but I can’t find an Aprilia drawing with the pivot dimensions so I can lay them over the each other for a comparison.

So my questions are,
has anyone out there had similar issues which have been sorted?
are the standard Cagiva triangles used as a compromise and hope for the best?
has anyone worked out the triangles correctly?
If it is a triangle issue has anyone got the correct dimensions so I can cut out new ones?

My apologies for the long-winded post but I hope someone out there can help!!

Cheers from Boofhead

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Trevor68
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Re: Cagiva/Aprilia suspension triangles

Post by Trevor68 » Fri Oct 11, 2019 10:43 am

Have you checked all the bearings in all of the suspension pivots?
I recently replaced the rear shock on mine and every bearing was stuffed, including the ones in the swingarm too

Boofhead
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Re: Cagiva/Aprilia suspension triangles

Post by Boofhead » Fri Oct 11, 2019 8:23 pm

Thanks for your input,

Mine were all stuffed as well, so I’ve replaced all the bearings in the suspension and the swingarm.

However, the bearing supplier couldn’t get bushes for the dog bone. They must be a weird Cagiva size (I think the length was the problem) so I’ll see if they are still available through an MVA dealer a little later on when I re-engineer the linkages so they can have grease nipples for easier maintenance. If not, I’ll figure out a way to use bits that are readily available.

On the triangle subject, another thing that makes me question the ratios is that when you look at the Cagiva drawings that has all the dimensions of the linkage and pivot points, which I gather are taken when the bike is static under its own weight. The angle of the triangle between the shock mount and the swingarm mount slopes down toward the front of the bike by 22 degrees. But on my bike and on all the other bikes that I’ve looked at with the conversion, the triangle slopes up a little. And yes, I have put them in the correct way !! lol

Also, the dog bone linkage on the Cagiva drawing slopes down 4 degrees toward the front of the bike. But once again, mine and the others slope up. Surely this has to have an effect on how it all works.

If I can find a drawing of the Aprilia pivot/mount points and a drawing of the Cagiva/Aprilia swing arms that have all the necessary dimensions, I can draw them with autocad and overlay them for a comparison and figure out a better set up. I wouldn’t be surprised if the dog bone length is adding to the problem because of the difference in distance from the swingarm pivot point to the dog bone mounting point on the swingarm.

Any more thoughts? Or anyone else have any ideas or the drawing I’m after?

Cheers from Boofhead

nickst4
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Re: Cagiva/Aprilia suspension triangles

Post by nickst4 » Sat Oct 12, 2019 9:00 am

Hi Boof,

I can't provide any input on your Aprilia conversion but you can forget trying to source the inner sleeves for the dog-bone bearings as MV can't supply and no-one else that I could find makes proper hardened pieces of the right length. For what I'm confident is a satisfactory solution, see the relevant thread on here:
viewtopic.php?f=11&t=5163

By the way, do you still have a spare Raptor headlamp tucked away? :wink:

Nick

Aussiejoe
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Re: Cagiva/Aprilia suspension triangles

Post by Aussiejoe » Thu Nov 07, 2019 5:33 am

Maybe some custom triangles with the 57mm/62mm dimensions changed. These are the dimensions for the jack up triangle.
Raptertriangles.jpg
Raptertriangles.jpg (84.48 KiB) Viewed 61 times
Also be aware the V-raptor/Xtra Raptor and 650IE have a different part number for the suspension link, maybe that needs to be lengthened or shortened. Shouldn't be hard if you know an ali fabricator. chop a bit out or add a bit in the middle, weld up and add some stiffeners.

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