Hello Dave. And these 17 inch wheels and tires are for 35mm forks and the Pantah swingarm? Sounds like things could get all twisty here. MikeV

I hear you Mike. Better grip from better tires and all of a sudden the suspension is overwhelmed. I am running the 35mm forks with full racetech internals and a pretty stout fork brace. The swingarm is bone stock however.

My class allows up to 41mm forks (M1R is out), 2 piston brake calipers, and upgraded swingarms. I was thinking about swapping a complete Honda 600f4 front end onto the bike.

Technically speaking, did you mean a complete CBR600 F3 (1995-1998) front end?
http://chrisdube.com/motorcycles/CBR600-F3-Specs.php
Looks the rules for your swing arm are wide open. What would you do for a 4.5x17 rear wheel?
Bill

Yes complete f3 front end. Can't do f4 front end since it is 43mm. Although will all of my geometry be messed up by different triples? Rear wheel I was thinking a monster rear, 17x4.5. Maybe brace the stock swingarm to keep things simple.

Of course, how could I forget Ducati as a source for a rear wheel? Several models used that size. You'd have to measure what differences there are on the triple clamps, but I'll guess not too much. And the F3 also has two piston calipers.

The later YZF-600R I believe were 41mm conventional forks and used proper cartridge damping (96 and on?). Some times best to do a whole front end swap. When choosing 2 piston calipers as required by rules make sure race pads are available first. 88-90 GSXR-750 rear wheels are 4.5 wide and a good candidates to covert to. I think they are quite a bit lighter than the 4.5 Monster wheels.
Frame gussets especially at the motor mount would be first before considering swing arm reinforcement. While doing that reposition the motor to make the swing arm pivot a little lower if you can.

It has been a while since I read Tony Foale's "Chassis and suspension design", so I need an update : why is it better to reposition the swingarm pivot ?
I can see the sence in placing extra gussets on certain points, but lowering the swingarm pivot changes the forces while accelerating (and minimizes the scoring of the chain on the swingarm
You say it's better to go to the dimensions like 916 cases (where the swingarm sits lower) ?

ciao
ducadini

Yep. You opened a can of worms on this one Cranky. If he keeps the same shocks won't this lower the rear end?

I have noticed that Ducati can't make up its mind on this, and has changed the swingarm pin location on many of the cases over time on the small engines. Of course, so have the frames and suspensions changed significantly, so it is hard to compare them.

Tell us Obiewan, why should he do this thing?

MikeV

I had the pleasure of meeting Mr. Cranky this past July at the New Jersey Motorsports Park AHRMA race. He was kind enough to give me some pointers and ideas about making my Pantah work better on track. I will try my best to explain what was told to me.

In order to get the Pantah to turn faster, you need to "stand it on it's nose." Longer shocks is one way to accomplish this. I am planning on getting a set of 330mm race tech shocks. When you start to jack up the rear end however you run into problems with the chain running over the top of the swingarm. You also have problems with squat and anti-squat. Can't remember which as I was on a high from having just won my race! Another problem that the Pantah's have is a loose rear end due to the crappy swingarm bushings, but also because of the flimsy upper engine mounts which are just tabs welded onto the frame tube.

So the fix for all of these things, from what I remember, is to gusset the upper rear mounts and fit longer shocks. I think that changing the swingarm pivot will help with squat. To drop the swingarm pivot could I abandon the lower rear mounts, gusset the upper rear mounts and raise the front mounts? In effect tilting the front of the engine up in the frame and dropping the pivot?

If I got any of this wrong, please let me know.

Dave

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