Followup on turn in and suspension

I finished a day at Thunderhill today, got in maybe 120-40 miles or so. It was basically my start slow and work with the bike day, and had good but mixed results.

I am running a Penske shock 8 mm longer than stock. Stock forks, I weigh 150, 30 mm rear sag and 35 front.

Immediately noticed a problem with the rear sliding under hard braking into three an off camber slightly down hill fairly sharp blind curve. It was actually coming around on hard stand up braking. This has never happened to me before on this bike. I talked to the GP suspension guy and he backed of rear rebound damping several clicks, which made the problem promptly disappear.

My primary complaint with the bike has been getting it turned in comfortably, and with the shock this length I am pretty happy. I was having no problem establishing and holding a line and no problems getting the bike turned. I was happy as a clam with it. Also turning really slow laps. 2:18 - 2:20. A good racer will get this bike under 2 minutes on this track. I can go 2:13s with my built SV. So no joy for Ernie about the slow laps, but I kept plugging away. Finally, last session of the day I went out to just relax and have fun and not worry about fast laps and promptly started turning 2:15s, which, while still not as fast as the Sv, made me smile at the end of the day. I can see easily several ways to go faster, so am feeling better about the whole thing.

I also spoke with the suspension tech about the front feeling a bit vague and he set rear sag at 25 mm and backed off the front compression and preload a bit, to weight the front end more. Worked fairly well, I did start turning faster laps after this. Sato rearsets will arrive next week, that should help a bit too. I wil be grinding pegs soon.

Anyway, a work in progress.

One of the riders took a bad crash in turn ten, Jeff Gruetter and was medavaced, dont know how he is doing, I was first instructor ( or track helper, really) to where he was lying, he was unconscious and looked like he had at least a broken shoulder. Did not look good. His CBR1000rr was really trashed. What a drag.

ernie

Well I'm jealous that you gat to ride today. Glad your getting everything worked out and are feeling more comfortable on the bike.

I was wondering when you would get a chance to work on this.

When you say 8mm ride height, is that measured at the shock or the rear of the swing arm? What is the ratio ( it that was at the shock )?

Some have posted that they have heard that raising the rear ride height too much on the RR causes it to tuck it's front end. Did you notice any such tendencies?

Later, and thanks.

PS-If you get any word on the riders condition, let us know. Hate to see somebody go down....

I added 8mm to the shock length, that is 8 mm over standard length which is 12 1/2 inches or so... I have it written somewhere. I think it raised the rear an inch or so.

Well I did not notice any tendency for the front to tuck. We'll see, I imagine that will be more likely if the fork tubes are raised as well.

Will see. I may shorten the shock a few mm, I dont like having any more length there than is actually needed, it does nothing for stability.

Ernie

Got ya!

I got a chance to ride mine hard for the first time today, and i didn't notice the handling problem we discussed in the "flick it to full lean" post.

I think i need to find someone to help me set the sag. I'm getting a lot of weight transfer in the chassis ( i STILL can't believe Sport Riders suspension numbers! ), and it's pointless to mess with the dampers until i get the sag where it should be ( if i can with the stock springs ).

The front-tuck talk was in a post about raising the tubes, so you are likely right. I always thought that raising the rear ride height too much compromised rear traction myself.

Thanks, and good luck with your set-up.