jt1 Posted November 12, 2009 Share Posted November 12, 2009 Shouts of "Oh Shiit!"? That was me when I was a passenger. Tom seemed to take it very well, although he did cut the chatterbox off. Alan, there wasn't any noise I could associated with the chattering. One other clue is that Tom said it wasn't as bad when I was riding with him. Maybe it's a ballast issue. John Quote Link to comment Share on other sites More sharing options...
DrSideways Posted November 12, 2009 Share Posted November 12, 2009 So it would go away if I was riding with him:) Alan Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 13, 2009 Author Share Posted November 13, 2009 Alan, Other than John's "oh ♥♥♥♥" screams coming from the passenger seat, there are no sounds associated with the hopping deal. The outer P car 930 cv shaft ends were touching the frame on compression and after hitting a curb, especially if I had the left set occupied, so I raised the rear end about 3/4". The chattering deal does seam to be more pronounced with extra weight in the other seat, but not much. The Koni tech guy suggested too low tire pressures could be causing it to hop. I normally run my 275-16 Hoosiers at 27/28 lbs cold, and even a bit lower during very hot summer runs. 265-16 710 Kumhos are my favorite and seam to respond better at even lower temperatures. Quote Link to comment Share on other sites More sharing options...
DrSideways Posted November 13, 2009 Share Posted November 13, 2009 OK so this seems to be basic wheel hop. Does it do it in both turning directions? Got any shock dyno results yet? Has anyone outside the car been able to see it happening? Does it happen after jumping a curb like turn 3 @ VIR? So the wheel gets a big bump from the curb and then won't stop bouncing up & down. Which rear control arms do you have? Alan Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 13, 2009 Author Share Posted November 13, 2009 Alan, The shocks are at Koni but I havent got the results. It hops mid corner and on exit when adding power. It bounces and chatters before the curbs are hit. JT has experienced it from within. No one has commedted on a view from outside the car. Quote Link to comment Share on other sites More sharing options...
DrSideways Posted November 13, 2009 Share Posted November 13, 2009 Inside wheel more or both? Both directions? Alan Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 13, 2009 Author Share Posted November 13, 2009 Alan, It does it's thing in both directions. As to inside wheel more than the outside, I' m not that good to be able to interpolate the info. My guess would be both wheels about the same. Quote Link to comment Share on other sites More sharing options...
DrSideways Posted November 13, 2009 Share Posted November 13, 2009 So if it is both wheels then you can narrow things down to what connects them both or both have in common. Parts that connect, axles, third member. Things they have in common, tire pressure, tires, shock settings and shocks. Springs and sway bar. Do you run a rear bar? As far as interpolating the deal you would feel the inside wheel on left turns more with your butt. It would be great to see it happening from the outside. Like standing on the hill looking at 5a-b @ VIR. Like I tell my students .... motorsports is a desire and problem solving program. If you don't desire to solve problems it may not be for you. You have gotten other issues solved and you will get this one too. Alan Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 13, 2009 Author Share Posted November 13, 2009 Alan, I normally run a bar but removed it at CMP when working to find the cause of this problem. It didn't help the chattering but I sure new that it was missing. I plan to put the bar back on the car. Quote Link to comment Share on other sites More sharing options...
DrSideways Posted November 13, 2009 Share Posted November 13, 2009 I looked up photos of your car to see the rear suspension. Are you sure all of the extra bolts on the mustache bar and lateral connector are tight? I run some additional tubes with rod ends from the frame rail down close to where the back of the control arm bolts to the plates coming down from the top. They come in at about a 45 degree angle when looking in from the rear. I did this to more firmly lock the whole assembly in place side to side. With all of the aluminum parts there are extra fasteners. Make sure they are all tight. Maybe even paint the heads to make sure something is not happening with heat. It will be interesting to see what Koni says when the shocks come back. Alan Quote Link to comment Share on other sites More sharing options...
mark Posted November 14, 2009 Share Posted November 14, 2009 How long have you been running the new halfshaft with the 930 P car cv's? Did this start after the new halfshafts? Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 15, 2009 Author Share Posted November 15, 2009 Quote: I run some additional tubes with rod ends from the frame rail down close to where the back of the control arm bolts to the plates coming down from the top. They come in at about a 45 degree angle when looking in from the rear. I did this to more firmly lock the whole assembly in place side to side. Alan, Do you have any pictures of the support tubes you added? I don't remember seeing them before. QUOTE: How long have you been running the new halfshaft with the 930 P car cv's? Did this start after the new halfshafts? Mark, The shafts have been in there for a while. I converted to the 930 "P" car ends so that I could easily find parts when needed. The Nissan turbo four bolt ends are becoming scarce. The hopping deal started before I changed to the new setup. Quote Link to comment Share on other sites More sharing options...
DrSideways Posted November 15, 2009 Share Posted November 15, 2009 I don't have any here. I will try and get to the shop this week. Alan Quote Link to comment Share on other sites More sharing options...
DrSideways Posted November 21, 2009 Share Posted November 21, 2009 I finally got to the shop for those photos. These brackets go from the outer frame rail down to the rear suspension inner pick up point area. Hope this helps. Sorry for the less than stellar photos. Alan Quote Link to comment Share on other sites More sharing options...
Mayolives Posted November 22, 2009 Author Share Posted November 22, 2009 Hopefully, I have discovered the cause of the chattering and hoping issues I have been experiencing. One of the rear 8610 dampers (RR) was bad and not functioning on the compression side. Also, I have installed Koni 8611 dampers that will allow me to adjust both rebound and compression. Thank you JohnC, at Beta Motorsports, for the fast service and installation advice. I'll be able to test the new setup, that includes lowering the rear spring from 350 lbs to 325 lbs, next Monday during the Asphalt Ventures track day at VIR. Yahoo. Alan, Thanks for the pictures. Now I remember seeing your setup and braces, but it was years ago and at that time I probably didn't know what I was looking at. Quote Link to comment Share on other sites More sharing options...
mark Posted November 22, 2009 Share Posted November 22, 2009 Tom, Glad to hear you have found the problem. Keep us updated with a report from VIR. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 23, 2009 Share Posted November 23, 2009 One of the rear 8610 dampers (RR) was bad and not functioning on the compression side. Everyone please take note. No racing shock lasts forever and they are the first item to check when suspension behavior changes. Quote Link to comment Share on other sites More sharing options...
DrSideways Posted December 2, 2009 Share Posted December 2, 2009 Tom, Did you do the track day Monday? Any results from your new shocks? Alan Quote Link to comment Share on other sites More sharing options...
Mayolives Posted December 2, 2009 Author Share Posted December 2, 2009 Alan, I had to cancel my trip to VIR due to a transmission problem with my truck. (speed sensor) Apparently it rained up there for most of the day so I really didn't miss much. I hope to take the car over to CMP later this month and test the new setup. Quote Link to comment Share on other sites More sharing options...
DrSideways Posted December 2, 2009 Share Posted December 2, 2009 Too bad you missed it and it rained. I'm thinking the issue will be taken care of. CMP will tell for sure. A. Quote Link to comment Share on other sites More sharing options...
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