Miata Hop Hop

[IPRESS]

Finally got to do a session with the new suspension setup in my miata. ISC stuff plus the heavier springs and your basic "cheater SM + shocks". Mmeaning they were heavily revalved and shortened. (No wonder I had no chance in SM. I didn't know enough tricks!) I don't know the exact specs.
I noticed my car wanting to hop instead of drift in high speed turns. Seemed to be even more so when getting back on the throttle. Do you think the shock rebound is too soft?

Andy? Bueller? Andy?

My budget constraints put a dampner on some custom shocks from a guy on the left coast, but if this is the cause of my hippity hop, I will have to do something.

Thanks for any ideas. (They have to be simple... not quit Forrest Gump, but close on anything mechanical.

Mac

[Andy Bettencourt]

I don't have this problem. Is it possible you are hitting the bump stops in the rear?

[IPRESS]

Actually I think the rear was setup too high. Maybe the whole car. The shop that set it up tried a little higher setting then usual. They were not around when I got a little time to run out to MSR. I have been worried about the Bielsteins not being strong enough on the rebound for the stronger springs. We are changing the setup back to the SM height and see how it reacts.
Anything I might notice with the delrin bushings and spherical bearings other then it should have less roll?
I have been expecting it to feel so much better that I was sort of dissappointed when it hopped around. Maybe a better ride height will fix it.
Thanks, Mac

[tnord]

is karl setting your stuff up mac?

you might want to check for places the bushings are binding, but i don't think that is what's happening. to do this you could put the car up on stands and take the wheels off, then put your jack under each brake rotor and jack the suspension up through it's range of motion and watch/listen for anyplace it might be catching. if it's ISC stuff, i doubt that's the problem though.

you could check your swaybars as well. i've heard of them binding up in the bushings.....which i think would effectively jack the spring rate way up and not really allow any compression of the suspension. all you have to do to check this is disconnect each end of the bars then try and rotate it by hand. it should be really easy. i've seen bars that were so bound up people could do pull-ups on them without the bar moving.

i'm certainly no expert, just a couple of ideas.

[IPRESS]

Thanks Travis,

Car is on the lift getting a looksee. I just think we made some setup mistakes. Hope to run it again the end of the week. The shocks were a deal so if I have to change them it wouldn't be a huge loss, but I really think these that I have should work. Gotta be setup. Todd & Chris will hunt the problem down.
Mac

[ldp82]

I’m assuming you got an alignment after putting everything in and checked the tires before heading out on the track. My first thought when reading was also bump stops or something binding I would do what has already been said in the thread and maybe check to make sure all the bolts are tight.

[cmaclean]

Mac, did you get the problems sorted out?

[IPRESS]

I think so it was just a bad setup. I ran a session this weekend and didn't notice the hop. The new front bar from ISC is a little different then my past SM bar so we are going to have to experiment some. I noticed that the car turns right much better then left. Lefthanders seemed to need more effort and then the rear would want to get loose. Going to have to change that before going to Memphis, although left turns don't count much there.
Colin, those SMs are getting faster all the time. Foss and Blake both ran 1:25s (maybe even below that) on MSR 1.7 and I can remember when a 1.28 was quick.

[zracre]

Every time I had a car that went one way better I cross weighted it and did a full setup/alignment. You will be amazed at the difference.

[IPRESS]

Journal entry 6 (Just seems like I am writing a book)

Got Eric Foss one of RAtlanta's ddriving instructors (and a top five SM finisher at the Runoffs) to make a session in my car last weekend. (I needed some Hoosiers heat cycled and who better then a Foss to do that!) Eric was pretty quick, but his first comment was " This thing is hard to drive." Miatas are NOT suppose to be hard to drive. He had some thoughts and with his seat time knowledgd he can FEEL what I can't. So our next move was to get Eric, Jason (MX5 Cup Pro Hotshoe) Saini, and Shannon (Mr. Texas Mazda) McMasters pooling their heads and figure out the problems and solutions.
Problem one was one different size endlink from the other three. Problem two was a another endlink that was bent.
Above caused binding of the suspension. We are not sure, but the delrin bushings seem to be so tight that there may be some binding in the rear suspension. (Maybe a little use will make this better.) Andy any thoughts here? We should have some real good feedback later this week as Jason will check it out on track.
I am really looking forward to getting it straight as Andy told me when I started this conversion that it would be a dream to drive with the ISC parts installed. Once we get the bugs out I hope his words come true. From his results it couldn't be bad.

Mac

[Andy Bettencourt]

Sounds like you need a real detailed corner weight first off. The rear upper control arms have the delrin and a large metal sleeve. That sleeve needs to move independently of the delrin. The 'ears' on the arms that compress as you tighten the bolts will grab the metal and the delrin will pivot on them.

Call Mike V for more info.

[cmaclean]

When we installed Delrin bushings in my buddies ITA car, we had to ream the delrin to give free movement. Otherwise it was too tight and was binding.

[Andy Bettencourt]

One other thing that I have realized is that with a 'chock-full-o-sphericals' suspension, it is far from a build it, forget it and adjust it scenario. These things are now maintenece items. Our initial diassembly / clean up and reassembly is done but I plan on one mid-year and once before our Championship race.

It is what it is - much more 'improved' now than hopped-up daily driver.

[IPRESS]

Thanks for the replys guys. i did talk to Mike and so did the MER guys. We have most stuff figured out, but I think we will need to work on the rear bushings to free them up. (just like you said.) Saini is testing on track tomorrow so we expect to find out it is much better. Mike has got to quit coming up with all these great IT parts cause they are like drugs.......you never get enough!

[ldp82]

i got my control arms back from ISC racing and will be installing them soon. Any tips? or things you guys did that worked out or didnt
thanks,
-Luke

[IPRESS]

Call Mike at ISC before you start your install, he will help you. I am just now picking up a little knowledge on suspension and what causes what, so Saini and Shannon have been working with Mike. Although he spent some time and knowledge with me on the phone. Trying to get me to retain this suspension stuff is like me trying to get my 2 year old grandaughter to eat her good stuff on the plate. She doesn't remember what was kinda good, as well as what is REAL good. That is me in the car. I don't feel stuff unless it is REAL bad! Jason took it out and beat his best SM time and says it is much much better. He still feels a little :026: :026: hop hop and thinks we can get the rear freed up and better.
I need that for sure before I go thru the Ms and Grant's Tomb up at Ribsville!

[tnord]

glad you got your issues sorted out mac. how much quicker was jason in your car than his SM time? i think i'm in for a whooppin this year. if you see some strange feet sticking out from under your car at a MiDiv race, that's probably me inspecting all your nice equipment.

[IPRESS]

Travis,
Just go to the ISC website to see all the stuff. You are welcome to look under, over, and around anytime.
As far as a whoopin, there is a huge talent gap between me and Jason. I mean H U G E ! I think he was exactly 1 second faster in mine then the SM. That's on the MSR 1.7 (old track) which is pretty twisty and technical. To show you what has happened in SM, a good lap in SM in 2002 was in the 1:27s a couple of weekends ago two or three differnt guys edged under 1:25. I don't think you will have much to fear from the Texas racer unless Stretch decides to run up north, then all bets are off!