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 Post subject: shock problem?
 Post Posted: Mon Jul 23, 2007 8:26 am 
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I have been struggling lately with my car going to the left (maybe it's a NASCAR thing).  The problem was slight at 1st but has been getting worse. Since  the problem has started I have swapped the slicks, changed the rear springs, aligned &  scaled the car, reised the left wheelie bar & changed the arms on the anti-roll bar from bolt on to weld on. I have changed the preload in the rear to the point to where the preload is slightly negative. Friday the problem was bad enough I elected not to compete. I pulled the shocks off of it and it seems with the settings the same the shock that came off the right is softer than the left.  I know compressing these thing by hand is not an accurate method of testing so I am getting ready to send them back to strange for testing & rebuilding. I borrowed a set of used Koni's from a friend that I will try next weekend because I don't think the Strange shocks will be back in less than a week. Our regular track is closed next weekend so if I race next weekend it will be about 120 mile trip each way. I really don't want to haul that far without thinking I have corrected the problem. I think this is an unusual problem and was wondering if anyone else had run into it?

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 Post Posted: Mon Jul 23, 2007 8:57 am 
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Did this just start on its own or did you make any changes at all before noticing the problem?  Depending on how much anti-squat you have, it would seem that a softer rebound on the right side could cause the tire to hit harder and possibly drive it left.  Conversely, if the 4-link is set up to squat, a soft compression on the left could have the same effect.  Since it seems to be getting worse gradually I think you're on the right track with the shocks.  An internal leak could be getting worse.  Did you try different shock adjustments side to side?  Single or double adjustables?

There's nothing worse than sitting at the line with your thumb on the button not knowing what's gonna happen when you release it!

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 Post Posted: Mon Jul 23, 2007 9:50 am 
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gdmii wrote:
Did this just start on its own or did you make any changes at all before noticing the problem?  Depending on how much anti-squat you have, it would seem that a softer rebound on the right side could cause the tire to hit harder and possibly drive it left.  Conversely, if the 4-link is set up to squat, a soft compression on the left could have the same effect.  Since it seems to be getting worse gradually I think you're on the right track with the shocks.  An internal leak could be getting worse.  Did you try different shock adjustments side to side?  Single or double adjustables?

There's nothing worse than sitting at the line with your thumb on the button not knowing what's gonna happen when you release it!

George


George it started on it's own,  I didn't make any changes. The 1st time I had the problem was the last time out last year. I broke a ring & pinion at the bracket finals and replaced it and took the car to bowling green for the last race. We thought it was the track. This year it has done it a little but like I said it has gotten worse.  Friday I did stiffen the compression on the right side, and it seemed a little better to me but the guys watching the car said it looked the same. The shocks are dbl. adjustable strange.

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 Post Posted: Mon Jul 23, 2007 10:18 am 
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The shocks may very well be the problem, but I think I'd do a lot of looking (if you haven't already) under the car. May be something cracked and slowly bending, breaking etc.

Shock brackets, 4-link brackets, wheelie bar brackets, rear end housing and tube ends. Basically everything underneath the car.

From the looks of your pics, you are putting some stress on things. =;

Rick


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 Post Posted: Mon Jul 23, 2007 10:32 am 
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Rick360 wrote:
The shocks may very well be the problem, but I think I'd do a lot of looking (if you haven't already) under the car. May be something cracked and slowly bending, breaking etc.

Shock brackets, 4-link brackets, wheelie bar brackets, rear end housing and tube ends. Basically everything underneath the car.

From the looks of your pics, you are putting some stress on things. =;

Rick


I did look it over some but could probably look a little closer.  The thing is everything stays set where it was. I have seen that before and usually you will lose your preload if something is moving. That and every time I have seen that type of problem on a car it starts to go to the right.

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 Post Posted: Mon Jul 23, 2007 10:51 am 
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gearhead1011 wrote:
George it started on it's own,  I didn't make any changes. The 1st time I had the problem was the last time out last year. I broke a ring & pinion at the bracket finals and replaced it and took the car to bowling green for the last race. We thought it was the track. This year it has done it a little but like I said it has gotten worse.  Friday I did stiffen the compression on the right side, and it seemed a little better to me but the guys watching the car said it looked the same. The shocks are dbl. adjustable strange.


Ummm...I think I would do just the opposite.  Keep the right side compression where it was and stiffen the rebound.  That will slow the separation and should not hit the right slick so hard.  If you're gonna stiffen compression at all I would do it on the left side.

George


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 Post subject:
 Post Posted: Mon Jul 23, 2007 11:00 am 
 
Chuck my car did that a couple of years ago and we changed everything under the car and come to find out the right side 4 link bracket was cracked around the rear end housing and couldn't see it until we dropped the rear down out of the car when it wasn't under load it would be close enough that you couldn't see the crack .
So ya look over it real good just don't over look it  something could definitely be cracked


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 Post Posted: Mon Jul 23, 2007 1:09 pm 
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I would also check every joint in the car plus the suspension mounting points. If your scales are reading the same as when you was getting hooked up, and you eliminated a tire difference, and I assume you have a spool in it. You must be getting a flex or it's getting a work stiffening some where to make your torque nullification change. I suppose a change in the shock/spring rate could be a problem. You may want to check spring rates to compare to new ones. Lighter rate springs can get weak fast and cause problems. On stock cars we block chassis for towing to save them. Another thing that comes to mind is chassis rigidity. We have all heard of wearing out a chassis. What this is, is part of your chassis that flexes gets more rigid much like if you bend a paper clip over and over. A very rigid chassis has less of this problem and if you get it, it don't mean a throw away, you just have to change your set up to compensate. A trick I learned from go kart racing is to check new chassis and compare later checks to that. To do this you place a piece of paper under one front wheel, then jack the other from a specific point on lower control arm. when paper is released measure hight on all for corners, repeat on other side and them numbers are you rigidity base line to compare to any others later on. You would want to eliminate springs from this,so place chassis on jack stands and put paper between jack stand and frame. This rigidity will effect the tire contact pressure, and also make spring/shock changes not as dependable..  The factory team always had the winning go kart for sale. People preferred to buy a winner than getting a new one. If you get to thinking that when you wear them out you need to throw them away, wait. Once the chassis on a dual engine dirt kart was sold and there wasn't a replacement available. It was sold to the guy second in points, he traded in a 4 year old piece of junk. The dealer who's shop we operated out of said here use his old one. I asked him if he cared what we did to it and he said he didn't as long as he had a kart to sell after. We took old base lines and cut and replaced tubing till we got close and when out and kicked the old karts butt. I guess the moral of this long story is if you know where you want to go, it makes it a lot easier to get there.

Over at www.speedtalk.com Billy Shope has his blog listed. his Chassis dyno may be just the thing you need right now. I have never tried it but seems a lot simpler that my old fashion ways. With a piece of chain a jack and scales you could find exactly what you want to know right now. You could find what, not why it changed.

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 Post subject:
 Post Posted: Mon Jul 23, 2007 4:23 pm 
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Chuck could you test at the valley on wed night instead of traveling all that way?  Is Greg going to do the JR dragster event at the valley this weekend?

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 Post Posted: Mon Jul 23, 2007 4:44 pm 
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WR169 wrote:
Chuck could you test at the valley on wed night instead of traveling all that way?  Is Greg going to do the JR dragster event at the valley this weekend?


I thought about testing at the valley but they barley prep the track during an event,  I don't think they prep it at all for test and tune. that and the fact they run a lot of street tires there on test and tune nights, I don't think there's much of a chance of actually testing anything that requires any traction.  Of course I haven't run there for probably 14 years, partly because of the track prep, so I asked Darrin when I borrowed the shocks from him if they were doing any better job these days...he just laughed.

Greg wasn't interested in running the big jr race at the valley, and I don't think it's just my negative attitude about that track, he ran the Kaylee benefit race. We're trying to get his car painted while he has an extra week.

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 Post subject:
 Post Posted: Mon Jul 23, 2007 6:34 pm 
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From what I hear I believe Darrin. TheWeek break will be nice. We are going to somerset for the summer nights car show. Suppose to be 1500-2000 cars there. O:)  \:D/  \:D/


http://www.somernitescruise.com/index.html

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 Post Posted: Mon Aug 06, 2007 5:40 pm 
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OK here's the latest.  Strange called me thursday to tell me they had their shock dyno up and had tested my shocks. They said they were within 10% of each other and they didn't find anything wrong with them, so I had them freshen  them up, put new fluoid in them and valve them just a little stiffer (I just didn't need the soft settings on them). I decided to try the car out with the Koni's I had borrowed so we went to us60 friday. I left everything the same as before except the shock settings, I left that a little stiffer intentionally.  I left the preload neutral as opposed to the 1/2 flat I had in it. The air was kinda of nasty, it was hot and the DA was 3,300'. The car still went to the left and didn't pick the front end up much,  60' was 1.252 and ran a 5.694. For the next pass I loosened the compression on the shocks 2 clicks and made my top right bar 2 flats longer (negative preload?).  This pass was better, still a little to the left, on the back wheels a little harder and the 60' was 1.216 with the air slightly worse at 3,349 and ran 5.643.  So for my next pass I loosened the shocks 1 more click and turned the top right bar another 1 1/2 flats.  The car went just as straight as it ever has but because I was anticipating something other than a straight pass I wasn't on my game with the shift. I missed the 2nd gear shift by 600 rpm (late) and this hurts my 60' because when I hit the shift right it's 1.10 seconds into the run. Still my 60 was 1.231 and ran a 5.637 with a DA of 2,955.  I was confident with how the car would get down the track and concentrated on driving for my last time run.  The air improved a little to 2,888 DA, it hooked good, went straight 60'd 1.216 and ran 5.620, I was happy.  According to my weather station my et was right at what it should've been with the conditions being what they were. I don't know why I had to change my set up but I think it may be the tires, they have a bunch of runs on them and may be loading the chassis different now.  George, I did stiffen the compression on the left shock before, I just said it wrong in the 2nd post I made in this thread.

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 Post Posted: Mon Aug 06, 2007 5:59 pm 
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It is good to here you got it back where it was Chuck. =D>


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 Post Posted: Mon Aug 06, 2007 6:15 pm 
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That's good news Chuck.  Of course it raises the question of what changed in the setup to cause this amount of correction.  If it changes on you again you can bet something is moving underneath that probably shouldn't be.  But, yep, for now drive straight and be happy!

Just another thought...have you ever scaled the car so you know the corner weights?  That's always a good idea, then if something at all changes you'll be better able to analyze where the change occured.

George


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 Post Posted: Mon Aug 06, 2007 6:48 pm 
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Thinking about this, the tires, especially sense you switched them side to side, would be a stretch.  Is there any possible way you gained left side weight, more so left front weight, or lost right side weight. Anything to allow more chassis flex would explain it also. Is all the suspension links and control arms free to move? Anything to decrease it's ability to compress the right rear or rebound the left rear? Was the rear end breaking violent enough to tweak a link or pan hard bar bracket? Might just be me, but I hate it when I find the answer to a puzzle and don't know how I got it. Maybe because sometimes my fix was just a band aid and it  come back to bite me later.

George is fast, guess we are on the same wave link.

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