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 Post subject: Roadster runs
 Post Posted: Sat Nov 29, 2008 12:52 pm 
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Well, the roadster finally runs!!! Now its time to make it run straight. #-o

Made 2 runs last Sunday and it didn't go straight under power. I didn't really lean on it off the line and when I put the foot down it wanted to aim left. Even on the second pass when I left in high gear and gradually got down on it, it won't go straight. 1st pass 1.38 60' and 6.52 (1/8th) easy and lifting a lot.

About the car.
110" WB. 4-link car w/anti-roll bar. Weight unknown, but I would guess 1800# race ready. Left side drive street roadster. straight front axle with torsion bar (i guess thats what it is). 16x33" Hoosier tires (5psi).

Things I've done.
Checked rear alignment with string etc and it might have a very small thrust angle issue. Plan to check better and adjust out. Took all preload out and maybe slightly neg preload between run 1 & 2 (barely had any).

Planning to scale to see actual corner weights and adjust accordingly.

Looking at buying scales, any experiences with these
http://www.jegs.com/i/Intercomp/541/170125/10002/-1

Any other suggestions, ideas of thing to check etc.

Thanks,
Rick


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 Post subject:
 Post Posted: Sat Nov 29, 2008 1:10 pm 
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Rick is there any way to adjust the height of the front corners??  What I mean is if it's driving left then there has to be more weight on the right rear at static height.  If you can put some additional spring in the right front and left rear then you should be able to balance it out.  Either that or take some out of the left front and right rear.  Just remember that each time you change something you need to make sure that the 4 link and anti-roll are still neutral.  

If there's no way to adjust the front then you'll have to just use the rear springs.  From what I've found it's better to use the springs to change the corner weights than trying to do it with preload on the suspension, which kinda puts it in a bind.  

As far as the thrust angle goes I'm not sure it will have that much of an affect on this as mine was off quite a bit but never was a problem at the hit and, it actually did some 1.16 short times with it like that.  And, look at the NASCAR cars now running down the straight away like a crab!

But it is good to hear that you did get some seat time before years end.  That will help keep those juices flowing until next season, hey! ;-)

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 Post subject:
 Post Posted: Sat Nov 29, 2008 3:15 pm 
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Few things come to mind.

Rear tire rollout.

**** Very Important: Check front end toe.
Broken chassis or rear end housing.


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 Post subject:
 Post Posted: Sat Nov 29, 2008 7:35 pm 
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hi Rick

as Scott has already said, check the roll out on the rear tyres

also if it has a rear torsion bar leave one of the drop links disconnected to see if it is causing the problem

does the rear suspension go into bind anywere through the travel

regards
rod

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 Post subject: reply
 Post Posted: Sat Nov 29, 2008 7:38 pm 
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You don't have a calipar hanging up do ya? sounds dumb, but the stupid things can kill us :-k   just a thought...

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 Post subject:
 Post Posted: Sat Nov 29, 2008 10:10 pm 
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Planning on checking front and rear toe-in tomorrow. I'll also move rear thru full travel up-down to check for binding etc. Measure tire rollout also. I've already looked the rear over and the 4-link mounts, but I will look the rest of the chassis over closer looking for possible broken welds.

It has Ford R&P steering. How long are the steering arms on you guys spindles? I've seen these being too short cause the steering to be too touchy.

Ken,
The thrust angle on the Nascar cars still may be pushing at the center of weight, just have the body mounted crooked. My roadster has me sitting over to the left and the engine/trans is mounted right of center an inch or two. The frame rails are angled (narrower at front). Very hard to figure where things should be on one of these. I measured diagonally from four-link brackets to spindles before and it measured ~ 1/8" ... very close. The front has no springs and almost no travel. The pivots/torsion bars on the straight axle allow body roll w/o one tire coming off the ground.

Elkyman,
I assume you are referring to the front calipers? It seems to roll easy after releasing them.

Along with the checks and adjustments already discussed, I plan to add some weight to the car and reduce power some before next pass (Spring).

What about the scales??? anybody used them or heard about that brand?

Thanks,
Rick


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 Post subject:
 Post Posted: Sat Nov 29, 2008 10:20 pm 
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I check axle thrust like this on a drag car which I still don't think it's your problem because it would be turning sideways in the water box and dog tracking down the track.

I mark chassis C/L as far front in the car as I can and one as far back as I can. Plumbob it down to the floor and snap a chalk line the entire length of the car. Then drop a plumbob at the end of each axle tube and snap a chalk line.
Then use a framing square where the 2 lines intersect usually using a 6 foot level on the short line holding the square against it.


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 Post Posted: Sun Nov 30, 2008 5:51 am 
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Keep the info coming. I found some more horsepower this fall and my car suddenly started going to the right. I will be going through all these ideas on my altered this winter.
Barry, Glad to see the roadster alive.

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 Post subject: krazy55ken
 Post Posted: Sun Nov 30, 2008 1:26 pm 
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Hey rick if you would like to put your car on a alignment rack let me know and I can make it happen..  krazyken

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 Post subject:
 Post Posted: Sun Nov 30, 2008 8:19 pm 
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Rick on that thrust angle, I had my local front end shop set my car up to check the 4 wheel alignment.  That was how I found out that it was off.  

After I got the car setup in my shop, I checked the housing to see if I could come up with the same numbers he did, and I did, so I went from there and squared the housing to the chassis centerline.

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 Post subject:
 Post Posted: Mon Dec 01, 2008 7:29 am 
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Ken0069 wrote:
Rick on that thrust angle, I had my local front end shop set my car up to check the 4 wheel alignment.  That was how I found out that it was off.  

After I got the car setup in my shop, I checked the housing to see if I could come up with the same numbers he did, and I did, so I went from there and squared the housing to the chassis centerline.




How did you do that Ken???

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 Post subject: Re: krazy55ken
 Post Posted: Tue Dec 02, 2008 10:06 pm 
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krazy55ken wrote:
Hey rick if you would like to put your car on a alignment rack let me know and I can make it happen..  krazyken



There you go Rick.In the matter of a few minutes Ken can tell you how far its out =;  =;

I wish there was someone that I can use to get my Beretta  on the rack!!!

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 Post subject: Re: krazy55ken
 Post Posted: Tue Dec 02, 2008 11:11 pm 
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Beretta wrote:
krazy55ken wrote:
Hey rick if you would like to put your car on a alignment rack let me know and I can make it happen..  krazyken


There you go Rick.In the matter of a few minutes Ken can tell you how far its out =;  =;

I wish there was someone that I can use to get my Beretta  on the rack!!!


Krazyken I appreciate the offer but I have an alignment guy when I need that and the main part of this isn't something I want to trust to a alignment system made for factory cars. They base alignments off the front tires and I am not sure the front tire position relative to everything else on this car.

I used the method Scott Smith suggested for defining a chassis centerline and I think that is the best way. I used the frame rails to find a center in front and the four link brackets in the back. The rear is aiming 5/32" (.156") off center to the left at 20ft in front of rear tires. Seems pretty small to me.

The rear has a very slight amount of toe out. .009" per 10' total toe out (both sides). Works for me.

The tire rollout was 104.5"L, 104"R. Off a little, but should make it push right I would think.

I got my new scales today and did some preliminary weighing.
These are without the body or collector mufflers, but with me in the car with no changes to chassis/suspension since ran.

LF=449  RF=388
LR=481  RR=469
Rear wt% =53.16%
Total wt. 1787.

Body will be ~100# (maybe more as it is a heavy fiberglass body) and is probably a little more toward rear, but even side-side.

Another thing I checked was 4-link position.
109"wb, IC at 53" out, 6.1" high for 74.3% anti-squat

Nothing is jumping out at me as the problem. I've looked everything over for cracks or broken welds etc. Nothing so far.

The rack & pinion I believe is from a Dodge Omni and has 5" steering arms on spindles. I plan to have a friend make new steering arms at 5.5" and 6" lengths to reduce turn per steering input. Maybe its all the driver??
#-o

Rick


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 Post subject:
 Post Posted: Tue Dec 02, 2008 11:19 pm 
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Beretta wrote:
How did you do that Ken???


This probably would require a phone call Barry.  It's a rather lengthy process and probably easier to explain on the phone than here.  The way I did it you can check the front for stagger also, ie, one tire in front of the other.

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 Post subject: alignment
 Post Posted: Wed Dec 03, 2008 7:23 am 
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No problem Rick. If i can help let me know..  KRAZYKEN

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