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Post by powercar82 on Sept 16, 2013 12:14:44 GMT -6
I am switching from a 3link with the LR clamped in front and the RR on top of the housing to a swingarm 3link on both sides (just to try as it is the hot setup around here). I have heard it is a little more forgiving for track conditions than the clamped setup. Right now I am decent on a tacky track, but have really been fighting getting the car to hookup when the track gets rubbered up or dryslick). I currently run a 125 spring in the LR and a 150 RR spring. When choosing spring rates for the swingarm, should I start with the calculation of the motion ratio (about 225 LR and 250 RR)? What other changes do people think should be made? I currently run about 80 lbs of bite, so maybe I should double that (which may require me to add spring rate)? Any other suggestions are welcome! Also, here is a link to a video I made of my suspension during hotlaps and the heat race: I had a push on entry. You’ll notice my left rear bar (set at 17 degrees) is in the top hole. My hike is limited when it hits the underslung bar. I definitely need more fwd bite, so I have my toplink set at 19 degrees down to compensate. I feel if I redo my frame mount to get more angle (25 degrees maybe) in the LR, it will give me more hike (the underslung slopes down significantly as it goes further fwd). I’m thinking this should allow me to get more FWD bite, but with the extra rear steer, the car should rotate better in the corner. Let me know what you think. Any other observations from the video that anyone might have? Maybe I should just start by changing the LR bar angle before going swingarm?
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Post by clbaker25x on Sept 16, 2013 13:20:01 GMT -6
Great video. I really like how much your right front was getting over and compressing. What rate of right front spring and what stub are you running? If looked like you had your jbar pretty low on your pinion unless your track is really slick much of the time. I would not think you would need it that low on the pinion side. Your left rear would get up quite a bit more if you had some more bite in your car. It will compress the left rear spring quite a bit more and really get the car to jump up on the left rear bar.
We normally run a 175 right rear spring in our car, but will go as high as 200 to free the car up in the middle of the corner and go down to a 150 if the track gets really dusty slick. We adjust our right side bar throughout the night to give the car more forward and side bite as the track slicks off.
Cool video, thanks again for posting.
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Post by powercar82 on Sept 17, 2013 7:22:49 GMT -6
It is an Impala Stub with 600 LF and 650 RF. During the heat race I felt it bottom out twice and the track was extremely tacky. I'm thinking about putting a 600 in the RF with a rubber for heavy tracks and taking it out when it slicks off.
Right now my LR hits the underslung, so I definitely need to change that one way or another. I'm going to up the angle to about 25 degrees which should slide the rear end further forward into the underslung "pocket."
Do you only adjust spring rate and bar angle on the rr generally as the track slicks off? I'm really looking for ideas to simply and effectively adjust from a heavy track to slick track.
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Post by clbaker25x on Sept 17, 2013 11:13:19 GMT -6
With that spring rate on the right front you shouldn't be bottoming out. We run 550 on RF when it is heavy and go light to really light on RF on the super slick. Last Saturday at Columbus we had a 300 pound RF spring in the car when it was dusty slick in hot laps. You might want to think about raising your RF ride height just a little, we generally get about 4" of travel on our RF and get a little more when we run the soft stuff on the super slick. I am a big believer in using up as much travel as you can get out of the RF without damaging your shocks. We can't run spring rubbers though. If we could I would probably run a 450 or 400 with a spring rubber for my starting the night setup. Our primary adjustment is to adjust the right side bar up or down depending on tacky or slick. We normally run a 175 RR spring, but go to a 200 on really heavy tracks. We go down to a 150 if the track gets stupid slick. Normally you can adjust the car by lowering the right side bar with the 175 for most track conditions. Is your car a Jet mod? If so feel free to give my brother Trevor Baker a call at Jet racing for more help. He works there and is the driver of our car.
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Post by ljsracing on Sept 18, 2013 16:36:33 GMT -6
I would cut out the underslung bar and redo it before i ran 25* of bar angle.. Thats a bit excessive.. and by a bit i mean its ALOT. usually you never want to go over 18* give or take 1-2... JMO
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Post by Toywagon on Sept 18, 2013 18:46:53 GMT -6
Gonna throw out a few more suggestions for you to think about.
Don't forget static trail by lengthening the right rear back. You have to keep an eye on your driveshaft to make sure you dont pull it too far out of the tail shaft.
The positive of trailing the RR instead of raising the RR depends on track shape and how much bite is in the track. I use it to loosen the car up on entry, and when I come back to the throttle hard, I don't have the RR bar's increased bar angle trying to lift the right side of the chassis. It gives loose roll steer without the negative of a looser on throttle.
You do have more rear steer in the car, but you would have also had more rear steer in the car if you had raised the RR bar. It's just a good way to adjust entry and mid corner, without effecting forward bite as much when you come back to the throttle.
Now if your on a track that needs the car freed up pretty much on and off the throttle, RR bar angle does the trick.
That being said, 99% of the time I raise and lower the right bar, and leave trail alone, LOL Our track is really heavy in the heats, and I need to free up on and off throttle.
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Post by clbaker25x on Sept 19, 2013 12:27:12 GMT -6
We put quite a bit more drop in our left rear this year and I think it helped to add some roll steer to our car. Definetly a good idea to add the travel.
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