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DRR Trophy |
No sir, one adjuster on top | |||
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DRR Sportsman |
I think the wheelie bars are playing a negative role. An easy approach might be to raise them, and just kill timing. I was surprised to find that leaving with -19 retard and ramping back in over 2.2 sec my 60ft times were not drastically different (quicker). So if you are not worried about ET that is an easy fix. Also, you would be surprised what 40 pounds on the nose would do for stopping wheelies. Might wanna hang some weight. Slowing the weight transfer with good fronts or chains/stops would also keep it down. There are likely 10 different ways to get it fixed - but I think your wheelie bars are unloading the tires and causing your inconsistency. Figure out a way to get them on there for safety only and get it to launch and I bet your more consistent. | |||
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DRR Trophy |
I'm actually trying to get some wheel speed. Can't dead hook the car unless I want to kill it a bunch to not destroy the tire. At this point not sure I could dead hook it if wanted to. They were higher at one point and the car just shakes like crazy from driving over the tire. I would need a gear change to maybe help kill it and don't really want to do that but we shall see what happens. | |||
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DRR Sportsman |
Sounds like it's close--I wouldn't want to make any drastic changes. Tighten struts and/or hang 10lbs on the nose. Shocks--Tighten compression, loosen rebound. Take some bottom bar angle out of it by raising ride height. Once we get into summer you may find how it's set up now is good. Regarding the 1.69--if you do not change the rear gear, I'd be really surprised if the 1.69 doesn't slow the car down. I typically run around 4.20 and my car is about .05 slower with a 1.64 vs 1.80.This message has been edited. Last edited by: N2Ofrog, | |||
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DRR Trophy |
I could lower front ride height and that would move some weight forward but would that make the lower bar angel worse? I went from a 4.56 to 4.86 rear gear and nothing changed. All the splits were basicly dead on each other. Struts are full tight. I may need to add a way to put weight on the front. Thanks, those are in line with what I was thinking. | |||
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DRR Trophy |
First question: Are you happy with the 60 ft times and is the car printing time slips? This is where you're at, right? Here are all the combinations to go from you're current static 67% AS to closer to the AS line. The highlighted combo is where you are at now. Don't get hung up on the AS% as they are dynamic and not static. (If I put the measurements in a static 4 link calculator, I get the same values as you list in the first post.) There's a whole lot more adjustments left but not enough time in your life to try all of them. You want less squat so pick a combination that moves 10% from where you're at, say, 74% AS or so. Think about limiting front end travel. You can still see almost 4" of front end movement with about 2" of droop and the tire lifts about 2" off the track (while on the bars). The bottom line is there is a bit too much squat built in and you want to reduce that by moving closer to the AS line (but still stay below it). The number 1 positions are the uppermost holes on each end. The centers of the rear wheels look sketchy af. You'll want to inspect the hubs regularly for cracks. | |||
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DRR Trophy |
Yes that's where it is now. It will be really consistent for a few runs until it gets a little to much bite and it will lose 200 driveshaft rpm at .5 and slow down .02. I think I just need slightly less bite in the car. Going to try less air, stiffer compression, put full timing back in and maybe bump launch if those 3 don't get me where I want to be. Possibly raise ride height to see what that does. There are a few 4 link settings that I could try but to get similar length IC would have to change the lower bars up near the rear housing and not sure what that does if anything. I could also move top bar down 1 hole front and rear to get 77.9 from current 66.8 AS but shortens the ic to 52.953 from current 60.399. I'm not sure what effect that would have shortening ic 7.5". I feel like it's really close so going try the small changes 1st. | |||
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DRR Top Comp |
That's one approach to keep the tire round (efficient) repeatedly. The other approach is a relatively long low IC, relatively low wheely bar, relatively loose compression, relatively tight rebound, relatively high tire pressure. I wouldn't rule this out either. Use the wheely bar to kick the tire in the azz. | |||
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DRR Top Comp |
If I was gonna use a wheely bar, I'd lean to the wheely bar kicking the tire in the azz approach, on a car like Inferno's. IF, I weren't satisfied, using a stiff compression setting to kick the tire off. I think learning that wheely bar, would be, not only interesting, but worthwhile. Faster too. | |||
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DRR Top Comp |
Or you have a third option, an in between the first two, with a two way clicker adjuster on compression. I'm pretty sure 99.9%, the Penske 8300 will accept a two clicker on compression, is compatible. Is it a piggy back Penske 8300, or hose cannister 8300? | |||
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DRR Sportsman |
Have you looked at all other reasons the tire could be slowing down? Is the engine rpm also acting different? Possibly related to the timing curve and weather changes? | |||
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DRR Trophy |
All I really see is wheel speed lower. I can't post a picture to this sight or I'd put 2 runs up. | |||
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DRR Trophy |
Piggy back.
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DRR Top Comp |
He's asking you if the tune is good? Converter is right? How much converter pressure ya got? There's so many different adjustments ya could make, to make it perfect. To me, the tire looks slightly better at the leave in the first video, looks like there may be a hump in the ds graph 20- 30ft out. Piggy back or cannister on a hose Penske 8300's? | |||
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DRR Trophy |
Piggy
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DRR Trophy |
I could also lower rear top bar and raise front lower bar and lower the car 1/2" to end up 55.27"out and around 80-85% anti squat. Old course adjust 4 link brackets really limit the useable settings. | |||
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DRR Top Comp |
That's a good thing. Tell me this, did the gear change from 4.56 to 4.88 help the ds graph early? Did that change help in managing the tire? | |||
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DRR Trophy |
I honestly can't say for sure, I don't think my old shocks were good enough to really handle the job. It didn't really look any different between the 2. The graph looks way better with the new shocks. Also changed tires and added beadlocks at the same time so can't say 100% its the shocks but I'm pretty confident that was the the biggest change.
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DRR Trophy |
Well the things I tried didn't seem work. It did have its best 60' 1.077 to date but tires were being demolished and it had some shake. Going to chassis shop tomorrow for new wheelie bars and going to have them give it quick look over and see what their opinion is? Thinking I may have to either go to a 1.64 or 1.59 planetary or just put a 4.30 gear in to settle it down. https://youtu.be/Nx6YN84Qg5U | |||
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DRR Trophy |
This was later in the day after taking power away again. 1.092 60' shifting ay 1.15 seconds to calm the car down on this rough azz track. https://youtu.be/z7IR7-VKY7U | |||
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