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Post by racinfan83 on Aug 30, 2014 11:55:46 GMT -6
Long time crew guy on a UMP Mod. We have had this problem for a couple years and tried so many things to fix it. We are at a loss what to do. Car is BAD FAST on wet/tacky tracks and JUNK on black/slick. Set fast time in Hot Laps often. We have run heat races and blown away some of the best cars in the National points - then went backwards like dragging anchor in the feature when slick. Driver has lots of experience and has tried many lines/techniques, to the point he is getting frustrated. Car goes into corner good maybe a bit tight, but the second he gets in the gas the rear just snaps loose and blazes the tires. Once he gets out of the gas and straightens it up it launches like a friggin rocket - but we are getting killed in/off the corners. 2014 Impressive Mod. We had a 2012 Impressive before and had same issue. Standard 4 bar, pull bar with 1200# spring, 22 gallon cell, rear percentage about 56% on scales, roughly 80# left rear. 600 rf 650lf 225 lr 200 rr. Standard shock package, we have run both 2" and 3" offset wheels lr, and either 3" or 4" offset RR in different combos. We try to keep around 3" rear stagger and 1" front. 3/8 banked track. I can't tell you the exact angles we run on the bars but we have moved them around in different combos and nothing seems to help. At a loss as to what is causing the car to be so good in higher traction and SO bad on slick. And we have the slick almost ALWAYS by the time we run. What can we be missing on the setup to constantly be so good on wet and junk on slick???
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Post by flipflopoo1oo on Aug 30, 2014 15:53:40 GMT -6
No different than most but spring package and ft. placement and split is your problem! Pull bar spring too too radical for smooth traction! Adjustable I hope! My stuff is close to some setups but they just missed a factor or two that put a kink in the mix! Once there it expands at any change to repair! You set ranges, get to their middles and then you have less margin of err! Start with total weight , axles, springs fit and compete for transfer (BALANCE) with shocks! Lean it left and un nosed with more right bar than left only to even out when rolled for even traction! Then roll out might have a shot at working to get you around the track if grooving is correct! If not its hard to tell what is doing or causing what! New rears corrects best in testing!
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Post by racinfan83 on Aug 31, 2014 9:18:11 GMT -6
Brother I need some clarification on some of what you said. What is "ft. placement and split"? We have an adjustable pull bar and can change springs - but which way is it "too radical"? Do we need a stiffer or lighter spring? "Lean it left and un nosed with more right bar than left only to even out when rolled for even traction!" - Not sure what you mean here? Friday night we had R lower bar about level and upper 4 holes from top. L lower was I think 4 holes up from level and upper was 3 down from top. We don't get to test and we run one night a week. SO anything we do other then scaling the car which is done every week in the shop is on the fly...
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Post by flipflopoo1oo on Aug 31, 2014 22:11:49 GMT -6
Where the stronger ft. spring location is and the difference in the poundage of the two! Softer sometimes helps but it may depend on movement too in transfer by angles changing if adding steer in the process! Radical means movement or changes that occurs from that point of interest! Soft may give and hook but move more things and it shouldn't! I have to have all info or you change entirely to get it all to work together! Holes ? It would be degrees not knowing ride heights ect... You could jack it up and change them all! No movement wanted!!! On the left rear! The right will drop and steer all you need! Indexing and perches??? Its a bit more than holes to me not knowing where they are but angles and degrees we can adjust once springs, shocks, and ride heights have been established to be correct for traction with steer with said angles, in the bars! So how many bar holes top and bottom? Is the indexing the same on both sides? Rear springs on top or where?
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Post by flipflopoo1oo on Sept 1, 2014 10:19:44 GMT -6
Can't remember or not if I mentioned to get rid of 3s or 4s on the right rear! A 2 works best at not letting incorrect air from sudden load by added roll or too much j-bar angle throwing the load and rolling the tire under the car adding jump up to loose momentary traction of the right rear!--- Follow by drift?---- Sorry but I could not refuse that one!!!! 14 pounds is not enough if gauge is off or showing signs of wear touching the writing on the side of the tire! Tale-tale signs of over 2 inches of shock travel on right rear is signs of load shifting too much! Try 17 psi if not wishing to change else where! If not collapsing it should be a tighter car as squish is spring tension too!!! A 2 with 17 would show you quickly how far your set-up is off if using a 4 offset and low air to get you around the turn now!
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Post by racinfan83 on Sept 2, 2014 9:21:58 GMT -6
Well we don't have a 2" beadlock. And we build a lot of pressure in the RR as it is - if we started with 17 we might be on the edge of failure as it builds. Everyone we know runs 12-14, and we aren't wearing to the letters. I do understand what you are saying about the 2" RR - might have to borrow one and see what it does.
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Post by flipflopoo1oo on Sept 2, 2014 10:08:46 GMT -6
If building heat, it is lack of planting and a traction issue! if not steering enough and tight it scruffs heavier! The two idea or 17 is just a hot lap test to find factors! We sometimes run 11 on a wet track but you have to get right back in it or it too rolls under and throws the car loose! Traction if soup but it changes all kinds of settings in the set-up at the same time! A lesser of changing 20 things for 10 laps! We run 12-14 too! I have ran 17 in mods but built no air with all else working! I started with 14 but was always 17 so I went there! Gaining changes a lot of things and you loose control of them! Go to messaging and give me all the info you can! Even roll out if hooked has to slip one wheel to move straight ahead! A 1/2" works great for us once getting right drive pounds to match left!
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Post by flipflopoo1oo on Sept 2, 2014 11:22:54 GMT -6
Working with others now on similar problems! Got them hooked and working faster! Most seem pleased with progress made first time out! Old habits or past knowledge of todays set ups has to go in understanding why and how it works differently with each kind of setup! Calming down left drive and j-bar helping to much to get traction is where most tight loose comes into play! Its a trade of in weight to the right side and rear percentage while holding the left steadly hooked that I have found to work on any set-up staring with springs and placement with less variables thrown in by un-needed movement of all and more on the right rear by pounds changing and little roll factors to deal with! Less bar angle changes holds drive thrust to change pounds at the right rear to add traction! It is a process, as any thing moving changes more than you or I can control! Help in debate may help but not many as willing as I to be proved wrong which is why preconceived things are so hard to change! Take a little left out and add it to the right in drive thrust pounds in traction but not on the scales as each has its on purpose in the set-up! Static, transfer and drive pounds have to even things out when rolled over! I don't believe the right should ever overcome the left in this process but the same goes for the left ever exceeding the right over 60- to 80 pounds either! Both should only gain towards equal to improve to a constant traction on all tracks! Please help in discussing all points of interest! Right or wrong has only to do with each set-up and the reaction to its factors!
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rickd39
Fourth Place
www.duricaracing.com
Posts: 54
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Post by rickd39 on Sept 3, 2014 15:27:57 GMT -6
I would try a softer pull bar spring for the dry slick. I like to run the softest progressive spring from Eibach. the 500-1000 lbs spring when it is really slick
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Post by racinfan83 on Sept 4, 2014 4:52:46 GMT -6
We discussed that earlier this year, and someone said you couldn't run less then 1200 without issues?
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Post by confused on Sept 4, 2014 5:56:13 GMT -6
Using a 2 off on the RR will loosen the car everywhere on the track. Have you considered dropping the RR spring to a 175? Or even dropping both rear springs 25lbs. I would do that if bar changes have been tried. Otherwise I would look at changing bar angles when it dries out.
I run on Hoosier g-60s and I drop the LRU on the bird cage and both RS bars on the frame when it slicks off. Also, I'm running a 200 RR and a 175 LR.
Hope this helps some.
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Post by flipflopoo1oo on Sept 4, 2014 8:56:43 GMT -6
We discussed that earlier this year, and someone said you couldn't run less then 1200 without issues? Only the extra movement is at fault in changing too many others you have not corrected yet! Most every different set-up reacts different to each change in respects to other factors! A frustrating but loveable sport much like my wife! Try getting her to change is not much of a challenge compared to a race car and I have all the wrenches!!!! As with most progressive lets you decide instead of her! Isn't that nice for a change to have something else to adjust on in the dirt that can do some good! Once all else is correct!
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Post by racinfan83 on Sept 4, 2014 9:52:57 GMT -6
Sounds like we are too radical with bars and are "slamming" the car loose? I read ur msg and that's what I'm gathering is that we need to change to a "calmer" setup. And makes sense too cuz there is one guy we race with that pretty much runs a straight rear and he is pretty fast...
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Post by flipflopoo1oo on Sept 4, 2014 17:17:54 GMT -6
Having springs on perches forward still needs little to no movement! Any drop or hike changes settings on all bars and has to be addressed by some other means of correction! Thus the indexing of floated or control of twist if clamped! All of the extras is trying to regain traction by moving the rear end forward under the chassis without adding any extra weight! With no weight or too much thrust angle, or to heavy of springs with lift occurring brings more air down force (Pounds anyway you look at it with drag of the spoiler)! Less in the turn and more in the straits! At least I figure the lead plays fair with less air drag and traction in the turn with added transfer qualities when and where you need it! With out all the hassle and holds left so the right naturally does the most steer and what is needed to hook both wheels without having to roll over to get its help! This is while using the left ft. to hold traction on the right rear, at least when still with in spring's range with added lt. ft. steer traction being that the tire is on the track! More drivable I have been told! I've never driven a lap but watched a few thousand made easier this way to win!
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Post by flipflopoo1oo on Sept 4, 2014 17:42:50 GMT -6
If the rules allowed spring loaded spoilers, I would still have to move both rear wheels forward to add traction! Some already do but with most even settings and you still have air to deal with in the body angle change! A spring loaded body might be best! I have seen this done also, the sides flexed! Actually the pins fell out holding it up! Adjustable by design track to track and air density! Topless can show you a thing or two about roof down-force and spoilers along with car rake making it tight and loose! Pounds when you need them or air drag when you don't want any! Most cars don't need help once off the turn and moving faster or is it the ones moving off the turn faster that needs less down force???
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