I have a 41 Willys coupe (fibreglass) which I am having problems with the rear end lifting and tires spinning at end of track. It starts to wander and spin at speeds over 120. I would like an alternative idea to a wing. Any ideas.
Printable View
I have a 41 Willys coupe (fibreglass) which I am having problems with the rear end lifting and tires spinning at end of track. It starts to wander and spin at speeds over 120. I would like an alternative idea to a wing. Any ideas.
hmmmm... What kind of tires and what air pressure? Did you scale the car? Curious what the rear weight is compared to the coil over (I assume it's coilover suspension) spring rate... Does the rear of the car lift, sag, or stay neutral when you launch? 4 bar rear suspension???
I would say it's a suspension issue... A Willy's coupe, even if it had a full belly pan, should never get into an aero condition enough to unload the rear..... A wing IMO wouldn't be a fix, just a band aid....
A bit more information about the car's construction would help........
The Willys weighs 2780. It has Hoosier 31x14x15 slicks. I run between 9 and 11 lbs. It is a four link. The suspension is quite rigid. No sag. What has happened is I had big wheelie problems to point of almost going over, I had the 4 link put to lower hole and scaled it. I had wheelie bars put on but they were improperly installed and pulled the back wheels off ground when it wheelied. Before I adjusted the four link I could run it up to 129 mph with slight wandering, but manageable, but extreme front end lift, thus the four link adjustment, which has given me top end lift. I intend on putting the four link back where it was and put properly installed wheelie bars on, but I am putting a 572/620 hp in opposed to the 406 small block I had in it, so I will have a little more weight on front, but will have a lot more torque and speed. This car actually blew over in Bakersfield about 7 years ago. It was told it was going in the 150 mph range when it went over. With with the new engine I should see mid to high 9 with 140 to 150 mph
I found some of the same issues with a Pinto funny car and a Chevy Monza pro-stocker
new i guy with a willys they put a wing on it
The willys has 31 x 14 x15 Hoosier slicks. Air 9 -11 lbs. It has a four link. Mustang front end. No sag in suspension. Launches straight. problem is that when I was running mid 11 and 124 mph it was perfect. I repowered (406) and ran 10.4. Problem was I was doing major wheelies. I put the top bars on four link down a hole and scaled it, and had wheelie bars put on. Unfortunately the guy that put the wheelie bars screwed up and the pulled the back tires off the ground at launch. I removed them. My front end was more controllable at launch but then I started getting wandering at the top. I intend on putting my four link back where it was, but I am also repowering with a 572/620 hp which will put me into the 9 with speeds in the 130 -140 mph range. I have talked to other people with same car and they are running wings at these speeds. This car actually blew over in Bakersfield about 6 years ago.
Keep the front end down low so the air can't get underneath the car. The nose-high attitude that looks so great on a Willys isn't the best for high speeds.
I have 31 x 14 x 15 Hoosier slicks. Four link with a mustang front clip. It launches and runs good. Weighs 2750 with small block and iron heads. No sag or soft suspension. Run 9 to 11 lbs. My problem is when I was running mid 11 at about 124 mph it ran great. Then put in 406 which got me 10.4 @ 129, but had wheelie problems. (almost going over) I put the top bar on four link down a hole and scaled it, and put wheelie bars on, unfortunately they were put on wrong and I had to remove them. Anyway, now if I go over 120 I start wandering bad and one run it felt like me front end dropped, which was actually my rear lifting off. I am in the process of putting in a 572/620 hp which will be putting me into the 9 with speeds between 130 to 140 .I've talked to people with 41 Willys and they tell me it is a problem with them and normally over 130 they will run wings. My car actually blew over in Bakersfield about 6 years ago, before I owned it. I plan on putting the four link back to where it was, get some proper wheelie bars and rescale the car.
Got pics. of the Willys? Side shot?
Testing. I am new on site. trying to reply
it weighs 2750 with small block. four link and mustang front clip. run 9 to 11 lb. air. suspension good, no sag., launches and runs flat. problem is originally ran mid 11 @ 120 plus and ran out great. changed power and ran 10.4 @ 129, but had problem wheeling (almost went over) so I moved top bars on four link down a hole and scaled it. Put wheelie bars on, but were not installed properly and had to remove. The wheelies were a little more controllable, but then it started to wander real bad at 120 plus mph. One run it felt like the front end dropped violently, which was actually my rear lifting. I talked to a fellow who had the same car and had exactly the same thing happened. He installed a wing and picked up 6 mph with less rpm at the end. I have a ZZ572/620 hp I am installing. I intend are moving the four link bars back, put on proper wheelie bars and scaling it. With the new power I will be in the nines with 130 plus mph. Before I owned the car it blew over in Bakersfield about 6 years ago. Any suggestions will be greatly appreciated.
I'd say you'd better get it handling right with the present power before adding a bunch more. Looks like there's a wing in your future, or one hell of a wreck!
Curious to see the scale weights.....and some pics of the car. What is the ride height front and rear? Could you put an angle finder or protractor on your upper and lower bars and see what the angles are.... How much setback on the engine....? If the car is lifting in the rear on the big end, it's losing forward bite and for some reason, could be coil springs or shock settings, unloading the rear suspension.
A wing wouldn't fix the problem with the suspension, but it would stabilize the car (somewhat) on the big end. IMO kind of a band aid approach and not addressing the problem of why the rear suspension is unloading.....
If it's up on the wheelie bars, it's not launching correctly. Too much lift on the front. By bar adjustment and changing the instant center the car should just barely lift the front wheels, maybe an inch or two max, and apply the rest of the torque to forward bite..... Spent years trying to make cars hook up. Once 4 bars and good tires came around had to learn to unhook them a bit, more just change the weight transfer to forward bite.
Does the rear lift happen under power, or when you lift at the end of the pass???
Guess I still don't see where a Willys coupe is going to have aero issues at 120 that would be severe enough to unload the rear end. A few decades back, we built one for a fellow named Ted Moe with a blown bbc, 4 link, glide, IFS--sounds similar to your car. It ran 9.90's at 135-140 and was dang near a hands off car on the big end....
My ol pal Tech gave me this link a couple years back, it has all the good formulas and information for diagnosing problems with suspension. Might want to check it out.....
home.earthlink.net/~whshope/
The Link did not work Dave, I would love to read it.
the air follows the roof line all the way down the back of the car, and then rolls under the rear of the car creating an updraft under the cars rear end. Thats why you see these long wings on these pro mods and boxy cars, is to get the air back far enough to keep the air from getting under the car, as they were not aerodynamicaly designed to go that fast. And like Dave said earlier if there are issues with the way the cars weight is disstributed on the chassis, or susspension, this could be the real problem.
I was hanging out with a guy at the Goodguys Nationals one year getting tips for building my boxy anglia for speed. This guy had the same issue a year before @ 125 mph and rolled his anglia 5 times at the big end. He had just gotten it rebuilt and added the wing about 1/2 way down the rear of the car, and lengthened the chassis 10 inches. Right there in front of me, ive got pictures of it. He rolled the car 6 times at the big end again, thak god he walked away from it. Needless to say the car was destroyed.
This had me wondering and kinda freaked out, Im thinking I am not building my car like his. Maybe it was the cars susspension or scaled weight design I dont know. There was another guy with an anglia there that ran 160 mph in the 1/4 but his wing was on the back of the roof. And it was smooth sailing, so wing placement could be crucial if you try that route first. Either way you need to figure it out before you crash really bad. Good luck on your quest to figure this out.
What color is the car???? I have had severe problems with some blue ones!!!!!
Seriously====many of the vehicles built before the late 90s become an nightmare at high speeds, but us racers are trying to drive them much faster than they ran originally----on our Pinto ( someone actually put a pinto in a wind tunnel and tested both directions---they were far better backwards!!!!!) we cut out the tail lights and lower part of rear window to vent pressure from under rear of car--we also put louvers over the rest of the rear window area and vented between them also( should of pattened the louvers, they got copied for the aftermarket)and changed the rear spoiler quite a bit to sorta resemble the trunk lids/rear of other cars at the time ( Mopar 'cudas, etc)
all this helped, but then the car went into giant wheel stand (pics around here somewhere) Built a Mustang, problem solved---
On my Monza pro stocker--sorta same scene---changed springs, schock settings, wheelie bars----made a different spoiler and it became one of the first 7 second cars--didn't have handling problem until about 140 but after that----- with the spoiler change 180 plus---
Keep in mind that most airplanes will stay airborn down to around 120 so aero at that speed is pretty signicant---course that was in a different lifetime also
As to the color comment---put some brightly colored yarn on the car and photo graft it at speed ( can be very enlightening as slow as 40-50) to see where the air is going and in what direction
oops, http://home.earthlink.net/~whshope/ Try the link again, I probably didn't put it in the thread right...nothing new for me I guess!!!!!
Thanks for the awsome link Dave, lots of great reading to be had there. As soon as I get done procrastinating I will read some of it.
I've had that link in my favorites for a long time, but haven't looked at it much yet.
Procrastinators unite.:LOL: ohhhhh wait......wrong thread. Sorry:o
Quote:
Originally Posted by mooneye777
Yer welcome, Techinspector put that one up a year or two back, been one of my steady reference sources ever since.... Tons of good information in there!!!!!
excellent link Dave. Thanks I have a lot of homework to do. I will be going away for a week and will continue then. One point you brought up was when the power was on or off. When it violently dropped it was at the end of the run and I had let off. When I get back I will measure my four link and checkback. Really appreciate the help.
Thanks,Terry
Yup, when the slicks unload it would be the worst.... Had a couple cars that I had to lift lightly and let the slicks up slow or they'd bounce terrible...... Goodyear tires????
Please post a picture... side view.
If you have it set up like a 60's gasser I think the lifting will continue no matter what you do. Many of these cars crashed in the haydays on the top end. You don't hear too much about it but they did. When they got to 140+ they surely were not the most stable cars around. I can remember at least 4 Willys and a couple Anglias crashing at Minn Dragways back in the old days.
With your 4 link you should not have to have the front end way up like the old cars. Maybe level to slightly nose down and some 90/10 front shocks so the front end settles down on the top end.
My Willys only weighs 2440 with 1100 even on the rear end and it hooks pretty hard with just the Hoosier street radials. Just for reference my front end center section is only 5 inches off the ground and the top of the front fender radius is 23 inches. I really haven't had the chance to try it at speed but I don't really expect any problems. I don't have your power but when the blower comes I still have some 4 linke adjustment available.
Here is the side view of the gentlemens anglia with the same described problem. Of coarse this is after it was destroyed. I could not find the other side, where the roof took the biggest hit.
Most of these problems of ill handling cars come from a combination of several design flaws---any object will have varying amounts of lift/downforce from aero and it becomes signifinate enough at around 140mph for a 2500 pound vehicle to take FLIGHT----
But, with everyone in the world is making so many chassis kits, ladder bar, 4 link, coil over, air bag suspensions and every imaginable front suspension, anyone can go on the web and purchase kits and a 100 mig welder and build a racing chassis---- with an ompossible combination of angles, shock settings, spring rates, bump steer to sort out---every one of these suspensions have a point in there range where the angles bind up and will instantly transmit an uncontrollable dart/dive wander into the cars intended path that the driver can't control
Add that to the fact that the vehicle is probably either in flight or on the verge of flight that it really needs aero controls instead of a wheel steering apparatus and you have disaster
The more pronounced vertical shape that gives the higher lift/drag numbers becomes an object with a high roll rate one it gets sideways to the intended direction of travel--
All the 1940s era vehicle shapes should be restricted in there class structures that are allowed as they are and have demostrated that they are really unstable at the speeds people are trying to run them and there is absolutely no format for teching the complete vehicle---sure there are chassis/roll bar specs, but nothing else
Hi. Back from holidays. Any input on putting a 90 degree angle strip about 5/8 inch high across the width of the roof to disrupt the air from flowing smoothly over roof. A oval track racer told me about this. This should interrupt the different pressures between the top of car and the underneathe of car which I believe is part of this problem. I will post pictures of stance of car when I figure out how to post the pictures. Thanks again for the input.
A small strip might make a differance if you were close to being aero correct----In the case of your car--you have to not only work to being aero correct but within a set of rules---like 3 inches under the front of the car--
Your car will need considerable work top and bottom to stop the lifting and you still have the problem of the binding suspension angles/shock settings
Did you ever get the problem solved? First problem like others have stated would be horrible aerodynamics, IMO. I would imagine that the tall roof design and almost 90 degree windshield would be most of the problem. Probably the limit for that style car.
Why would a wing be a band-aid? I do agree the suspension should be tuned first.