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Post by floppyfoot on Aug 18, 2013 17:53:28 GMT -6
What would be a good starting point angle for the 3rd link on a GM metric chassis? Ours is about 14 degrees down to the chassis. The trailing arms are level and the car has plenty of adjustment for them, they are in the stock location on the body. The panhard bar is also level and has to run to the frame on the right side and must be at least 28". The car has 53.7% left side weight and 51.6% cross and rear. It also has a little over 200# bite.
Springs are, LF 1100#: RF 1000#: RR 250#[5"x13"]: LR 200#[5"x13"]. Adjustable ride height spacers in the front and spring jacks in the rear. Tires are Hoosier 90x11x15 on 12" wheels. Running a 9" floater rear with 650 gears and turning 6800 to 7200 rpm's. Had a dry slick track last week, rained out this week and the car has some push going in the turns. Side bite seems good but need a little more forward bite. The track is 3/8 mile with long turns and short straights, do not loose to many rpm's in the turns. Just changed the car from a 4 link and trying to learn whatever I can about a 3 link, this is all new to me.
I would love any help that I can get, we have been out of racing for 10 years. |
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Post by clbaker25x on Aug 19, 2013 10:59:45 GMT -6
Your car is probably a little tight on entry because your right rear spring is too stiff. I would go to a 225 RR spring and that will loosen your entry a little and tighten your car middle off. The other thing is with your LF being a stiffer spring than your right front that will make the car a little tighter throughout the turns. If you soften your left front spring that will also free up the car on entry.
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Post by floppyfoot on Aug 19, 2013 12:30:44 GMT -6
The next softer front spring I have is a 900#. I have a 225 that I can put on the RR but it is an 11" spring where I have 13" springs now. I have a 200 13" but want to keep a long spring on the LR. I had them switched when the car was a 4 link. The car never would hook up very well. It was always loose on exit no matter what we did to it. We are driving the car off the RR, that is why the LF and RR are the stronger springs. Ride heights are RF 6 1/2": LF 7 5/8": RR 8 1/4": LR 9 1/8". The car gets good side bite this way and better forward bite than it had. With the 13" 200 spring on the RR, the frame came down enough to bend the brake bleeder on the RR. I am worried about using a weaker spring there.
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Post by floppyfoot on Aug 19, 2013 12:34:21 GMT -6
When the car was a 4 link, I had these springs in it:
RF 900#: LF 800#: RR 200#: LR 250#, 13" springs across therear and 9 1/2" springs on the front.
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Post by clbaker25x on Aug 19, 2013 15:05:46 GMT -6
I am not a big fan of driving the car off the right rear no matter the class. I think that leads to a car that is fairly consistently too tight on entry and loose on exit which is the condition it sounds like you are trying to remedy. In cars I have raced previously it has also led to wearing out the right rear tire way to fast.
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Post by clbaker25x on Aug 19, 2013 15:16:29 GMT -6
The other thing you could do to free up entry and tighten exit would be too add some bite to the car.
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Post by floppyfoot on Aug 19, 2013 17:32:58 GMT -6
Do you think that if I swap the rear springs that it would help? Since both of them are 13" springs. Right now buying new springs is not in the budget. The car that i am asking about belongs to my son.
My grandson also has a car in the same class. The car he has was bult by someone we know and won 30 races with it in 3 years. It came with the setup like I put in my sons car when I changed it to a 3 link last week. I do know that the other cars in the class are running this type of setup also, that is why I used the springs that I did. My grandson cut a tire 2 weeks ago and hit the end of the guard rail head on. Just got it back from the frame machine last Thursday. By usingthe 200# 13" spring on the RR, I am trying to keep it from rolling over and the frame hitting the brake caliper.
If I swap the rear springs, just how much bite should I put in the car? Also, should I swap the LF 1100# spring for the 900# spring. With the ride heights higher on the left, the car has not been loose off the turns for the 1st time. The track was very dry slick and has only ran 1 race with the 3 link.
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Post by clbaker25x on Aug 20, 2013 7:04:40 GMT -6
I wouldn't recommend stiffening your left rear spring, so if I was in your situation I don't think I would do anything with springs. Do you have any video posted on youtube where I can watch this car go around the corner. Is there anything he can do with the brakes to free the car up? Can you run wheel spacers? Possible do something with air pressure. If you can lower your left front air pressure a little or go to a little smaller left front tire that would help the car turn into the corner under braking on a slick track.
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Post by floppyfoot on Aug 20, 2013 7:55:25 GMT -6
I can use a smaller LF tire. Also can run wheel spacers. I have 2 each 1/4" spacers but cannot quite get a full wheel lug on the threads on the studs with them. The wheel studs are 5/8" and longer than stock. Also have 2 each 3/16" wheel spacers, one on RF and one on RR. Have adjustable spring spacers on top of front spring. The RR spring jack is backed all the way off.
My grandson drove the car last race, that is the only time the car has run with the 3 link installed. He has just driven a few races. He informed me that he did not even use the brakes. The car has a brake bios adjustment which my son will use. My son likes to drive deep into the turns, jam the brakes and floor it. It usually works except with the 4 link it was very loose. He uses mostly rear brake.
Looking for a way to PM you with a link to the track's website with pictures. They are not video's, just still pictures.
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Post by floppyfoot on Sept 26, 2013 6:23:55 GMT -6
Springs right now are LF-1100#: RF-1000#: LR-250#: RR-200#:
55% left side: 54.5% rear: 51% cross. Car still has a push in. Bite is 214#. 4" stagger. Car for some reason now is not rolling over on the RF. Should I go to a 900 or a 850 spring on the RF and a 1000 on the LF.
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Post by clbaker25x on Sept 30, 2013 12:47:32 GMT -6
If the car is still a little tight on entry, you might think about softening your left front spring. Go 900 left front, and keep your 1000 RF and that should free the car up on entry and through the corner. Biggest area you will feel the difference will be entry.
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Post by floppyfoot on Oct 22, 2013 18:30:30 GMT -6
Went with a 900 RF, 1000 LF, 200 LR, 250 RR. Scaled the car. Raised the left lower trailing arm 1 hole. Track was dry slick. Ran 4th, car had good side and forward bite.
Did not change anything for the next race. Track was tacky and real fast. led 24 of 25 laps and won. Engine turning 7850. It has never turned that before and it still was pulling real strong. This is with vortec heads, holley 4412, headers, 650 gears.
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Post by clbaker25x on Oct 23, 2013 11:30:01 GMT -6
Congrats on the win, glad to hear you got your car going better!
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Post by floppyfoot on Oct 24, 2013 14:26:03 GMT -6
THANKS, it has been a very trying time getting it there.
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