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The Liquor Makes Me Think
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Discussion Starter #1
Stepping up to a 4 link. Backhalfing my truck. I have prebent rails with out the brackets installed. Will start with big tire (33x16) but would like the option of dropping down to 275 if i wanted.
112" wheel base. Turbo 1500hp. ~3000lbs. How do i determine the hieght of the front bracket? Seems like 2* down hill is where most ppl like the lower bar. but what hole should i put that at?
I was thinking 2nd from the bottom on the front bracket and lowest on the axle bracket.
 

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Since you have the brackets, I would use them to lay out the suspension full scale either on the floor, or on a wall at your desired ride height. You can move the rear brackets around to simulate the different tire sizes. I can run 33's and 28's on my car, it kinda happened by accident, the car was originally built around a 32" tire. I will say the brackets on the frame actually hang below the bottom of the frame. Also keep in mind your cross member will need clear your driveshaft when the rear is hanging or extended. I had to modify my cross member when I went to the 28's. Mounting an ARB will need to be considered also, I will probably make some longer links for mine if I was to put the 33's back on,
 

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Keep in mind, your radial (275?) plot will be considerably different than 2* down (towards front) and will turn into 8* ish up, plus. Make sure your brackets will not limit your ability to tune this way.
 

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I’ve read where chassis guys hate it when people say they want to run two different tire sizes depending on the race. I guess it’s hard to be optimal for both. Makes sense really.
 

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The Liquor Makes Me Think
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Discussion Starter #5
Keep in mind, your radial (275?) plot will be considerably different than 2* down (towards front) and will turn into 8* ish up, plus. Make sure your brackets will not limit your ability to tune this way.
Thats why im wondering what holes to start with. Probably need to keep the bar spacing in mind too.
But i guess i could plot it all out and try to find see whats possible.
 

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The Liquor Makes Me Think
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Discussion Starter #6
How many threads do you all normally leave out when setting the links up?
I believe they are 20" fully threaded in.
 

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The lowers I will go 50/50 showing (not including nut) on the uppers, I prefer more thread engagement as those are being pulled, as supposed to the lowers that are being pushed. I also run top quality rod ends as well. No cheap junk there!
 

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Since you have the brackets, I would use them to lay out the suspension full scale either on the floor, or on a wall at your desired ride height. You can move the rear brackets around to simulate the different tire sizes. I can run 33's and 28's on my car, it kinda happened by accident, the car was originally built around a 32" tire. I will say the brackets on the frame actually hang below the bottom of the frame. Also keep in mind your cross member will need clear your driveshaft when the rear is hanging or extended. I had to modify my cross member when I went to the 28's. Mounting an ARB will need to be considered also, I will probably make some longer links for mine if I was to put the 33's back on,
I would do this and also use one of the many, inexpensive 4-link programs to try to get both tires to work. It's going to be a compromise so decide which tire is more important and bias bracket placements in that direction. Do you have corner weights already?
 

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The Liquor Makes Me Think
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Discussion Starter #9
I would do this and also use one of the many, inexpensive 4-link programs to try to get both tires to work. It's going to be a compromise so decide which tire is more important and bias bracket placements in that direction. Do you have corner weights already?
i do not have corner weights. The truck is in half right now, cut off rigth behind the cab. I'm trying to figure out what spec cage to put in and I need to figure out a way to make a chassis jig or some.
I guess i need to figure out front tire diameter and ride heigth as well. then start with that rear cross member.
 

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FYI, my chassis was built by a big tire guy, and the original 4 link plot reflected that. The first time I met the guy who wrote my holley tunes for the car (Greg Powrie) he commented on the four link plot that was in the car at the time. He asked who built the chassis, and I told him. He replied, "he's a big tire guy isn't he". I laugh and said yeah. At that time I had a 325/50 et street on the car. He recommend a radial style plot, even though we were going to run a 28x10.5W tire. The car ended up with a best of 1.29 60' with the slicks. After a couple of summers of working with Greg, he was confident we could make a drag radial work on the car, so we switch to a 275 pro. With the same plot the car 60's at 1.31, and with two upper bar adjustments (I am out of adjustment on the lower bar.....hence my original comment) the car now 60's in the 1.25 range, leaving on less power. We have a couple of tunes leaving on more power, but the day we wrote those tunes, the tracks timing system was malfunctioning, so we got no slips. Greg thinks the car can 60' in the very low 20's, to a high teen........at 3400#. So even on the 10.5W's, and single adjustable shocks, the car could work a slick using a radial style plot. Food for thought.
 

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FYI, my chassis was built by a big tire guy, and the original 4 link plot reflected that. The first time I met the guy who wrote my holley tunes for the car (Greg Powrie) he commented on the four link plot that was in the car at the time. He asked who built the chassis, and I told him. He replied, "he's a big tire guy isn't he". I laugh and said yeah. At that time I had a 325/50 et street on the car. He recommend a radial style plot, even though we were going to run a 28x10.5W tire. The car ended up with a best of 1.29 60' with the slicks. After a couple of summers of working with Greg, he was confident we could make a drag radial work on the car, so we switch to a 275 pro. With the same plot the car 60's at 1.31, and with two upper bar adjustments (I am out of adjustment on the lower bar.....hence my original comment) the car now 60's in the 1.25 range, leaving on less power. We have a couple of tunes leaving on more power, but the day we wrote those tunes, the tracks timing system was malfunctioning, so we got no slips. Greg thinks the car can 60' in the very low 20's, to a high teen........at 3400#. So even on the 10.5W's, and single adjustable shocks, the car could work a slick using a radial style plot. Food for thought.
Good info in there!!!!!
 

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The Liquor Makes Me Think
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Discussion Starter #12
FYI, my chassis was built by a big tire guy, and the original 4 link plot reflected that. The first time I met the guy who wrote my holley tunes for the car (Greg Powrie) he commented on the four link plot that was in the car at the time. He asked who built the chassis, and I told him. He replied, "he's a big tire guy isn't he". I laugh and said yeah. At that time I had a 325/50 et street on the car. He recommend a radial style plot, even though we were going to run a 28x10.5W tire. The car ended up with a best of 1.29 60' with the slicks. After a couple of summers of working with Greg, he was confident we could make a drag radial work on the car, so we switch to a 275 pro. With the same plot the car 60's at 1.31, and with two upper bar adjustments (I am out of adjustment on the lower bar.....hence my original comment) the car now 60's in the 1.25 range, leaving on less power. We have a couple of tunes leaving on more power, but the day we wrote those tunes, the tracks timing system was malfunctioning, so we got no slips. Greg thinks the car can 60' in the very low 20's, to a high teen........at 3400#. So even on the 10.5W's, and single adjustable shocks, the car could work a slick using a radial style plot. Food for thought.
Greta info. Thank you. 10.5w is the small tire i was thinking of running too.
Ill have to play with some plotting and find a sweet spot for the front bracket to mount.
 
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