instant center and pinion angle for BioMax

Im finally getting around to setting up my four link and just want to make sure I get everything right. If the rear tabs on the axel are 9 7/8 apart,and it measures 144" from the axel to the grill, what would my instant center be? And if my transmission angle is pointing down 3 degrees would my rear end angle be pointing up 3 to make it parrell or should I set it at 0 for the most travel? Thanks,Joe/515CUSTOMS

you need more information for instant center

your top bar is 9/78 heightwize from your bottom bar at the axle?

youll need to find out the verticle hieght difference at their mounting points on the frame
thats how youll be able to find the angle
if your looking for mathematics anyways

draw it out on paper and scale it down and draw in the imaginary lines to find the instant center

I think i have it down enough to explain it, but i'll let someone else explain it further, here's the diagram and link to his article.



http://www.streetsourcemag.com/forum/topic.aspx?method=reply&topic_id=85853&forum_id=16&forum_title=&M=False&S=True

If you really want to get down and dirty and measure it all out, I'll try and explain it the best that I can...

Looking at the diagram that Terry posted, you would first want to find your over-all length (which you have- 144") then you would find the distance that the tabs on the rearend are apart (you have that too- 9 7/8") then you need to decide how long your bars are going to be (that's fairly easy let's use 36" to keep things simple) With these numbers you can calculate the disatnce that your front tabs should be apart.

9.875(rear tab distance) / 144(overall length) = .069(tab ic ratio)
144(overall length) - 36 (bar length) = 108(let's call this the secondary bar length)

108(secondary bar lengt) x .069(tab ic ratio) = 7.45(front tab distance)

Hopefully that all made sence...

From here you would need to make sure that your bars are near parallel to the ground a half travel to keep rollsteer in check.

As for your pinion angle, it sounds to me that your half travel angle should be 0.

The lowers are 30" and im geting ready to do the uppers. and the pinion thing i want to get right so I can drive at full lift and not have any binding.

You can use the same formula if you want and just average the bar lengths to get your tab distance. Remember tho, the distance would only be measured as how much above or below they are of each other not that actual distance apart.
For example... If one bar is 30" long and the tab is 12" from the ground (assuming the truck is level) and the other bar is 20" long and 19" from the ground. The measurement that you are concerned with is just the 7" difference between the two from the ground, not the actual distance from each other, which would be more like 17" or so.

Get it?

make me waffles tonight Max!

Shouldn't you be working on a video?

How dose 7 13/16" apart sound for the front mounts

Sounds good to me. I usually use the 1.5" to 2" rule. As long as the front tabs are 1.5" to 2" closer than the rears, I'm good.