Installing front and rear shocks on a hot rod build just seems to happen or go where they fit. What is the science behind have the shocks mounted in theoretical correct position and what should a guy take into account when doing this?
I havent even began to tackle my suspension yet, but from what I've found is that shocks perform at different levels depending upon the mounting angle. Vehicle weight, Spring rate (SR), Shock Travel, and your Angle Correction Factor(ACF) based upon your mounting angle. Consider your vehicle weight to find your needed SR and your mounting angle to find your ACF for your shocks, then divide your ACF by your SR to find how much spring is needed at that particular mounting angle. Too much I dont know yet, but someone on here surely does! You should do a search first, but heres some info I've found that might be helpful. AV8 Front shock mounts, how to. http://www.jalopyjournal.com/forum/showthread.php?t=293236&highlight=shock+mounting Projects Its a shocking experience! Finished my front mounts, what do you think? http://www.jalopyjournal.com/forum/showthread.php?t=281262&highlight=shock+mounting Spring rates http://www.jalopyjournal.com/forum/showthread.php?t=273610&highlight=shock+mounting mounting coilovers http://www.jalopyjournal.com/forum/showthread.php?t=208551&highlight=shock+mounting Way too many to list them all, but they are on here! Good luck! Help me out guys! I dont want to screw him up!
I read somewhere that the most efficient postioning for shocks is vertical or in line with the line of travel, so the more vertical or in line you can get them the better. Thats just what i remember, cant remember the rational behind it. I think it has something to do with the more the angle the more the rotation of the shock on the pivots, obviously that rotation would be reduced with the the shocks being in the direct line of travel, so increasing the shock effectivness...........if you get what i mean. I think this would be more for the 4WD guys and the like........
You want the top and bottom shock mounts as close as possible to the arc that the suspended end (the axle) would normally travel when it hits a bump. Normally, this is pretty close to vertical, but with the top end leaning inboard ~5-10 degrees. The reason for this is that their effectiveness decreases proportionally to the cosine of the angle between the shock and that arc of travel. Yes- High School trigonometry does have applications in Hot Rodding. Wow- you guys type fast!
Too much info needed to list just general ideas. Drag racing, handling, comfort, off road, all like different locations. The the type of spring used needs to be considered. A leaf spring can use an angled mounting for shocks to aid lateral control. Drag race coilovers like to be straight up as well as behind the rear axle, mounting behind reduces the spring rate needed to carry the static weight and then the reduced rate makes load transfer to the tires easier and faster. The early stuff used hydraulic arms to simply dampen spring action for comfort. Like I said, much to consider depending on the build/car/usage.
30 degrees is the absolute maximum and 5 degrees being ideal. Body roll is a function of suspension geometry...
So why is it that some Ford trucks used to have the rear shocks staggered, with one angled forward and the other angled back?
Vertical is the ideal shock mount orientation. However that is rarely acheviable. What others have said is correct, there is a wide range of acceptable shock angles. The more angle in the shock, the more travel the shock has to do relative to the suspension travel. If you have an extreme angle, 30 deg. then the shock may not be long enough and actually bottom out before the designed rebound. Body roll is based on the suspension architecture and the roll center of the suspension, not the shocks.
Probably due to packaging, I should mention when I say angled I meant inboard/outboard, not fore-aft. Angled fore aft will also effect the shock length vs. suspension travel as well.
Seems for such a simple thing that most of take for granted, there is a lot of explaining to do. I am asking because I want to understand the basics for my streetable model A hot rod, but it seems there is a lot of things to take into account. Should my front shocks be at the same angle as the rears or what???
Always wondered why, on my Ford Ranger pickup, one rear shock is in front of the axle and the other is behind the axle.
Yep...it is always a compromise, drag car different from handling car, different from truck...etc. It really comes down to what you expect from your ride, nice comfy ride or do you want to handle like a slot car. Technology is giving us more knowledge and advancements in design that can make the compromise less all the time. This comes down to bucks but for a basic hot rod, employ basic design.
No insult to any one and I admire your interest, I would recommend investing in books to educate your self. Forums can some times lead to not accurate info, and there is some great reading material to guide you. Boyd Coddington's how to build a hot rod comes to mind along with Chassis Engineering by Herb Adams and Stock Car Set up Secrets by Bob Bolles. Really gets into the how's and whys which explains it clearly.
As creepybaby guy Sloorider intoned, this is done on some vehicles (not just Ford trucks) to utliize the shocks to eliminate axle wrap/hop.
Look at a production car,(zillions of R&D, road testing, etc.) with axle configuration similar to yours. As with mine which is RWD I used an S-10 pickup as a model. I figured later model, more R&D. Actually they are similar on all makes and models since the 1950s.
If I remember correctly I read in 'Muscle Car Confidential' that Mopar started the staggard rear shocks for their early muscle cars to fix the axle wrap/tire hop issue?? Bluto......FORD is King!!
Is there an angle or a dimension needed for your sketch or is it that an arc is drawn from the center of the tire base and where the arc contacts the chassis is where the top end of the shock ends up?
I try to keep both ends of the shock on that arc. The height is usually dependent on type of car/driving, etc. A street setup might mount lower than you would on a dirt track racer because of more body lean on an oval track.
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