design advice

90ranger2wd

Member
hey guys, i know you guys are tired of people asking "how to build long travel" but im just wondering if im headed in the right direction with my calculations so far. i cant find anyone who will post any kind of numbers, so i figured id post my numbers and see if you guys could at least tell me if im headed in the right direction or if my camber angles are way off from desired.

I have a 2000 chevy silverado, using stock suspension mounts and im desiring 17 inches of travel. is more travel possible?? I want to fabricate spindles and arms using heimed uppers with vertical uniball(bolt going horizontal) and bushing lowers with flat uniball(bolt going Vertical) in my numbers i accounted for 7.750 inches up travel and 9.25 down travel. are these numbers in spec?? i want to think i need more up travel but im not sure. all my numbers are in inches and are from pivot point to pivot point.

LCA... UCA... Spindle... droop... ride... bump... droop... bump
18.5... 14.5... 15.......... 6+........ 3-... 10-...
18.5... 14.5... 14.......... 3+.......4-.......9-... -3.625... -1.5
18.5... 14.5... 13.......... 1-.........4-... 8-...-3.75... -1.25
18.5... 14.5... 12.......... 8-.........7-... 7-... -4.375... -1.25
18.5... 15.5... 12.......... 0..........1-... 3-... -3.875... -1.125

Sorry if its hard to understand but i copied it from excel and it didnt go well. first two colums are a arm lengths. third colum is spindle pivot to pivot. 4, 5, 6th colums are degrees of camber change from droop to ride height to bump. 6th and 7th are inches of "scrub" (not sure if thats the word) from ride height. negative means snout face moved inwards towards chassis.

Any help would be greatly appreciated. im not asking for anybody's secrets, im just afraid im not getting acceptable numbers. I know if someone can help its you guys!!!
 

motorhead

Well-Known Member
In my opinion the scrub is a little excessive. I woud suggest keeping it under 3 inches but less would be even better. Minimal scrub, "theoretically:D" will keep the vehicle from wanting to push side to side as the suspension cycles. I've been working on a design in solidworks, with a LCA almost the same length as yours and have reduced the scrub to just under 2 inches with 16 inches of travel. Remember, more travel equates to additional scrub. Also, you can effect scrub with UCA lengths.

You should get neg camber in droop and bump, but more importantly in bump, to help the tire sidewall from folding on itself.
 

90ranger2wd

Member
do you think my lower arm is too long?? i thought it was easier to keep scrub down by using a longer lower. i have my lower arm set up at 5 degrees at ride height. does that seem right? it always seems like most trucks have a pretty flat lower at ride height
 

Triaged

Well-Known Member
I prefer to call it "track width change" rather than "scrub" to keep from being confused with "scrub radius" which is something different entirely. You need to measure it at the center of the contact patch and not at the spindle (snout) axis, which is where it sounds like you are measuring it.
 

motorhead

Well-Known Member
do you think my lower arm is too long?? i thought it was easier to keep scrub down by using a longer lower. i have my lower arm set up at 5 degrees at ride height. does that seem right? it always seems like most trucks have a pretty flat lower at ride height
You are right, a longer LCA will create a larger radius, therefore less scrub or track width change.

As far as angle at ride height and arm length, both are to be considered and designed at the discretion of the designer. In other words, no one correct way.
 

90ranger2wd

Member
thanks for all your help. i just got done checking out the build on your t100 and all i can say is that is one bad mamajama!! how come you are selling it? you had mentioned you are designing a suspension in solidworks...what is it for??
 

motorhead

Well-Known Member
thanks for all your help. i just got done checking out the build on your t100 and all i can say is that is one bad mamajama!! how come you are selling it? you had mentioned you are designing a suspension in solidworks...what is it for??
Finals are over, I now have some forum cruzing time:D. Thanks for the compliment on the truck. I have it for sale because I lost my job right as I finished the truck so I depleted my savings very quickly since I spent almost everything just getting the truck running. I have since been designing in solidworks (since its free) and have my mind focused on the new project, which is another T100. I plan to buid it to 1450 specs and design something I can afford to crash, flip back over and keep going. If I rolled my current truck I might go into a deep state of depression and never return.
 

90ranger2wd

Member
ok, so here is where im at now. i think i have my arm lengths figured out but im not sure on my caster angles. i have measered a few different trucks and found that alot of configurations are running thier lower mounts 5 to 7 degrees tilted up in the front. which i under stand helps absorb some hits from the front-(correct me if im wrong). my question now is do i want to translate this angle out to my spindle caster or do i want to keep my spindle at 0 to keep from making my tires have a wierd steering?

I dont have solid works or any program like that to figure out full on geometry like that, is there any kind of trick to help doing it on paper before i start getting **BAN ME****BAN ME****BAN ME****BAN ME** cut??? What did people do before solidworks?? sorry if these are stupid questions. im trying to read as many forums as i can but it doesnt seem like people really give out tricks or tips on this kind of stuff.
 
man.. someone doesnt like you.. ^^^

well You are correct about the lowers being mounted sort of at an angle.. the front LCA mount is a few degrees higher then the rear LCA mount..

well Im going to download solidworks as it is free and mess with it myself.. you should to. just takes some time to figure it out.
 

mcheck

STEEEKERS!!
man.. someone doesnt like you.. ^^^

well You are correct about the lowers being mounted sort of at an angle.. the front LCA mount is a few degrees higher then the rear LCA mount..

well Im going to download solidworks as it is free and mess with it myself.. you should to. just takes some time to figure it out.
where did u find it for free?
 

90ranger2wd

Member
where did u find it for free?
x2, i have used programs like autocad and featurecam, but never messed with solid works. do you get it at limewire or a site like that??

sorry for the language in my last post, forgot about the rules on here. used to some of the other sites where it is allowed.

any advice on whether im wasting my time as far as cost effectiveness vs. just buying a kit from blitzkrieg or mazulla would be appreciated.
anybody on here have expirence on these kits or others please chime in.
 

Haycock

Well-Known Member
tilting the arms back is a usual thing. if you put to much angle on them though youll get alot of dive from braking. people sometimes tilt the upper arm mounts more than the lower to get a little anti-dive.

as for the scrub or trackwidth change, you need to measure from the center of the bottom of the tire. tire hight will affect this so make sure you use the correct size.

what is your arm seperation at the chassis?
 
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