why does a drop axle and mono's cause bump steer

[buick320a]

I call bullshit on the " bump steer "

[Crease]

Originally Posted by 93chevy55

hey guys i got a 55 chevyy pu 2nd and i want to lower the front and back. ive been told that if you put a drop axle and mono's for the front it causes bumb steer why does it acually cause that. and for the back im thinking a axle flip. if any one has info please let me know
thank you
kujo

Perhaps more susceptible to bump steer? Can't imagine causing it!

Was this a multileaf spring salesman?

[ArtGeco]

Originally Posted by 93chevy55

for the back im thinking a axle flip.

I used a 72 Nova rear end, it literally bolted right in and gave me around 5 inches of drop. I could add blocks and drop it more but would need a notch.

[58Fridge100]

Originally Posted by 93chevy55

58fridge100 so the dropped tie rod kit will help alot with mono's and the drop axle? and thanks for all the info also everyone else thank you so much
-kujo

It may be enough to get you out of trouble. I'm assuming that if you're doing a drop axle (2-4"), and monoleafs (4-5") you may end up with a 7" drop, right(?) Honestly, I'd hit up some of the Chevy guys here, or go to CPP's website for better details on everything.

Originally Posted by buick320a

I call bullshit on the " bump steer "

The point isn't that monoleafs will cause bump steer, while "regular" stacked leafs won't..........
The issue is that monos LOWER ride height, and that a lowered ride height can affect clearance and steering geometry. Lowering a straight axle front end significantly without making an effort to restore proper geometry to the steering linkage steering is likely to produce some bump steer.

I assume that if you are "calling bullshit" then you understand what bump steer is and what causes it(?)

[Evil Wicked Mean & Nasty]

Originally Posted by ArtGeco

I used a 72 Nova rear end, it literally bolted right in and gave me around 5 inches of drop. I could add blocks and drop it more but would need a notch.

Hey ArtGeco, that is one sharp truck!




58Fridge100, The story you have just seen is true, the names have been changed to protect the innocent.

I like your signature line and that's a fact.

[93chevy55]

ok so im just wondering if i do a mono and drop axle in front that should give me about a 6-7 inch drop (using 3inch drop axle and 3-4 inch mono's)

[parksquijada]

if the spring change didnt change the angle of the drag link it would not bump steer no matter the type of spring. if it is a straight shot from the pitman arm ( arm coming from box ) to the arm at the spindle ( level or close, not angled up or down ) then you wont get bump steer unless you have alot of suspension travel and real soft springs that let the drag link achieve that angle we dont want when you hit a big bump or drop into a big pothole. if you do have the radical angle on the drag link ( higher at spindle on lowered car...lower at spindle on raised 4x4 ) when the axle moves up or down yet the axle cant move forward or backward ( just straight up/down )the distance between the spindle and the draglink gets shorter or longer by maybe an inch or more. try it with a pencil or something. hold one end in your fingers and hold the other end down at a 45 degree angle with your other hand. as you move the end on the down side up and down ( alot ) you will see the distance between the 2 ends gets longer and shorter between your two hands as the free end swings in an arc up and down. the more the pencil is close to level the less this distance changes if you move the free end up and down. if the draglink has the radical angle or as you hit a large bump and that distance between the pitman arm abd spindle increases or decreases if you are holding the steering wheel tight it will push or pull on the spindle making the car steer rt or left very quickly (bumpsteer) if you had a light grip on the steering wheel it rips the steering wheel from your hands because when the draglink moved it moved the pitman arm end instead of the spindle arm end ripping the wheel from your hands ( ripped hands, OUCH! ) instead of steering the car rt or left . in other words try to keep drag link level whether lowering or raising the car or truck. make any sense? WHEW! now i have a headache.

vaya con Dios

[58Fridge100]

Good link!

http://www.classictrucks.com/tech/09.../photo_02.html

[HELLMET]

my truck has a mono leaf in front but i want to put a drop axle on it. also i have a 55-57 car rearend is the 72 nova the same width? . thanks billy

[58Fridge100]

Originally Posted by HELLMET

my truck has a mono leaf in front but i want to put a drop axle on it. also i have a 55-57 car rearend is the 72 nova the same width? . thanks billy

Great looking truck. I have been debating whether to go with a copper color on mine.

[93chevy55]

58fridge100 i have that article and thats why i was wandering but thanks for all the info. also if i do a 4inch drop in back will it make the ride level since the back is higher or if i do the drop the back and do just the drop axle? what do you guys think
thanks for everything guys
-kujo

[torchmann]

every situation every angle is different even on the same vehicles.
It is purely a problem of geometry, your own personal geometry on your vehicle not a question of materials or name brands or even the style of suspension your running. it is an engineering, setup and adjustment issue.

anything that causes the up and down of the suspension to push and pull on the steering causes bumpsteer.
bad gas, mismatched brand names, and religious affiliation will not cause it. No amount of superstition hear-say or "what he did on his car" will fix it on your car. you have to learn about suspension and steering geometry if your going to change anything.from stock and be happy with it(unless your lucky)

It cant turn the steering wheel in the bump because your hand is holding it still so it turns the tires instead.

[blown49]

As Tommy's drawing shows you need to keep the drag link parallel with the ground to keep the up and down arcs at a minimum and equal.

[AnimalAin]

There was a thread some time ago about a dropped straight axle setup (think it involved "flipping" the axle over the springs) where the builder moved the steering box up about six or so inches to tame the bump steer. Might be in the tech archives?

[budd]

also the greater the distance of up and down travel in your suspension is what
increases the amount of bump steer you will have if your geometry is
incorrect, if you had no movement then the angle of your drag link wont matter,
no sway bar can allow bump steer to occur, poor shocks can as well, so my point
is if you can't get the geometry to work out so as much bump steer is
eliminated as possible then keep the ride stiff and bump steer won't show up.

[461/2ton]

I have a 4 inch dropped axle with mono's and cross steering in my '46.. Absolutely no bump steer. Drag link is very close to parallel with tie rod. Also have reversed eye mono's on rear.