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

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

 

That's a new one. Did they tell you why it would cause it?.I really doubt it will cause bump steer.

 

I have a 4" MorDrop axle & Mono leafs on the front of my '55 Ford Pick Up with no bump steer.

But i did alot of Custom work to keep the Drag Link straight in line & not at a steep incline.

 

The only thing i have heard that causes real bad bump steer is big tires on 4x4s. Im still green when it comes to just about everything automotive though.

 

like desoto said, the bump steer will come when your draglink angle strays to far from your tierod, keep it close to the same plane and you'll be good to go!

 

Desotos got it....the drop axle moves the steering arm in relation to the pitman, putting the draglink at an angle....just like a lifted 4x4.
If the angle isn't that much, it shouldn't be a problem, as a lowered truck probably doesn't have much suspension travel anyway.

But it's best to have the draglink follow the same arc as the axle. And yes, it travels in an arc, even with leaf springs....

 

ok so let me make sure i got this right. it should be ok with mono's and a drop axel as long as i have the drag link at the right angel. also would you guys trust mono's?

 

im trying to get the truck lowered just until it looks really good and thank you for all the info its a big help

 

Some like them,,,some don't,,I have them on the front and rear of my 32 pickup,,,on the front of my roadster and the front of my sedan,,,no problem with them.

If they were a problem like some say they wouldn't be making them! HRP

 

i put reversed eye monos and a 2 inch dropped axle on my 1960 f100.the upward angle of the draglink definately made a difference.not too bad though.definately make sure your steering gear box is adjusted properly and not loose.also requires tie rod drops equal to the drop of your axle.im getting ready to add a steering stabilizer as well.one thing i did notice is bias ply tires and a little bump steer can make for a wild ride on uneven streets.lower is always better.good luck!

 

Doesn't installing dropped steering arms help eliminate bumpsteer?

 

I have reversed eye monoleafs on my '62 uni-body, been on for 8 yrs.& lots of miles with no prblems...............yet!

 

Depends if you're raising or lowering the suspension...

 

Here's something to think about.

http://www.jalopyjournal.com/forum/showthread.php?t=148978&highlight=camaro+clip

 

If you are doing a 6-8" drop on a straight axle front end without relocating anything- there's a real good chance that you'll encounter some bump steer.
This could come from a couple of sources: center link contacting the frame rail/ oil pan, or the pitman arm being forced into a binding position. CPP makes a "Tie rod drop Kit" that spaces the tie rod and center link mounting downwards to help restore geometry. It's only an inch, but may be enough.

Keep in mind that the drop axle will give you suspension drop without your having to worry about axle clearance against the frame rails or oil pan, but both the monoleafs and the drop axle will both compromise the original geometry of the steering linkage. Seven inches or so is alot to ask.

 

Not to appear stupid,but what is "bump steer"?Thanks Phil

 

"ive been told that if you " Words not to live by. Thomas Edison once said "Inventions are made by people too stupid to know they wont work" And that was probably after someone just told him he was stupid and it wont work. I have a friend who looks at everything i do and says "that will never work." )Funny thing he has been coming here for specialty engines for his race car for almst 20 years. If I am so dumb i wonder why he desnt go somewhere else!) In fact some other friends know he is like that and follow him around saying that right in front of him. He doesnt even catch on they are mocking him. Of course everthing he says that about works just fine. As mentioned above If the linkage swings thorugh a similar arc it is not a problem. Also as mentioned above the less suspension travel the less the problem is. Sometimes we forget about the Freigtliners and Kenworths and Peterbuilts running by us everyday with 500 hp at 70 to 80 MPH with straight axle front ends not to mention the 50 million or so farm and dump trucks. Plan well and it will work well.
Don

 

You'll probably get a bunch of definitions. I was taught that bump steer occurs when the up and down travel of the tire rolling over a bump causes the tires to change direction momentarily and the steering wheel to whip left and right. The steering wheel may not move very much so it might not be noticeable on some less severe cases. In mild cases the steering wheel may feel like a wiggle and not a gigantic whip saw action. Lots of hot rods have the strict definition of bump steer and it's not a problem. Some cars with worn out linkage can change direction because of all the slop in the linkage. This is not bump steer as I was taught. It's just worn out crap.



This ugly diagram shows what happens when you change the angle of the drag link by lowering the front suspension without changing anything else. The arcs and links are all the same.

You can get bump steer in independent front ends also. The causes will be different but if your steering wheel moves left and right as you go over a bump then you have what I was taught to be bump steer.

Now you can hear how I'm all wet.

 

Makes sense,Thanks Phil

 

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

 

I call bullshit on the " bump steer "

 

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

Was this a multileaf spring salesman?

 

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.

 

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.

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(?)

 

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.

 

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)

 

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

 

Good link!

http://www.classictrucks.com/tech/0...mance_products_dropped_axle_kit/photo_02.html

 

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.