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-   -   car still WHEEL HOPS why???? (http://www.hotrodders.com/forum/car-still-wheel-hops-why-20643.html)

tyson 08-02-2003 08:04 PM

car still WHEEL HOPS why????
 
I have a g body monte and it wheel hops every time i spin.Today i put in elderbrocks upper and lower control arms with tubular braces and still. I ordered the anti hop brackets but they look cheezieee.What is causing this,it appered after i raised the back end to high,so i lowered it back down.Ever since i can't get it to stop doing it.I also put in new coils and new monroe coil over shocks. I NEED WORDS OF WISDOM FOR THE MONEY PIT!!!!! :confused: :pimp:

johnsongrass1 08-03-2003 08:48 PM

Have you checked for proper drive angles. They need to be the same only opposite angles. With a max of 4" total. Measure the rear tial shaft angle verses the angle of the rear U-joint. Both should be same angle. i.e., tail shaft 4", rear U-joint -4".

You maybe looking at chassis flex. Or misalignment of the rear end.

tyson 08-04-2003 11:44 PM

drive shaft angle and diff angle are in spec.could this come from bad body mounts?Or where would i be getting chassis flex from.The frame looks strong,no rust or cracks. :confused: :pimp:

johnsongrass1 08-05-2003 08:56 AM

Frame twisting under severe loads. The car might be loading the right rear, unloading the left rear and twisting the frame to the point that the frame springs back and loads the left rear while unloading the right rear. It could be so severe the springs and shocks can't controll the wheels. I could help more if you would tell me what year we are working on here. What engine and approximetly how much power. What trans and rear gear ratio? What shocks? What other chassis mods have you performed?

tyson 08-05-2003 10:17 PM

I should start off by saying thanks for showing interest.The car is a 78 monte carlo(g body).I bought from my brother when i was 13.I bolted a 69 350 4 bolt with edelbrock package,11:1etc::: Dyno at 475hp with a super t10 4speed and centerforce clutch.The weak part of the car is the 7.5 10 bolt with 3.73 gears, the axles turn into twizzlers.I want to put a ford 9 inch kit in,just looking for a good deal.Seem to range in price from 675 to 1100 for housing and axles.The wheels are 17 by 11 ameri racings with yokahoma 315-35-17s on the back. The shocks are monroe over loaders (coil over) with 2inch extensions. Cars stance sits about 2 inchs higher in back than the front,nothing to extreme.There is also a sub box over the rear wheels about 300 pounds.Trans gear ratio is 2.64 1st gear.I like to pull wrenches, just out of ideas????? :confused: :pimp:

TurboS10 08-06-2003 05:22 AM

Quote:

Originally posted by johnsongrass1
Frame twisting under severe loads. The car might be loading the right rear, unloading the left rear and twisting the frame to the point that the frame springs back and loads the left rear while unloading the right rear.
Not to pick, but the car will load the left rear and unload the right first. Seems backwards, but think about with tire always spins first.

I am curious how bad the wheel hop is. Does it just do it once on take off, or does it shake the car under power?

Chris

tyson 08-06-2003 12:34 PM

It produces good power so under take off,when i am doing 50 km,when ever i give it a chance to.The wheel hops are very extreme,breaking axles and housings etc....

Hollywooding 08-06-2003 01:19 PM

Tyson!

Dude were you at big valley this last weekend? Good stuff there,

anyway, this might sound kinda wierd but what if it's the posi in the diff slipping intermittently???? Kinda like a grab, let loose, grab, let loose vibration that's shaking the ******* outta your ride?

Like you said though, I've done lots of research into those rear ends and yes your overpowering it, thats' why it's chewing through axles and could be the source of your wheel hop.

Just my Opinion, I'll have to do some research for this one.
HTH
Hollywooding :cool:

tyson 08-06-2003 01:50 PM

Can't be the posi i have broke several different kinds

Dave E Shank 08-06-2003 02:57 PM

HEY TYSON: iI was at Street Rod Nationals last week and attended a technical seminar on leaf spring suspensions. It was put on by Eaton Detroit Spring, Inc. www.eatonsprings.com or 313-963-3839 or sales@eatonsprings.com E mail The owner talked about your type of problems and said to call with problems and they would be glad to help solve difficulties like yours....DAVE

johnsongrass1 08-08-2003 11:21 AM

TurboS10, Please don't take this as a aggressive response. You are confused slightly. I don't know how much chassis dynamics you do know so I will explain. If you already know this then good,will be elementary for you.

As engines turn counter-clockwise the torque of the engine will attempt to lift the left front tire. That weight, expressed in pounds, will be transfered the the right rear. If you ever watch a circle track race you would have surely heard of cross weight's,weight jacking or wedge. They all mean the same thing. It just a theory that states when you move weight from one corner the opposite corner's weight will decrease as well as increase the the adjacent corners weights

Lets say you have a table top with four legs. If you friend stands in the middle of the table than the weight of you friend will be the same on all four legs. If you friend moves to the right then the weight will be increased on the right side and reduced on the left side. If you friend moves to the right rear than the weight increase will follow him wherever he go's.

Engine torque lifting the left front "leg" will make you friend lean his body toward the left front in order to keep himself sliding off. This will increase the weight of the right rear and left rear(although not to the same extent as the right rear) because of the weight transfer. This act of weight movement will load the right rear first.

Take a look at my avatar, that's me in the yellow car, No. 11. This car makes 770 horsepower at 8600 RPM with a RPM limit of 9200, using methanol fuel. If you look real close you can see that the left front tires is lifted nearly a foot off the ground. This pic was taken while coming out of the middle of the corner. I get back on the throttle just before mid-corner and the engine torque coupled with good forward bite and indexing of the bird cages will transfer weight to the right rear so violently that the wheel will lift and it will be carried all the way down the chutes. It only comes down for a split second while braking to make the next corner. This is a classic example of weight distribution. I have tried to add weight from the right rear and add it to the left front(called weight jacking, Nascar uses screws in the back glass to do the same thing) to move the weight around to keep the front down so it will steer better. But I lose a certain amount turn in weight on the left front in mid turn due to the weight transfer to the rear when the bird cages index and moves the weight. So it's easier and faster for me to just three wheel it. The left front tire only touches the ground twice for about a total of three seconds on 12 1/2 second lap time.

I hope I have explained this well enough. Please feel free to reply and challenge anything I have said.

tyson 08-08-2003 01:07 PM

So is what you are trying to say is that i should try to get more weight transfer or WHAT?????Or should i try to stiffin the frame???? :confused: :pimp:

johnsongrass1 08-08-2003 01:19 PM

Tyson, You need good bushing's that support the rear end, Good geometry to start with, things like ensuring the rear is square with the centerline of the car and all angles are correct.

With a little tuning. if there are adjustable, And stiffen the chassis than you will be well on your way to long burnout's with out the shakes. Sounds as if you just have too much flex into the chassis. If applicable, build a roll cage. If not, than things like frame connectors and sway bars and other stuff should get you what you want.

TurboS10 08-08-2003 02:26 PM

Yes, I understand chassis engineering. Kindof have to be to design and build a new chassis for a vehicle. I hate to be the bearer of bad new to you, but you are mistaken on this application. Circle track and drag racing are two different animals......totally different.

While wieght is transferred to the rear right the axle torque will cause the rear right tire to lift. If you go back and look at what ever books you have read you will see this. This is why drag cars add preload to the right rear suspension to counteract the lifting of the rear right tire on launch. If it is not done, the car will not launch straight. This is also why any one holer street car will spin the right rear tire every time.

Chris

johnsongrass1 08-08-2003 07:54 PM

I'll check it out and see what I can find. Fight with ya later!:spank:


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