wheel hop

mopower · Post by **mopower** » Fri Dec 17, 2004 2:41 am

I have a '72 4x4 f-100 it has bad wheel hop when It looses traction both 2wd on the road or 4wd off the road when I climb a hill.
I had this in my dodge truck I had 10 years ago too but it was not as bad
I could tell the wheels were hopping,
, it was an automatic my ford now is a 4 speed manual, The F-100 Hops really violentally I am afraid I am going to throw a driveshaft.If I drive normally it doesnt do this.I dont even get any vibrations on the freeway...
I know bad motor/transmission mounts can cause this but I have not found any bad from visual inspection.Can anyone tell me where to look first?
Should I just replace all the motor/trans/transfercase mounts? Could it be shocks?

magnethead · Post by **magnethead** » Fri Dec 17, 2004 2:15 pm

Posi? Locker malfunction?

heep70 · Post by **heep70** » Fri Dec 17, 2004 10:50 pm

Its called axle wrap. It is caused when the rearend is under torque. The springs bend allowing the rearend to twist until the tires break traction and the rearend slams back into position.

You will adventualy bust the drive line out if you keep doing it. Rock crawlers solve the problem by installing an anti axle wrap bar. Its kinda like a single traction bar. Here is an article on it.

http://www.4x4wire.com/jeep/tech/susp/axlewrap/

magnethead · Post by **magnethead** » Sat Dec 18, 2004 12:00 am

which is why you see high power rigs almost always running traction bars or 4 links. Very rarely do they run stand alone leafs.

Post by **DuckRyder** » Sat Dec 18, 2004 9:42 am

Bob on the FE page has adapted a set of Cal-Trac's to his Drag Truck (Mayhem) and says they work well. Its a 64-66 but I'm sure the same could be done with a 67-72.

http://www.calvertracing.com/

James Duff also sells a similat set up for Broncos that could probably be made to work.

http://www.jamesduff.com/eb/susp_parts.html

mopower · Post by **mopower** » Sat Dec 18, 2004 9:33 pm

So you guys dont think it has anything to do with my mounts?
I have noticed when I give it some gas when I have the clutch in, basically a little rev up, I can feel the clutch pedal moving.
Also the wheel hop happens on the front too, I confirmed this a few days ago, My friend got out and watched as I climbed a hill in 4wd and sure enough the front tires are bouncing too.
I know its going to break if i dont fix it, I just want to try to resolve it with one fix instead of buying parts installing, see if that fixes, buy more parts install.....

mopower · Post by **mopower** » Sat Dec 18, 2004 9:34 pm

Oh by the way both diffs are open.

heep70 · Post by **heep70** » Sat Dec 18, 2004 9:50 pm

No, even if the mounts are lose that won't make the axles bounce. Your engine, tranny or T-case would jar around, but not the axles. Have your buddy watch the springs. He will see them bend around into a somewhat "S" shape before it bounces. Read that article I attached above.

Do you still have the factory springs?

mopower · Post by **mopower** » Sat Dec 18, 2004 10:21 pm

I am sure the springs are factory, no lift or anything and everything else looks original on the truck.pics here-> http://home.comcast.net/~schaffer.d/f100/index.html

The shocks look like they were replaced sometime atleast 15 years ago.

The front has coil springs as this is a f-100, can those still bounce like leafs?

magnethead · Post by **magnethead** » Sun Dec 19, 2004 2:28 am

no, coils can't do that ............... as easily. If both are open and even the front does that, pull the diff covers off and count the teeth- sounds like the axles are geared differently (one axle spins faster than the other in 4wd). If the fronts wheel hopped in 2wd, then theres something i don't know about (thats unlikely anyway). The rear, if on leafs, is no question true wheel hop.

heep70 · Post by **heep70** » Sun Dec 19, 2004 11:25 am

magnethead might be onto something. I am not sure of the F100 R&P but the F250s (most of them) had a one tooth difference from the front to back (4:10 & 4:09). If they have been change you will see a big tooth difference. The numbers are also stanped on the ring. Maybe if you are lucky the diff tags are still attached.

You can also check the gearing by lifting the reareand and front end (one end at at time) of your pick up off the ground. Turn the tire one full rotation and count how many times the yoke turns. The last spin the yoke makes will more than likely not be a full rotation. You will have to guesstemate that part. Example: 3-3/4 rotations of the yoke is a 3:73 R&P

If the rearend or frontend is open there is a chance that you will need to only lift one side of the pick up and spin the tire. If the yoke spins more then 5 full revalutions then do only one side off the ground.

Let us know what you find.

jor · Post by **jor** » Sun Dec 19, 2004 12:33 pm

Everyone seems to be posting complex solutions. I'm thinking a set of shocks would help him out quite a bit. He mentions the shocks are 15 years old so that would probably equate to no shocks at all. I would buy a set of quality shocks and give it a try.
jor

morganater · Post by **morganater** » Thu Dec 23, 2004 4:22 am

thats an interesting thing to consider (new rear shocks). I dont know, but I think my motor mount rubber is cracked too now. MY wheelhop equated to a fragged flexfan and totally annhilated radiator.

magnethead · Post by **magnethead** » Thu Dec 23, 2004 12:11 pm

if they were 3 1/2 turns, then your gearing is 3.56:1.

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