Then your problem is not spring wrap up. I'd be looking at the contact with the crossmember, a bent driveshaft or an out of balance driveshaft, or finally U joint bind. After checking and eliminating those possibilities: Block the engine level and measure the angle of the carb mounting surface on the intake manifold or block the frame level and measure the angle of the radiator mount face in the radiator support. This should be close ( + - 1/2 degree) to your engine/tranny angle at rest. If not I'd start by adjusting the tranny mount, then reset the pinion angle.

 

i never had a wheel hop problem on the trucks with the driveshaft hitting crossmember problem. the problem was the springs being too week.

me and ax posted at the same time lol.
resetting that tranny mount is a good idea too.

 

Okay guys, with all of this great input I'm gonna go out to the garage in the morning and see what I can come up with. Thanx a bunch

 

I'm goin' out to the garage and clamp my !@#$%^& head in a vise....

Great...I'm movin' crap around to get at my 9" stuff & 4-link stuff figurin'
that the whole 1-2* thing is the way to go...



THEN...everyone starts sayin' THIS setup is the whip...


So...now I gotta ask...'cause I was goin' by the FTE article about driveline phasing... sooooo.......which is it???

I thought a slight angle kept the needles from smokin' in the u-joints?????

............somebody get me a cheeseburger......

 

I dont know if i can help but it sounds like you have alot of spring rap . On a leafspring truck with tracion control ladder bars ect the rear pinion angle is usually set at about 2 deg neg . Rear end down compared to driveshaft angle . With just leaf springs the angle will be more because you will get more spring rap when under load . That angle would be more like 4-6 deg neg...So when the truck is under load the the drive shaft & pinon will be close to 0...Lew

 

rockher_man,
don't get frazzled, your second drawing and third are saying basically the same thing. The engine is typically mounted with the tail slightly lower than the front for floor clearance and to reduce the driveshaft angle to lessen risk of bind. (This can be acertained by the fact that the intake mainifold carb mounting surface is machined at an angle, the front is lower than the rear, so the carb will still sit horizontal, and the radiator is tipped back at the top so it stays parallel to the face of the fan.)
If you draw a line throught the centerline of the crankshaft/tranny output shaft, and extend it to the rear, and draw another thru the pinion gear shaft centerline and extend it forwards, the two lines need to be parallel, but not form a single straight line. The drive shaft then simply connects the tranny to the rear, it's angle is immaterial, it can be angled up, down or horizontal, doesn't matter.
Take a look under a late model truck with a lift kit, the driveshaft is at a significant downward angle. A heavily lowered vehicle's drive shaft may be angled upwards.
Vehicles set up for drag racing, not street use, may have the pinion angle set slightly different to compensate for axle wrap or rear end squat at launch. Don't copy race practices unless you are only racing.

 

2losteve, i just read a article about your situation, it was on a s-10tho, but the tranny sat below the axle, and had the same drive shaft u-joint problem.
what they did was put a 3/4 shim under the transmission,

then used the rear end shims to change the angle of the axle.
AX is totally right when he was talkin about the lifted trucks and lowered trucks, every car/truck is different, so there is really no "book" to go by, depending on how low you are changes things dramatically. good luck.

 

One thing that puzzles me is which crossmember the drive shaft hit?

 

I have tried to post twice so far today - with photos and details of yesterdays trials & triumphs - but for some reason they were trashed or whatever!

 

rockher_man, you are 100% right. my dad taught me this when i was about 12 years old. we would set up well motors. the drive shaft was set just like the pictures. we never set those well motors up with the driveshaft in a straight line. the motor was always a couple of inches higher than the well head. but the crankshaft line and the well head line was parallel. we did not have u joint trouble.

 

With all of the great input and looking at my u-joints, I'm tending towards the leaf spring (without trac-bars) theory and I'll tell you why. I've found that only my rear joint is thrashed; the front one is A-OK. So I installed 2 1/2 degree wedges to tilt the diff. back down a bit without lifting the trans. I drove it on a short test drive of about 5 miles and the only thing that I noticed when I returned is that the pinion housing was a bit warm. Don't know if that is normal or not for such a short trip, but the u-joints weren't warm.
This is a photo of the crossmember(not!) that my pinion was hitting. It is actually a tubular housing which the anti-sway bar rides in(TCI).
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This is a photo of the new shaft/pinion angle.
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Good it soundes like your going in the direction . As long as you have some neg pinon angle thats good . All springs flex on street trucks or race trucks . Even stock trucks have a neg pinion angle compared to the drive shaft angle ...

 

if you throw your trans in neutral and jack up the rear wheels off the ground you can turn the drive shaft by hand. your hands will feel any binding. we ran my son inlaws drag mustang about 4 degrees down from parallel. that was under alot of torque. your axle is moving up and down all the time so there is no perfect angle like on the well motors i talked about. a junkyard walk with a angle finder would get you to the point where you know how the factorys set up the driveshaft engine/ axle angles. take a tape withyou also. better yet, you can most likely go out to your own drive way and take a look unless you have front drivers only.

 

your truck looks very clean!! i wish mine was that clean...
are you going to notch that cross member i little bit, or make a loop for it?

 

From what I see in the last picture, your pinion and driveshaft are at nearly at the same angle. In fact it looks like the pinion is angled up rather than down. This may be just an optical illusion. If not, then you need to tilt your pinion down more.