Do you think my pinion angle is the problem?

here we go, another pinion angle thread. sorry. my shoebox just doesnt like to go fast. at around 50 mph i get the wur, vibration noise under my seat area. this is a air ride car with a 4-link and the angles you see are at ride height. the trans angle is the angle that ford put there, its all stock . should i shim up the trans to get it to the 3 degrees that i have read about? then adjust pinion down to 3 also? thanks. <TABLE style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; FONT-FAMILY: Myriad, Helvetica, Verdana, sans-serif; BORDER-TOP: medium none; BORDER-RIGHT: medium none" border=0 width=799><TBODY><TR><TD style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; BORDER-TOP: medium none; BORDER-RIGHT: medium none" colSpan=2><EMBED type=application/x-shockwave-flash src="<a href=" wmode="transparent" allowNetworking="all" http: w185.photobucket.com flash tagWidget.swf?mediaURL='aHR0cDovL2kxODUucGhvdG9idWNrZXQuY29tL2FsYnVtcy94NjYvZG91Ymxlem8xL0lNQUcwMDIzLTIuanBn"' target="_blank"></TD></TR></TBODY></TABLE>

 

Thats a good place to start. I might be way off but have you checked to see if the tires are balanced also.

 

I would check driveshaft balance as well

 

I would check the uni's first , to make sure they are greased and are not frozen , then do the above .

Steve in Oz

 

sorry I can't help with your problem but just wondering if you can help me with what brand and where I might be able to purchase one of those fancy digital angle gauges in your pic.

 

http://www.harborfreight.com/digital-angle-gauge-95998.html

 

If you had the car sitting in the same position when measuring both angles and had the angle finder vertical to the world-------------NO CHANGE NEEDED.
HERE IS WHY, THIS IS A SMALL PART OF HOW I MAKE A PAYCHECK.
My rule is based on what I was taught by a Dana/Spicer trainer and is in a few brochures I have saved from over the years and understand well.
Dana/Spicer says that in a driveshaft that has two u-joints, the operating angle thru the two u-joints must be withing 1 degree angle of each other.
With the 7.7 degree tranny output measurement taken at a machined acceptable location and the 6.6 degree pinion measurement at another machined acceptable location, this gives SOOOOO close to within one degree diifference of drive end and driven end angles, that the comparison to having an angle measurement on the driveshaft will conclude to angles being to within 1 degree difference from each other or close enough to not matter.
The vehicle has some other kind of problem. Good pictures to help me explain how driveline math works.
6-16-2011, I taught three classes today to advise 114 school bus mechanics of how to inspect, troubleshoot, maintain, lubricate, and work safely with driveshafts under their fleet vehicles. Was only the 6th time I've done this in my 22 year career of building driveshafts and working with angles, etc.

 

I think you need to start with the obvious wear-point stuff.

a) U-joints

b) Tailshaft/slip yoke spline wear

c) Driveshaft balance/runout/damage

Was this car together and functional and this problem just started, or has it been there since the car went together? How old are all the parts?

If you put the slip yoke in the transmission and push it in until it bottoms, how much does it pull out from that point when you fit the rear U-joint in its yoke?

 

Thanks EnglishBob, this little tool will make it far easier to adjust my pinion angles.

 

Sounds like worn/loose u-joints or splines maybe? Just my .02.

 

thanks for the input so far. i guess i should of given some more info. new u joints and drive line balanced three times because thats what i thought it was. brand new slip yoke. tried two different gear boxes. just had the rear completly rebuilt. ive also swapped tires around. i had the driveline out and got the car up to 60 on the speedo and did not have the noise. the only thing that has not been replaced is the front brake drums and front wheel bearings. could a out of balance drum do this? or maybe a bad wheel bearing.

 

when the air ride was complete we were able to drive at freeway speeds, no problem. i think just about every part on this car is new, except front drums and bearings. i dont know the exact measurment on the slip yoke, but i know its correct. i had the drive line made longer becade it was to short after it was lowered.

 

X2 been there.

 

2-3-1221X for a new 1310 series slip yoke. A 57 Chevy car has the same spline size and snout size if yours has wear.
I just checked my employers parts distribution system and didn't find any available in any of our stores or warehouses. If was available there, could help you get one thru Bayshore in West Sacremento.
Powertrain Industries, Coast Driveline, somebody with NOS Ford or Chevy stuff?
Get your driveshaft checked out and rebalanced.

 

Any more thoughts on the pinion angle pictured. Patrick, i respect your opinion but would llike to hear from others on what they think. And yes the angles pictured were taken at ride height. Today while on a lift without driveline, i got the car into third and the speedo was reading 60 with no vlbes. Put driveline in , up on stands at ride height. 50 mph got the dreaded vibe, noise. I was thinking it could be the front tires but now that's ruled out. Once again, I've had the driveline balanced 3 times and the u joints are good,new and made in the USA. I'm still thinking its a bad angle. Thoughts??????? Thanks.

 

Start eliminating things, take the tires off, then the brake drums, then the axles, etc. etc.


dave

 

I chased a vibration like yours on my O/T G body car.Had the driveshaft checked,it was bent.How did that happen???? .They,Fleet Pride", built me a new shaft.Same vibration but now around 65 MPH.They balanced it again,still vibrated.Checked tire balance,runoff,all the usual shit.On a hunch I had another driveshaft made at a place I picked on the Internet because they had a nice ad and was in Texas.Texans drive fast and are honest...........Vibration gone......I suggest you have the driveshaft checked at another shop.

 

don't forget U-joint phasing

 

Two things come to mind.

First off, are you going to the same shop each of the three times the balance has been checked? It is not impossible for their machine to be out.

My other thought is ... based on the easy pinion adjustment of a fourlink, I would shim the trans (just temporarily) and once the trans has been shimmed up, lower the pinion angle till it is within "spec" relating to the trans angle. If this eliminates the vibration, make up a permanent shim for the trans. (watch for driveshaft length issues that "could" crop up once the trans has been shimmed up and the pinion down).

As for U-joint phasing, early Camaros came from the factory with the joints not in phase ... no idea why but I have seen it myself.

 

Something else to check , when the suspension is down ,check the driveshaft still has enough room to slide into the gearbox , as in it's not a bit too long when the suspension is down and bottoming out on the end of the output shaft , seen this before with bagged cars, driveshaft is fine when jacked up but is too long when at ride height or slammed ,
Good luck

 

What about a slightly bent axle shaft?

 

I would try a different set of tires-wheels just to eliminate them. You should be able to check runout of driveshaft and axles with a simple block of wood placed next to them and wheels turned by hand. Try the simple stuff first.

 

If your car is at ride height and the trans is at 7.7 place the drive shaft in and off center from the side view and put the angle at 7.7minis 3 =4.7 see how close you are the center of u joint.
side view then if off angle rearend to meet.

 

Don't forget the rear axle, lost of things to go wrong there. Any welding done on the axle? It could have warped from the heat enough to cause the shaft to bind, or one of the bearings could be bad.

 

I chased a noise/vibration in the Falcon last summer. Replaced both U-joints and had the driveshaft balanced. the noise ended up being a rear a rear wheel bearing. It was a low rumbling noise that increased with speed. I would have bet money it was a U-joint..

 

correct me if i am wrong but isn't ride height when all 4 wheels on the ground?

 

Years ago most vibratons at or near 50-55 mph were rear tires out of balance,and it was felt mostly in the seat.Just another thing to ck.One of all these suggesions will be the one .

 

I had the same thing on a 51 Mercury -- replaced the U joints, no help -- it was the rear axle bearings.

 

ive been thinking about taking the drive line to another shop, just tired of wasting money. not a bad idea at all though. shimming the trans up and changing the pinion angle might be my best bet to rule out bad angle.

u joint phasing, what is it?

im going to try this this week. if all of this is from out of round or badly balanced tires i will , well i dont know what ill do. drink most likely.

say huh? what chu talkin bout willis?

four link bars welded to rear. all was fine when car was first done. rear was just rebuilt , new bearings etc, etc.

all new, made in the usa!

the car is on a quick lift tat is level. car is at ride height on the lift.

this is what is happening. i hope its the tires, ill get to them this week

when i first posted this thread i thought the pics would have had people telling me the pinion angle was way off. nobody really has. the one thing that has not been double checked is the tires. they could be the problem. the tires are new, well maybe 500 miles on them. the car does go thru long periods of sitting. maybe its a flat spot, i dont know. im going to check the tires this week and if they are good and balanced, im seeking professional and medical help. thanks for all the help!

 

Did the vibration start immediately after the rebuild, or some time later? It could be ring and pinion related. I had to re shim mine a couple of times when I rebuilt it.