Also, do yourself a favor and get yourself a magnetic digital angle indicator. You can get one at Harbor Freight for a little over $20 when they are on sale, and they will make life a whole lot easier! They read down to 1/10 of a degree and are easy to see in the dark under the car. You can stick it to the pinion flange and adjust the upper arms until the angle is perfect! I have one of those gravity angle protractors that I used for years, but they are hard to read in the dark under the car, and you can't get in tight spaces with them like you can with the digital one.

Regards, John McGraw

 

John, i have considered the cv joint. Did the driveshaft shop quot a price for you. my trans is very exaggerated downward. I have the f-body problem with the front steering clearance AND my car is lowered. im afraid that my be my only option.

 

Here is my driveshaft that uses a CV in the front. Mine is carbon fiber and it was stupid money, but it solved my vibration problems. I too had a very exaggerated front operating angle.

You can easily go with an aluminum shaft with the CV and a lower cost. I'd contact Frank @ DSS for a quote.



Andrew

 

Frank quoted me about $700 for an aluminum shaft with the CV joint. He talked me out of buying it and sold me an aluminum U joint shaft instead. I am glad he did, because it was way less, and the shaft works well with no vibration. The only thing to be seen is how long the u joints will last. Even if I only get 20K or 30K miles out of them, I don't put that many miles on the car in years.

If I were you, I would get out the angle gauge and see just how much operating angle you will have when the front and rear match each other, before I dropped the money on a shaft. If the rear of your car is not lowered dramatically, it may not be as bad as you think. Just getting the two operating angles to be opposite of each other, will probably make the vibration go away, even if the angle is much higher than optimum for good joint life. The first thing Frank will ask you is what your operating angles are. If you have not done your homework, he will probably tell you to call him back when you have properly measured all the angles!

If you go with the CV joint shaft, you will need to get the rear operating angle pretty close to 0 to minimize the vibration. Since the front joint is CV. it will not give any counteracting force to balance out the rear U Joint, so the rear joint need to have very little operating angle. 1/2 degree will be more than enough to assure good roller bearing movement and avoid brinneling of the bearing.

Regards, John McGraw

 

OK guys, i bought the digital angle finder dillio at harbor freight this morning on the way home from my neck MRI ( long story ). i jacked the whole car up and leveled it with a 4 ft level on the rocker panel and i did put the jackstands on the axle tubes. i let the front suspension hang because it has no bearing on the engine -trans location. my front yoke was at a 3.5 degree downward angle and the pinion yoke was at a 1.8 downward angle. recon that would cause a vibration !? there is no way to alter the front yoke as i am tapped out on clearance (headers in the rear, pan clearance in the front). i flipped the tapered shims i had on the rear spring perches and brought the pinion yoke to 3.5 degrees upward angle. i then rechecked the trans yoke and it read 3.8. SO i have a working angle of 7.3 degrees, correct? and they are within .3 of a degree, but opposing. My question is, is that way too much working angle? I seriously doubt i will put more than 1000 mls a year on this car, but there may be some trips of 300 mls or so round trip. Do the brains of this forum think im ok with this set-up? Thanks Guys.

 

Newschool,

I'm on my phone so I can't type a novel, but you didn't quite follow what was said earlier. Check the picture that I posted. The angle of the car is irrelevant. You need to measure the working (operating) angle in the front and in the rear. I described what those angles mean before and the picture shows then as well. You need to measure the angle of the driveshaft.

Also, when you changed the angle of the pinion that should not have altered the angle of the transmission. So if you first got 3.5 and the. 3.8. You're not measurements are not reliable.

Andrew

 

It sounds like you are gaining on it, but you still do not understand the term "operating angle". The operating angle of the joint is simply the angular difference between the center line of either yoke, and the centerline of the shaft. The fact that your rear yoke was angled down, was clearly your problem, and I have no doubt that you will be able to get the vibration to go away.

To check the operating angle of the joints, follow this peocedure:

1. Remove the shaft from the car.
2. Set the magnetic base of the angle indicator flat on the end of the outout shaft of the transmission.
3. Set the zero of the indicator so that it is reading "0".
4. Move the indicator to the rear pinion flange and attach it to the parting face of the yoke.
5. Adjust the angle of the yoke until it reads "0".

You are halfway done now. You now have the centerline of the two yokes parallel to each other, but you know nothing about what the operating angle of the joints are. Do not be surprised that the gauge did not go back to exactly 3.5. These gauges are not high quality instruments, and a 0.3 degree variation is nothing to be concerned about.
Now to check the operating angles:

1.Put the indicator back on the output shaft end and zero it (if it is not already zero).

2. Slide the shaft back in and set the rear U joints back into the rear yoke. (no need to install the U bolts.

3. Attach the indicator to the bottom of the driveshaft, and read the angle.
The angle will be 90 degrees off of zero plus or minus the operating angle.
If the angle is 94 degrees, the operating angle is 4 degrees. Likewise, if the angle is 86 degrees, the operating angle will also be 4 degrees.

4. Repeat the process on the rear joint, and you will have the operating angle of the U joints. I would say that if the operating angle does not exceed 4 degrees by very much, that you are probably fine without the CV joint. If the angle exceeds 5 degrees, you may want to consider the CV joint.

Keeping the centerlines parallel will keep the vibration away. but high operating angles will eventually cause U joints to fail. The ideal situation is exactly opposite operating angles front and rear, and that angle is about 1 degree, but the most important thing is that both angles are opposite of each other. That is where the vibration will be the least.


Regards, John McGraw

 

I am sorry for my ignorance , i guess that is why i am a tech apprentice !LOL. Ok, lets try this again. On the front angle (trans) i have 3.7* on the tailshaft and .7* on the driveshaft, on the rear i have 3.5 on the pinion yoke and .5 on the driveshaft. These angles are being measured with a devise that is 2" long on a surface that is 1 1/2", so slight deviations are possible. Do i subtract the smaller # from the larger to get my working angle ?

 

I posted up before i saw your post John. THANK YOU!!!! Got it loud and clear. i will go check it right now. I will post up shortly. Again thanks for the instruction.

David

 

Yea right! Im posting up . most aggravating thing i can remember doing in a long time. I pulled shims , added shims, swapped shims etc...etc... Closest ive been able to get is 1.7* difference in tail shaft to pinion yoke. Its my birthday today and im not going to abuse myself anymore today. we will start fresh tomorrow. dang guys, sure hope it worth it in the end. thanks again for the input. David.

 

David, I will be interested to see what you come up with. Hopefully your vibration goes away!

 

SS TEN, me too. i know im on the right path. i have learned a lot from these guys. IM not really use to being the student. in my last line of work, i was the tell all , go to guy. its been a very humbling experience for me. thats why we come to these forums. to gather knowledge from those that know. there is alot if opinions and BS, but weed through all that , and there are things to be learned.

 

newschool72 - first, happy birthday!

Second, don't feel bad about learning this process. I am sure I am not the only person on here intently reading your posts, as I will be going through this same process in the (hopefully) near future.

Troy

 

Thanks for the b-day wishes. ive had more than a few.47 yrs old today. for all u young bucks, dont think u ever stop learning. Somebody will always know more than u do. Now if i could just make my 13 yr old understand that ! LOL. Troy be glad to help u understand it when the time comes.

 

VICTORY IS MINE!!!!!! finally got it. Im just wondering if the working angle is too much. I have both surfaces perfectly set and have a working angle of 4.6* on both ends but at opposing angles. Is 4.6 too much?

 

I took it for a ride and the vibration is gone for the most part. Very livable. Before i got the angles right, my family would be grabbing interior parts to stop the buzz. Not a very fun ride ! i owe a special thanks to Andrew and John for helping me to understand how this works. Next time this question comes up, i will have the answers. Its a good day.

 

4.6 degrees is a little on the high side, but I would run with it a while and see how it works. The worst thing that can happen, is that the U joints may have a short life, but you can always get a CV shaft made for it in the future. Talk to Frank and see what he thinks, but I'll bet he says the same. If you were making huge amounts of power, it might be a concern, but a stock LS should not present a problem to this operating angle, unless you were drag racing the car on a regular basis. I am guessing that on a street car, it will be fine.


Regards, John McGraw

 

Im pretty happy with it , at this point. It is a street car, although a trip to the track is not out of the question. The motor is probably making around 525-540 fwhp, so not a monster ,but very strong. I only have 70 or so miles on the total car, so have not opened her up. We will drive around a little while and see what happens.Thanks again for your help. David

 

You're never too old to learn. I'm 10 years older than you and still learn new stuff everyday. The power these engines can make, for their size, just amazes me.

 

Yes sir, i agree on both counts. The power these motors make is crazy. 11 sec quarter mile times with a cam swap( and a mild one at that) and exhaust is stupid ! Miles ahead of the old sbc motors im use to working on.