Kevin97ss

Ideally you would want a dial indicator and a digital angle finder capable of reading tenths of a degree.

Use the dial indicator to check for driveshaft run out in three areas on the ds tube, just behind each weld for the yoke and in the middle. This will check both yokes and the driveshaft for excessive run out(.010in can be acceptable but strive for less, more can be felt as a nervous feeling in the car at cruise) If you have an issue with run out at either end of the shaft there are more measurements that need to be done. If this is the case I can guide you through the procedure.

To check driveshaft weld yoke clocking, use the digital angle finder on the machined flat of the shaft weld yoke or better yet on the end of the u-joint cap(you can start on the slip yoke side). Face the driveshaft u-joint cap downward and stick your angle finder, slowly rotate the shaft until it reads either 90 or 0 degrees. With out moving the shaft, move the angle finder to the pinion yoke side of the shaft. It should give you the exact same reading within three tenths of a degree.

The rear not being "perfectly" centered typically will not cause an issue by it self but can compound other angular issues.

FirebirdStud

iTrader: (5)

Alright, I am bringing this back up. It still isn't fixed and I am low on patience.

This summer I had my driveshaft rebuilt (new u joints, new billet yoke). The yoke was getting buggered up in the trans output bushing. No idea how this is possible since the bushing is made of less dense material, but it happened.
Here is a couple pictures.. it was getting very messed up where the yoke contacted the back of the bushing. The pics don't look bad, but if you drug your fingernail over it, you could feel how it was very rough and definitely was not right. Further, it was only happening 50% around the yoke, not all the way around. This led me to believe the shaft was bent, unbalanced, or the main shaft of the trans was bent.


the first yoke, cast, buggered up.

it might not look bad, but when I drug my fingernail over it, it was very rough and clearly not right

$340 later, driveshaft is rebuilt. New u joints, new billet yoke. yippie, should be fixed.wrong. Now the new billet yoke is doing the same ****, and this was inside 10-15 miles. I could feel the same bad vibrations between accel and deccel as before. So I put it back up on ramps and pulled out the driveshaft. Ugh.


second yoke, did the same damn thing

Now I figure I have a trans problem. Pulled the trans out.. PITA on ramps but I did it. Took it to a local shop in town, and he pulled it all apart to inspect it. Found the rear output bushing is wearing very funny. Ended up having to send the tailhousing back to Tick Performance to drill the hole correctly (they have changed their CNC program since they built my trans 10 years ago and we couldn't get a bushing it without it collapsing). got it back, and the shop said everything else looked good except the 5-6 gear. You can see in the pic that it was wearing out quickly. As a side note, Tick re-used this gear when clearly they shouldn't have, I got my original mainshaft back and it was just as bad. We verified the new Viper mainshaft was ok and it was, barely any wear where this gear rides, so we put it all together with a brand new gear. $500 later, put the car back together.


trans output bushing

5-6 gear, clearly you can see the inside splines chewed up

Take it for a ride, and I feel the SAME DAMN VIBRATION between accel and deccel. I pulled the driveshaft after 10 miles, starting the same damn nasty wear on the yoke.


yoke doing the same thing after the rebuild of trans

there is a deep gouge close to the tip

I cleaned up the yoke with emory cloth, and put it back in. Now I called the maker of my lowering springs for help with driveshaft angles. I currently have the trans output shaft at a downward sloping 2.9* angle, front to back. So, I set the pinion shaft angle a positive 2.9* angle sloping up towards the engine. In all my research, the angles should cancel out and the trans line is parallel to the pinion line. Sam said the pinion should never point up, and that these cars are funny like that. He suggested I start with stock setting. I took this to mean if I still had the stock torque arm, it would point the pinion directly at the trans, regardless of what the trans to driveshaft angle is. Everything I have seen online said not to do this, but I thought he knew way more than me, so I gave it a shot. I set the pinion angle to the exact angle of the driveshaft. It ended up being .7* sloping down towards the trans. This means the rear ujoint had a 0 working angle and the trans u joint has a 2.2 working angle (2.9 - .7 = 2.2).
10 miles later, I didn't feel the nasty vibration in-between accel and deccel. However, now I have a very tight vibration starting at 3.5k rpms, and gradually gets worse until 5k (all the higher I pushed it on this test ride).
My thinking is that running the pinion angle pointed up at 2.9* was putting too much stress on the yoke, and forcing it into the bushing at awkward. Now that I have that issue gone (I think) now I need to reduce the vibration created related to RPM and a zero working angle on the pinion side ujoint.
I put the car back up on ramps to check the driveshaft to see if it was marring again, and it looks alright. It has the obvious rubbing marks, but it isn't rough like it was. However, now I have a new f*cking problem. The inside splines have an obvious hard wearing spot, about an inch inside of the yoke. There are metal shavings everywhere. We didn't see anything wrong with the mainshaft when it was apart, but I looked at the old cast yoke, and it too has the same issue in the same spot, but much, much less pronounced. I would have never noticed it in the cast yoke if not for this new billet one getting chewed up so bad. There must be material density differences, with the cast yoke being much harder.


the inside splines are now wearing hard

Now I am left wondering what the F to do. Some days I want to light this car on fire and push it off a cliff.

Which direction do I go in adjusting the pinion angle to try to get rid of vibrations?
What do I do about the yoke inside splines clearly having a wear issue? I do not want to drop the trans and take it back to the builder if I can avoid it.

I feel like I got rid of one issue and gained two new ones. Any ideas? Experiences?

FirebirdStud

iTrader: (5)

Also, since I can't put all the info in my signature, here is the car's setup currently:
poly engine mounts
poly trans mount
trans is shimmed up all the way to the tunnel
Sam Strano lowering springs
koni shocks
Dana 60
Strange engineering chrome moly dirveshaft
Spohn adjustable torque arm
boxed factory lower control arms with 1LE rubber bushings
Lower control arm relocation brackets welded to Dana 60
Spohn adjustable panhard bar
Tick viper conversion mainshaft t56
Mcleod street twin clutch
385 stroker motor

I just purchased but haven't installed:
Founders performance panhard bar relocation bar (stock one is contacting the Dana rear cover sometimes)
UMI panhard lowering bracket for the differential attachment point to keep the bar as parallel to the ground as possible
Founders Performance adjustable tubular lower control arms to center the axle in the wheel wells. It is currently pushed backwards in the car from lowering it (I bought the fancy bushing ones, the outside is rubber and the middle is a polly ball to allow the arm to articulate as it should)

Anything else you want to know, just ask.

FirebirdStud

iTrader: (5)

Does anyone have some ideas?
I'd like to get this thing figured out before it gets put away for the winter..

98cherrySS

iTrader: (2)

This may sound counter-intuitive but I would consider installing one or two hose clamps to the drive shaft. I have a friend with an LT1 that had a vibration nearly identical to yours. We worked the working & pinion angles on his setup for months. We double and triple checked the balance of the driveshaft. A local transmission guy suggested that we install a hose clamp on the drive shaft. We tossed a clamp on and after adjusting the clock of the band a few times, we saw improvement. Ultimately we installed (2) band clamps (clocked about 45° from each other) and the car has been smooth ever since.

This prompted me to test the same theory on my setup and I was able to tweak/tune out the last little bit of vibes out with a hose clamp. May seem a little shade tree (probably is) but I've run this car with those clamps for years without issue. I just drove it 8hrs away a few weeks ago and it was great.

I know the struggle. **** like this makes you want to sell the car. Ugh! Good luck man. Stay engaged and you'll eventually resolve it.

FirebirdStud

iTrader: (5)

You're right, this **** makes me want to burn it. hahahaha.

I am curious, does the hose clamps help cancel out imbalance in the rear end? If the driveshaft was 100 percent smooth, then maybe that is what it was doing?

Where did you place the hose clamps?

98cherrySS

iTrader: (2)

We mounted the clamps 6-10" from the rear u-joint. I went a little closer to the u-joint on mine. The process requires a little bit of trial and error and alot of patience.

Check out the link below.

1955Belair

Wow never seen that before,thanks for posting

FirebirdStud

iTrader: (5)

As an update for those going through similar frustrations..

I went back to ground zero.

I measured how the engine sits in the car side to side.
I took that measurement and put the tail of the trans in the same spot.
I then measured the differential and put it in the same spot (adjustable pan-hard)
I can't guarantee that it is exactly parallel, but it's spot on from car sub frames.
Now I am installing Founders adjustable lower control arms, to pull the diff back into center of the wheel wells. It was pushed back due to it being lowered.

I also bought poly spring mounts and put heater hose on the top of the spring to try to raise the rear end, got 3/4" higher. I did this because the u joint working angle at the trans was excessive. It is now 3.5 degrees and I cant make that any better. This angle was what was making the output shaft bushing ravage the slip yoke at higher speeds. I am fighting the 4:10 gears as it is spinning the dirveshaft much faster than the stock 3:42s ever thought of doing.

I am literally going through it step by step and setting everything as best I can. If this vibration is still there, then I will have no idea what to do lol. I travel a ton for work, so it has been a long process.. and will take probably another month before I have time to finish it, just in time for spring trials.

Stay tuned~

kenp

iTrader: (9)

Staying Tuned.

01ssreda4

iTrader: (96)

Sounds funny, but i got a shuttering vibration on accel as soon as i centered my rear end left to right. Drove me nuts. Went back and put the adjustable panhard almost stock length (leaving the tire to quarter panel measurements unequal) and the vibe went away. I just said **** it and left it like that.

trik396

iTrader: (4)

I don't know if you know but Strange had a problem a few years ago with incorrect machining of their yokes. You might want to call them. My guess is if it was one of the incorrectly machined pieces, that it buggerred up your trans output. I had one of the bad ones and it vibrated. Contacted Strange and they took care of it. There is a thread on this somewhere here.

FirebirdStud

iTrader: (5)

That's interesting! I cant have mine off center, the tire to inner wheel well doesn't have enough wiggle room.. it's already iffy. haha. But thanks for the tip!

Thanks for the info! I bought mine in 2008 I believe. Is that part of the affected units? I tried searching this topic, and I couldn't find anything..

FirebirdStud

iTrader: (5)

Update time again:

I got the adjustable lower control arms installed. Measured, and remeasured to ensure the axle is square in the body, and I am confident it is now. I measured each tube by the lower control arm brackets to a center point up on the k member. Then I used a self leveling laser to measure where the axle is in relation to the front tires. Pretty neat trick I learned on here - they called it poor man's alignment or some damn thing..

anyways, the car is now back together. I am just waiting for some good weather to put the battery in it and take it for a rip.

The engine ended up being 2.6 degrees down, the driveshaft is 1 degree up, and rear end is 1.6 degrees down: this is as you are looking at the car from the drivers side, going from front to rear of car. This leaves me with a negative 1 degree pinion angle. I didn't feel I needed any more as all of my suspension components are poly and very stiff.

Just for my knowledge I also measured the driveshaft to see how much higher the rear of the drive shaft is than the front. If you again look at it from the drivers side, the front of the shaft is 22" from the ground. The rear of the shaft is 22 3/4" from the ground. So over a run of 34", the driveshaft slopes up only 3/4 of an inch. Not sure if this makes any difference, but now I know.

The pan hard bar is now .6 degrees down sloping towards passenger side of the car.

trik396

iTrader: (4)

It might be. I would contact Strange directly. They were very helpful and it didn't cost me a dime. It's been quite a few years. The only way to know is to contact them because if you have one that was machined incorrectly, you are never going to get rid of the vibration

FirebirdStud

iTrader: (5)

great, thank you for the info. I will search to see if I can find what you are talking about so I can talk to them intelligently.

trik396

iTrader: (4)

I searched and I couldn't find the thread I thought it was in.... pretty sure I started the discussion OR i just added info to an ongoing discussion

There has got to be others here who had the same situation because I remember the girl at Strange telling me how much money it was costing them to replace all the yokes.....

FirebirdStud

iTrader: (5)

Now that I am just waiting for weather, I started playing around with Spicer's Angle Finder..

https://spicerparts.com/calculators/...gle-calculator

Looks like the front operating angle is 3.6 degrees, and the rear operating angle is 2.6
I read somewhere that any angle over 3 degrees is going to give you heartburn. Looks like I am stuck with this.. there isn't any way to make the engine sit more horizontal in the chassis without seriously cutting **** up.

Any ideas? or will 3.6 degrees be ok?

To be fair, I calculated the angles as it was pre me spending a metric fuckton of money this fall on all these adjustable pieces to make it more gooder, and the front operating angle was 4.5 and rear operating angle was 3.5.

FirebirdStud

iTrader: (5)

I just completed some more research.

@trik396 I did a bunch of research around the Strange yoke problem. If I understand you correctly, you are talking about the driveshaft yoke, right? If so, that wouldn't apply to me, as I have a Tick Performance Viper mainshaft conversion, so bigger splines and a bigger hole in the trans output bushing. I now have a Sonnax billet yoke on my Strange driveshaft. If you are talking about the yoke on the rear end, then I didn't find much on that, and I would appreciate some help with the research on that..

I looked at some people saying that Strange driveshafts are too short (I bought their chrome moly DS when I bought their rear). My output shaft seal on the trans has a dust cover. I measured my yoke to output on the trans.. the dust seal is about 1 inch protrusion from the output housing. The yoke has just less than a 1/2" left before it grows bigger for the u joints. So, my yoke sticks out about 1 1/2" from the output housing. I couldn't possibly have a longer shaft without the yoke eating the **** out of the dust boot on the output seal of the trans.

I also found that most people do not like measuring the rear end angle at the Sphon torque arm bracket. I measured my car using the torque arm bracket, and it is exactly 1.6 degrees. I measuring using the u joint cap method, again 1.6 degrees. So on my car, both are exactly the same.

FirebirdStud

iTrader: (5)

I finally caught a break in the weather - I took it out and drove it.

Not fixed. All of this work I have done, and I still have the same problem. Uuuuggghhhhhh

I tried to understand the vibration:
kicks in around 70 miles per hour. 5th or 6th gear. Definitely a lot worse on de-acceleration. Present in acceleration as well, and at an even speed.
I can hear the noise, not just feel it.

What ideas are left?