Vibration over 40 mph.

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Clelan

Clelan

Inferno Red Duster
FABO Gold Member
Joined
May 11, 2006
Messages
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Location
Martensville Sask. Can.
The patient:
74 Duster
360/A-500 (fresh rebuild)/8 1/4
TCI flex plate
Neutral balance stock truck convertor.
Slip yoke from a C body 727
New driveshaft built by a reputable shop 53.5" (high speed balanced)
1310 to 7260 conversion u joints.

The problem:
Vibration over 40 mph. Regardless of OD on or off, vibration is the same.

It rode nice and smooth last season with the A-998 but the trans shifted bad so I convinced myslf to rebuild and install an A-500. The driveshaft ended up 7" shorter. I installed the trans with the output shaft centerline at exactly the same height as the 998, just 7" back.
When I measured the driveshaft, I bottomed the slip yoke out on the transmission and pulled it back 1".
It is up on stands now and the u joints are tight. The only movement I can feel is less than a 16th" (guessing) at the slip yoke.
Below is a pic of the angle measurements I got with the Tremec App. It looks to me like these angles are too close to the same and when torque is applied causing the pinion to raise, that causes my vibration.
Am I on the right track?
Cley
Screenshot_20180503-112314.png
 
U changed the angle with the 7 in longer tranny. R both those angles up? As in positive. If tranny is up 2.3. I like 4-5 degree’s difference. Diff needs to be down 2.3-3.00. Kim
 
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You mentioned you have a 360 and are using a neutral balanced converter. Has your 360 been internally balanced or is the TCI plate one of the ones that is designed to balance a 360 as they are internally balanced engines
 
fishy68 said:
You mentioned you have a 360 and are using a neutral balanced converter. Has your 360 been internally balanced or is the TCI plate one of the ones that is designed to balance a 360 as they are internally balanced engines
Click to expand...

360 are externally balanced.
 
I have the correct flex plate for the 360 and a neutral balanced convertor. It was used with an A-998 and neutral balance convertor to I'm sure it is right.
Cley
 
In a correction of what I said earlier, it' a B&M flex plate but the 10239 number is correct. I installed wedges for 2 degrees pinion down from where it was. It's different but not good. Today I will get the tires balanced to eliminate that as an issue and measure my angles with a protractor instead of the Tremec App.
Cley
 
89on35s said:
In a correction of what I said earlier, it' a B&M flex plate but the 10239 number is correct. I installed wedges for 2 degrees pinion down from where it was. It's different but not good. Today I will get the tires balanced to eliminate that as an issue and measure my angles with a protractor instead of the Tremec App.
Cley
Click to expand...
Also tried rotating your tires also from front to back and see if the vibration moves? But yeah I was going towards that wedge you were talking about.
 
I just test drove it again. The wedge made it way worse on acceleration. I guess I'm starting from scratch!
Cley
 
No I don't. The more I figure on this, the more I convince myself it' in the driveline. I was driving it today and it was vibrating mildly at 60 mph cruise. I got the OD on switch, the rpm dropped to 2000 and the vibration stayed constant. Going to remeasure angles now. My "honey do" list is done.
Cley
 
89on35s said:
No I don't. The more I figure on this, the more I convince myself it' in the driveline. I was driving it today and it was vibrating mildly at 60 mph cruise. I got the OD on switch, the rpm dropped to 2000 and the vibration stayed constant. Going to remeasure angles now. My "honey do" list is done.
Cley
Click to expand...

A couple of things.
No one mentioned if the car vibrates at that RPM without rolling, but from what you say in your posts I think you would realize that and what it means.
The other thing is that I paid a "race" shop to balance my driveline to the tune of 150 bucks and it was still out of balance.

I ended up wanting to prove it, so I marked the driveline in quarters on the trans end and numbered the marks 1-2-3-4.
I put a 3" hose clamp around the driveline at the trans end (because that was where it felt like it was) and aligned the screw of the clamp with line #1
Tested on stands and worked my way around the driveline to each line.

When the screw ended up on line #3 it was WAY smoother, so that not only proved it was the driveline, but proved at which end and where it was lacking balance weight.

I did move to line #4 after that but the vibration came back, so I moved it back to line #3.
 
Ok. I should have never even used the Tremec App because I really didn't understand what it was telling me anyway. Here are my u joint angle measurements as I just measured them.
20180504_130549.jpg

I took the driveshaft off to measure the diff end and the trans end. Ignore the 3.2 number. It measures 4 deg. down at the pinion after I added my 2 deg. Shim. Where do I go from here?
Cley
 
89on35s said:
Ok. I should have never even used the Tremec App because I really didn't understand what it was telling me anyway. Here are my u joint angle measurements as I just measured them.
View attachment 1715172116
I took the driveshaft off to measure the diff end and the trans end. Ignore the 3.2 number. It measures 4 deg. down at the pinion after I added my 2 deg. Shim. Where do I go from here?
Cley
Click to expand...

The trans and pinion angles should be about the same.
I know people say you should make the pinion angle compensate for being loaded, but in a driver car there just isn't enough load to change it much in normal driving.

Your Ujoint crosses are in line with each other, right?

You can also try swapping your front yoke 180, as it CAN make a difference if it was originally assembled and balanced one way and someone changed the ujoint without putting the yoke back the same way.
They were originally built and balance with the yoke in that ONE position, and putting one back on 180 off from that can and will cause balance issue's.
 
If you mean side to side, yes my u joints are in line as far as I can tell. I'l take a closer look at that.
Cley
 
89on35s said:
Ok. I should have never even used the Tremec App because I really didn't understand what it was telling me anyway. Here are my u joint angle measurements as I just measured them.
View attachment 1715172116
I took the driveshaft off to measure the diff end and the trans end. Ignore the 3.2 number. It measures 4 deg. down at the pinion after I added my 2 deg. Shim. Where do I go from here?
Cley
Click to expand...


you should be close on the angles.how bad is the vibration?if it gets worse with speed,its drive line related.
 
I removed the shims and got back to 2.3 degrees up on the trans and 2 degrees down on the pinion which is the same as before I started with this whole adventure. These are real measurements with a protractor, no app. I believe @TrailBeast had the solution in the side to side alignment of the trans and pinion. It took a little doin' but I slid the slip yoke over about a 1/2 inch with a modification to my trans cross member and mount. If I make another one it won't be so damn tight. I had to get a sturdy pry bar in there and pry the transmission over and snug down the trans mount bolts to hold it. With that done, I reinstalled the driveshaft and took it for a drive.

Like magic! Vibration was gone. I drove it about 25 miles and by the time I got home, the vibration was back as before, so I think likely the trans slid back to it's previous misaligned spot on the trans mount. Obviously there is too much torque trying to keep it in the misaligned spot so I'll have to maybe loosen the motor mounts, line everything up and tighten it all back down. I even thought I may have to add some shims to the motor mounts at the block mounting ears if necessary. Has anyone ever had to do this? My only assumption is that with the 998 in there and a 7" longer driveshaft, it was not enough angle to cause issue.

Cley
 
fishy68 said:
Yeah I meant externally. If you read my first part you'll notice I asked if it had been internally balanced meaning they are originally externally balanced. Goofed up the last sentence. Shouldn't answer things when I'm half asleep, lol
Click to expand...

If it is internally balanced the balancer will look like a 318 or a 340 balancer.

If it is externally balanced the harmonic balancer will look like it is out of balance because they have cast it differently. like a part of it is missing.
 
Jadaharabi said:
If it is internally balanced the balancer will look like a 318 or a 340 balancer.

If it is externally balanced the harmonic balancer will look like it is out of balance because they have cast it differently. like a part of it is missing.
Click to expand...
The early 360 balancers had an extra piece cast onto them to balance them. Around 74 they changed the balancer design to the cut out like you described
 
fishy68 said:
The early 360 balancers had an extra piece cast onto them to balance them. Around 74 they changed the balancer design to the cut out like you described
Click to expand...

Was the balancer smooth like a 318 and 340 or was it like the 360s?
 
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Well, I got to drive the car about 100 miles this weekend, combination city, highway and a burn out! It is smooth as silk. I guess my problem was the horizontal alignment all the time. I ended up moving it 1/2" towards the passenger side at the trans mounting bolts. Thanks for all the help everyone! And thanks to @oldkimmer for calling me back. I really appreciate your advice. Now I just want to drive it!!!!!
Cley
 
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