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Matt
draw us a picture of what you have..
is the trans up or down to the rear ?? is the pinion up or down to the front ??
use the bottom of the long flat frame rails as 0 ..
.
check the phase first..
make sure the DS is the same on both ends..
the pic is the WRONG way to do it..
drive-shaft-incorrecly-phased.jpg

I used my digital level against the face of the trans tail shaft, set zero.
Then set the pinion 3 degrees off of that.
i assume the 3 degrees is so that when you’re under load It runs parallel, correct?
not necessarily ..
it depends on what you got and where you start at..
.
heres a read, maybe it will clear some things up without a lot of typing...
DriveShaftAngles
 

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Matt
draw us a picture of what you have..
is the trans up or down to the rear ?? is the pinion up or down to the front ??
use the bottom of the long flat frame rails as 0 ..
.
check the phase first..
make sure the DS is the same on both ends..
the pic is the WRONG way to do it..
View attachment 127525


not necessarily ..
it depends on what you got and where you start at..
.
heres a read, maybe it will clear some things up without a lot of typing...
DriveShaftAngles
JJ remembers more than I forget!
 

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Discussion Starter #23
I have a free day tomorrow. I’m going to do some investigating and get back to you...

...But IIRC my trans yoke is pointed slightly downwards, and I set the parallel to that (up). Maybe I’ll remove the trans mount and belt it down so the trans line is horizontal. And I’m certain the driveshaft is in phase.

Tomorrow I’m going to find a safe place to put the rear end on jacks and get up to speed. Then we can narrow down wether it’s driveline, chassis, etc.
 

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Can you get it to shake just running the rear wheels off the ground with jack stands under the rear end?
 

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Discussion Starter #26
I’m confident I figured it out. Though, I think it’s a combination of things.

I put my car on jack stands and brought to speed which in my case is 60+, and it still shook. So I know it was in the driveline.
After much thought on the cars maintenance history, possible causes, etc, I decided to work back from the rear end.
I pulled off the wheels, put the lugs back on, same issues.
I pulled off the drums and bam, no shaking! Smooth as can be!
I’m sure my front wheels are out of wack too. When I drive really slow on a well paved surface, I can feel and see the front end bob up and down.
But anyways, I’m going to buy new drums and install them and I’ll report back in a few days! Amazing that a slight out of balance in the drum causes shaking that severe.
 

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Expensive discovery with all the previous work. Glad you got it figured out.😎🍺
Not too expensive. Remember, there was a combination of problems. And the experience will show up next time someone has a similar problem. And what is wrong with some new control arms and a properly adjusted pinion angle? Probably would have been needed anyway. Mine are worn out and squeaking, I've already got new arms here and never had a vibe problem! Bonus points! Just glad the problem has been solved. Looks like it's time to drop that new motor in!

Joe
 

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Discussion Starter #29
Not too expensive. Remember, there was a combination of problems. And the experience will show up next time someone has a similar problem. And what is wrong with some new control arms and a properly adjusted pinion angle? Probably would have been needed anyway. Mine are worn out and squeaking, I've already got new arms here and never had a vibe problem! Bonus points! Just glad the problem has been solved. Looks like it's time to drop that new motor in!

Joe
I agree.
Reality is, my pinion angles were bad and absolutely needed to be address, especially before dropping in the new motor with twice the hp & torque.

We’ll see in a few days if the new rotors clear up all the shaking. I’ll report back!
 

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It's great that you found the problem.
Never crossed my mind that drums could have caused it.

Any chance a factory balancing weight (.25"×.75"×1.25") (appx.) could have come off the drum? They may have been spot welded on.
Didn't some drums come with a "spring" wrapped around the circumference at the inside edge?
 

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Yes some had the spring. I still don't know what that was for.. You might have to go through four or five drums to find good ones. I had to on my 69 el Camino.. They also make real nice looking aluminum drums for the G and A body, Rock Auto has them. Some guys switch to the 11" drums..
 

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Greetings El Bambino, Have you replaced the drums/breaks? Test drove at high speeds? Sorry if I missed it. I hope that was the cause. Bright side is, everything is new now.....and as another member posted, hopefully it’ll help the next Elky with a similar issue.
 

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Discussion Starter #33
Hey fellas.

I replaced the drums yesterday with some Bendix ones from Summit. The new ones were counterweighted.
The drums I removed from the car were very very worn.
On top of that I did not see any counterweights like the new ones did, but I also didn't look for any signs that they had some to begin with.

Anyways, It cut the vibrations down by half or more.

I'm still feeling shakes but it's not nearly as harsh. And it's not traveling through the entire body of the car anymore. It's just in the front.

Now it's just the front end shaking...
...On the freeway in heavy traffic I can feel the front end bobbing up at down.
With the car off the ground, the front wheels are out of round by .100-.200 thousands.
This weekend I'll put a dial indicator on the rims to see if it's the rim. If so, I may try pulling them into shape myself before going to a shop.
I wonder if a portapower would do the trick? We'll see..
 
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