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Discussion Starter · #1 ·
Hey there all.

I thought I would post something up on here to get the insight of the great forum.

I just got finished with a T56 install on a friends car and I did all of the precursor measurements of the pinion angle, driveshaft angle, output shaft angle, distance from floor measurement, but something is a miss. The owner of the car needed to take the rearend with him to get it regeared when he dropped the car off so that could be another factor.

Now on with the measurements, I went through everything that I had written down before I dismantled the car and everything as far as angles and what not, falls into what it should be before and after. But it doesn't meet the specifications that are listed in the FSM, the pinion is fine where as the rear u joint angle, as the FSM states, comes in at -2.5 degrees which is well within the called out 2.6 + or - .3, but the front u joint angle is falling in out of spec. When measuring the output of the trans it is at -5.0 degrees and the driveshaft is at -2.5, giving me a front u joint angle of 2.5, which is way off from the factory spec of 1.3. I guess that I don't know what I am doing wrong here, I have measured it at least 10 times now. When I started I had left the rear control arm loose, but since then I have tightened them down with the pinion set at 0 degrees, which is the most that I can get out of it.

Now with that being said I did use the vibratesoftware tool that was posted in a previous thread, by JonRobbin I do believe, and it says that it is within spec, but the nose of the rearend could come up a bit, .8 of a degree. Which one should I follow? What are the measurements that you guys have seen on the front u joint? I am planning on doing all the measurements again once I get the Denny's driveshaft as it will be a new starting point and a fresh surface to get angles from.

Any thoughts that you all may have that you would think would help, would be much appreciated. Thanks in advance.
 

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Mike:

the -5 sounds right for the front. did you use any shims (same as with auto) and is the new tranny mount the same thickness as the one that was removed?

didn't you also replace rear springs?

IIRC my front angle is 1 - 1.2
 

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Ok, here is my two bits.

Unless you are scratch building the car , you are stuck with many of the numbers.

If you have the transmission as high as you can without doing any more floor mods then you are stuck with the crank angle too.

If you are keeping your ride height the same, more numbers set in stone.

This leaves the pinion angle as the only thing you can change.

At ride height put a angle finder (digital level better) on the crank pulley
Record the number.

Put it on the pinion flange, adjust the upper arms till the number is the same.

Now your crank and pinion are parallel , LIKE MAGIC , your front and rear pinion angle will be equal.

If you have soft bushings in the rear or big power sure you might bring the nose done a bit , but most peoples foray into pinion angles is in a quest to remove steady state vibration.

Getting the crank and pinion angles the same is the place , IMHO, to start.

The driveshaft angles, you are stuck with unless you are going to change the actual height of the engine or pinion.
 

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Discussion Starter · #4 ·
Hey Roger,

When I installed the trans with the mount supplied with the Bowtie X member it was too low, as per the measurement that I took before I disassembled it, also there were no shims in the original trans. So I purchased an energy suspension mount and installed and it looked like it came right in as far as angle. but when measuring and having everything completely installed I found it to be off a smidge, so I added a shim to bring it to -5.0 degrees.

As far as rear springs yes, I did replace them, but they are new factory B4U replacements, no change in the height at all, I did let them settle for a few days with full weight on the axle as well.
 

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Discussion Starter · #5 ·
Ok, here is my two bits.

Unless you are scratch building the car , you are stuck with many of the numbers.

If you have the transmission as high as you can without doing any more floor mods then you are stuck with the crank angle too.

If you are keeping your ride height the same, more numbers set in stone.

This leaves the pinion angle as the only thing you can change.

At ride height put a angle finder (digital level better) on the crank pulley
Record the number.

Put it on the pinion flange, adjust the upper arms till the number is the same.

Now your crank and pinion are parallel , LIKE MAGIC , your front and rear pinion angle will be equal.

If you have soft bushings in the rear or big power sure you might bring the nose done a bit , but most peoples foray into pinion angles is in a quest to remove steady state vibration.

Getting the crank and pinion angles the same is the place , IMHO, to start.

The driveshaft angles, you are stuck with unless you are going to change the actual height of the engine or pinion.
Thanks Gerry,

As far as getting the pinion and the crank to align it will be near impossible as it has factory arms for the uppers and lowers. when I put the rearend back with all the control arm bolts loose pinion as at +2.5 degrees or in other words, down. So I was able to rotate the assembly enough to get the pinion at dead zero. And I couldn't go any more. And really if IIRC the pinion was in a down position before I started. I don't have the sheet I wrote the numbers down in front of me. Also with the pinion angle software that I downloaded it stated that for high speed driveshafts the u joint working angles should be within .500 of a degree of each other, so 2.5 on the front and 2.5 on the back. I would think that this is correct, but it doesn't fall with what the FSM states.

I haven't driven the car yet, just doing precursor checks, I just want to make sure this is right as it would be a swift kick in the balls if it vibrates like a bastard when the owner drives it for the first time. :)
 

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Gerry

shouldn't the angles between rear & front NOT be =??

Mike

did you try and add a 2nd shim under tranny mount?

factory came with 2 ....which is what I wound up with

also without over analizeing this...take the car for a drive to see if you have any vibes...
 

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Discussion Starter · #7 ·
Yeah that is what I was planning on doing, I would add another shim, but it is getting pretty tight against the firewall, I am going to wait for the Denny's drive shaft to get here and see what happens then, I just wanted to make sure all was good so I didn't have to go back into it. IT should be here next week so I will advise, I guess I just posted this up to see what everyone else had seen when checking the angles. Thanks for the help.
 

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One of countless sights
http://www.markwilliams.com/driveshafttech.aspx

As you know the driveshaft running at an angle to the crank shaft (u joint angle) actually speeds up and slows down as it rotates. be keeping the angle at the other end the same this phenomena is canceled out.

Like I said, if the pinion and crank are parallel, the front and rear u joints are automatically at the same angle. The actual angle is governed by the difference of the crank to ground and pinion to ground.

As for stock arms and pinion lightly push up with a jack on the yoke while doing up the hardware to raise the nose as much as possible.
Next step would be slot the uppers and weld washers in to change the angle.

Back to the original question. All you can do is cram the trans as high as you can, and then try and get the pinion yoke as high as you can.

It is my experience that must T56 "B" bodies have the trans down as it takes a bunch of work in the tunnel to get it up to at least stock 4L60E height.
 

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Discussion Starter · #9 ·
Thanks for the info Gerry, as always a plethora of knowledge. As far as the pinion I did just that, with a jack on the forward nose of the pumpkin jacked it up and tightened all the fasteners.

As far as the trans it is about a finger width from touching the body right now. I am going to wait for the new driveshaft and measure again, I am also going to toss my angle finder and get a new one and see what it says. I Will advise on what I find when I drive it, I think that it is almost right. But we will see. On another note didn't you modify your tunnel in your car?
 

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Gerry, this may be outdated information but they used to not want the angles to be equal so that you would get some rotation of the u-joint which would make them last longer. Is this still true?
 

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I do know people stress the U joint angles should not be zero for that reason. That being said with the unequal length control arms and resulting pinion angle change, no matter if you were able to set the drive line angles ALL to zero , they are only going to be that at one exact ride height anyway. So at that you are going to see a different front and rear angle at times no matter how close you are at rest. Personally I will continue to try and have the pinion and crank as close to the same angle as I can and if possible, the ujoint angles equal and as low as I can .
Then again, I'm the guy currently running around with a stock driveshaft and 4.56 gears :)
 

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I do know people stress the U joint angles should not be zero for that reason. That being said with the unequal length control arms and resulting pinion angle change, no matter if you were able to set the drive line angles ALL to zero , they are only going to be that at one exact ride height anyway. So at that you are going to see a different front and rear angle at times no matter how close you are at rest. Personally I will continue to try and have the pinion and crank as close to the same angle as I can and if possible, the ujoint angles equal and as low as I can .
Then again, I'm the guy currently running around with a stock driveshaft and 4.56 gears :)
Gerry, don't feel like the Lone Ranger! I'm running 4.56 gears, stock driveshaft and original u-joints (175,000 miles). I just put my t56 as high as I could and hoped for the best. So far, so good!
 

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You can also measure the engine angle via the LT1 intake manifold - the top of the manifold is parallel with the crankshaft.

The bottom of the 4l60E pan and the pan rail is actually tilted downward in the front 5 degrees. Don't know if the T56 is the same way.

Gerry is right - the only adjustment you really have is the trans mount and the slop in the rear control arm bushings.
 

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Discussion Starter · #14 · (Edited)
Thanks guys I knew from previous experience about all that was said above. Good information on the stock driveshaft and 4.56's, maybe we found an answer to the elusive vibration, it all makes sense for sure.

I did however throw some numbers in that cool little trial tool that I downloaded, I think that it works on the working angles of the ujoints being within .500 of each other, as stated above and pretty much as Gerry has stated before which makes a hell of a lot of sense for sure. With that being said, even though the trans centerline and the rear centerline don't match in this current setup, the ujoint working angle factor is perfect, as per the tool. It still brings in to light that the FSM degrees that are relative can't be used in this conversion, for obvious reasons, as the T56 can't be pushed up as high as the 4L60 without floor panel modification's. I guess that it can throw another factor in there as well, I measure from the bottom of the output shaft of the 4L60 to the floor before yanking it out and after installing the T56 I did the same measurement and it came out perfect, only with the use of an energy suspension mount as the Bowtie X mount smooshes down too much. With that being said how can the front angle be different that it was before I installed the trans? I don't know, bunch of theories out there that is for sure on why, I can see the floor pan being one of those things that should be contended with. Also this makes me wonder as well, let's say you have a stock car with a 4L60 in it and you want to put in 4.56's, being that the u joint working angles from the factory weren't really equal or right, I am curious to see if you raise the trans to the point where the output angle matches the pinion angle and see if it vibrates. Very curious on that one.

I have a couple stock driveshafts in my shop, one was recently balanced, maybe if the Denny's unit takes too long I Will use that one and go for a drive and see what I come up with.

Thanks again for the information on this, just more sh$% to put in my storage cabinet in my head. And hopefully by me putting the title as I did, if someone has a problem they can use the search button and it will come up for them :)

Oh on another note, the vibration in my car even with a Denny's driveshaft isn't completely gone that is for sure. More good information that I thought I was doing right when I did my installation years ago now, I do have adjust uppers on my car, maybe I can get the angles just right finally and throw the GOD DAMN vibration out the window in my car. :)
 

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Oh on another note, the vibration in my car even with a Denny's driveshaft isn't completely gone that is for sure. More good information that I thought I was doing right when I did my installation years ago now, I do have adjust uppers on my car, maybe I can get the angles just right finally and throw the GOD DAMN vibration out the window in my car. :)
"adjustable uppers"....I suspect that you need adjustment in those to eliminate your vibe

FWIW with 2 shims under my tranny mount I have 3/8-1/2" +/- between tranny & tunnel. Enough room to add a 3rd if I needed.

Interesting notes on getting the T56 "high"...like you my measurement from rear of 4L60E & T56 are the same (measured from floor during swap) so that angle remained the same. I do have stock/original springs with Hotchkis upper/lower (stock fixed length) control arm which were on the car prior to T56 swap. So my only potential DL angle change would have been the tranny itself. I first used 1 shim and had a vibe....added a 2nd (which was on the car stock) and it cleared up and by measurement of DL angles did bring it back within FSM spec.

I have the $4 cheap angle finder which is hard to read...so a better tool (digital) when measureing within +/- 1 degree would be better.
 

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Just curious... Please post your angle on the intake manifold with you car on level ground. Mine is 4 degrees down (using my cheapo tool).
 

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Discussion Starter · #17 · (Edited)
I will post what I have, but looking through the pictures that I took from my car when I did it the intake was 4 degrees, now I did look through the notes that I took before removing the trans from the car I am working on now and the 4L60 was 4 degrees on the money and the T56 is at 4.5 right now, I re measured it last night. With a driveshaft angle of -2.8 and the pinion rested out at +.5 as it sits right now. so the ujoint angle on the front is 1.7 and the ujoint angle for the rear is 3.3, which is out of spec. I will try to tinker with it some more and see what I can come up with. I Would like to get it at least to factory spec. Maybe I will jack my car up and get underneath and see what I can come up with on that one, as I know it vibrates :)

I also went and bought a digital protractor as well, these problems can be on going so I hope that I figure something out that will benefit everyone doing these installations.
 

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Thanks, Mike. Roger, Gerry, Joel, do you happen to have your intake angle with your car on level ground?
 

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Discussion Starter · #19 ·
Sorry bud I fibbed a bit, here are some pics and I think it is the way my car is set up right now.
Intake

drive shaft

Pinion


As you can see by my measurements, I can see why my stuff is vibin a bit, these were taken sometime ago so it is hard to remember what it is actually at and I may have changed. Also you will notice that the measurements on my car are exactly the same as the one with factory control arms and factory B4U suspension, I am running Hotchkis on mine as well. Makes me want to go out and jack my car right now and see what it is;)

Also note and I am curious since I Am running poly bushings in my car, there will be limited axle wrap up, but with the car I am working on there maybe a .5 degree or so due to rubber bushings.

Just another factor, I will make some more measurements and see what I come up with.
 

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Intake angle on level ground , really doesn't do it unless you take into acount the frame to ground angle.
Case in point , my manifold is 2.9 degrees but know I have some rake in the frame.

I will try and get the frame angle tomorrow.
 
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