Will someone mark these pictures to show me how to measure pinion angles?

[XH29N0G]

I have attached two pictures.  I can measure the angle on the drive shaft easily (it sits exactly flat - 0 degrees).  I think the transmission is pointing down by about 3 degrees and the differential is pointing down by about 3 degrees, but I do not know where to get an exact measurement because both do not have flat surfaces to measure from (the bottom of the differential has a slight curve to it.

It would help me to see marks on the pictures about exactly what people measure to do this correctly.

Thanks in advance.

[flyinlow]

Mopar had special tools to measure this. I have never seen anything but pictures of them.

You know how to measure the driveshaft. I use the engine oil pan rail on BB's for the tail shaft. Should be parallel. I remove the driveshaft and measure across the companion flange screw holes ,from one u joint cap leg to the opposite side. Do both ways and see if they agree. The picture I drew on is not the way I do it. I was just marking the approximate surface I use. This requires rotating the angle meter ,don't get confused.  There might be better ways.   

[flyinlow]

What transmission?

[MSRacing89]

Front

[MSRacing89]

Rear.

Now I did some forensics on your photos and came up with the angles you see on the attachments.  I see a bit of an issue with your front working angle which appears to be around 5º.  This could produce some premature wear on the u-joints and a possible vibration at highway speeds.  Everything else looks to be in pretty good shape.  Obviously you can verify and let us know.

[XH29N0G]

What transmission?

Tremec TKO 600

Rear.

Now I did some forensics on your photos and came up with the angles you see on the attachments.  I see a bit of an issue with your front working angle which appears to be around 5º.  This could produce some premature wear on the u-joints and a possible vibration at highway speeds.  Everything else looks to be in pretty good shape.  Obviously you can verify and let us know.

I did not see the attachments.  I am having slight vibration at 70 mph. The transmission and driveshaft are newly installed/adapted.  The rear axle was also off during restoration.  I read somewhere that there can be issues with the transmission angle related to spacers and this is what I would like to measure.  I had not thought of using the flats on the u-joints as a reference (Thanks flyinlow).  I will do my best tonight to measure these now directly on the car and post to see if they sound OK.

Thanks for all the help.

[ottawamerc]

Also I noticed your drive shaft might be a tad too long? you should be able to bottom it out then pull it back about 1" - 1 1/2" into the rear yoke.

Scott

[XH29N0G]

Also I noticed your drive shaft might be a tad too long? you should be able to bottom it out then pull it back about 1" - 1 1/2" into the rear yoke.

Scott

Let's see if I understand correctly,  You mean the yoke into the transmission should be out of the transmission by about 1/2 to 1"  The yoke in the differential is bolted in place, right.  The yoke in the transmission sticks out 1/2 and 1", but without taking the driveshaft off, I cannot be sure that this represents the play you describe that is wanted.


As for the measurements, my most recent ones indicate that the transmission to driveshaft is with the angle opening upward about 4 (maybe 5) degrees off 180 degrees (like MSRacing89 noted), the driveshaft is pretty close to flat with respect to the ground, and the driveshaft to differential is with the angle opening upward about 3 degrees off 180 degrees.  So it is making a U shape.

Some questions:

Is a U-shape OK? 

If the angle is too large for the trans-driveshaft U joint, how would this be corrected - By raising the tailshaft of the transmission with a spacer?

I am chasing down a slight vibration, would it be best to get the new and balanced driveshaft rebalanced before seeing if the source is too large an angle with for the front U joint?

Thanks,

James

[ACUDANUT]

Also I noticed your drive shaft might be a tad too long? you should be able to bottom it out then pull it back about 1" - 1 1/2" into the rear yoke.

Scott

Agree. But I also can't see the front, where the shaft going into the transmission. The rear looks fine.

[MSRacing89]

The attachments are there on my posts.  They are PDF's. 

If you notice by the angles I took your front working angle is up around 5º.  This could be the source of your vibration.  You want to try and keep that working angle under 3º.  The trans may need to come up slightly to minimize this angle.

[XH29N0G]

The attachments are there on my posts.  They are PDF's. 

If you notice by the angles I took your front working angle is up around 5º.  This could be the source of your vibration.  You want to try and keep that working angle under 3º.  The trans may need to come up slightly to minimize this angle.

I see   

Thank you.  The pdf images and explanations are a big help.  Bringing the trans up will be a matter of spacers with the rear cross member/trans support, Right?

[MSRacing89]

The attachments are there on my posts.  They are PDF's. 

If you notice by the angles I took your front working angle is up around 5º.  This could be the source of your vibration.  You want to try and keep that working angle under 3º.  The trans may need to come up slightly to minimize this angle.

I see   

Thank you.  The pdf images and explanations are a big help.  Bringing the trans up will be a matter of spacers with the rear cross member/trans support, Right?

You may just be able to bring it up by spacing between the trans and trans mount.

[flyinlow]

.  Bringing the trans up will be a matter of spacers with the rear cross member/trans support, Right?

Yes if you have the room. Moving the tail shaft up will of course change the angles at the back, so recheck those.

If I understand It:

In a perfect word the driveline angles would be zero under load with the driveshaft only flexing for suspension movement for road conditions. I don't have that.
The next best choice is tailshaft and pinion parallel . I don't have this either.
What I ended up with is an OD trans as high as I can get it, almost touching the tunnel  and a small front angle ( 2* the wrong way for parallel tailshaft/pinion). The rear angle I shimmed to get 4-5* driveshaft /pinion angle static. The rear angle reduces under load as the pinion raises. Under high loads it might go past zero angle which in my case would help get the tailshaft/pinion closer to parallel , but will make the u-joints flex more under high torque loads.

Your front angle dose not compliment your rear angle. So the drive shaft would have to speedup and slowdown as it rotates. This can cause vibration. Raising the trans with spacers and reducing the front angle might help.

[XH29N0G]

Thanks.  This is very informative, and I find a lot of these things unintuitive so having them spelled out this way really helps. 

The next three questions relate spacers.  I took a look under the transmission at the transmission mount.  It is the red block in the two pictures I have attached. 

Is there any specific place I go to buy spacers? 

Do the spacers mount between the transmission and the mount (above the mount like in top image) or between the mount and the crossmember (below the mount - bottom image).  It looks to me like there is one above the mount and this is where I should put it, but I thought I would ask. 

Finally, is there a straightforward way to estimate how thick a spacer is needed to change the angle from 4-5 degrees to something more reasonable?

[flyinlow]

Yea ,sometimes I think Voodoo would help ,working with driveline set up. I got mine where there is no vibration or wheel hop and the u joint life is good, so I must be in the ballpark.

Factory shims looked like 1/8 stock about 1" wide by 1.5" long with a 1/2" hole.

I would vote for above the mount.

I added 1/4" to mine(a518, 3.5" longer than 727TF) changed a couple degrees or so ,its been awhile.