Driveshaft Alignment

[JIMLAND]

Got the Coyote engine and TKO600 installed yesterday. Started connecting the driveshaft today and looks like FFR didn't supply me the correct bolts to connect the driveshaft to the manual driveshaft adapter. Manual says to use the bolts that came with the driveshaft but they are M12x1.5 bolts which are too big. Looks like I need M10x1.5 bolts and I didn't see any in the parts I got. Will call FFR in the morning to get this straightened out.

Have a question on driveshaft alignment. I have the IRS rear end so the only adjustment as I see it using spacers under the transmission mount. Here's what I'm seeing:



I assume that I should go with setting the driveshaft at 0 degrees which puts me using a 0.55" spacer. Does this sound/look right?

[JIMLAND]

I think I found the driveshaft bolts. I see now where I got 10 of them and I used 6 a month ago to bolt the adapter to the pinion so I have 4 left over which must be for the driveshaft. Duh!

Still looking for feedback on the driveshaft alignment.

[edwardb]

The two important measurements are the diff and the driveline (engine + trans). The 3/4-inch spacer gives you a -.5 degree pinion angle. For IRS that's fine. Don't get hung up on the driveshaft angle other than confirming your U-joint operating angles are within spec, which you easily are. FWIW, I have a 3/4-inch spacer in #8674 and have the same numbers. Runs/drives great.

[Murd]

Not an expert, especially for IRS but the important part is to get the pinion flange on the diff and the transmission at the same angle, 0deg difference. This keeps the universals in phase. Right now it looks like you are at .5deg with the .75 shim which is pretty close. The angle of the driveshaft doesn’t really matter.
Someone who knows more will chin in with a better explanation I’m sure.

[JIMLAND]

Okay, now I understand, thanks!

Another question, when I was putting in the M10 - 25mm bolts they felt like they were bottoming out before they tightened up against the pinion flange. Took some measurements and it looks like the hole in the adapters is 0.625" deep and the driveshaft flange is 0.335" deep so total of 0.960". Well the bolt is 25mm or 0.985" long so that explains it. This was without any washers which they don't talk about using but looks like I will need some. I checked a washer and it's 0.075" thick so the total depth would be 1.035" which will give me about 0.050" gap (1.035" - 0.985") which I assume will be okay? I'm suppose to torque to 80 ft-lbs so I assume bolt stretch at this torque level won't have it bottoming out??

[edwardb]

Another question, when I was putting in the M10 - 25mm bolts they felt like they were bottoming out before they tightened up against the pinion flange. Took some measurements and it looks like the hole in the adapters is 0.625" deep and the driveshaft flange is 0.335" deep so total of 0.960". Well the bolt is 25mm or 0.985" long so that explains it. This was without any washers which they don't talk about using but looks like I will need some. I checked a washer and it's 0.075" thick so the total depth would be 1.035" which will give me about 0.050" gap (1.035" - 0.985") which I assume will be okay? I'm suppose to torque to 80 ft-lbs so I assume bolt stretch at this torque level won't have it bottoming out??

Strange. M10 - 25mm bolts are the right ones for the driveshaft attachment. Must be some variation in which adapter you have? Just a guess. I understand they're different depending on whether an aluminum case diff (Mustang automatic trans) or iron case (manual trans). Mine (iron case) measures 1.178 deep including the pinion flange (just checked) which easily clears the 25mm bolts. For your situation, I'd be inclined to trim a little off the bolts rather than add washers. Wouldn't take much. At least on mine, there's a countersink on the pinion flange that the bolt head just fits into. Would take a pretty small washer to fit properly. Whatever stretch the bolt might have when torqued doesn't change anything as long as it doesn't bottom out.

[CraigS]

If you do elect to go w/ washers be sure they are hardened. However, because of the countersink EdwardB points out, I agree, I'd grind off a little from the end of the bolt.

[JIMLAND]

I have a manual transmission (TKO600) connecting to a 3.73 Torsen Diff. FFR provided me the yellow zinc adapter.



Here is a side picture of the adapter bolted and torqued to the pinion flange. The thickness of the adapter is about 0.6 inches but I see there is an air gap you can see thru the slotted holes on the pinion flange. I believe the adapter is sitting hard against the internal lip of the pinion flange. Is this air gap normal?



Here is a zoomed in picture of one of the 4 holes in the adapter where the driveshaft bolt to it. You can see at the bottom of the hole the internal lip of the pinion flange that the adapter sits on. This lip is where the bolts are bottoming out on.



Here is a picture of the driveshaft flange. The thickness is about 0.335 inches. So with the adapter hole depth of 0.625 inches and thickness of the driveshaft flange of 0.335 inches, this is less than the 25MM bolt length.



I think I might pull off the adapter to see if can see anything funny.

[edwardb]

Well, there's the difference. My Factory Five supplied driveshaft has a Sonnax aluminum yoke. Measures .529 thick at the mounting bolt, minus a little because of the countersink. Your steel yoke at .335 is much thinner. Also doesn't have a countersink like mine. I don't think there's anything wrong with what you have. Just a variation, for whatever reason, in parts supplied. So a hardened washer could work. Or just trim the existing bolts.

My driveshaft adapter is identical to yours and also shows the same gap as yours. I don't believe there's any issue there.

[JIMLAND]

Well, there's the difference. My Factory Five supplied driveshaft has a Sonnax aluminum yoke. Measures .529 thick at the mounting bolt, minus a little because of the countersink. Your steel yoke at .335 is much thinner. Also doesn't have a countersink like mine. I don't think there's anything wrong with what you have. Just a variation, for whatever reason, in parts supplied. So a hardened washer could work. Or just trim the existing bolts.

My driveshaft adapter is identical to yours and also shows the same gap as yours. I don't believe there's any issue there.

I thought it might be a difference in the thickness of the driveshaft flange because my driveshaft was one of the last parts I received on backorder and maybe it came from an alternate supplier. The yokes on my driveshaft are steel and the one on the differential end is a Dana Spicer C3-2-531. Now I feel better knowing the reason for the problem and I think I'm going to go with hardened washers. Thanks!!!

[Fixit]

This is one of simplest and best explanations of driveline angles & U-joint phasing I've seen...
https://youtu.be/Idk3BVDVHq4

Another very good write-up
http://www.northstarchevelles.com/No...elineAlign.pdf

[Avalanche325]

You want the angle at the diff and the transmission to be the same. The driveshaft exact angle is not that important. However, too much angle is a bad thing. I chased a lift off throttle vibration for months. I had lowered my ride height (going for traction during autocross). The diff and trans angle were perfect relative to each other and I did not have any binding at the U-joints. However, the driveshaft angle must have been too severe. Another 1/4" spacer and a little more ride height and it was cured.

[CNIdog]

Another video about phase of the u-joints: https://www.youtube.com/watch?v=dt69zYAcXME

[boat737]

And for those of you who want to really trick out your trans... https://www.youtube.com/watch?v=my6ZjfNpVQE