Case through bolts - o-ring deformation

[85RedCarrera]

So, I put my 3.2 case back together using (red) Viton o-rings on the through bolts…

The side of the case where the head of the through bolts goes, does not have chamfered holes. The other side of the case where the nuts go has chamfered holes.

I installed the through bolts very carefully. The o-rings were lubed with Dow 55 and a thin piece of vinyl was wrapped around each threaded end when the o-rings were slipped over the bolts, so they wouldn’t get damaged.

The bolts were kept stable and did not rotate while being tightened & torqued.

After they were all torqued down, I can see a faint amount of flattened red o-ring barely emanating around the perimeter of at least half of the chamfered washers, where the o-ring is smashed between the unchamfered hole in the case and the chamfered washer….

I am concerned about this, but perhaps this is a normal deformation of the o-ring on this side of the bolt? Hard to believe, as I have never in my life installed an o-ring that was supposed to flatten out squeeze all the way to the edge of the washer.

Is this normal??

[stownsen914]

I posted above this same thing a few months ago. There were various opinions expressed but it's worth noting that leaking through bolts aren't a very common problem. Even though the o rings seem to get deformed. It was suggested to make sure the washers don't spin as you torque. I made sure to lube the face of the nuts to ease the tendency to spin. I did wind up chamfering the holes that weren't already chamfered.

Seeing an oring squeeze all the way past the washer would concern me too. Mine didn't squeeze out that much. Did the oring tear?

[mikedsilva]

Originally Posted by 85RedCarrera

After they were all torqued down, I can see a faint amount of flattened red o-ring barely emanating around the perimeter of at least half of the chamfered washers, where the o-ring is smashed between the unchamfered hole in the case and the chamfered washer….

I am concerned about this, but perhaps this is a normal deformation of the o-ring on this side of the bolt? Hard to believe, as I have never in my life installed an o-ring that was supposed to flatten out squeeze all the way to the edge of the washer.

Is this normal??

No.
This isn't normal.

Washers are bevelled on the inside so even if the case is not chamfered, the o rings should be contained inside the cavity of the washer chamfer.

Remove one of the washers that you can see the red? o-ring squished out, and take some photos for us here.

[85RedCarrera]

I must have allowed the bolt head to move during tightening...if I did, it was an not apparent to me. I'm guessing it doesn't take much movement at all to screw it up on the case side that has no chamfers, even when the 0-rings are lubed. Now I understand why people chamfer the side of the case that has no chamfers. Embarrassing, but perhaps this will help others to be more careful.

Makes me wonder if you are sometimes better off torquing the through studs with no o-rings, then come back and remove them one at a time and install the o-rings without the sealant clock ticking?

I'll take pics once removed- I don't want to de-torque anything right now, as I don't have replacement o-rings yet.

I went with the red Viton because our host was out of the green. They are special order and the wait is six days to ship, but I am going to wait on the green Viton rings and then replace them all, one bolt at a time.

Here's what they look like right now:

[mikedsilva]

dunno if this is of any help

[85RedCarrera]

Thanks Mike.

[Henry Schmidt]

Not all Viton is created equal. That is why we only use Green Viton o-rings from Wrightwood Racing.

[85RedCarrera]

Originally Posted by Henry Schmidt

Not all Viton is created equal. That is why we only use Green Viton o-rings from Wrightwood Racing.

Yeah, I couldn't get the green ones right away, and when the red ones showed up, they were a different texture than the green. I should have waited the extra week to get the green.... impatience certainly did not pay off this time.

[85RedCarrera]

Finally got the replacement green Viton o-rings. Pulled one through bolt at a time and replaced them. Took some pics of what I found. I used the same o-ring lubricant, the same techniques, and was just as careful to make sure that the chamfered washers didn’t turn.

Unlike the red Viton o-rings, the green o-rings did not squish out on the bolt head side when they were torqued…

I have no doubt that the green rings did deform as the torque squashed them flat, but I don’t think that they ‘exploded’ like the red ones.. I think that more of the green o-ring pushed its way into the bolt hole, where it belongs.

I can now see the value of having the remaining case holes chamfered. Next time!

Red Viton o-rings after torquing:




The green o-ring with bolt snugged up, then torqued.:

[proporsche]

I also only use the green Viton o rings plus my oldtimer-mentor showed me back in the 1980`s little trick.I punch 3x the inner side of the washer for the nut.This way when it meet the case it will not spin at all.....
Ivan

[85RedCarrera]

Originally Posted by proporsche

I also only use the green Viton o rings plus my oldtimer-mentor showed me back in the 1980`s little trick.I punch 3x the inner side of the washer for the nut.This way when it meet the case it will not spin at all.....
Ivan

That's a nifty trick...

[mikedsilva]

For what it's worth, if anything...
On the bolt side, the washer is installed with no fastener assembly lubricant.

On the dome nut side, the part of the washer that contacts the case is dry, but the contact area between the nut and the washer and of course the thread, is lubed.

When I do it this way, I find that when the nut is tightened down, as soon as the washer contacts the case, it stops rotating and only the dome nut is rotating (whilst of course holding the head of the bolt stationary).

Happy to be corrected or pointed toward a better way but so far this has worked well for me.

[85RedCarrera]

Originally Posted by mikedsilva

For what it's worth, if anything...
On the bolt side, the washer is installed with no fastener assembly lubricant.

On the dome nut side, the part of the washer that contacts the case is dry, but the contact area between the nut and the washer and of course the thread, is lubed.

When I do it this way, I find that when the nut is tightened down, as soon as the washer contacts the case, it stops rotating and only the dome nut is rotating (whilst of course holding the head of the bolt stationary).

Happy to be corrected or pointed toward a better way but so far this has worked well for me.

Yes, that is essentially what I did. Also- all of washers were marked when the nut was installed, to confirm that there was no rotation after tightening/torquing.

Now I can move on to the pistons & cylinders (again)!

[Jesse911]

I will be doing the same in a couple of weeks but is the general idea that it is best to chamfer the other half of the case also?

[85RedCarrera]

Hopefully a shop will chime in here, but it sounds like many of the shops are chamfering the other side of the case. I don't remember whether the older magnesium cases also had this problem, or whether they were already chamfered...