Reconstructing Constant Velocity (CV) Joints

[Westy]

I learn stuff here everyday, just not how to make my car run

[carnutzzz]

rcecale-

I might have seen your car a month or so ago in the Home Depot parking lot on Peachtree Dunwoody Road (next to Costco).

You ever over there?

It would be nice if all the ATL pelicans put pictures of their cars up- I see lots of older 911s running around and I always wonder if I they are pelicans...

[Zeke]

Well, Randy (with the axle, not Webb), you have your work cut out for you. You will have to be very careful to "chase" the threads in your hub before installing NEW bolts.

Be sure to buy a thread "chaser" and not a tap so you don't remove any more thread than what is damaged. Be very careful starting it in and you will save the hub. Otherwise, remove the hub and go in from the backside, which would be preferable for a shop with a lift anyway. And faster.

[Blanco]

Originally posted by carnutzzz
rcecale-

I might have seen your car a month or so ago in the Home Depot parking lot on Peachtree Dunwoody Road (next to Costco).

You ever over there?

It would be nice if all the ATL pelicans put pictures of their cars up- I see lots of older 911s running around and I always wonder if I they are pelicans...

I work in the Perimeter Center area and commute from Snellville.

We do have a list going for Atlanta Pelicanites that Blackbird started. We are notified of Atlanta events and gatherings. We should have sticker of sorts to identify our fellow brethern.

I might need rcecale expertise as my 915 is acting up.

[Rufblackbird]

Originally posted by pwd72s
Just want to thank all for a very informative thread.

no kidding...this page is getting bookmarked

[carnutzzz]

How do I get on the list?

Sorry about the hijack...

[Blanco]

Originally posted by carnutzzz
How do I get on the list?

Sorry about the hijack...

PM Sent.

[rcecale]

Carnutzz, I don't believe that was me at that particular Home Depot.

While I do tend to frequent that fine establishment, my trips are usually limited to either the Dallas Hwy HD or the Vinings HD, right next to their HQ (I work near there as well.)

I'm always on the look out for other P-cars. Had a nice little run with a C4S a few weeks ago down Atlanta Rd. Was pretty fun, to say the least.

It would be great to have some kind of sticker on our cars so we know at least can recognize a fellow Pelican. Maybe some secret hand-wave out the window or something.

Zeke, I have a new set of thread chasers I'll use to clean out my threads. Gonna order all new bolts from Pelican when I get home this evening. Following Grady's advice of installing the schnorr washers, even though the PET doesn't call for them. Couldn't hurt!!!

Randy

Randy

[Grady Clay]

Let me add some thoughts about the bolts (socket head cap
screws), washers and moon plates:

For a lock washer like the Schnorr washer to work there needs to
be a difference in hardness among the materials. The tin cover
that retains the CV boot is very soft plated steel that was easily
formed into its convoluted form.

The Schnorr washer is very hard spring steel. I think it is slightly
harder than the 12.9 bolts. These are alloy steel forged bolts
with rolled threads – about as strong as you can get.

I think the reason the moon plates and Schnorr washers were
left out of some models was a simple “how to reduce
manufacturing costs” decision. None of the bean counters
consulted the design engineers. The problem doesn’t show up
when PAG assembles everything with all new parts. When there
was a problem with a car that had been serviced, the blame fell
to the technician.

With no Schnorr washer or moon plate, the soft steel cover can
deform under the head of the bolt and eventually relieve the
clamping pressure. The same is true with just a Schnorr washer
under the bolt head because it has the same OD as the bolt
head.

The moon plates provide three functions: First they spread the
load so as to not deform the tin cover. Second they provide an
intermediate hardness material for the Schnorr washer to
properly bite into. Finally they connect two adjoining bolts to
prevent turning of a surface between the tin cover and the moon
plate.

The M10 moon plate I’m looking at is from a ’72-’73 and is 2.50
mm thickness. A well used M10 Schnorr washer measures a
nominal 1.0 mm. A new Schnorr washer measures about the
same. This is not measuring the conical spring effect as the
Schnorr washer becomes flat under the compression from the
bolt. The combination of adding a Schnorr washer and a moon
plate adds 3.5 mm to the required bolt length. The bolts have a
thread pitch of 1.5 mm/turn. This means that an existing bolt will
end up 2 1/3 turn less penetration in the flange. I measure
a ’69-’71 flange as having six turns of threads for the bolt to be
flush on the back side. If the bolt originally had little penetration
past flush of the flange this means the bolt could engage only
about half of the threads in the flange. I think that only three
threads will pull out. I prefer to see 1-2 threads penetration
with 1 ½ as the ideal.

The moon plates see some pretty significant deformation from the
teeth of the Schnorr washers and the clamping force of the bolt.
I may rethink reusing them more than twice. I would certainly
turn them over after the first use.

These 12.9 bolts are commercially available and from our host. In
the lengths we are talking about they usually come in 5 mm
increments of lengths. The Factory specified the exact length for
each application. I am measuring a Factory bolt at 52 mm. Any
competent machine shop can mount the bolt in a collet and cut it
to the desired length. You want to stress that there be
absolutely no damage to the threads or shank of the bolt.
Carefully dress the last thread toward the end for proper
starting.

If the threads in the flange need repair, a Helicoil is the best
product. The flange is easy to remove from the transmission.
The repair should be done on a mill to keep the threads in the
proper axis.

All this may seem like excessive attention to something as simple
as a few bolts. Randy is lucky he was practically stopped. I
have seen the situation where the loose inner CV took off the
starter motor along with some of the transmission case and
engine case, not to mention the exhaust system, cooler and
more.

Just remember that your life and that of your 911 depend on
these bolts proper functioning.





Best,
Grady

[rcecale]

Originally posted by Grady Clay
Randy is lucky he was practically stopped.

And even luckier to have your advice!

Took a few pics this evening after disconnecting both sides.







Figured since I had the rear-end raised, I might as well replace the cap screws on BOTH sides and to also include the schnorr washers in the stackup.

My guess is the cap screw on the right in pic 1 would be te last one to finally give way. Closer shots in pics 2 and 3 show the thread damage. I'll be running a thread chaser through the flanges just to make sure they aren't damaged.

Calling Pelican in the AM to get 12 cap screws and 12 schnorr washers on order. Also going to order #4 from the pic below. Seems to have come up missing. Must have fallen off when it all came apart.



I'll try for more pics tomorrow...in the day light.

Thanks again to everyone!

Randy

[Grady Clay]

Randy,

Good eyes.

Was there an end cap on one side and not the other? Look and see if the flange has the space cut for a gasket or is it flat?

I don’t think #4 – End Cap is a spare part although I may be wrong. I think it is installed on later 911s and is available only with a complete axle assembly or with the boot kit that includes a new CV and hardware. If it is a spare part, please post the part number.

What do you think the bent bolts hit?


You are welcome; however I should thank you and everyone else. This Forum gives me a reason to get up every morning. I’m getting very tired of doctors. The latest is a little spot on the inside of my left ring finger is melanoma (now surgically removed.) Now come all the tests to see if there is metastatic melanoma. Ugh.

Best,
Grady

[rcecale]

Argh, I feel for you, Grady! Hope they return a clean bull of health. I just had a carcinoma removed a few weeks ago. Not something to mess with, that's for sure!

Here's a bit more info on the car...

It was the driver's side shaft that came off. The passenger side was still intact; all 6 bolts still tightened down.

As far as the end cap goes. I seem recall that both sides had them when I removed my tranny last year. Currently, the passenger side still has the cap attached.

The driver's side end-cap is not to be found. Looking at the end of the shaft, all I can see is a lot of grease....black grease! The 6 cap screws were coated with the stuff, as were the moon clips.

As stated above, my guess is that it came off when the shaft disconnected last night. Grady, looking at this pic you posted in this thread,


It looks like part number 15, up towards the top, could be the cap. What say you?

Randy

[Grady Clay]

Randy,

I think axle assembly #1 and the associated repair sets are for the 100 mm CV axle that has the friction welded outer connection and six M8 bolts. Axle assembly #2 and associated repair sets are the 108 mm CV and has M10 bolts at both ends. I’ll check PET6 again tomorrow. You ask Pelican Parts and perhaps look at a local Dealer’s parts display. They can print you pages with part numbers and illustrations.

Best,
Grady

[pwd72s]

[i]Originally posted by Grady Clay


You are welcome; however I should thank you and everyone else. This Forum gives me a reason to get up every morning. I’m getting very tired of doctors. The latest is a little spot on the inside of my left ring finger is melanoma (now surgically removed.) Now come all the tests to see if there is metastatic melanoma. Ugh.

Best,
Grady [/B]

Grady, You'd damned well better keep getting up in the morning! Not just for this board...so you can see what the HELL is happening next...right? Believe me, you are very appreciated here...and other places as well. Best, Paul

[RoninLB]

neuro stimulation is everlasting life.

[bigchillcar]

neuro stimulation is everlasting life.

sign me up for some of that, ron...i'll swap for i what take in a bottle...
ryan

[RoninLB]

Originally posted by bigchillcar

sign me up for some of that, ron...

no prob.
I'm presently in discussions with the Pope on establishing a joint communique'. As soon as that's resolved you're in.

[bigchillcar]

man, i'm catholic..and in the friggin' SOUTH! i'm half way to paradise with you..
ryan

[RoninLB]

Originally posted by bigchillcar

man, i'm catholic..and in the friggin' SOUTH! i'm half way to paradise with you..

That's understandable because I was an altar boy and I'm a 6day/week church vet.

ps: I'm RC

[bigchillcar]

ditto..bell-ringer in the early 70's..and enough cathechismal background (sp?) to at leat face-off with the occasional, inspired missionary baptist who demands to know WHY....why 'i worship mary'...and 'why i confess my sins to a priest'. don't i know god can hear ME?? hope we haven't hijacked..what was this thread?
ryan