I've taken one apart after having used the Loctite on it. It didn't exactly
fall apart by itself, but then there wasn't any need for high explosives to get
it apart either. Heating it up got it loose. I've also read where acetone will
help release parts that have been put together with Loctite, but have never
tried that. I might try the acetone if I ever have to go back in there. I'm
thinking that probably won't be for another 100,000+ miles or so.
Z
======
Dave,
I have used loctite in many applications in my career and in this instance with
290, I obtained the Technical Data Sheet and the Material Safety Data Sheet. It
is interesting to note that the product has been tested to Mil-S-46163A and ASTM
D5363.
The Data Sheet gives the break loose torque, ISO 10964, pre-torqued to 5N-m is 30
N-m (45lb-in) and (270lb in).
For disassembly:
1. Remove with standard hand tools.
2. In rare instances where hand tools do not work, because of excessive
engagement length, apply localized heat to nut and bolt ot approximately 250
degrees C. Disassembly whilst hot.
Your will note that they quote Mil spec, ASTM spec and the ISO standards.
Manufacture do not quote these specifications and standards without acceptance
and audit procedures within industry.
Tails 1990 928S4 Auto
======
One question is, can this loctited assembly be loosened, repositioned and
reclamped in a new position if needed with the torque tube (TT) and transmission
still together in the car. From my experience, no.
The heating and subsequent pulling, prying, tugging and hammering is done upon
disassembly of the TT from the car since there is no other way to generate
enough force on the assembly to release the drive shaft from the clamp.
These actions usually cause the drive shaft to move within the TT. The heating,
tugging and banging actions are also transferred to the engine internals,
flywheel seal, TT bearings and if the transmission is still connected, the
transmission converter bearings and internals.
The heat needed in this instance will not come from a heat gun, but usually an
open flame source, not too good under the car to begin with, from possibly a
welding torch or maybe butane canister. Since the surrounding materials are
metal, it will take a long time to heat soak the clamp. The way some are making
it sound, it's as if you can run a candle underneath the clamp and give a tug
with one hand and the clamp disengages easily. Not.
One thing that is concerning is the white washing of the distinct negative
ramifications from using loctite for this purpose. Even from those that are
regarded as gurus on this list.
But hey, Loctite sure is cheap!
If cost is an issue, recommend the circlip, bearing and washers routine over
loctite.
Constantine
=======
Constantine and Dave,
Great comments. It is always good to present both sides of an argument, the pro
and cons that allows individuals to make a considered choice of what they wish
to do. One thing about RL it is not a dictatorial process.
If I ever need to remove or move the clamp and spline section of the flexplate,
well that is another question. The spec for loctite 290 quote heat to 250
degrees C, however the extraction force required to move the actual splines is
the nub or the question of which I don't have an answer. The specifications for
290 has a section on "clean up" as follows:
"Cured product can be removed with a combination of soaking in a Loctite solvent
and mechanical abrasion such as a wire brush".
Maybe the way to go would be first to soak the clamp section with solvent to
soften up the 290 and if heat is required to brake the bond then air blow dry
and apply the heat via a LPG torch or oxy-acetylene ensuring all safety and fire
procedures are adhered to.
The actual method of applying axial force to the clamp to brake it loose and
move it will require a bit of investigation and lateral thinking to ensure that
no damage is done to crankshaft and engine internals.
However, if and when this occasions and if I'm still capable of crawling under
and working on the car, I sure that I will be able to devise a method of
manufacturing a puller/breaker to remove the spline with no depremental affect
on the crankshaft and the internal bearings. Hopefully this will not happen as
my car has only 97,000 km on the clock and all is working fine with minimum
kilometer clocked up each year as most of the time I away in my motor home.
Constantine bring up a good point relating to moving and re-clamping. Maybe when
and if the clamp is moved after using 290 and then reposition on the spline to
give no preloading to the crankshaft, any residue of 290 on the splines will
increase the coefficient of friction between both splines and may preclude the
further use of any 290? Who knows as the bonding surface is microscopic as the
adhesion is by wicking?
As expounded in previous post on the subject of migrating flexplate clamps, I
firmly believe Constantine has developed the best method of clamping, however,
it is like the old saying goes "horses for courses", so it is up to the
individual which route is taken taking all external factors into account in the
decision making process of the individual.
As an aside, I once superintended repairing a slipped crankshaft main journal
within the crank web where the pin, with a diameter was 550mm, slipped 9.5mm
within the crank. In the repair no hammering was used, only heat, dry ice and
hydraulic jacks were used. This repair was done in situ as the horsepower of the
engine was a mere 6,800HP. Upon completion the engine worked satisfactory.
Tails 1990 928S4 Auto
========
Starting from the beginning, here's basically how things went in regards to the
clamping of the front of the drive shaft. When I initially loosened the clamp,
it moved back along the splines, as it typically does, indicating that there had
been some pressure on the flexplate. I checked the crank end play and found it
to be well within the specified tolerances. I thoroughly cleaned the clamp and
shaft as well as I could with brake cleaner, and blew everything dry with
compressed air. I applied the Loctite all around the shaft where the splines
entered the clamp, and also into the three slots of the clamp. I tightened a new
pinch bolt with blue Loctite on it into the clamp to the 66 ft/lbs that some
have said Porsche suggested, then marked the junction of the clamp and shaft so
that any future clamp movement along the shaft could be easily seen. The
assembly was left for a day or two before the engine was started, to make sure
that the Loctite had fully cured. After that, the clamp position was checked
when oil changes were done, and it had never moved from where it was when I had
initially tightened it with the Loctite applied.
A couple of years after having applied the Loctite, I decided to replace some
seals in the transmission, get the transmission lines rebuilt, rebuild the
torque tube, and replace the torque converter bearings, mostly as preventative
maintenance, and to give me something to do as a winter project for that year. At
that time the clamp still had not moved at all along the splines of the shaft.
When taking everything apart, the front clamp bolt was removed and a small
propane torch was used to heat things up. I have no real idea how hot it had to
get to loosen the Loctite, but I don't see any reason to think it was much
different than what Tails said was the information he got from Loctite. A mapp
gas or other hotter torch probably would have sped things up compared to the
torch that I used. It's kind of hard to remember any kind of exact amount of
force that was required back then. It seems that it really wasn't that much
after things got fully warmed up though.
Once the shaft was out of the clamp, I used a toothbrush sized wire brush to
clean the remains of the Loctite from both the splines of the shaft and the
clamp. That didn't take much effort at all, and the clamp easily slid back and
forth on the shaft after I had removed the residue, basically the same as it
does with any other clean and loosened clamp and shaft. After everything was put
back together, I applied Loctite again the same way I had done originally. That
was around six years ago now, and I've never had a reason to touch any of it
again since. When checking for any signs of movement, there still hasn't been
any. If I ever do have to take things apart again, I might try using the acetone
method of loosening the Loctite first, to see how that works. If it doesn't,
I'll use heat again.
Z
=========
I had my 87 up in the air last week to top off the auto trans fluid (slow
leak somewhere up around torque converter). While I was under there, I used the
inspection hole to check my drive shaft spline position at the flex plate. I had
performed the locktite procedure over three years ago with, so far, no movement.
So I was surprised to discover that the white paint I had applied was split, and
there was about 2-3 mm of shaft showing between the two paint lines.
So I removed the cover, loosened the clamp, and the shaft retracted back into
the coupling to where the paint crack closed up completely again. I didn't have
time to reapply the locktite procedure, so I just tightened it again, and
reinstalled the cover. I know I'll need to get back in there again soon to
address it. For now, I've left out the two rear cover bolts. I'm gonna install
shorter ones so I don't have to drop the exhaust each time.
I had heard that the locktite approach was virtually permanent and would require
substantial heat if/when it ever needed to be taken apart. And perhaps I missed
it, but I've never heard of anyone ever having the locktite break loose. Clearly
it did the job for over three years. I will probably just apply it again, and
hope it gets me through another three or four years...
Mark in Atlanta.
87 S4 Grandprixweiss Auto (Daily, Since 2005).
88 S4 Silbermetallic 5 Speed Manual (Weekends).
84 S Schwarz Auto (Daily, 97-05, Sold, Still running around North Atlanta).