Lotus Elan

Rear shock insert stuck in housing

PostPost by: stugilmour » Sat Oct 07, 2017 7:00 pm

I have completely removed the right side strut housing from the car. I can?t get the old shock insert out of the tube. I have let it soak over night in PB Blaster, but still won?t budge. The other side just pulled out with minimal effort.

Any suggestions?

Stu
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PostPost by: prezoom » Sat Oct 07, 2017 7:58 pm

Try pouring some ATF mixed with a little acetone in the tube. There was an article in, I believe Home Shop Machinest that compared various fluids used to break things stuck together apart, and that mixture proved to be the best. Kano Kroil was second best.
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PostPost by: nmauduit » Sun Oct 08, 2017 1:11 pm

alternating head and cold may be useful to break oxidation bonding (heat gun may be easier to use than propane flame, esp. if you want to reuse the shock)
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PostPost by: stugilmour » Sun Oct 08, 2017 3:38 pm

Thanks for the great suggestions.

Left it to soak with the ATF / Acetone brew over night.

I had placed it outside to prevent acetone odour, so the housing would have got just below freezing over night. I will alternate between outside and the warm garage. Trying the heat gun later today.

I have rigged up several pieces of 2? nominal PVC pipe over the tube and resting on the spring perch. This allows pretty stout vertical force on the shock rod nut with various levers. So far I have not budged the shock.

The original shock is toast due to thread damage on the rod. I was never intending to rebuild it anyway. Don?t really want to have to use a torch for heat though as I figure the bearings would have to be removed.

Perhaps I can get a 1? drive socket that will fit over the shock rod and allow me to apply torque to the shock body through the shock top nut (with a pipe wrench or some other bodge).

Cheers!

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PostPost by: 2cams70 » Mon Oct 09, 2017 12:23 pm

I find soaking parts in Diesel for a few days works wonders in these sorts of situations. If you aren't reusing the insert why cant you hold the piston rod in a vice whilst carefully tapping the lower knuckle with a plastic or maybe copper hammer?

Maybe post a few pics so we can see it.
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PostPost by: stugilmour » Mon Oct 09, 2017 3:02 pm

Finally got the shock insert free of the housing.

I did several heat and cool cycles while soaking with a mixture of acetone and ATF. Found the acetone a bit too volatile for use with the heat gun, and changed to brake fluid for a few cycles. Applied tension to the shock rod by screwing the top nut down on 2? nominal PVC pipe. No joy.

I ended up connecting the shock rod to my engine hoist with a heavy duty carabiner. Restrained the cast housing below the engine hoist legs with a square steel tube and a flat nylon sling. Took a few tries to get the awkwardly shaped housing tied down so the rod tension was pretty close to straight and there was no danger of crushing or bending anything. I also added a second sling to prevent the casting hitting the floor if and when the shock insert finally popped free. Placed a foam mat under the casting just in case.

Applied so much tension I thought the sling was going to break (it actually did once, and I think they are rated to a couple of thousand pounds). Left it soaking for several hours with tension applied, while periodically beating on the shock rod to hopefully move things around a bit. Worked up the guts to add even more tension, and it finally popped. There was enough corrosion product on the outside of the shock insert that it only came half way out rather than dropping the casting to the floor.

The learnings from this experience are to make sure the bearing housing sleeve is filled with oil or antifreeze to prevent corrosion (mine were not filled). :oops: If you can?t get the insert out with a modest pull, come up with a way to apply a Hell of a lot of tension without bending or crushing anything; the PVC pipe I had to hand was inadequate, the acetone would dissolve it. I considered using 2? iron pipe, but I would be concerned about breaking or distorting the spring perch with this method.

Thanks for all the suggestions. I was really running out of patience on this one, which is never a good thing around the Lotus! :D

Stu

Here are a couple of pictures.
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34aa839d-3bdf-4e48-9eed-b3cebf2e5620.jpeg and
This picture shows the corrosion product on the shock insert barrel. It extends all the way around the barrel on the lower three to six inches. I expect any water that manages to get into the steel sleeve falls to the bottom. It is more difficult to apply heat to this portion of the barrel though as the casting is pretty thick in some places, and I was trying to keep from overheating the bearings.
a0bfe768-4aa3-46c7-9e86-4a9b882a4fa9.jpeg and
This picture shows the casting strung up in the hoist. I was able to occasionally hammer on the shock rod with tension applied to try and get the corroded shock barrel to break free. The shock barrel tends to lay over to one side of the sleeve as the tension is slightly offset. Note the second sling to keep the casting from crashing in to the floor.
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PostPost by: john.p.clegg » Mon Oct 09, 2017 3:55 pm

"make sure the bearing housing sleeve is filled with oil or antifreeze to prevent corrosion "

and to disperse the heat generated by the damper...

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