Removing Rear Dampers

[Certified Lotus]

I am carefully disassembling my car and haven't been able to completely understand how to remove the rear dampers from the outer tube. I have unscrewed the top threaded collar inside of the tube and removed a number of spacers and a rubber washer. I can't seem to pull out the damper. Haven't taken a slide hammer to it yet ( I'm replacing the dampers so not worried about the after effects of some force) as I don't want to damage anything in the process.

I've searched the forum and can find the info I'm looking for. Any insights on this?
Any help would be appreciated!

Here are photo's of what I have:

[john.p.clegg]

Bit different to mine but looks like you have a slotted piece to remove/unscrew at the top ??

John ...

[Certified Lotus]

John, You are absolutely right! How I missed that the top piece was threaded inside and outside I'll never know. Always takes a second set of eyes and of course someone like you with experience Thanks for your quick response. I got the right side off without problems but the left side will not come off despite it being fully unscrewed. Sprayed some penetrating oil and will let it sit for a while.

Some more photos for further reference to others.

[Certified Lotus]

And now my question is, should I replace the entire damper tube with new ones? These are a bit beat up and even have some small holes drilled in them.

How hard is it to remove the original ones and install new ones with spring adjustments? Is it just heating up the aluminum bearing housing to remove the damper tube?

[tvacc]

It is just a tube to hold the damper. On a friends car I was working on the bottom of the tube, which is steel rusted out and we had to buy all new uprights

Other than that going bad, I don't see a reason to replace the tube.

Tony V

[Certified Lotus]

I thought the tube needed to have oil in it? With the holes in the tube it won't hold oil.

[tvacc]

I thought the tube needed to have oil in it? With the holes in the tube it won't hold oil.

If you are using inserts, like the shock shown, then the oil is in the insert. Does not leave the insert unless there are bigger issues!

[Certified Lotus]

I'm confused, the instructions that come with the TTR supplied Koni shocks say to pour some oil down the shock tubes to keep the shocks cool.

Am I not understanding this properly?

[collins_dan]

How is the spring platform held in place on your upright? You may want to go to rdent.com and take a look at the various insert options. I am assumed you are going for narrower springs. Dan

[elansprint]

Glen you are correct it aids heat transfer to the outside world from the damper
Ian

[Certified Lotus]

So the big question is how important is having oil in the shock tube?

I would assume that because the shock is mounted inside a steel tube the ability for it to cool via air flow is minimal as friction heat transfer keeps the steel tube hot and the shock doesn't cool easily which changes the viscosity of the oil inside the shock and therefore the performance of the shock.

But the amount of oil in the tube is minimal. How much cooling could be accomplished with a thin layer of oil?

[mbell]

The oil doesn't cool the shock directly, it provides a good thermal link to the shock tube allowing improved heat transfer to the shock tube where the heat can be dissipated.

If you don't have the oil then you have air which doesn't do a good job of heat transfer.

No idea how much heat the shock generate but we talking about a small amount of oil so better safe than sorry...

[tvacc]

I would think that the amount of oil is so small that it wont even run out of the holes you have in the tubes. It will just be a coating I would suspect.

[Bud English]

If the holes are around the top, in the vicinity of the threaded insert, this is normal. Once that threaded cap is tightened down, the tube is dented with a center punch to keep the cap tight. It's a common practice to drill out the dent to remove the insert. I thought that whole procedure was in the workshop manual. Now that I've checked, I remember that Lotus suggested replacing the whole assembly. I'm sure that it's explained here on the forum though.

Edit: Tried to make that clearer. It's the outer tube that is center punched to lock the threaded cap in place once tightened down on the new shock (damper) insert.

[Andy8421]

Dampers can get extremely hot. The energy absorbed by the damper has to go somewhere, and it gets dissipated as heat. While not the same as a street driven Elan, rally cars go to significant trouble to supply dampers with cooling - fins and air ducting are not uncommon. There has been at least one case in a rally car where a damper overheated and exploded, spraying hot oil around which subsequently caught fire.

As mentioned above, the additional oil around the damper is not there to absorb the heat, but to transfer the heat to the outer tube which is air cooled in the wheelarch. Without the oil, the air between the inner and outer tube acts as an insulator in the same way as the air in a double glazed window unit.