when are shocks bad?

[dlb]

i am in the middle of replacing the strut mounts on a t4 right now and have never been sure how to tell when shocks are bad. as a kid, my dad said a general test was to push down on a corner of a vehicle and then take the weight off suddenly. he said that corner should bounce up once, then down to its resting position again. if it kept bouncing two or three times, the shock was worn out. is that fairly accurate?

what about when the shocks are out of the car? the FSM says "pull the shock absorber piston rod at a constant speed and check to see that the pull feeling throughout the stroke is the same." next, it says "check to see there is no change in the pull when the piston rod is rapidly moved up and down with a stroke of 5-10 mm."

i can follow those directions but what has me confused is that one of the strut inserts on this car likes to rest in the compressed position (when the strut is upright). with some effort, i can extend and compress it smoothly but if i leave it extended it will slowly slide back down to the compressed position. the other insert likes to rest in the extended position. i can compress it smoothly but if i let go of it, the pressure in the insert will push it back out to the extended position. which of those is normal? any other tips on how to tell a good shock from a bad one?

[rer233]

My guess is you've got mis-matched inserts- the one that automatically extends is gas-filled and the other is not. Repacement inserts come either way (i prefer the gas-filled.) The PO probably only replaced one at some time.

[Petros]

most modern inserts have compressed inert gas in the "air" space inside. this is what causes the piston to extend on their own when not installed. If one of them is not extending, that means the seal is compromised and it no longer is pressureized. So it needs to be replaced.

The other way you can tell it is bad, beside the "bounce" test when installed in the car, when they are out of the strut, compress and extend the shaft its full length by hand. there should be as steady resistance the whole length of the stroke. No "free" movement of the piston, and no gurgling of the fluid as it passes through the valving in the piston. This usually means it has lost some of the fluid through the seal and there is not enough to dampen the shock though the full travel. Usually (but not always), this accompanied with oilly dust stuck to the outside of strut where it seeped past the seal. Also, damaged/worn shafts, obvious leaks, or severe external or mount damage is also basis for replacement.

Undampend wheels not only risk losing control when driving, but greatly increased braking distance since the tire does not stay in contact with the ground, and the undampened movement can cause extremely large impact forces on the suspension components, usually resulting in damage to the suspension. loss of control of your car at any speed is extremely dangerous. Bad shocks should be replaced.

[dlb]

great info, thanks. i just ordered a new pair of inserts and should have them in by tomorrow.

so is the bounce test that i described actually a fair way to test shocks and struts?

[dlb]

next question: how do i remove the insert from the strut? the FSM doesn't mention this in the 'shock absorber' section. is it supposed to thread in and out? if so, mine is very corroded in place. i will spray pb blaster between the insert and strut and give it some time before trying again.

[Mark]

so is the bounce test that i described actually a fair way to test shocks and struts?

I haven't had much luck with that test. All my vehicles act the same during that test (bounce back up and stay there), but I know my soon-to-be-ex hatchback has destroyed struts. When I'm driving it it bounces up and down for quite a while when there's weight in the back and I go over a bump. The strut "piston shafts?" are all pitted and corroded (my other cars have shiny ones). When I go over speed bumps it sometimes bottoms out. So I know they're wrecked, but the bounce test says they're fine. Maybe that test only works with massive, heavy vehicles or something.

[rer233]

There should be a large nut at the top of the strut tube. I clamp the strut in the vise and use a pipe wrench to unscrew the nut (i usually have to put a pipe on the end of the pipe wrench for added leverage.) Once the nut's off, the insert should just pull out of the strut tube. Good luck.

[Jarf]

DLB - one little word of caution -
When these things were brand new, the strut tubes were "non-serviceable" in that the insert was not replaceable.
I do remember seeing some tsb's about how to cut the top with a large pipe cutter to release the cartridge, done it a few times on other beasts but never had the pleasure on a T4.
(factory tubes had the inside threads cut for the shock retaining nuts)
Last time around I replaced the struts on the current ride, dealer got me replacement cartridges that turned out to be complete struts, of the non-replaceable cartridge type.
So it is entirely possible that the nut at the top is welded, clean it well, if they are split'able than you should be able to see the cut line, if not the threads.
From memory, the sealed type have a slight radius reduction near the top of the tube and the nut is welded to the tube.
The serviceable type have the strut tube straight to the nut and sometimes you can even see a thread or 2 above the cartridge top.
If it is the sealed type, it is possible to cut the tops off and there SHOULD be threads inside the original cartridge.
Some (A/M) replacement struts also came as completes too, but they are totally non-servicable.
And yes, I did keep the old serviceable strut tubes, just in case I have to do this again someday

[Petros]

I have taken a number of tercel struts apart, nut comes off with a large pipe wrench, no cutting required. the factory shock is actually integral to the strut. You remove the nut at the top and just dump all of the oil, the tube, piston/valve and shaft out, and clean it out and install the insert that threads into where the nut went. As the Brits say "easy peasy".

[keith]

Here is how I put cartridges in my OEM struts. It is tricky, but not hard. Just pay close attention to how to put on the top spring seat.

https://tercel4wd.com/forums/viewtopic.php?f=7&t=4704

Moderator, would you consider putting this topic permanently on the top of the first page of repair guides. While being a big ego boost to me, I do honestly think it will be helpful.

[dlb]

thanks for all the info, everyone. i can see the threads of the insert retaining nut but i guess it's super rusted because even with a pipe wrench on it, it won't budge. i've let it sit for a day or two now with a few treatments of pb blaster (still need to get an old fashioned oiler can to put ATF in so i can use that as a penetrant) so i'll give it another go tomorrow.

[ARCHINSTL]

Moderator, would you consider putting this topic permanently on the top of the first page of repair guides. While being a big ego boost to me, I do honestly think it will be helpful.

Done - I would add I did not use the suicide sticks, but Harbor Freight's clamshell tool*. I admit it - I be chicken.
Tom M.

* Wow - it was $30 in 2007 and 6 years later it is "on sale" for $70! http://www.harborfreight.com/single-act ... 43753.html

[Jarf]

Petros - I have only done 2 sets of turtle struts (both were serviceable), so I will bow to your more extensive knowledge.
I was quite surprised when I opened the box on the new struts, first time I had seen sealed tubes in a lot of years, other than the odd A/M unit.
Back in my days at the speed shop, we used to cut a lot of tubes for inserts, but they may have been Datsun's, it was a long time ago.

DLB - I used to use PB Blaster and thought it was the best, until I tried the Seafoam penetrant (CTC), might be worth a try.
I am also thinking about a good pump oiler for the ATF. That was all we used back in the day and it worked just fine.
Those nuts can be a real buggar sometimes, I have memories of a 3ft long pipe wrench(sometimes with a handle extension) working in a big vice bolted to a steel table.
(side note - if mounting in a vice, clamp at the base where the tube is build up for the mounting bolts, anywhere else and it can deform the tube)

[dlb]

(side note - if mounting in a vice, clamp at the base where the tube is build up for the mounting bolts, anywhere else and it can deform the tube)

yes, i followed the FSM advice of putting the strut-to-knuckle nut and bolt back through the bolt holes at the bottom of the strut and put that in the vice. definitely don't want to deform the strut casing, or whatever it's actually called.

[dlb]

You remove the nut at the top and just dump all of the oil, the tube, piston/valve and shaft out, and clean it out and install the insert that threads into where the nut went. As the Brits say "easy peasy".

i finally got the inserts out, using a pipe wrench with a handle extension like rer233 suggested. next question is why is there oil in the bottom of the strut case? is that from the old insert leaking or is it in there intentionally to prevent corrosion?