Strut Top Bearings and Front Shocks.

[Billy1mate]

Ladies and gents, I am midway through changing the strut top bearings on my ZTT everything came apart ok but I am having a nightmare trying to extend the inner shock absorber piston to reassemble the assembly.
I have compressed the spring as far as the compressors will allow the problem is with the piston. There appears to be some sort of suction/vacuum as the piston can be drawn out an inch (25.4mm) or so and once released pulls back in. Now I've changed shock absorbers before but never experienced this vacuum effect, I am aware of the steady pressure required to draw the piston out.
I currently have the shock, disc & hub hanging from the piston rod from the garage roof as there should be more than enough weight for the piston to extend but it isn't happening.
Any pointers or something I am missing will be greatly appreciated.
:shrug:

[Dave-M]

Try pulling the piston right out then tighten a jubilee clip onto the bottom of it to stop it from sliding back in. Use some tape or rubber around the piston to stop it getting marked. A large cable tie, or just tape might do the trick too, but it depends on how strong the suction is.

Once the spring is on and the compressor removed you should have enough room between the coils to get in and remove it.

[Billy1mate]

Try pulling the piston right out then tighten a jubilee clip onto the bottom of it to stop it from sliding back in. Use some tape or rubber around the piston to stop it getting marked. A large cable tie, or just tape might do the trick too, but it depends on how strong the suction is.

Once the spring is on and the compressor removed you should have enough room between the coils to get in and remove it.

Thanks Dave, I'll try it. I did hang the shock from the garage roof by the piston rod and stood on the brake disc & it didn't make any difference. I am wondering if something has failed internally.

[DMGRS]

It sounds to me like the shock could have failed - especially if the other side doesn't behave the same way.

[Billy1mate]

Problem solved, it's always easier to have a fresh go at it the next day. Both shocks are the same, in that neither extends much but by repositioning the spring compressors and using a couple of ratchet straps I managed to compress the springs enough for them to go back together.
Thanks for the help Dave.

[Phil-Hex]

i always thought the shocks should stay extended, my new ones had a wire hook around them to keep them closed whilst packaged
the old empty ones retracted and didnt come back out which i presumed was maybe caused by a vacuum due to all the fluid being missing :shrug:

[Billy1mate]

Fair one & you've got a point, both my shock pistons are dry so no leaks (unless they are empty) but they both might be shot. New shocks do have the clips on them to stop them extending. Looking at the springs I think I might be due new shocks & springs. Thanks Phil.

[DMGRS]

Agreed - all new shocks I've had, have had the restraining clamps to keep them 'short' while boxed.
As soon as they're removed, there's not much you can do to stop them extending... :D

[ryszard]

Hi,been interested in this thread,I too have just replaced a worn looking front spring on the launch car,I had the same problem,the piston rod would not extend,I thought it very strange at the time but not having done one before assumed this was normal as the shock had no sign of undue wear,managed to compress the spring using 4 compressors! Seems like I will need to take it off again to change the shock.Will wait until I change the spring on the other side in case I need to order 2 front shocks!Will go out today to try the old fashion push down on the wing and see how many times it bounces up!Regards Ry....

[Phil-Hex]

i would always change shocks in pairs, otherwise the handling could become suspect as you'll have full dampening on one side and a possibly well worn one on the other

[Billy1mate]

Hi,been interested in this thread,I too have just replaced a worn looking front spring on the launch car,I had the same problem,the piston rod would not extend,I thought it very strange at the time but not having done one before assumed this was normal as the shock had no sign of undue wear,managed to compress the spring using 4 compressors! Seems like I will need to take it off again to change the shock.Will wait until I change the spring on the other side in case I need to order 2 front shocks!Will go out today to try the old fashion push down on the wing and see how many times it bounces up!Regards Ry....

That's what I'm looking at too but funds are short to do it at the moment, plus I need 4 tyres too. I am looking for 2 tyre protectors just incase but Mat doesn't have any & Rimmers are pricey, knowing my luck I'll put new tyres on and a spring will fail. Worthy of note my bottom arms are date stamped as '03 and are still serviceable with 136000 on the clock.

[DMGRS]

Hi,been interested in this thread,I too have just replaced a worn looking front spring on the launch car,I had the same problem,the piston rod would not extend,I thought it very strange at the time but not having done one before assumed this was normal as the shock had no sign of undue wear,managed to compress the spring using 4 compressors! Seems like I will need to take it off again to change the shock.Will wait until I change the spring on the other side in case I need to order 2 front shocks!Will go out today to try the old fashion push down on the wing and see how many times it bounces up!Regards Ry....

At least on a 75, the KYB shock absorbers are a lot cheaper than the items for a ZT. :)

That's what I'm looking at too but funds are short to do it at the moment, plus I need 4 tyres too. I am looking for 2 tyre protectors just incase but Mat doesn't have any & Rimmers are pricey, knowing my luck I'll put new tyres on and a spring will fail. Worthy of note my bottom arms are date stamped as '03 and are still serviceable with 136000 on the clock.

Same here with my arms - 53 plate car, 150,000 miles and the arms are OK - in the end my knocking was drop links. :)