shock behaviour ??
08 June 2003, 11:26 PM
#1
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so what should a shock do, if you have it on it's own & you press it down ? should it spring back up ? or be hard to pull back up?
should it be hard to press down in the 1st place ?
Steve
should it be hard to press down in the 1st place ?
Steve
09 June 2003, 04:55 PM
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kippax,
thanks for the reply - but ... I'm trying to work out what a shock on it's own should do! ? i.e. no spring, not on a car, just in my grubby mitts!
I would expect them to at-least do the same sort of thing on all 4, but they dont! so I'm a bit concerned, hence why I'm trying to find out before I stick them on the car.
Steve
thanks for the reply - but ... I'm trying to work out what a shock on it's own should do! ? i.e. no spring, not on a car, just in my grubby mitts!
I would expect them to at-least do the same sort of thing on all 4, but they dont! so I'm a bit concerned, hence why I'm trying to find out before I stick them on the car.
Steve
09 June 2003, 05:04 PM
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steve,
sorry i didnt read your thread properly so i just edited. get one of the fronts and pull it fully open. hold it upright and put a heavy weight on the top and see how long it takes to fully compress. repeat with the other front. if the time isnt roughly the same then damping rate is different and they may be worn. the rears should match too.
stu.
sorry i didnt read your thread properly so i just edited. get one of the fronts and pull it fully open. hold it upright and put a heavy weight on the top and see how long it takes to fully compress. repeat with the other front. if the time isnt roughly the same then damping rate is different and they may be worn. the rears should match too.
stu.
09 June 2003, 05:08 PM
#5
I'm no expert, but the shock absorbers job is just to control the spring. If you push it in, it should generally stay there, as it is the spring that would normally pull it back out.
Depends what type of car it is for as to how stiff it will be, but it should take a bit of effort. But, if you have 4 they should all be the same (or at least the front pair should react the same, as should the rear). If they all react differently, are they adjustable? A lot of shocks have different settings for bump and rebound so wont necessarily come out as easily as it pushes in.
I would be careful if I were you - maybe get them checked out before fitting them if you are in doubt.
Steve
PS is there a record for the highest number of unintentional innuendoes in one post?
Depends what type of car it is for as to how stiff it will be, but it should take a bit of effort. But, if you have 4 they should all be the same (or at least the front pair should react the same, as should the rear). If they all react differently, are they adjustable? A lot of shocks have different settings for bump and rebound so wont necessarily come out as easily as it pushes in.
I would be careful if I were you - maybe get them checked out before fitting them if you are in doubt.
Steve
PS is there a record for the highest number of unintentional innuendoes in one post?
10 June 2003, 12:42 PM
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As Kippax and RB5320 have said the fronts should feel the same and rears should feel the same. If they are adjustable then you would need to make sure that the pair are on the same setting. The resistance will be different on the in and out stroke as the bump and rebound settings will not be the same. The units will not spring back up on its on unless it is pressurised in some way (for example with an external gas cannister).
If your anywhere near the Braintree area pop in and I'll put then on our test rig for you.
If your anywhere near the Braintree area pop in and I'll put then on our test rig for you.
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10 June 2003, 05:43 PM
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thanks Andy .. but not really in that area ! 
I didnt managae to test them last night, will try tonight.
I will test front to fron & rear to rear & see what I get.
thanks for the 'different on up & down stroke' that makes sence, but I'm sure one goes down really easliy & the others dont & push themselves back up!
will confirm 100% when I give it a go...
Steve
I didnt managae to test them last night, will try tonight.
I will test front to fron & rear to rear & see what I get.
thanks for the 'different on up & down stroke' that makes sence, but I'm sure one goes down really easliy & the others dont & push themselves back up!
will confirm 100% when I give it a go...
Steve
10 June 2003, 10:00 PM
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ok ... so , here's the results...
front to front comparison.
one definatly compresses quicker than the other, but then the other is harder to extend. so similar .. but a bit different!
rear to rear
both quite similar, quite easy to compress.
one of these seems to be not passnig the oil(gas?) through,and it bounces back up when you let go, instead of actually staying down (almost like there's a football underneath it - if u get what I mean?)
all of them (apart from the hard to extend front) gardually & slowly seem to extend a little after you compress them.
Steve
front to front comparison.
one definatly compresses quicker than the other, but then the other is harder to extend. so similar .. but a bit different!
rear to rear
both quite similar, quite easy to compress.
one of these seems to be not passnig the oil(gas?) through,and it bounces back up when you let go, instead of actually staying down (almost like there's a football underneath it - if u get what I mean?)
all of them (apart from the hard to extend front) gardually & slowly seem to extend a little after you compress them.
Steve
11 June 2003, 11:46 PM
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steve, its hard to say how much variation is tolerable. it maybe that new dampers vary slightly but andy will be able to tell you i think. have you considered having them refurbished?
12 June 2003, 10:27 AM
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Do you know what manufacturer they are? If these were ours then I would be recommending getting them back for a service as the behaviour is different between them. Without putting them on a rig its difficult to say whether the different forces required are significant enough, but the pairs should match. Its difficult without seeing the units but the one that return extends itself sounds like it gas pressurised, which would concern me about the others. I really think you should get them all checked out.
12 June 2003, 12:29 PM
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thanks guys ..
they are s/hand units of a low mileage car. they are original Subaru (KYB - i think) jobbies and I wanted to replace my 100k+ jobies as they must be tired by now & the springs certainly are !
The gas pressured one was a bit of a consern, as surely this will not act correctly. could it be that they havent been used for a while & have been layed down & this will sort itself out after a few miles on the car doing what they're ment to do ?
Andy - I'm not sure where locally I can get shocks tested as all we have around here is Quick type establishments (wont call them garages!
) will have to do a web search on that one... any ideas on cost?
thanks for your help!
Steve
they are s/hand units of a low mileage car. they are original Subaru (KYB - i think) jobbies and I wanted to replace my 100k+ jobies as they must be tired by now & the springs certainly are !
The gas pressured one was a bit of a consern, as surely this will not act correctly. could it be that they havent been used for a while & have been layed down & this will sort itself out after a few miles on the car doing what they're ment to do ?
Andy - I'm not sure where locally I can get shocks tested as all we have around here is Quick type establishments (wont call them garages!
) will have to do a web search on that one... any ideas on cost?thanks for your help!
Steve
15 June 2003, 05:33 PM
#15
As I am sure Andy will tell you...
The KYB units are gas pressurised so there should be a springyness to their motion, rebound damping is higher than compression, often about 3:1 ratio.
Also make sure they are not aerated. A few full strokes of the shaft (OMG) up and down (it gets worse) should help. You should hear and feel the bubbles being moved around when you do this, and it should get quieter.
The correct motion should be, relatively easy to compress, getting much harder to do it the faster you try. Once compressed, the shock should slowly extend of it's own accord, you can pull it to make it faster, but to a lesser extent than the compression.
Paul
The KYB units are gas pressurised so there should be a springyness to their motion, rebound damping is higher than compression, often about 3:1 ratio.
Also make sure they are not aerated. A few full strokes of the shaft (OMG) up and down (it gets worse) should help. You should hear and feel the bubbles being moved around when you do this, and it should get quieter.
The correct motion should be, relatively easy to compress, getting much harder to do it the faster you try. Once compressed, the shock should slowly extend of it's own accord, you can pull it to make it faster, but to a lesser extent than the compression.
Paul
16 June 2003, 10:28 PM
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Paul,
thanks mate - thats EXACTLY what I'm getting ! they had been laying down for a while, so when I first did it, they did sound bubbly . . . but then they stopped after a few up/downs.
they are harder up than down .. and probably 3 times.. but so hard to tell ... but one deffinatly pushes up much more than the others, so it's a matching issue
Steve
p.s. this thread is SOOOO dodgy !
[Edited by ScoobyDuck - 6/16/2003 10:29:08 PM]
thanks mate - thats EXACTLY what I'm getting ! they had been laying down for a while, so when I first did it, they did sound bubbly . . . but then they stopped after a few up/downs.
they are harder up than down .. and probably 3 times.. but so hard to tell ... but one deffinatly pushes up much more than the others, so it's a matching issue
Steve
p.s. this thread is SOOOO dodgy !
[Edited by ScoobyDuck - 6/16/2003 10:29:08 PM]
06 September 2003, 04:50 PM
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SD,
modern dampers usually stay where you move them to (not move back). if its hard to move try moving it slowly. a set of dampers should be matched side to side but not front to rear as the damping force should change with different spring stiffness.
kippax.
[Edited by Kippax - 6/9/2003 4:57:07 PM]
modern dampers usually stay where you move them to (not move back). if its hard to move try moving it slowly. a set of dampers should be matched side to side but not front to rear as the damping force should change with different spring stiffness.
kippax.
[Edited by Kippax - 6/9/2003 4:57:07 PM]
06 September 2003, 05:09 PM
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cheers Stu,
well I've pushed them down by hand & some are stiff & some are easy. but they seem to be stiff to pull back up ! I take it they should be the same resistance up& down ? or is most of the damping done on the up-stroke?
Steve
RB5320 - yeah good eh ! I take your point tho .. will check the front-fron & rear-rear similarities tonight & see whats what. how on earth can I get them tested !?
[Edited by ScoobyDuck - 6/9/2003 5:11:19 PM]
well I've pushed them down by hand & some are stiff & some are easy. but they seem to be stiff to pull back up ! I take it they should be the same resistance up& down ? or is most of the damping done on the up-stroke?
Steve
RB5320 - yeah
good eh ! I take your point tho .. will check the front-fron & rear-rear similarities tonight & see whats what. how on earth can I get them tested !?[Edited by ScoobyDuck - 6/9/2003 5:11:19 PM]
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