Suspension (shocks) imbalance question nct

spider_pig

Failed the nct last week on a leaking shock which i had replaced and test redone today which passed, I'm just curious about the reading

Last week was

front axle nearside 39mm offside 99mm 61% imbalance

Today after the retest it's

front axle nearside 30mm offside 27mm 10% imbalance

Considering above 30% is a fail and for new parts fitted less then 7 days ago is 10% normal or has it been fitted with cheap shocks that are failing already? Because the rear imbalance is 3%

BeatBoxing Blowfish

Did you replace both sides?
If not there's a reason for that.

spider_pig

BeatBoxing Blowfish wrote: »

Did you replace both sides?
If not there's a reason for that.

Yes had them both changed by a mechanic on Monday

Renegade Mechanic

If you forget the % and go purely on mm, you've gone from a difference of 60, to a difference of just 3. Which is actually small. Generally speaking on two new shocks, the variation in spring rate itself will now come into play. Shocks mainly control the movement of the springs, but shocks (dampers, really) and springs also work against each other. It's that opposition, that generates a difference, too. So, if a spring has started to fatigue a bit on the passenger side but is still ok on the drivers, then the left side will still perform slightly differently to the right, despite new parts elsewhere. Not hugely different - not even enough to fail an NCT - but still different. I wouldn't be too worried about it.

For a start its Nm IIRC.

Nothing to worry about, 10% across is close to perfect all things considered.

spider_pig

Augeo wrote: »

For a start its Nm IIRC.

Nothing to worry about, 10% across is close to perfect all things considered.

Great to hear, it was the 3% on the back with them being there since the car was bought (07) and the new ones showing 10% had me thinking the mechanic done me

CiniO

After I changes set of shocks (4) I had NCT 8 months later. about 10k km mileage since change.
Front imbalance was 0% and rear imbalance was 2%.

Have a look at the shocks if they were actually replaces and if they are new.
What brand were they?
Also lack of calibration of NCT equipment could cause your result.
Difference is tyre pressure between left and right as well.
And as mentioned about spring could have some effect here as well.

Renegade Mechanic

spider_pig wrote: »

Great to hear, it was the 3% on the back with them being there since the car was bought (07) and the new ones showing 10% had me thinking the mechanic done me

Very easily checked. Just look over the wheel for the shock.

It should look close enough like this:

Nice and glossy.


If it looks like this:

Then yeah. Somebody's got some explaining to do

CiniO

Augeo wrote: »

For a start its Nm IIRC.

No it's not.
It's Mm.

Nm (newton-metre) is unit of torque.

macplaxton

spider_pig wrote: »

39mm...99mm

It isn't "mm". That the SI abbreviation for "millimetre"

Augeo wrote: »

For a start its Nm IIRC.

It isn't Nm either, that's "Newton metre"

What they print in some cod-on science way is "Mm" which if it were a true unit, would be a Megametre (1,000 kilometres)


Something to do with manufacturer of the suspension test equipment - Maha + meter/machine.

spider_pig

CiniO wrote: »

After I changes set of shocks (4) I had NCT 8 months later. about 10k km mileage since change.
Front imbalance was 0% and rear imbalance was 2%.

Have a look at the shocks if they were actually replaces and if they are new.
What brand were they?
Also lack of calibration of NCT equipment could cause your result.
Difference is tyre pressure between left and right as well.
And as mentioned about spring could have some effect here as well.

Iv no idea of brand but i could see by looking at them they were changed as the colour is different to what was there before all i know it they are a spurious part.

n1st

Is there a workaround for imbalance? tyre pressure or anything?

mine failed last week, it is 32% imbalance and the max allowed is 30%

To repair is 200+ euro, the car is over 10years old and driving perfectly, is there something I can do myself to decrease the imbalance?

Nearside Offside Imbalance
Rear Axle : 36Mm 53Mm 32% Imbalance Above 30% fail

jelutong

I replied to your post on another thread. Run it through the test again as it is.