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Old 28th February 2019, 13:09   #1
Canonite
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Default Will 1.8T Dampers Fit On A CDTi ?

So i'm wanting to renew all four dampers on my ZT CDTi and also fit lowering springs. Of course I know they will fit.
My question is, is it safe to fit brand new ZT dampers for the 1.8T to the ZT diesel? Surely they will be better than my 16yr old ones ??

It boils down to cost and availability really. I know Mat sells the complete assemblies from China but Rimmer Brothers also have original stock.

Im guessing it would sit a little lower as the 1.8T damper would have a lower compression pressure, but would it be safe?
How much difference is there in weight?
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Old 28th February 2019, 13:18   #2
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The dampers don't determine ride height, the springs do that. The front springs for the CDTI have a higher spring rate than the 1.8 to cope with the engine weight, I suspect the rears are also different in order to balance with the front. The dampers have different damping parameters to suit the spring rate and the mass being supported by the strut assembly, Using 1.8 dampers with cdti springs may lead to a very bouncy ride (i.e. underdamped). Whether or not that would still be better than the aging dampers in place?
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Old 28th February 2019, 13:24   #3
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Quote:
Originally Posted by Avulon View Post
The dampers don't determine ride height, the springs do that. The front springs for the CDTI have a higher spring rate than the 1.8 to cope with the engine weight, I suspect the rears are also different in order to balance with the front. The dampers have different damping parameters to suit the spring rate and the mass being supported by the strut assembly, Using 1.8 dampers with cdti springs may lead to a very bouncy ride (i.e. underdamped). Whether or not that would still be better than the aging dampers in place?
Thanks for the reply. This is what I am wanting to establish.
I'll be fitting lowering springs anyway which many people do to all kinds of dampers without too much trouble.
I'm wanting to know if a 1.8T damper with a CDTi specific lowering spring would be a safe combo
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Old 28th February 2019, 14:49   #4
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Quote:
Originally Posted by Canonite View Post
Thanks for the reply. This is what I am wanting to establish.

I'll be fitting lowering springs anyway which many people do to all kinds of dampers without too much trouble.

I'm wanting to know if a 1.8T damper with a CDTi specific lowering spring would be a safe combo
I don't know how much of a difference it would make, but I imagine with the lighter engine (overall mass difference if I recall was 200kg?), heavy braking is where you would notice it most. I would think the weight transfer would be heavier than it needed to be. That s just my thinking of it rather than any basis in fact.

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Old 28th February 2019, 15:21   #5
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IMHO, using the wrong new dampers from a lighter car, as opposed using the correct new dampers: it'll handle like a bouncy castle. If you're fitting lowering springs for handling improvements then with the wrong dampers you'd be wasting your time (with less spring travel you need higher and more progressive compression damping). If you're doing it for looks it may not matter much to you and would pass MOT - depends on what your measure of 'safe' is I suppose. Myself, I wouldn't except maybe as an experiment. If you're willing to test it out and change again if necessary then give it a try.
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Old 28th February 2019, 15:33   #6
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The rear of the car will be fine, I wouldn’t use 1.8 on the front of a diesel though, even with the lowering springs.
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Old 1st March 2019, 08:35   #7
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In the event of a serious accident, what would the police and insurers make of a car with non-standard lowered springs and incorrect dampers?
Sorry to be a kill-joy but these things can and do happen. Accident probably won't even be your fault.
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Old 1st March 2019, 10:03   #8
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The difference in damping will only be slightly softer, no more than having a partly worn shock absorber on the car

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Old 1st March 2019, 10:32   #9
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I fitted a set of front spring assemblies from Matt onto my V6 with no adverse effect.
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Old 1st March 2019, 12:33   #10
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I too am looking at replacing the front strut assemblies on my ZT-T derv … I have one leaking front shocker so obviously gonna replace both sides . A few years ago I had to fit aftermarket front springs as an emergency measure so now wanna fit correct (ish) springs . As the whole strut complete is available from Matt it makes sense to replace everything in one hit . Its quoted as being about 7mm lower than standard which I can live with , its just the damping effect I'm concerned about ???
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