So decided to replace my 18 year old boot gas struts as they were getting weak. Found a few sellers as recommended on here and Stabilus seems to have good reviews etc. Put my car details in and ordered some struts.

They duly arrived and I fitted them in minutes. Easy as. Trouble is they seem far to strong. If I was much lighter I could probably do chin-ups off the edge of the boot lid!  Double checked my details and cross referenced with other sites to see if I had mis-ordered. Everywhere is giving me the same strut spec of struts with 460Nm force. Some even suggest 525Nm.  I have removed them as I didn't want to put undue force on my boot structure.

 

The outer of my struts are quite rusty so I couldn't tell with them on the car, but now removed and cleaned with some wire wool and oil I can see a ref number of 9533ny and 0402N. Searching for these gives me struts of the same length but lesser force. The only place that lists struts similar to my spec is https://www.sgs-engineering.com/gsc2639-skoda-octavia-tailgate-strut 

 

Now, who/what is correct?  Why should I have different struts to those suggested in most places?  What have others used in the past?

 

Any help most appreciated.

 

 

Is yours an estate or hatch?

It's a Hatch.

0402N is 402 Newton metres isn't it. I would go with that if the 460N is feeling inappropriate. 18 years? In estates I'm lucky to get 6 or 7 years before needing replacement!!! 

@Golf-Fiend Brand new gas struts will always be "stronger" than 18 year old ones the same new spec.

I had exactly the same issue on my 2005 hatch. Feels very resistant when pulling down on the hatch to close. But at under £20 a pair they were cheap including a 5 year warranty.  I fitted them about a month ago on a car with 257k on it. I am on bangernomics territory. Used ones were too risky and £10-20 a set not worth it in my mind. 
 

https://www.ebay.co.uk/itm/274305477507?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=Ewc_ewyzRjS&sssrc=2349624&ssuid=45o-tdWCRea&var=&widget_ver=artemis&media=COPY
 

As @KenONeillsays we probability got used to the gradual decline in strength as they got weaker 

Forgot to say I could not read anything of use off my old struts and not about to pay £40 odd for a genuine strut each!

A gas spring is very unique in that it has a very high preload with a by comparison very low spring rate, this gives them the ability to work over a very long travel without the force going up massively.

 

As they get old and lose pressure the initial preload reduces until they will no longer support the tailgate, new gas springs will always feel much stronger than the ones that they replace

 

Another phenomenon is heat, I replaced the tailgate struts on my Yeti a couple of years ago, the force of the new ones was correct, initial force to overcome the preload high then a gradual increase which is not felt due to the geometry, there is virtually no assistance at the slam point.

 

 

This summer and especially in the 40° plus heat at my new property in Nouvelle Aquitaine I have found that after leaving the tailgate open for a long time it takes a huge amount of initial force to get the struts moving, once moving the force and resistance is as it should be.

 

@TheClient The force measurement is Newtons, Newton metres is a measure of a turning moment or torque. Divide Newtons by 10 (actually 9.81) to get the force in kgs (actually KgF)

Looking on autodoc with the oem part number it produces a number of manufacturer struts, with varying force from 390N to 460N

 And stroke 235 to 245 mm.

 

The Monroe ML5665 for example is listed as 405N. 

 

Sgs struts are usually OK as well I've used them once. 

On 07/07/2022 at 22:54, gav_is_con said:

I had exactly the same issue on my 2005 hatch. Feels very resistant when pulling down on the hatch to close. But at under £20 a pair they were cheap including a 5 year warranty.  I fitted them about a month ago on a car with 257k on it. I am on bangernomics territory. Used ones were too risky and £10-20 a set not worth it in my mind. 
 

https://www.ebay.co.uk/itm/274305477507?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=Ewc_ewyzRjS&sssrc=2349624&ssuid=45o-tdWCRea&var=&widget_ver=artemis&media=COPY
 

As @KenONeillsays we probability got used to the gradual decline in strength as they got weaker 

 

Thanks for this link. I ordered these and they arrived the next day. FItted in seconds. I have to say they are OK. Not bad considering the price. Not the smoothest at the end of the travel and they give a bit of bounce if you let the tailgate up by itself. The pull-down force is a lot more acceptable now. It doesn't feel like I'm going to bend anything or break the mounting points.

 

Still confused why there is such a variation in some sites stating 405N and a lot of others stating 460N for the same car. That's 110N difference.

 

460N struts now returned for a refund.

 

Thanks for the help on this.

3 hours ago, Golf-Fiend said:

 

Thanks for this link. I ordered these and they arrived the next day. FItted in seconds. I have to say they are OK. Not bad considering the price. Not the smoothest at the end of the travel and they give a bit of bounce if you let the tailgate up by itself. The pull-down force is a lot more acceptable now. It doesn't feel like I'm going to bend anything or break the mounting points.

 

Still confused why there is such a variation in some sites stating 405N and a lot of others stating 460N for the same car. That's 110N difference.

 

460N struts now returned for a refund.

 

Thanks for the help on this.

It does seem a large variation. I suppose it is the aftermarket catalogue where they try to consolidate offerings so you end up with a one fits all say for example combi tailgate or hatch even though they require different forces specified by original parts. Similar things can happen with suspension springs.