Boot door gas struts

[Amarillo]

Visited my dealer today and asked about upgrading the gas struts on the boot.

Apparently the standard gas struts for the T6 California boot door are 1200 N-m, and for £160 I can have them upgraded to 1270 N-m. That seems like an awful lot of money for a 5.8% increase in performance. However, I am aware that the standard T6 transporter has 1000 NM gas struts for the boot door, so the 70 NM as a percentage of the extra 200 N-m gas struts for the California is a more worthwhile 35%.

While my command of mathematics is reasonable, my command of mechanics or physics is less solid. 70 N-m equates to about 7.14 Kg-m. Does that mean that the gas struts will hold an extra 7.14 Kg or so on a fully open boot, or is there some mathematical equation due to the angle of the struts which would affect that?

 

[Days out]

Visited my dealer today and asked about upgrading the gas struts on the boot.

Apparently the standard gas struts for the T6 California boot door are 1200 N-m, and for £160 I can have them upgraded to 1270 N-m. That seems like an awful lot of money for a 5.8% increase in performance. However, I am aware that the standard T6 transporter has 1000 NM gas struts for the boot door, so the 70 NM as a percentage of the extra 200 N-m gas struts for the California is a more worthwhile 35%.

While my command of mathematics is reasonable, my command of mechanics or physics is less solid. 70 N-m equates to about 7.14 Kg-m. Does that mean that the gas struts will hold an extra 7.14 Kg or so on a fully open boot, or is there some mathematical equation due to the angle of the struts which would affect that?

Your mathematics is superb...

...I thought "gas struts" was a funny walk you did when you had wind....

 

[WelshGas]

Visited my dealer today and asked about upgrading the gas struts on the boot.

Apparently the standard gas struts for the T6 California boot door are 1200 N-m, and for £160 I can have them upgraded to 1270 N-m. That seems like an awful lot of money for a 5.8% increase in performance. However, I am aware that the standard T6 transporter has 1000 NM gas struts for the boot door, so the 70 NM as a percentage of the extra 200 N-m gas struts for the California is a more worthwhile 35%.

While my command of mathematics is reasonable, my command of mechanics or physics is less solid. 70 N-m equates to about 7.14 Kg-m. Does that mean that the gas struts will hold an extra 7.14 Kg or so on a fully open boot, or is there some mathematical equation due to the angle of the struts which would affect that?

There probably is a formula, for ideal conditions. Ambient temperature has a not insignificant effect on the gas struts function/lifting capacity.
You could find it difficult to close in a warm/hot climate without the added weight of bicycles on the rack and definitely without the rack on.
I would also check if the upgraded gas struts are VW parts or Approved by VW because if not it could have an effect on any warranty claim affecting the Tailgate.
Your decision of course.

This company have a very good reputation. If the Dealership are not offering VW supplied/approved parts and you want to fit uprated struts. £50 + a pair.
http://www.sgs-engineering.com/car-...nsporter/gsc3098-volkswagen-t6-tailgait-strut

 

[briwy]

SGS are near us and we have used them in the past for new struts when we had a Bongo.
Sometimes they will uprate the existing struts but as WG said at £50 for a new pair that's probably not worth it.
Word of warning. If you change the struts yourself the tailgate is VERY heavy. You need something solid to prop it up, one strut will not hold it.

 

[Amarillo]

SGS are near us and we have used them in the past for new struts when we had a Bongo.
Sometimes they will uprate the existing struts but as WG said at £50 for a new pair that's probably not worth it.
Word of warning. If you change the struts yourself the tailgate is VERY heavy. You need something solid to prop it up, one strut will not hold it.

The the standard T6 Transporter struts are 1000N-m, I would expect the tailgate without rack and chairs to weigh in the region of 100Kg. But, as I say, I'm struggling to understand how much extra weight can sit on a fully open tailgate per extra Newton metre of gas strut.

 

[Amarillo]

There probably is a formula, for ideal conditions. Ambient temperature has a not insignificant effect on the gas struts function/lifting capacity.
You could find it difficult to close in a warm/hot climate without the added weight of bicycles on the rack and definitely without the rack on.
I would also check if the upgraded gas struts are VW parts or Approved by VW because if not it could have an effect on any warranty claim affecting the Tailgate.
Your decision of course.

This company have a very good reputation. If the Dealership are not offering VW supplied/approved parts and you want to fit uprated struts. £50 + a pair.
http://www.sgs-engineering.com/car-...nsporter/gsc3098-volkswagen-t6-tailgait-strut

I would expect the calculations to be based on standard temperature and pressure.

The upgraded struts, with the quoted price of £132.74 + VAT are VW parts from SMG Tonbridge. They quoted £188.45 inc. VAT for the struts and fitting. It doesn't sound like good value. I'm probably better off using a telescopic mop handle as a prop.

 

[Amarillo]

There probably is a formula

I found this, but am still unsure how to use it to calculate the extra weight that could be supported by an extra 70 N-m strut. Using it how I think it might be used returns about 3Kg with two struts.

 

[briwy]

It's complicated by the fact that the angle of the strut varies as the tailgate goes up and down.
I guess the critical thing is to ensure that it stays up once it's in position so in effect you need to measure the angle of the strut then.
I'm not sure where the Nm comes in as Nm is a measurement of torque not force.
I think you already have established that Force = mass x acceleration so if the standard strut exerts a force of 1000N then it will hold up a mass of 1000/9.81 = 101Kg.
However as the strut isn't vertical this figure will be reduced by the sine of the angle between the strut and the tailgate. I haven't got a technical calculator and haven't seen my sin tables or slide rule in years so can't help with the calc but as you say Tom the extra cost for a small ammount of extra lift seems disproportionate.
You also need to take into account that if you fit uprated struts to take care of bikes etc on the rack then the tailgate will likely take your head off when it's not loaded.
Perhaps the easiest/cheapest way is to get a prop for it.

 

[Amarillo]

It's complicated by the fact that the angle of the strut varies as the tailgate goes up and down.
I guess the critical thing is to ensure that it stays up once it's in position so in effect you need to measure the angle of the strut then.
I'm not sure where the Nm comes in as Nm is a measurement of torque not force.
I think you already have established that Force = mass x acceleration so if the standard strut exerts a force of 1000N then it will hold up a mass of 1000/9.81 = 101Kg.
However as the strut isn't vertical this figure will be reduced by the sine of the angle between the strut and the tailgate. I haven't got a technical calculator and haven't seen my sin tables or slide rule in years so can't help with the calc but as you say Tom the extra cost for a small ammount of extra lift seems disproportionate.
You also need to take into account that if you fit uprated struts to take care of bikes etc on the rack then the tailgate will likely take your head off when it's not loaded.
Perhaps the easiest/cheapest way is to get a prop for it.

I'm no longer interested in upgrading the struts, as you say, they appears to represent especially poor value for money, and a prop would offer far better value. However, my curiosity into the calculations required to covert 70N of extra force into extra KG hanging on the tailgate is piqued.

With the tailgate open, the gas struts are 170mm from the hinge. The tailgate is about 1500mm, so the centre of gravity will be about 750mm from the hinge.
F1 = 70
l = 750
c = 170
F = (70 x 170) / (1.06 x 750)
F = 14.96N = 1.53Kg
So two upgraded gas struts would support an extra 3Kg or so.

 

[briwy]

Sounds about right Tom
Your formula is basically working out the sine of the angle from the dimensions rather than using a table.

 

[Amarillo]

Sounds about right Tom
Your formula is basically working out the sine of the angle from the dimensions rather than using a table.

I don't see that in the formula: I can see Pythagoras being used to calculate the extended length of the strut, but that information is not used. The main formula appears to calculate the vertical force at the point where the strut meets the tailgate. The formula seems to rely on the fact that the sin of an angle between 90 and 65 degrees is approximately equal to 1 (sin 65 = 0.91).

 

[WelshGas]

Personally I would suggest an extendable pole to hold up the loaded tailgate as this would help with weight distribution. The heavier the loaded tailgate then the more weight/force applied to the gas strut attachments.
I've seen 1 of the lower attachment points give way and the strut go straight through the rear light assembly. It was a difficult job getting the tailgate open , let alone repair/replace the attachment.

 

[Amarillo]

Personally I would suggest an extendable pole to hold up the loaded tailgate as this would help with weight distribution. The heavier the loaded tailgate then the more weight/force applied to the gas strut attachments.
I've seen 1 of the lower attachment points give way and the strut go straight through the rear light assembly. It was a difficult job getting the tailgate open , let alone repair/replace the attachment.

I've come to the same conclusion about using a support pole, these look perfect:
http://www.nuovarade.com/product.php?productId=366&categoryId=59

However, I am still interested in the way the force on the struts is calculated.

 

[flying banana]

be careful. why are you wanting stronger gas struts.? if you have a bike rack like me the original struts should still lift and hold it empty. with bikes on it drops down. but you think an uprated strut is the answer. but holding up too much weight on your tailgate can dent it where the bike rack meets the tailgate. don't do it.

 

[Hotel California]

I found this, but am still unsure how to use it to calculate the extra weight that could be supported by an extra 70 N-m strut. Using it how I think it might be used returns about 3Kg with two struts.

Now i feel realy stupid not to understand a thing....
Should have gone to school much longer

 

[flying banana]

was only trying to help smarty pants

 

[Amarillo]

I've come to the same conclusion about using a support pole, these look perfect:
http://www.nuovarade.com/product.php?productId=366&categoryId=59

And as near perfect as can be: extends from 1255mm to 2020mm. A hemispherical rubber cap both ends spreads the load from the tailgate one end, and reduces the risk of it sinking into soft ground, or slipping on hard ground the other end. Collapsed, it fits exactly across the bottom rear of the boot, ready to be deployed the moment the tailgate is opened. Pictured the upper hemispherical rubber cap is covering the tailgate latch. I'm not yet convinced this is the best location.

 

[andyinluton]

how much is one of those? I use an extending prop from screw fix cost about £12 designed for holding up plasterboard to ceilings whilst its being screwed up.

I find it hard to shut the bootlid when the chairs are not in it, I think uprated struts could make it impossible.

 

[Amarillo]

how much is one of those? I use an extending prop from screw fix cost about £12 designed for holding up plasterboard to ceilings whilst its being screwed up.

27.54 Euros plus 21.80 Euros shipping from a Spanish supplier, I couldn't find a UK supplier for this length, so it worked out bloody expensive for what it is.

A good addition for the club shop perhaps.

 

[jts46]

I used to use some old aluminium tent frame tubing cost about a £5iver

 

[bvddobb]

We use two pieces of aluminum U-profile whenever our hatch is heavier than normal (e.g. when we have our second spare wheel on the hatch). Doesn't cost a thing:



The disadvantage is of course that all the extra weight comes down on the standard hinges still, so one shouldn't exaggerate it. We never open the hatch with bikes on it.

Terranger sells reinforced struts for various weights, but then they also sell reinforced hinges.

 

[Trebor]

No mention of temperature in the formula . Very significant .

 

[thehorse]

I've noticed for the past few weeks the tailgate doesn't quite open fully under its own steam. I have to give it a little push to get it to open the last 7-8 inches.

Is this just a 'feature' in cold weather or do I need to get the struts replaced under warranty.

Not really an issue at the moment but wondering if this would be a lot worse when/if I get the bike rack fitted?

Anyone else experiencing this?

 

[GrannyJen]

There have ben previous threads on this and the consensus is yes, cold affects the responsiveness of the hydraulic fluid.

I personally am in the habit anyway of giving the tailgate struts a helping hand. Far better being manual about things than having a bruised forehead.

 

[SimonB]

As @GrannyJen says there have been previous threads on this. There is a link here to one thread
https://vwcaliforniaclub.com/threads/boot-door-gas-struts.18254/ and you will find a range of answers here.

Do be aware that if you uprate them for the winter with bikes on the back, when the summer comes and the warmth makes the struts more effective you might find the door flies up when you unlock it and is very hard for a lighter person to close.