Tow with Astra cabrio or sell your caravan? Opinions needed.

[jon_5103124]

1.8 petrol Astra cabrio - new shape. 1300kg

Eldiss wisp 450 - 1994 - 4 berth 1080 - maximum weight 15ft.

It's the only car and only caravan I have.

Based on weight I thought I had a match, as a novice reading these forums I'm starting to get nervous.

Do I tow or sell the caravan? Opinions needed....

I love both, and was dreaming of weekends away.

What would you do?

 

[cris_408518]

Sell the car !

 

[ProfJohnL]

Hello Jon,

My source does not list your model, but most 1.8 Litre Astra's are rated to 1300Kg maximum trailer mass. Do not relie on what I have writen as being appropriate for your car, you must check its limits.

Your owners hand book should indicate what the "Maximum Technically Permitted Laden Mass" (MTPLM) of trailer your car can tow. If it does not list such a figure contact your selling dealer for confirmation of limits.

It is possible that the model of your car is not approved for towing. Vauxhall should be able to confirm any limitations.

Best of luck

 

[Lutz]

I do hope I haven't caused you sleepless nights with my response elsewhere in this forum but my advice was based on your original statement that you also have a Hyundai Coupe as an alternative. All I wanted to say was that if I have 2 cars that I can tow with then I wouldn't use the convertible. However, if that isn't really an option, then by all means use the Astra. The caravan is well within the approved towing limit of the Astra and if it's approved, it must have been tested without serious material consequences. Also, one does see other convertibles towing caravans now and again. I'd just take it easy if I were you and try to avoid bad roads as much as possible.

 

[RogerL]

I don't shate Lutz's reservations about towing with a convertible. Manufacturers go to great lengths to ensure that they're as stiff and strong as their roofed counterparts with extra stiffening panels.

The Astra convertible is based on the saloon which is significantly stiffer than the hatchback or estate so I doubt very much if a modern convertible is any "weaker" than a modern estate.

In any case a towbar will often stiffen a car's structure by adding an extra torsion box to the chassis rails right at the back.

Jon, as long as you're within Vauxhalls towing and noseweight limits, then go for it. If the MTPLM of your caravan is 1080kg your Astra will handle it without any problem.

If you're still not happy, let me know - I'll swap my Astra saloon for your Astra convertible!

 

[Lutz]

I don't want to raise doubts in Jon's mind again but the fact that there is no connection between the A- and B-pillar on a convertible other than through the floor pan does reduce torsional stiffness. I agree that manufacturers go to great lengths to offset weaknesses in this area by adding substantial reinforcements but they will never achieve 100% the same results as with a closed body shell.

 

[RogerL]

Lutz, it's engineering simplicity to add SUFFICIENT extra stiffness to compensate for the roof not being there but cost cutting has led some older convertibles to suffer from "scuttle-shake" which indicates poor torsional stiffness.

Where manufacturers produce various bodyshells from the same basic exterior design it's usually the estate version which is the least stiff. Some manufacturers still fit pegs to the tailgate which engage with the bodyshell to use this to stiffen a weak shell.

Most modern convertibles are heavier than their saloon counterpart as more metal is added as stiffening than is removed in the roof.

In the case of the Astra convertible substantial torsional strength comes from the C-post bulkhead and the parcel shelf. Both these panels are missing or non-structural on the hatch and estate versions. There are also additional fore-and-aft box sections both internally and externally to compensate for the missing roof.

 

[Lutz]

The fact that the new Astra Twin Top convertible that has just been announced has over 30% more torsional stiffness than its predecessor shows what opportunities for improvement were available.

 

[jon_5103124]

Nice debate guys.

I have mailed vauxhall and many towbar companies.

Guess what, in the small print on towing capacity it states that all models of the cabrio are good to tow except the ones with 17" and 18" alloys.

They throw in the 17" alloys, air con, leather, cruise control ,foggs and remote power hood to shift the end of the line model, and call it the exclusive.

And would you beleive mine are 17" ;-( Fat lot of good they did me!

So I either see if the dealer will trade for the 16" alloys or go sit in my caravan and sulk until my wife gives in to a towbar on her car.

Oh well, I got the caravan I winged for, and the car.

Sometimes you get what you ask for eh?

Jon

 

[Lutz]

I may have good news for you that could save you a lot of money, Jon.

The restriction that the Astra Cabrio with 17" wheels is not approved for towing only applies to vehicles manufactured before Chassis No. 2B0008525 (implementation date 24.01.2002) so if your Astra was made after that, you'll be OK.

I would advise you to recheck.

 

[trucker]

Jon, see if she will go for a detechable tow bar. They only realy show if the towball is on ,when off you can hardly see the bar itself, maybe an option

Kevin H

 

[RogerL]

jon, there are a number of vehicles which can't tow even though their related models can. It's often caused by lowered suspension which drops the ball height below the minimum and type approval which would require a complete new towbar being designed, tested and approved.

When customers order factory-fit towing equipment on a new vehicle, the ordering system alerts them and the dealer to any mismatch and the order can't be processed. Most UK customers order dealer-fit or third-party towbars which doesn't highlight this problem and of course second-hand cars also run into the same problem.

BMW's with lowered suspension options seem to get caught by this.

It might be easier to sell your 17" wheels/tyres to Astra enthusiasts who always want bigger wheels. Try www.AstraSport.co.uk

 

[jon_5103124]

Thanks again guys.

My Astra is an 06 - spanking new, so I checked on the lowered suspension and that only comes on the 18 inch wheels, and then its only an option.

So it looks like I could be in business after all.

Will let you know how I get on, in the mean time thanks to you all for you expertise. ou have all been most helpful.

Jon

 

[Lutz]

Actually, the restriction was not a blanket restriction on 17" wheels but specifically for wheels with 215R17-83W tyres. As these have a load index of only 487kg, I presume it has more to do with their inadequate load carrying capacity than with suspension heights.

 

[RogerL]

Actually, the restriction was not a blanket restriction on 17" wheels but specifically for wheels with 215R17-83W tyres. As these have a load index of only 487kg, I presume it has more to do with their inadequate load carrying capacity than with suspension heights.

Tyres with Load Index 83 are right on the limit for an Astra, many models of which have a front axle loading of 935 kg, and are normally equipped with LI 87/88 tyres.

 

[Lutz]

Actually, the restriction was not a blanket restriction on 17" wheels but specifically for wheels with 215R17-83W tyres. As these have a load index of only 487kg, I presume it has more to do with their inadequate load carrying capacity than with suspension heights.

That would confirm my suspiscion. Perhaps 215R17 tyres with a higher load carrying capacity were not available before 2002. It would be interesting to know the Load Index of the tyres fitted to Jon's Astra.

 

[RogerL]

That would confirm my suspiscion. Perhaps 215R17 tyres with a higher load carrying capacity were not available before 2002. It would be interesting to know the Load Index of the tyres fitted to Jon's Astra.

Ultra low profile tyres have generally poor load ratings. If you compare standard construction tyres of the same rim diameter and section width, you'll find that the load index reduces as the profile drops. Heavy duty tyre construction (reinforced, 6-ply or 8-ply) tend to be restricted to higher profiles.

Some Volvos have ultra low profile tyres with load index only marginally above gross axle load. Unlike caravan manufacturers, car makers have usually left a large safety margin between max axle load and max tyre load. There is however an increasing element of fashion over-riding function.