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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 327
Registered: 9-2004
Posted on Monday, 28 February, 2005 - 06:05:   Edit PostDelete PostView Post/Check IP

Having towed a caravan with the Shadow.1 without any faults.
However now i find the rear crossmember etc needs attention i thought i would look into the build strength off the car.
Having heard a story of the rear window falling out by as it now seems by an unreliable source.

It seems the car without the sub frames was built to a torsional stiffness between the wheel planes of about 10800to 11000 lb.ft/degrees and that was not taking any rigidity from the roof WOW.
The only car at the time to beat this was the Austin 1800.
So with the Shadow the weak part is the fixings of the sub frames to the body.
I will after my repairs to the rear mountings etc carry out further checks on all other points as the car is now 31years young.

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Bill Coburn
Grand Master
Username: bill_coburn

Post Number: 365
Registered: 4-2003
Posted on Tuesday, 22 March, 2005 - 09:38:   Edit PostDelete PostView Post/Check IP

Patrick et al

David Gore nominated our local man in Canberra, George Shores for advice on fitting tow bars to Shadows. He had quite a flow of enquiries and I thought it would be useful to include here a recent advice he gave to a correspondent.

The towbar on my Silver Shadow II was already fitted when I purchased the car in 1995. I left it there for protection and I would only consider towing relatively light loads. It is connected to the two bumper attachment points (two bolts each side) with an additional arm from the towbar side supports to the subframe for added strength. Any towbar fitting facility should be able to adapt or manufacture a towbar of sufficient capacity for your needs.

I would pause to consider the risks though. The following should be discussed with either your service provider or with the technical officer of your branch (if you are a member of the RROC).
* The final drive subframe and its mounting points are often found to be fractured in cars that have never towed. I advise you to have yours checked before putting a strain on it as they can be cracked and go undetected for years. Failure can be catastrophic.
* Each rear stub axle has a woodruff key which can shear causing the axle to spin in the hub (I discovered one of mine had done that very thing when I replaced the rear wheel bearings).
* The vibration dampers (a.k.a. 'pot scrubbers) can wear rapidly causing the whole final drive assembly to float. An easy test to check those is to have someone place the car in forward gear with the foot brake applied, then place the gear selector into reverse while you check for any movement of the driving wheels.
* The lead wipes (joins in the body shell) may crack and leave unsightly scars on your paintwork.
* The self levelling system in the car should be leak free and fully functional. "Duckarse syndrome" where the rear end of the car is too close to the ground can cause the half shafts in the final drive to operate at incorrect angles for prolonged periods and may cause damage to the rear wheel bearings, universals and CV joints.
* Rear springs should be checked for correct riding height. There should be a good clearance between the top of the rear tyre and the mudguard when viewed from the side.

So much for the alarmist view. If your Avan is relatively light and is well balanced, i.e. the downforce on the tow ball is not exessive, (your tow bar supplier/fitter should be consulted) and you have a smooth approach to towing, and you keep the above points in mind, you should not have any trouble towing on the highway. Please avoid towing on rough roads though as forces are dramatically magnified. "

George Shores Canberra
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 378
Registered: 9-2004
Posted on Tuesday, 22 March, 2005 - 17:55:   Edit PostDelete PostView Post/Check IP

Ah Ha,I shall cause a stir,It is my belielf that that they have it wrong!
To put the fixings on each outer side of the cars "box" structure is in fact asking for trouble with towing heavy loads.
As you can see from my pics the centre fixing puts a third point that minimises the stress on the outer body structure!
As for the rest, point taken.