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John Rowney
Experienced User
Username: johnrowney

Post Number: 190
Registered: 02-2015
Posted on Monday, 21 July, 2025 - 09:03:   Edit PostDelete PostView Post/Check IP

I am removing the axle of my 1938 Wraith, WXA68 (see a separate thread - Wraith Differential Oil Seal Leak). I noticed that there are indications of the axle hitting things that it really should not hit.

The photo below shows the paint removed where the right hand axle tube has been hitting the exhaust pipe.
LH Tube

The photo below shows the damaged exhaust insulation (asbestos?) where the axle tube has struck it.

exhaust

The following photo shows the paint damage to the Right Hand axle tube where it has hit the upper rubber bumper.

RH tube damage

I know that on my last trip to Newcastle to attend the 2025 RROCA National Rally, I often had banging noises from the rear when I was going over some wonderful potholes in the NSW roads (which couldn't be avoided). Obviously the noise was the axle tubes hitting the exhaust or the rubber upper bumper.

Someone suggested to me, and I can't remember who, that I need to get my rear springs re-tempered, to eliminate this unwanted bottoming of the car on the rear axles. Once I get the complete differential assembly removed for the other job, It will be a great opportunity to get the springs removed and tempered.

Can anyone advise me if this is a feasible option, and is there any workshop in South East Queensland that they would trust for such a job?

Many thanks

John Rowney
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Koen Dierckxsens
New User
Username: prewarrb

Post Number: 13
Registered: 04-2024
Posted on Saturday, 26 July, 2025 - 01:54:   Edit PostDelete PostView Post/Check IP

John,
Things are obvious: your rear axle should have full FREE travel between extreme low position (axle hanging fee) and extreme high position (when you enjoy the Australian potholes). Rubber bump stops are mounted to the chassis rails, limiting movement of axle upwards. When interference with exhaust is noted, most probably the exhaust is at stake here. Indeed, your swan neck looks a little flat to me. An original swan neck would have a steeper design. Also, the rear part of the exhaust may need to be moved to the rear? People should realise with RR there is not much room for error. Mount a cheap exhaust that is not according original specifications and you may run into troubles.
Regarding the springs (re-tempering): Your thoughts may be true/valid for a lot of cars (other makes), however I recommend you to think twice. First of all, correct standing height is of utmost importance. When your car is fully laden, the distance between rubber buffer (of original thickness, mounted to rear chassis rails) and axle should be 3.5" - then the rear standing height is correct. Result: it is a VERY bad idea to have your rear springs worked on (re-tempering, re-settling, etc...), without measuring your standing height FIRST! If not, you could very well end up with a wrong looking car.
If ever you did measure correct standing height BEFORE you started work (removal axle, etc...), then a re-set of the springs may be envisaged, and the work may be done taking into account your previous measurements (weight, deflection, etc...). If this is not the case, I suggest leaving things alone - for now.
However, while you are at it, I suggest performing a thorough maintenance of the spring leaves: undo all leaves, clean and repack with grease. You will be surprised with the result!
Regards, Koen,

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