Jacking Points

and.nox · Post by **and.nox** » Mon Jun 01, 2015 6:44 am

I have a S3 V12 coupe which is generally in good shape body-wise. Very little rust. The exception appears to be around the rear jacking points which I understand is very common. Upon recently attempting to lift the car using the jacking point, it quickly punched itself up into the underside of the car. Is anyone aware of a restoration project on this forum which clearly shows the panel work required to reinstate the jacking point. I'm capable of doing the job but aren't familiar with the internal structural elements which directly support the jacking point, or how to access them. Just don't want to do any additional work on the body than I need to. I assume it can be rectified from beneath the car or inside the car behind the back seat. Any photos would be greatly appreciated.

MarekH · Post by **MarekH** » Mon Jun 01, 2015 7:20 am

Dear Andrew,

If you look around at where the radius arms join the body, you'll see that there are vertical surfaces joining the horizontal, going across the car and also front to back. The strongest points on the car for jacking will be where these intersect, so fabricate a few small blocks to get yourself in contact with as much "box" section as possible and always use these points if you need to jack the rear bodywork up.

The official jacking point may be resonablty good, but as you have proved, over time it becomes a reasonably bad one.

kind regards
Marek

and.nox · Post by **and.nox** » Mon Jun 01, 2015 7:59 am

Thanks Merak,

I actually want to rebuild the original jacking point support structure. That's why I've requested any photos that were taken of such a refabrication, showing the best methods and points of access.

PeterCrespin · Post by **PeterCrespin** » Mon Jun 01, 2015 11:20 am

The jacking point and radius arm mount are contiguous and composed of multiple layers. Happily, the LWB cars where this arrangement obtains have very good access from above if you remove the seat cushion.

The jacking point itself may be the same as the Series XJ saloons but in any case that specific part is heavy section and can probably be used again once you grind the flakes of rotted thin- section bodywork off it. Ditto probably the cup. This is not an area for plating but proper repair,

As for the specific construction details - tricky without a car to poke into. See me waving my arms? Suffice to say I think only the radius arm cup and jacking nipple are available separately (along with outer wings and boot lids etc.) The rear internal floor and unibody chassis rails was one large spare part, at least from Jaguar. The pre-assembled condition is reflected in the opaqueness of the spare parts catalogue drawings. I think you're going to have to cut it away carefully and reconstruct what you see, as per Marek's suggestions, without skimping on this high-stress area.

One final cheery word...

You described the car as having very little rust. Either it has been repaired some time ago when that part was still sound, or you just haven't found the rest of the rust yet. By the time a rear jacking point (the light end) with all its internal reinforcement 'quickly' gives way, there is almost certain to be significant rust elsewhere - in your case probably in the sills and rear bulkhead. The only way I could imagine that not applying would be if a car were stood outside at an angle with a leaky convertible top, such that the water puddled in that one spot and nowhere else. But yours is a 2+2...

You don't say which side, but the usual worst/first rot culprit is the passenger (road puddle) side. If yours happens to be the driver side and the car has not recently changed steering, then be pessimistic that the passenger side is worse.

Pete

MarekH · Post by **MarekH** » Mon Jun 01, 2015 12:15 pm

What I didn't really want to say, to let you down gently, is that this area is a good indicator of the general condition of the car rust wise.

Now that Peter has done the job of being the fall guy - a bad dose of rust in and around the rear radius arm mounting points isn't a good news story. So far, you have described it as rusty about 10cm away at the rear jacking points, nearer the end of the radius arm strap.

What I am saying is that that is a poor place to be jacking it anyway, so even if you repair it to good as new, I still wouldn't jack it there. The area which can take the high stresses is easily visible from above as you can see the box section metalwork when you look at the top of the big radius arm bush from inside - it is between there and the back and edges of the car where lots of vertical panels are welded against horizontal panels. There is a box section going across the car here.

I use an assortment of tiny parquet blocks to spread the load over 2x10cms into the gap between the radius arm big bush and the side of the car. Jacking it, even if that is the Jaguar jacking point, partly on a flat piece of sheet metal is a recipie for flexing the rear floor of the car.

The same logic is also true at the front (although the jacking points are closer the edge front corners) in that the reaction plate - a thick piece of angle iron designed to transmit several times the front weight of the car into the body shell as you fly over hump back bridges or the mega thick front picture frame are far more sturdy than the middle of a 40 year old biscuit tin that is the floor.

kind regards
Marek

and.nox · Post by **and.nox** » Tue Jun 02, 2015 2:45 am

Thanks gents,
At least now I've got a starting point ie from inside the car under the rear seats. Happy with that. Just on the rust situation, there was some in the front floors but these have been replaced. I do take your point about the potential for the sills to be somewhat suspect. It's an ex-Arizona car so I'm hoping for the best.

I'd still love to see some photos before I start if anyone has undertaken this particular surgery? ie re-fabricating the box sections and plates to support the radius arm front bush and jacking points.

Post by **mgcjag** » Tue Jun 02, 2015 8:54 am

Hi Andrew this post pas the photoes you are after viewtopic.php?t=5318&highlight=radius+cup hope it helps Steve

and.nox · Post by **and.nox** » Wed Jun 03, 2015 6:44 am

Steve,

Thanks for that - looking at the photos it appears to resemble my cay around the radius arm mountings but differs around the area where my jacking points are. This is obviously a S2 car so the jacking points are quite different, and it's a roadster so the internal panelwork over the area is quite different, given it doesn't support a rear seat. However, thanks for your input.

Peter - your comments regarding the rust ring true. You said -"the usual worst/first rot culprit is the passenger (road puddle) side. If yours happens to be the driver side and the car has not recently changed steering, then be pessimistic that the passenger side is worse." My worst side is indeed the drivers side, but this is because it's an ex-Arizona car that has been converted to RHD!!

Post by **mgcjag** » Wed Jun 03, 2015 8:18 am

Hi Andrew....have a look through the posts on the restoration pages....you can also PM anyone there and see if they have any extra photoes Steve

and.nox · Post by **and.nox** » Wed Jun 03, 2015 11:41 am

Yeah, just started doing that. They're fantastic. Yet to find a V12 coupe resto.

PeterCrespin · Post by **PeterCrespin** » Wed Jun 03, 2015 12:52 pm

Any long wheelbase body will do.

So any Series 1 or 2 2+2, or a Series 3 2+2 or OTS. All the above have the same 'laid down' rear bulkhead structure.

and.nox · Post by **and.nox** » Wed Jun 03, 2015 10:06 pm

Thanks peter - Found the Resto story by CTDavies who's got a1969 Series 2 2+2 Coupe. Internal panelwork definitely the same.

and.nox · Post by **and.nox** » Fri Jun 05, 2015 4:25 am

For those who might want to use this for future reference, I found exactly what I was looking for in the Restoration Stories and Owners Gallery section of the forum, under the heading of "Not bad considering it was MOT'd 4 days before collection!"

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