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993 Chassis Legs - Corrosion ISSUES

ballcock

Well-known member
Joined
22 Jul 2008
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3,011
I had my 993 down at a bodyshop this morning , arranging to get the alloys refurbed. I'd chosen this particular bodyshop as he specialises in Porsches and has had recommendations from a number of 993 owners in recent times.

To the real point of the thread , he asked me if I'd had my rear chassis arms checked out... HUH!!? .. I'd not heard of a problem in this area , so he started showing me pics of work he'd done on about 4 different 993's.

Apparently , when sealer was applied at factory , one section was missed out and has become a haven for the tinworm , but can't be seen unless , firstly the rear PU is taken off , and then a side support to the rear chassis leg is removed. On each of the cars he's checked , it's been riddled with rust and only going to get worse, needs a new bit welded in and new chassis arms (sorry I don't know the exact term but I'll clarify with him in the coming days) need replacing , they cost £80 each (one for each side) from the friendly opc.

I'm getting him to strip my PU and have a look to see if this needs doing in my car . I've also asked him to take photos, so I'll keep y'all informed.

In the meantime , has anyone else heard of this phenomenon?? :nooo:


ballcock said:
I popped back over to the bodyshop today , in the quest for more knowledge for you guys (The things I do for you .... :D)

Well the upshot is ... Guards , take a bow , you're 100% correct.
It's the plate that supports the rear quarter panel , and somewhat the bumper thru the supports. Behind this plate and the chassis shields , lurks the mischief. The plate , and the shields need to be removed , work carried out to the chassis frame underneath , including stoneguard (well this is what my man does) , so there's no chance of the same damage being replicated in the future.

Ithink this image shows the offending area , with the shield and the plate showing...

993_Engine_Drop_-_8.jpg
 
Having been in there recently doing the covers and plugs the metal around that general area gets some abuse - I think mainly from heat but with spray, mud etc added in. There was rust on a lip off the chassic box sections that I saw, but I'm not sure what I would use to protect it.

If it's rusty but not badly then I would typically just use wax straight on it, but the position means it will just melt and probably drip off onto hot bits. So my second option would be something like Por-15 or even smootherite just to encapsulate and nutralise the surface rust. I was going to remove the heat shields to take a look when I was in there, but didn't - looks like I'll be going in again, and I'll get on this sooner than later. nAt least all my exhaust bolts are shiney and new now :)

Lee
 
There was a pretty scary thread with pics over on (somewhere>>?) a while back. I presumed the car had been in a smack and thought nothing more of it until now.

If my car has any such rot I would be gutted to the point where I'd probably fix up and sell up :(
 
My supports and shields are recently sorted ( 2 years ago)
According to the chap at the shop , it's a weakness inconstruction where there's slight movement between two metals coupled with lack of sealing which let's water lodge ...


To be fair this guy has disassembled a fair Number of 993's and feels they're at least as long lasting as the older cars with the exception of this bit I'm rattling on about. The quote for the work if it needs to be done is around £600 Inc vat so it's not a bank breaker ... But if we generally need to get this done , I feel its important to bring to all you guys attention rather than not know about it until it has become a massive job ...

Tbf I must emphasise that I've posted this with a fair few information holes , but I wanted y'all to know asap.
I'll definitely update tho.
 
Right then, are you ready for this... :eek: :eek: :eek: :eek: :eek:

Spent the last hour dismantling (ignore the exhaust paste on the silencer - I have a replacement silencer going on after this job)...

The aluminium heat shield did have a fare bit of crud behind it, but the chassis it was touching was ok. However the bumper support to chassis is clearly the issue here. But don't PANIC it's not a massive repair job and it's well out of the way cosmetically. I will get on with this now and provide photos as I go. The PU will have to come off, but then it's all quite accessible. I will probably repair the bumper supports with new metal as it's a pretty simple piece.
 

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samba-lee said:
Right then, are you ready for this... :eek: :eek: :eek: :eek: :eek:

Spent the last hour dismantling

This is why I love 911uk, in our hour of need, amidst confusion and dismay, when total blind panic is set to start, along come people like Samba-Lee to save the day with their insight and sleeves-rolled-up attitude.

:worship: :worship: :worship:
 
Hi Ballers,

I think I know what you (or you body guy) mean. The rear chassis legs can be seen from inside the engine bay, they are effectively two oval tubes that run from under the rear seat area and terminate right behind the bumper. The two main bumper bars bolt to them.

On the outside of these two legs, the bit you can't see, has a metal plate bolted to it about the size of a hand. They assist bumper mounting. The bad news is that they rust as water just sits on them and I'm not sure they're galvanised. This is one side:

http://cgi.ebay.co.uk/PORSCHE-911-9...arts_Vehicles_CarParts_SM&hash=item2a0add56b8

And this is the other:

http://cgi.ebay.co.uk/PORSCHE-911-9...arts_Vehicles_CarParts_SM&hash=item230aaef70e.

The good news is they are not welded on, just a bolt on job assuming the bolts don't shear off.

The other issue, and more of concern in my humble opinion are the heat shields screwed to the chassis legs inside the exhaust cans. Porsche thoughtfully formed these to be tight fitting to to the legs but they slowly filll up with mud and rot the metal. At the very least one should bend these at the lower edge away from the legs letting all the crap out.

Hope your well,

Regards
GR
 
Hi Dom,

The plates are directly to the sides of the bumper support holes (in your pic) and are bolted to the chassis legs. The heat shields are just forward of these and curl up under the chassis leg trapping mud and salt against the leg.

Regards
GR
 
Hi

I have heard about the chassis rail at the back being vulnerable as well. When I had my exhaust off I sprayed the area with rust preventing fluid. My rear PU is due to come off sometime soon (to fix an unsatisfactory paint repair at an approved bodyshop) and if I can I will have a look and see if the rust preventer has burned off.

Berni
 
guards red said:
Hi Dom,

The plates are directly to the sides of the bumper support holes (in your pic) and are bolted to the chassis legs. The heat shields are just forward of these and curl up under the chassis leg trapping mud and salt against the leg.

Regards
GR

I see what you mean GR. :chin: Im removing the PU etc over winter so will check this out, thank's for the heads up Ballers! :thumb:
 
I see them too but they appear to be supporting the rear wings not the PU?

Surly these can be inspected/treated with the arch liners out?
 
I believe they do a bit of both, the bumper behind the rear lights sits on these plates and they help to support the bumper at the sides.

I guess you could pull the wheel arch liner but I'm not sure you'd see the top without removing the exhausts. If you're going to do that, you may as well remove the bumper at it's pretty easy anyway.

All the above is from memory, a long time since I've seen the bit's in the flesh.
 
I'm surprised that the silencer has split Sambalee as its made from Stainless Steel. It shouldn't be too hard to fix though with a bit of stainless welding! :)
 
Absolutely fantastic Lee!
One of those pics shows rust on the chassis behind the plate;
How are you planning on tackling this , ie , cutting and welding a new piece??
 

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