One big bolt is missing from this plate underneath, it's not a problem, is it??

[Homeoboxter]

Hey Folks,

So I bought this boxster with only 22k miles in it but with a dead engine (I couldn't resist). I jacked up the car and inspected the underside when I noticed that one of the bolts that holds this bracket in place was missing.



This piece holds the left and right suspension in place. It's not just a cover, it's an important element of the rear suspension. If you remove this you can't even lower down the car on its wheels because the suspension won't withstand the cars's own weight and the suspension will need to be realigned. Hence the name, "chassis reinforcement plate" .

The car has all the maintenance records and a receipt shows that some service was done in February, including changing out all the fluids and a wheel alignment job on all 4 wheels. First I thought the bolt came loose and fell out, but the plate does not line up with the hole. Most members of this community know that this bracket usually goes back easily if you pull the two suspensions closer to each other, otherwise the holes for the six bolts don't line up.

So, it looks like this shop changed the oil in the tranny then left out one bolt from a critically important part of the rear suspension because they couldn't put it back in. On an almost new performance car. And then did a wheel alignment and charged the owner $2000. How about that? Just wanted to share.

[elgyqc]

I can only say

[theiceman]

Its a skid plate .. my car was completely missing this piece when i got it and the bolts were in the trunk. didnt even notice there was supposed to be something there until i looked online. didn't seem too important as the car drove fine .. but who knows. Picked up a used one for 80 bucks slapped it on and moved on ... i wouldn't sweat one bolt missing . Yes im sure the plate provides some rigidity to the car, but not the end of the world.

[Homeoboxter]

Originally Posted by theiceman

Its a skid plate .. my car was completely missing this piece when i got it and the bolts were in the trunk. didnt even notice there was supposed to be something there until i looked online. didn't seem too important as the car drove fine .. but who knows. Picked up a used one for 80 bucks slapped it on and moved on ... i wouldn't sweat one bolt missing . Yes im sure the plate provides some rigidity to the car, but not the end of the world.

I'm not saying it's the end of the world, but this is not a job done by the neighbor who knows cars and fix it up fo a six pack of beers. This was done by a reputable shop for a lot of $$$ so you would expect them not to leave out random bolts, especially one that play a role in the car's structural rigidity.

[Homeoboxter]

Originally Posted by theiceman

Its a skid plate ..

Just re-read your post. It's certainly not just a skid plate. It's clearly a structural element. Hence the name, reinforcement plate. This is what the rear susension looks like when it's off. The back side of the suspension bracket is just hanging in the air, nothing supports it against flexing toward the middle (apart from the sway bar which is obviously not for this job).

[theiceman]

Originally Posted by Homeoboxter

Just re-read your post. It's certainly not just a skid plate. It's clearly a structural element. Hence the name, reinforcement plate. This is what the rear susension looks like when it's off. The back side of the suspension bracket is just hanging in the air, nothing supports it against flexing toward the middle (apart from the sway bar which is obviously not for this job).

umm if that's all you have there .. you are missing some bits.. its very thin aluminum and its not a reinforcement plate , and although i will agree it helps keep things square it doesnt prevent anything from collapsing . my car was a track car and ran without it for years.. its just a bracket . P/N 986 331 161 03 if you want to look it up .. or you can google skid plate to find it

that is a massive cross member holding it towards the front of the car in the pic and there is more bracing taken off that car .. and there is a bunch of triangular braces not on that pic you showed ..

But i will leave you to it if you think your " reinforcement plate" is at peril and your alignment is off because you are missing a bolt , better park your car..
I will leave you with these parting words from Pedro's garage . Guy has forgotten more about Boxters than most people will ever know ..

... with Marc regarding the aluminum plate.
It doesn't really do anything to "keep things where they ought to be".
That's why AX cars need the TechnoBrace or similar. The aluminum plate deforms and bends.
The keeping things where they ought to be is done by the diagonal braces.
The aluminum plate is just there for protection and for channeling air to the tranny.
If you moved the eccentric, your alignment is off.
It is practically impossible to dial it back to where it was.
Happy Boxstering,
Pedro

oh and dont get me wrong. id be pissed if guy didnt put bolts back , i wonder if it was even there to start with . When i put mine back on it was a pain in the ass to line everything up , and this is a common complaint.. guy should have done the job right .. if i got mine on on axle stands and im a home mechanic, god knows he should have.

[Gilles]

Originally Posted by Homeoboxter

This was done by a reputable shop for a lot of $$$ so you would expect them not to leave out random bolts, especially one that play a role in the car's structural rigidity.

Homeboxter, since the OP stated that the shop charged the owner for an alignment afterwards, it seems that the missing bolt, somehow got loose and fell from the car 'after' it got aligned and delivered to the customer.

[Homeoboxter]

Originally Posted by theiceman

umm if that's all you have there .. you are missing some bits.. its very thin aluminum and its not a reinforcement plate , and although i will agree it helps keep things square it doesnt prevent anything from collapsing . my car was a track car and ran without it for years.. its just a bracket . P/N 986 331 161 03 if you want to look it up .. or you can google skid plate to find it

that is a massive cross member holding it towards the front of the car in the pic and there is more bracing taken off that car .. and there is a bunch of triangular braces not on that pic you showed ..

But i will leave you to it if you think your " reinforcement plate" is at peril and your alignment is off because you are missing a bolt , better park your car..
I will leave you with these parting words from Pedro's garage . Guy has forgotten more about Boxters than most people will ever know ..

... with Marc regarding the aluminum plate.
It doesn't really do anything to "keep things where they ought to be".
That's why AX cars need the TechnoBrace or similar. The aluminum plate deforms and bends.
The keeping things where they ought to be is done by the diagonal braces.
The aluminum plate is just there for protection and for channeling air to the tranny.
If you moved the eccentric, your alignment is off.
It is practically impossible to dial it back to where it was.
Happy Boxstering,
Pedro

oh and dont get me wrong. id be pissed if guy didnt put bolts back , i wonder if it was even there to start with . When i put mine back on it was a pain in the ass to line everything up , and this is a common complaint.. guy should have done the job right .. if i got mine on on axle stands and im a home mechanic, god knows he should have.

Nothing structural is really missing from the picture but the two diagonal brackets, but those are connected to the two bolts toward the front of the car. The two other ones (toward the back) are connected to the reinforcement plate. Which means, if the plate is not there, the back side of this double rectangular shape is still open on one side (on the back). The whole thing is bit like a cardboard structure: lightweight pieces are used but in a geometrically engineered way to give rise to the maximum strengths against rotating forces from any direction. If one side of the cardboard box is opened, it loses a lot of its rigidity. If you look at a picture of the assembled rear suspension you see what I'm talking about. The reinforcement plate itself does not have to be thick steel; supported by six bolts even a relatively thin aluminum plate can withstand really high forces. So, I don't know who Mark is, but I disagree with him on this

But, if you used your car even on the track and did not see any issues with it then probably this whole engineering from the Germans was an overkill.

And yes, this is not really what my post was about, it's more like why would you do half of a job because you are lazy and charge the owner for the full price. Pretty sure they didn't give the owner the missing bolt in a bag saying, sorry, we couldn't put this back in.

Based on the records (again, only 22k miles) this must have been the first time they took the plate off for a transmission oil change, and I don't see a reason why it would have been missing on a car that was assembled in the factory. And they couldn't put it back on because the holes were not lined up.

[elgyqc]

I'm with Homeoboxter, the fact that normally you have to pull the upright suspension brackets into place to be able to get the bolts in is the proof, for me, that that plate does something important. Don't forget that there is a U shaped support that attaches the rear of the plate to the body.

[997_986]

Originally Posted by Homeoboxter

[...]
But, if you used your car even on the track and did not see any issues with it then probably this whole engineering from the Germans was an overkill.
[...]

Porsche in particular is known for always wanting to achieve the optimum in terms of weight and rigidity. They would never fit an optional panel that could in principle be omitted.
Just my 5ct

[Homeoboxter]

Originally Posted by 997_986

Porsche in particular is known for always wanting to achieve the optimum in terms of weight and rigidity. They would never fit an optional panel that could in principle be omitted.
Just my 5ct

Yep, agreed.However, the argument was about whether it's just a skid plate or a structural element of the rear suspension. The former could be just left out without any consequence while the latter could not.

[Homeoboxter]

Originally Posted by elgyqc

I'm with Homeoboxter, the fact that normally you have to pull the upright suspension brackets into place to be able to get the bolts in is the proof, for me, that that plate does something important. Don't forget that there is a U shaped support that attaches the rear of the plate to the body.

Exactly. If you remove it the two brackets move out of place and then you need to pull them back in place. The U-shape support holds the plate in place in the vertical axis, does not seem to hold to much load in the horizontal direction.

[Smallblock454]

It's a structural plate. Please add the missing bolt.

[Homeoboxter]

Originally Posted by Smallblock454

It's a structural plate. Please add the missing bolt.

Sure thing. Thanks!