964 RS mounts... Am I missing something?

[Aaron]

Evening guys

 

I've had a fair bit of vibration when at low speeds in 4th develop recently; I guessed the mounts were dead.  Long story short there.

 

I've bought the 964 RS mounts as a replacement but I really can't see how they fit without a load of washers... See the pics.  The mount bracket looks a lot different too, but I suspect this is because of PDK.  I know the bolt/nut for the mount are upside down but it's just to demonstrate the fit without committing to grinding it shorter.

 

http://imgur.com/a/sotlluM

 

I know a couple of people here have done this - what am I missing?

[Aaron]

The gearbox was too low - it just had to be jacked up a bit higher!  No idea why that wasn't coming to me at the time FML.  I sat there, looking at the two mounts thinking to myself that it's the same distance from the top plate to the bottom of the mount, how can this be so far off?  Then it hit me... the box had drifted downwards whilst I was fannying around with the mount.

 

Nonetheless, this was easy enough once I raised the gearbox up.  The hardest part of this whole thing was torquing the mount to the bracket; you have to torque it but not twist the mount out of alignment.  It would have been a lot easier with two people (one to hold the mount, the other to torque it), but I managed to mangle my hand into position so that I could hold the spanner on the nut and also hold the mount in place.

 

Now the pics.  I wasn't able to find a single picture of these actually installed so I felt obligated to take some.  Installed:

 

 

Things to note:

 

1) Had to use three of the four supplied washers on one side.  The thread on the bolt did not cover the whole length of the bolt, just the end.  This meant that it was running out of thread before the nut could tighten (it was bottoming out before it was even hand tight).  I used the washer to space this out and ensure it could be torqued up.  I suspect this is more an issue with the hardware that's tossed in and is specific to this kit.  I was going to get a fully-threaded bolt but the washer works just fine and means that I can get one side done.

 

2) Reuse the original bolt/nut for the two outer mount fasteners rather than those in the kit (especially as there's no nut).

 

3) There is no way you'll torque that mount to bracket bolt (65nm) when it's installed on the car.  There's just not enough room between the mount and the gearbox.  You have to torque it up on a bench and then install it.  Luckily, there's two dimples that you can use on the mounts to line up with the bracket.  If those dimples are directly aligned to the bracket, the mount will line up perfectly when it's installed.  On the section of the bracket that the bolt goes through, there are two flat surfaces; clamp those in your vice so that you can torque the bolt up without bending the bracket.  You could probably do this with a spanner and three hands if you don't have a vice.

 

 

4) Once torqued up, the mount had a surprising amount of movement in it.  This gives me hope for a more positive NVH experience than I was anticipating. 

 

5) The thread on the bolt has to be cut or it will fowl the suspension arm below.  I could've probably taken another thread or two off but it's got reasonable clearance and that's good enough for me.

 

 

Have partially cut the other bolt ready for when I get another two washers (Monday).  The orange is a coating from my recipro saw blade, not rust.

 

On the original mount, there's an E24 e-torx/security nut holding it to the bracket.  I used a 19mm socket on my impact wrench (I only had E20) which made light work of it.

 

 

Finally, besides the seal rings, I feel the price difference between the mounts by themselves and the mounts+hardware are a bit hefty.  Buy the seal rings from your chosen specialist as I suspect these are OEM bits (being gold zinc coated) and they may be difficult to obtain local to you.

 

To summarise and save yourself some cash:

 

Buy the seal rings from a specialist (90130531100)

Buy 2x M10 bolts with 120mm legnth along with matching serrated flange nuts (about £5-10 online)

Buy 4x M10, 3mm thick washers (£2-3 at best online)

 

If you go to your local fastener supplier, you may get them significantly cheaper and I would highly recommend that before buying online.

 

I'll update this again on Monday once I have obtained washers, fitted the other side and of course taken it for a drive!

 

I'll be replacing the engine mount next if the 4th gear judder is still present, but one thing at a time.

Edited October 3, 2021 by Aaron

[Andyoz]

Interested how it all goes. I might tackle my mounts over winter

[Aaron]

6 hours ago, Andyoz said:

Interested how it all goes. I might tackle my mounts over winter

 

That's why I'm doing this now.  The weather is so poor at the moment that the car is just sat in the garage, so it might as well be sat on axle stands instead! 

 

I've decided that I'm going to get new bolts with more thread because the sight of that washer is driving me mad.

[swanny71]

25 minutes ago, Aaron said:

 

That's why I'm doing this now.  The weather is so poor at the moment that the car is just sat in the garage, so it might as well be sat on axle stands instead! 

 

I've decided that I'm going to get new bolts with more thread because the sight of that washer is driving me mad.

Or buy an M10 die to extend the thread?

[Aaron]

12 minutes ago, swanny71 said:

Or buy an M10 die to extend the thread?

 

Solid point.  I have dies kicking around but they stop at M8.  Maybe it's time for an upgrade.

[Andyoz]

1 hour ago, Aaron said:

 

That's why I'm doing this now.  The weather is so poor at the moment that the car is just sat in the garage, so it might as well be sat on axle stands instead! 

 

I've decided that I'm going to get new bolts with more thread because the sight of that washer is driving me mad.

 

I've read a few lads using different Porsche model mounts on their 987's and they make it sound easy but they mustn't have been 964RS mounts?

[Aaron]

I got a die, removed the new mount, disassembled, cut the thread, reassembled and then repeated.  There is a lot less room on the offside, just to forewarn anyone.

 

I used a 19mm and impact wrench on the security bolt again - made easy work of it.

 

There are NVH changes, but only on the N and they are all good noises.  Engine is a bit noisier at low RPM (no change at mid/high).  Can't comment on gear selection as I have PDK.  I took it for a smooth cruise, bumps, twisties, cattle grid... Didn't experience anything usual in the vibration or harshness departments.

 

Turn in was markedly improved but it was too wet to truly test that - verdict is still out there.

 

Overall, good upgrade if your mounts are knackered but I wouldn't go changing perfectly good stock mounts.

[Aaron]

Got some time to upload the extra pictures I took.

 

This is the bracket held in the vice to be torqued:

 

 

You could use a spanner to hold the same surfaces as the vice, but that would be more difficult as far as I can tell.

 

987.2 PDK bracket up close:

 

 

This looked nothing like the other brackets I saw online so it threw me a little.  I searched for the part number but no results turned up.

 

Factory mount:

 

 

As for the original issue I tried to tackle: the fourth gear judder.  The judder has significantly improved but it's still very much there.  This leaves the engine mount as the next probable cause (the engine itself runs smooth, but you can feel the car shaking/juddering).  That's going to be a coolant drain, hose removal, swap mount, and refill job.  Should be fun.

[Aaron]

I intended to update this thread but kept forgetting.  Alas, I have now remembered!

 

The fourth gear judder is totally cured.  It got better and better with every drive and is now totally eliminated.  I suspect the failed/failing stock mounts were introducing some vibrations that were unintentionally triggering the knock sensor causing ignition timing retardation, thus causing the judder (this was only experienced at low RPM in fourth).  It's just an hypothesis but it's all I have as a probable explanation.  The main thing is that it's gone!