muttster

Have gone thru the numerous threads on motor mounts and motor mount installation, and looks like a pretty straight forward DIY.

What is the most appropriate, cost effective motor mount for a GTS that will be driven primarily on streets -- OEM/Anchor/Ford/Volvo, and solid or fluid?

Rob Edwards

OEM. 928 375 039 00, about $650 for the pair. The volvos are cheaper and work, though they're a little too tall. I see that Hamburg tech is knocking off 'OEM' mounts for $160ish each. No idea what their longetivity will be.

GregBBRD

OEM work the best, by far. They absorb harmonics much better than any of the others. And raising the center of gravity above the height that Porsche designed the car around makes no sense.

They require the cooling ducts in the lower tray, to get long life out of them, which can be an extra cost, if you are missing the tray or ducts.

merchauser

with respect to OP, and no intent to hijack thread, where can I buy the cooling ducts?

ROG100

I have been selling the Volvo mounts for years WITH ZERO issues - 1000's at. $56 each - ask all the 928 experts who use them (apart from Greg who does not use them and is fully entitled to his opinion)
Have them on all my cars (except 78 to 82) and they work perfectly. My cars include two GTS's.
I have heard of dozens of failures of the original mounts - they leak and collapse at an alarming rate. Very few 928 owners use the original mounts because of the exorbitant cost and the high failure rate. Yes they are so susceptible to heat you need the belly pan with ducts to keep them cool.
Very few are sold so most sit on the shelves for years. Volvo mounts also stand up to heat much better than the Porsche mount. They do NOT need the ducting to SAVE them and last without it.
As for vibration being better absorbed by the originals I call BS. There is NO difference noticeable by the seat of the pants. I have researched, tested, cross sectioned, fitted, driven hundreds of mounts and by far the best bang for the $$$ is the Volvo mount.
Proof is in the pudding. As for taller not an issue once the weight of the engine is on the mount. The difference is about 3 mm and if that effects the center of gravity of the 928 i'll be a "suck egg mule".

GregBBRD

Sometimes you can find them used.

You can buy a complete lower tray, from Porsche, which includes the ducts.

I've got a client who has made molds to produce carbon fiber ducts, for me. Because of the shape, there are two molds required for each duct and then they have to be glued together, afterwards. Last we talked, here was some concern about the temperature tolerance of the glues. I'll check and see how this is proceeding.

GregBBRD

Roger and I are mature enough to have different opinions and still be friends. It's a rare thing, on this Forum.


It would be remiss of me to not point out that Roger sold Ford motor mounts, for years, and was absolutely convinced that they were the 100% "perfect" alternative. We all know how that turned out...especially Roger, who claims he "ate" a bunch of these mounts.

Beyond that:

I've changed quite a few sets of Volvo mounts back to Porsche mounts, to get rid of engine harmonic transfer, with 100% success. I have several clients that will attest to this.
I installed ~50 sets of Porsche motor mounts, last year....so unless I'm the only person on the planet using this part, there are a bunch more sold than Roger is aware of.
I've never had a Porsche motor mount fail or leak prematurely....and the vast majority of my clients keep their cars for long periods of time. (Which is why I sell mostly Porsche water pumps and factory Porsche water hoses....I got really tired of "eating" Laso water pumps and aftermarket radiator hoses a couple of years after installation.) (Yes, I do warranty things, for years.)
It was only a couple of months ago that Roger claimed that the Volvo motor mounts were exactly the same as the Porsche motor mounts, in terms of construction. Now, suddenly, they are more resistant to heat damage? If the rubber is different, that might explain why they are stiffer?
3mm height difference????? Texas must have a different calibration on their ruler, than here! Try 15mm, on a "California" ruler.

ROG100

Love you Greg - how did the condom work out 8>).

It would also be remiss of me to mention that the Ford mount issue was one of bad manufacture practice and not the MM design. Imagine how all the Ford Ranger owners suffered.

Bulvot

So, to hedge my bets, I should install one of each?

ROG100

You could really make our day and use solid alloy ones 8>)

GregBBRD

Could not bring myself to do that, although it did seem like a temporary solution.

I actually built a spacer to go into the bottom of the original early pod, so that the diaphragm from the 077 04 can be robbed and used. This actually holds the recirculation door open by about 6mm, so some air from inside the car will always be flowing past the door. After thinking about his, for a brief period, I decided that this was a positive thing....

GregBBRD

Yes, please do.

There's still too many 928's remaining for them to be super valuable.

Destroying a few more will help.

Wisconsin Joe

Well, you asked.

I'd suggest only the Volvo ones or Original Porsche.

The URO have a bad rep. Some say that it's 'old news' and that the new stuff is better, but I've heard that story before.*

I've got the Volvo ones (from Roger) in my car. They've been in since fall of 2013, about 15k miles. I'm very happy with them.

They do sit a bit higher, but even at 15mm, that's a bit over a half an inch.
I understand weight and balance from being a pilot, and I find it very hard to imagine that lifting the weight of the motor that little bit would produce enough 'moment' to change how the car handles enough for any ordinary driver to notice.

MAYBE a very skilled and experienced driver on a track, pushing the car to the edge of control would be able to tell the difference. Maybe.

* - Disclaimer - While I have Volvo mounts in my 928, I have knockoff URO in my 944. 10% of the price of Porsche ($20 each vs $195). I have no illusions that they are not likely to last as long as Porsche would, but for the price, and with the change a lot less difficult than on the 928, I will take my chances.

Bulvot

A car that I acquired a couple of years ago had a motor mount that had failed so badly that the motor was resting on the body of the car. For the very short time that I ran the motor, it was like a hammer hitting the body non-stop. At certain RPMs it was smooth-ish. I never want to relive that experience.

I'll pass on the solid metal mounts. Maybe what we really need are airbags just like used in truck suspension systems, but a bit smaller. Yeah...nothing could go wrong with that...

Anyway, back on topic...the motor mounts on the 928 look to be some of the more difficult and involved mounts that I've seen. All of the mounts that I've done in the past were simple. Jack the motor up from below, replace the mount, lower the mount onto the new mount and secure it. I need to do mine, mostly because the pan gasket is seeping and I might as well do them while I'm in there. And I'm not looking forward to rigging up a support from above.

merchauser

I just completed this project using a HF engine support, and it was no big deal. did not have time to do it all at once, so engine was supported for about 10 days.
hope this alleviates any fear of supporting engine; no dents, scratches, or marks left from the support

I went with the volvo mounts from roger and am very happy. my mounts were completely collapsed and riding on the crossmember. transformation is amazing. starting the car is
completely different. incredibly smooth. most noticeable at higher RPMs. sometimes I forget to shift because I can't "feel" the RPMs are at 3 or 4k.