550 motor mounts

Dang! Those look pretty nice. I thought the 575 redesign made those last just about forever? Did you notice any improvement like less bouncing of the shifter on bumpy roads? I wonder if these motor mounts go out all the time why don't they take out other mounts like the gearbox or bung up the shifter. I have never looked at the mounts up close off the car. If you don't want those I'd be glad to take them off your hands. My plan would be to take them apart and see if I could remake the rubber in polyurethane or delrin or delrin/rubber sandwich. If I could do that perhaps we could end the problem forever.

 

FBB- The new 575M mounts wear out, too, but Sark's do not look that bad. Another FChatter (John) sent me his set of old ones and they looked fine to me too. I was trying to get a couple of aftermarket manufacturers interested in making better ones, but no luck.

In my opinion, neither Sark's nor John's engine mounts needed changing, because I see no degradation in either of the sets of mounts. John's mounts are 1 9/16 inches in thickness including the washer, 1 1/2" without the washer.

 

Just as another datapoint, when Lilviv bought his '97 550, it already had 575 mounts on it, and they were sagging. Unfortunately he wasn't provided the service records for the car, so he didn't know how long they'd been on there.

Taz, who's the other John with a 550/575 who sent you his mounts?

 

OK I'll pm you my address and I'll start cutting. My car is on the rack now and might be the guinnea pig. I was going to start taking my dash apart for a refresh.

I have not looked at the issue but taking the rack out is easy. I think, but have not looked at it, that you would need to sever the headers to the exhaust so that you could move the motor easy without stressing or bending the exhaust system. You could probably "caveman it" but if your dealer did the extra work to do it right...good for them!
I'll have to start the job and see what happens and what needs to come off. Taking the rack out is easy I just rebuilt mine a few miles ago. I think that is most of the motormount job right there. The hardest thing to do is to bleed the air out of the reinstalled rack.

 

John- It was jaticker. We thought we might be able to get some better ones made that might also work for the 360 and F430, but no luck.

 

Taz,

How did making better mounts made on your project go bad? Cost? Manufacturer difficulties? I'm hoping 575 mounts can be fudged like delrin suspension Bushings I have done a zillion times before.

 

FBB- I tried to contact both the primary maker of Corvette aftermarket mounts and Paul Hill at Hill Engineering and never even got an answer back from either. I volunteered to send each of them a mount to see if there was anything they could do.

It should actually be very easy to design and implement a design that would work for the 360/F430 and V12s with much tougher synthetic rubber. Would be a good market for those if someone stepped up to the plate.

 

i have bought a pair on ebay recently for next time, so I measured them. 1.636 inch without spacer, and 1.734 inch with spacer.
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The only trouble with measuring a new set is that they have not been torqued and initially compressed at all. To get a real comparitive set of measurements, we would need to mount a new set, torque them down, remove them and then see what you get. It would probably be even better to put 1000 miles on them. That is not going to happen. I note from your measurements that it appears the steel parts like the washer also crush or compress.

The rubber parts, which concern us the most, appear to show a difference of a little over 1/8" between new, never compressed, and used.

 

Did your technician explain what it was about the mounts that indicated they needed to be replaced? Did he see dry rot and cracking in the rubber? Were the upper pads resting on the frame indicating they have collapsed? I tend to try and explain what it is that has deteriorated so we both feel comfortable that it's the right decision.

 

Josh- The ones replaced by John's techs I would be happy to have on my car. The ones from Sark's car looked about the same and measured the same thickness.

We have a nibble on making a replacement now. Maybe he will speak up about it. Will be mailing one to him this week.

 

Exellent point here, Terry. The 575's aren't a lot better in my opinion, it would be great if there were some better aftermarket ones available. Obviously, that's a heavy motor up there, and coupled with the fact they are quite close to the manifolds it's apparent they can't last long. I think poly-bushes may be a bit to hard though, i think it would be easy to introduce both noise and vibration by the selection of this material.

 

Eddie- You are correct on that. It would need to be a tougher material that has most of the same properties as the rubber compound currently in use. Too stiff a material and you might as well replace the rubber with steel, which would probably sound like an original Lotus Elite driving on a gravel driveway.

 

I agree, Eddie. My 550's motor mounts were last changed in November, 2004 at 43,327 miles. In those days it was common to replace the motor mounts with the existing 550 mounts in inventory and so my car got the "old solution" 550 motor mounts.

As my car is tracked and serviced frequently, we've been keeping our eyes on the motor mounts. In July, 2010 they looked pretty good and I posted some pictures in another thread:

http://ferrarichat.com/forum/showpost.php?p=139763498&postcount=45

The motor mounts were visually inspected about three weeks ago when the car was in for a new thermocouple and they were still doing well.

Barry

 

Sark,

I'm just wondering how your 550 managed to go through four sets of motor mounts in thirteen years.

Barry

 

When I bought my car from Sport Auto Tom Jones had just changed the mounts. He put the old solution mounts in and when I took the car to Brian Crall for a post purchase inspection Brian said the mounts were sagging and needed replacement.

Brian always knew that was something that I would do myself so there was nothing in it for him, no reason to exaggerate.

The thing is.....those mounts had less than 200 miles on them!

 

Sark, call me crazy, but those mounts of yours look like each one is sagging on one end to the point where the rubber cushion is touching the metal base. Compared of course with the new mounts pictured as well as the new ones I just put on those look like they DID need replacing.

 

That's some story, Sark! And I don't know anyone whose 550 required transmission mounts be changed. Mine were inspected about a month ago when I had my stock rear sway bar replaced with an HGTC bar. They were still good with over 68,000 miles on them. My 550 is also a 1999.

Barry

 

What did you see, Dave? I can understand new "old solution" engine mounts being compressed under load, but were they already sagging enough to require replacement?

My current "old solution" mounts are now over 7 years old with ~25,000 miles and are still doing well and providing appropriate clearances.

Barry

 

Barry,

My point was that even someone like Brian can call a good condition mount bad and in need of replacement.

There was no way those mounts were sagging enough to warrant replacement at that time and the call to replace them was done more out of concern that they were old solution mounts and failure could lead to catastrophic results.