A big thank-you to forum member "Churchkey" for making these mounts for my '92.

As far as I know, he's the only person out there making solid motor mounts for late model C4 owners.


Getting things ready for the new mounts:

The hardest part about replacing the motor mounts on my '92 was removing the stock factory mounts. The large bolt that passes through the mounts which attach them to the mounting brackets were positioned in such a way that removing them was impossible. Both passenger and driver side bolts were installed from back to front (the nut side facing the front of the car) so pulling these bolts out was impossible because my headers were in the way.

In order to avoid removing my headers to get those bolts out, I decided to take off the mounting plate from the block. The idea was that with the mounting plate off, I could twist/position the entire assembly so that the large bolt that holds the mount/mounting bracket together, would be facing downwards towards the floor. The headers would no longer be in the way and I could pull the bolt right out.

Of coarse, gaining access to the 3 smaller bolts that hold the bracket to the engine block was a chore in itself. For starters, the ugly looking heat shield insulation that wraps around the stock mounts covers everything up. It took me at least 30-40 minutes to take the stuff out. The insulation is cleverly wrapped around the mounts in such a way that it's just about impossible to remove without ripping it all apart, but since I wasn't going to be re-using the insulation anyway, that's exactly what I ended up doing...

Once that was done, I could finally see the mounting bracket bolts. Getting a clear shot at them was difficult due to the enormous size of the stock mounts which made it very hard to get either a socket or an open end wrench around the bolt heads. Eventually though, with the help of a few wobble extensions and a few scraped knuckles, I was able to get those little bastards out.

I found the passenger side to be easier because I was able to pull out the bracket and mount from up above. I found that I could snake my arm down the front of the engine bay (where the power steering reservoir is located) and just pull everything up from there.

The drivers side was more difficult as the mount and bracket could only be removed from the bottom of the car. When your car is only about 12" off the ground, you don't have a lot of space to work with. Especially when you have a floor jack under there next to you holding up the motor.

The only real "modification" you need to do in order to complete the install is to grind off a small (2-3 millimeter) "tab" on the stock mounting brackets (one tab on each bracket) so that the new mount can slide into the bracket. Not a big deal as I was able to just use a dremel and grind off the tab. Took all of about 2 minutes total for both brackets. A hand file would have worked just as well.

Since I knew I had to do this to the brackets before I bought the mounts, what I ended up doing was buying 2 new (NOS) brackets a head of time so I could grind off the tabs and have them already finished and ready to go once the new mounts arrived.


Installation of the new mounts:

Since the solid motor mounts are so much smaller than the originals, installing them was a breeze. I was able to install both the bracket and mount as a "completed" assembly,rather than first having to install the brackets then the mounts afterwords.

I actually put the two components together first (outside the car) then slide the whole thing in as one complete piece. The passenger side, again, from the top and the drivers side from the bottom.

This time though, I made sure that the bolt that attaches the mount to the bracket was facing the opposite way (the nut end towards the headers), so that if I ever have to remove the mounts again, the bolt gets pulled out towards the front of the car where there's plenty of clearance and the headers are no longer in the way.

Conclusion:

Overall, I'm VERY happy with the mounts. They're a really great piece. Top-notch quality for sure. Not only do they weigh less than the stock mounts, but they really do clean up the engine compartment and free up a lot of space.

They're basically a "bolt-on" deal too, other than the slight modification to the stock mounts which I mentioned above. There is an ever-so-slight vibration at idle, but honestly, the only reason I knew it was there was because I knew what the car felt like before hand. If someone else sat in the car who didn't know anything about the car having solid mounts, they'd never know.

Once you're up and running, you really can't feel any additional vibration at all, so if anyone's worried about having the fillings shaken out of their teeth with the addition of solid mounts, rest assured, it's not nearly as bad as people make it out to be...

With the engine now solidly mounted to the frame, when you rev the motor, it no longer shakes from side to side as it did with the stock mounts. I immediately noticed that throttle response has greatly improved in terms of how quickly the car reacts with even the slightest amount of throttle. The whole car just feels much more solid. Kind of hard to describe in words, but suffice to say, I really like the change.

As an added bonus, the transmission (black tag ZF6) also seems to shift a lot smoother/easier than it did before. At first I thought this was just my imagination, but after reading a post by forum member "RUKWKR" (who's also running the same mounts) - he too reported having a better shift feel, so unless he and I are both imagining the same thing, I'd say solid mounts definitely make for better shifting...

Any ways, still have a lot more driving to do before I give my final report but from what I've experienced so far, I love the new mounts.

In case anyone's interested, here some pictures I took of the new mounts.


Oh, and the new mounts lighten the front end by 4.64 pounds. Hey, every little bit counts.


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I think I read a similar post (of yours?) before regarding solid motor mounts.

What is the purpose of doing this?

 

i got a set also from him. these things are solid!!!! they'll never break. mine will be going in with my new motor so it will be awhile before i get a chance to try them out.
thanks churchkey!!!!

 

Thank you for mentioning this mod.

Do you have your batwing w/ solid bushings also? are they stock? replaced recently?

Do you have the trans mounted normally? (ie . w/ c-beam or w/ a transverse support across the tailshaft, as some have done to eliminate c-beam).

Everything else is all positive (handling, throttle response, feel, shift quality (interesting!).

I bet I would love this mod since I like mods that most other people dont (ex. aluminum flywheel. I love driving my car w/ the aluminum flywheel).

 

Thanks for the ++ feedback on the mounts guys.

I have 5 pairs on the shelf if anyone is interested in them.

Am not a vendor here, the mounts were built due to special request by a forum member.

If this post violates forum policy I apologize. Please delete if necessary or I will edit
if/when notified.

 

First I'd like to compliment you on an excellent write on the installation of a great looking product. However, as a guy who doesn't much care for "psychological improvements", I could use some help w/a couple of these claims:
Yes...I can see what you're saying. The engine compartment definitely looks FAR better now that those motor mounts are in there. (?) (though I will say that that IS a beautiful Corvette engine bay!)



How could motor mounts POSSIBLY improve the engine's ability to respond to throttle input?? Unless you're talking about when under way, and a noticeable absence of driveline slop? And trans shifting?? The trans/shifter assy are all one, self contained unit (unlike the older 4+3). Whether the motor moves around or not should have zero bearing on the shifter functioning. I don't get it...

Again, good work on the car, well made part...excellent write up of the install...but the claims seem a little hard over the top for what is really an incredibly simple and basic part change...

 

Since you didn't start the thread and it's just a "these are my impressions" type thread don't see any problems here.

I told you there would be a market for these things! Thanks again!

 

Why do I sense a bit sarcasm in that comment?

It was already night time when I took those photo's, so there wasn't enough daylight to show off the engine bay area but yes, things look much nicer without those huge bundles of heat wrap on either side of my engine. I'll try and snap off some pictures during the day to better illustrate just how much cleaner/less cluttered the engine looks without the stock mounts/insulation.

Until then, try doing this. Go out to your garage and look in your engine compartment. See those enormous ugly-@ss stock mounts wrapped up in that faded, crusty looking heat insulation?

Now imagine neither one of them are there any more. Imagine those two areas are now wide open and you have a nice clear view, right to the ground underneath the car...

Yes, the (much) smaller solid mounts clean things up quite a bit.

I can actually place a work light under the car now and there's enough light passing through, to help illuminate the whole side of the engine, making it easier to see things likes the spark plug opening in the cylinder heads for example.

The open space also allows for any socket/nut/bolt etc. that I may drop in that area, to fall straight down to the floor, rather than disappearing into the dark void that used to be there with the stock mounts/insulation. They blocked off all light from passing through and prevented any items accidentally dropped, from falling down to the floor underneath.

We've all had that happen to us before. You drop something in the engine compartment while working on the car and you hope to god you hear the sound of it hitting the floor but it never does. That's when you have to spend a half hour trying to locate the item you just dropped and then another half hour trying to reach it.

Now, you can actually see right to the floor underneath the car and anything dropped in that area, will fall right through. Heck, that alone would have been reason enough for me to switch mounts.



Okay, I might not have worded things properly, and it's causing some confusion so I'll try again. The engine itself, hasn't changed (obviously) so the engine's throttle response remains the same as it did before. The difference is how the "car" itself reacts to throttle input and that has most definitely changed. As I mentioned earlier...

... The key word being "car". Without having the stock mounts there to absorb/cushion the initial deliverance of power to the rest of the drive train, the car itself, reacts faster to throttle input, simply because the engine is now SOLIDLY mounted to the frame.

There's no delay. It's just an immediate transfer of power. No absorption. No cushioning. No flexing. No play and no "give" as the stock mounts allow for (and are designed for). Just 100% immediate power transfer.

The change was readily apparent the first time I drove the car. If you're not running solid mounts, you wouldn't understand. But for the record, yes, the car now reacts faster to throttle input then it did previously. So in some ways, I guess you can say the throttle response has improved, since the car itself reacts quicker to throttle input (even though the engine itself has remained unchanged).

Hope that clarifies things a little.


As far as shifting, I do feel a difference in gear changes. Not under "normal" driving conditions mind you, but while mowing through the gears at wide open throttle. Why this is, I cannot tell you as I'm not an engineer, but I'm certainly not the first person to notice this benefit (perceived or otherwise) as many others running solid mounts have come to the same conclusion as well, so unless we're all imagining it, there must be a technical explanation for it. Hopefully, someone more knowledgeable then myself can chime in and explain it better.


I cannot possibly "prove" on an internet forum what I'm describing using only words. That will never be enough for some people and I understand that. All I can do is describe my observations, so take my comments for what they're worth. This is one of those mods you really have to do for your self, to see for your self.

I will report back after some more seat time and update the thread again since there are some wanting to know more about any noise/vibration issues that these mounts may cause. Haven't taken the car out on the highway yet, there may or may not be issues there in terms of unwanted vibrations. I still need some more seat time before I can comment further than what I already have.

Stay tuned.

 

Id like to hear if there are unwanted vibrations on the highway.

Im going to guess that some people will hate this on their street/strip corvette other people will like this mod on their street/strip corvette.

Much like how I like my non-removable diagnoal sidebars on my street/strip corvette. Many people would hate those.

 

Good explanations. Thanks for taking the time to write all this out and respond. I do know what you mean about the wrapped, engine mounts. I had forgotten about those. I also understand what you're saying about the CAR's reaction to the mounts. I buy that, for sure. And shifting? I guess you've experienced it and I haven't, so I'll have to buy that too. Perhaps the motion of the motor trans, during a WOT shift is a subconscious distraction...with out that, it "feels" better? IDK...

Good report though! Thanks!

 

If mine was not a dedicated race/strip/autocross car I would think long and hard about solid mounts. Those stock mounts dampen out NVH, which some folks like to be dampened out. Darn few folks want that solid connection.

With that said a set of these are going on my 383 when it gets put in the dedicated track car.

 

Lots of folks report "shifter rise" with the ZF, some worse than others, but I would venture to say every single ZF car has a slight bit of shifter rise under hard acceleration. On several ZF cars I have driven, it's easily detectable with the eye. Even with ZF doc beam plates, it was still there.

I mainly wanted the solid motor mounts up front because my ZF is solidly mounted after my solid axle swap, so I didn't want the "rocking" of the motor to be transferred to my tailshaft housing. Now, my motor/trans is basically a single structural unit.

I think once more folks try these, and realize there is almost no detectable increase in NVH, you'll see a lot of C4's running around with these.

Again, NVH is not increased, at least not noticeably. I can tell NO difference on the highway.

The only thing I noticed is I started having a slight rattle near the base of the windshield on my dashboard - my dash is custom so most folks probably won't even have that problem. I pinpointed where the rattle was coming from underneath and put a dab of gorilla glue to expand in the gap where it was rattling and problem solved.

I don't doubt that on SOME vehicles that a solid motor mount greatly increases NVH, but so far I would have to say on a C4 it's not detectable. I suspect the sloppy C beam arrangement is soaking up a lot of it. In cars with more solidly mounted transmissions than a C4 I could see where NVH would probably increase more.

But keep in mind my car has the WORST possible scenario for this - a solidly mounted transmission. So if anyone should have an increase in NVH it should be me, and other than the dash thing I can't detect anything.

 

I think on one of the porsches (911 gt2 ?) Has solid motor mounts as an option.

If oems are doing it, then we should also.

Plus, if there is a nvh issue you can just swap back in stock mounts

 

Thats good to hear on the NVH issues!

For your ZF rise, CHECK ALL of the the shifter linkage pieces.
At one time my shifter would move inches when up- shifting and not as much downshifting. Found out the sortta S shaped piece was broken in the linkage. Replaced it and now it barely moves when shifting.

 

I wanted to update this thread one last time with my final thoughts on the switch-over to solid motor mounts. I've had a fair amount of seat time driving with them and thought I'd share my observations.

My original thoughts haven't changed...

There is not a significant increase in either noise or vibrations with the solid mounts on my '92. I got the chance to take the car out onto the freeway to see how the car would react to the solid mounts at highway speeds and I'm happy to report that the car is pretty much noise/vibration free at cruising speeds 99% of the time.

The only time I can feel any addition vibration is on the rare occasion where I lug the motor. For example, say I'm cruising in sixth gear at around 65mph and traffic starts slowing down up ahead. If I leave it in sixth and slow down to the point where engine rpm drops down below 1500rpm, there's a slight increase in vibration, just as there is with the stock mounts, only a tad bit more noticeable with the solid mounts, because I'm in too high a gear and the engine speed is too low. This shouldn't be an issue in real world driving conditions because you should be down-shifting into the proper gear anyway once rpm's drop down too far in the gear you're in, but I thought I should report it anyway.


The car itself is much more responsive then before. It "reacts" much quicker with throttle input and the driving experience just feels much more "engaging" with the motor solidly mounted to the frame. That may or may not be a good thing, depending on whom you ask.

Shift feel, as I mentioned earlier, is also improved under wide open throttle shifting. I thought it was my imagination at first, bun now that I've gotten ample seat time with the new set-up, I can report that it's not imagination. It's 100% fact. The ZF6 somehow just goes into gear "easier" under wide open throttle shifts. It just "feels" better rowing through the gears. It's hard to describe it in words, as it really is something you should experience for yourself, but for what it's worth, there's a noticeable improvement in wide open throttle shifting over the stock (flexible) mounts.

Over all, I'm totally happy with the upgrade and won't ever go back to the stock mounts. In my opinion, this is NOT a "race-car-only" mod as many are stating.

I wonder how many of the people claiming that actually speak from having first hand experience running solid mounts and how many of them are just regurgitating rumours they read on the internet made by others who had no experience either...

Thanks again, Churchkey for making these mounts, and thanks as well to RUKWKR for getting the ball rolling in order to get these mounts built in the first place.

 

Your quite welcome.

Lets not forget RUKWKR (Kevin) he deserves the majority of the credit, he initiated this product build. If it were not for his perseverance & determination to get a quality mount for his very special Vette build they would not be available.

 

I asked . . . you answered! Afraid I can't take much credit.

Thanks again!

 

So how can I get a pair of these mounts and how much.

 

The standard mount from the factory are encased fluid mounts.

A popular upgrade is the Wevo mount which is a stainless steel/urethane mount.

Solid mounts are available, but the Wevo mounts seems to be the most popular.

The latest optional mounts (2010+) are electromagnetic that have a variable rate depending on vehicle dynamics.

Kinda like the active shocks on the Corvette.

 

Just PM Churchkey