Solid Motor Mounts anyone?
12-29-2007, 05:08 PM
#1
Three Wheelin'
Thread Starter
Solid Motor Mounts anyone?
I made some mounts for my car and could make them for others if there's any interest. I'm very happy with the way they turned out, it took some effort to match the various angles and profiles in the crossmember. They'll be $250 for a set.
They're made from high strength 7075 aluminum and designed to handle high forces, notice the profile as they change in size towards the center. Installation requires slightly longer bolts for the block which would be included.
They're designed to be used with my block girdle which spaces the oil pan out 3/8".
They're made from high strength 7075 aluminum and designed to handle high forces, notice the profile as they change in size towards the center. Installation requires slightly longer bolts for the block which would be included.
They're designed to be used with my block girdle which spaces the oil pan out 3/8".
12-29-2007, 07:01 PM
#6
Drifting
Awesome work, Mike. Any worries about the transmission mounts after having solid motor mounts? I might be interested in a set of solid transmission mounts, depending on price. I have solid rubber engine mounts and don't really want to fork over the $$ for factory tranny mounts.
Trending Topics
12-29-2007, 08:08 PM
#9
Very nice Mike. My car will still be street driven, so I will pass on this latest creation, but looking forward to your other ideas.
12-29-2007, 09:43 PM
#10
Three Wheelin'
Thread Starter
Red, I do have some solid transaxle mounts too. They're also aluminum machinings and are probably the neatest looking parts on the car, I'll post some pics tommorow.
Bill, Red, I've heard that when a solid trans or motor mount is used it's important that both ends of the drivetrain be solid or both rubber. I don't understand the reasons but it's been discussed among the 944 types on Rennlist. I would not have considered a mix of solid/rubber mounts on the torque tube drivetrain to be any special cause of concern but since I'm not doing that I haven't given it any thought.
IMO solid mountings in general add rigidity and strength to the engine block aside from the obvious benefit of chassis rigidity. The transaxle mounts were tricky to design because the originals have an area where the transaxle sits against the mount away from the bolt at the top. I wasn't sure if that would be desired in a solid mount so I designed it that way for good measure even though it creates a fit dependant on the case casting consistancy. I've been mulling over whether to do anything else special with that feature and that's why the transaxle mounts haven't been mentioned yet.
Sterling, Bill, I'm not sure where these mounts sit relative to stock ones. I made them to fit based on measuring 79 and 87 engine blocks along with the 79 crossmember and made sure there was extra space for the girdle but no more than necessary. It's possible to shim the engine higher but something would have to be machined to lower it.
If there's a nominal measurement that a stock motor mount is supposed to be I'd be glad to compare but looking at an old mount isn't helpful. Don't those things vary like crazy depending on condition? I've seen transaxle mounts that had a very noticable height difference between new and used, something like 1/2" or so
For projects like this I start with a clean sheet and measure my car and place things in the optimal place based on those measurements but it would be helpful to the community to have a standard measurement of the motor mounts as well as the transaxle, does anyone have that?
Bill, Red, I've heard that when a solid trans or motor mount is used it's important that both ends of the drivetrain be solid or both rubber. I don't understand the reasons but it's been discussed among the 944 types on Rennlist. I would not have considered a mix of solid/rubber mounts on the torque tube drivetrain to be any special cause of concern but since I'm not doing that I haven't given it any thought.
IMO solid mountings in general add rigidity and strength to the engine block aside from the obvious benefit of chassis rigidity. The transaxle mounts were tricky to design because the originals have an area where the transaxle sits against the mount away from the bolt at the top. I wasn't sure if that would be desired in a solid mount so I designed it that way for good measure even though it creates a fit dependant on the case casting consistancy. I've been mulling over whether to do anything else special with that feature and that's why the transaxle mounts haven't been mentioned yet.
Sterling, Bill, I'm not sure where these mounts sit relative to stock ones. I made them to fit based on measuring 79 and 87 engine blocks along with the 79 crossmember and made sure there was extra space for the girdle but no more than necessary. It's possible to shim the engine higher but something would have to be machined to lower it.
If there's a nominal measurement that a stock motor mount is supposed to be I'd be glad to compare but looking at an old mount isn't helpful. Don't those things vary like crazy depending on condition? I've seen transaxle mounts that had a very noticable height difference between new and used, something like 1/2" or so
For projects like this I start with a clean sheet and measure my car and place things in the optimal place based on those measurements but it would be helpful to the community to have a standard measurement of the motor mounts as well as the transaxle, does anyone have that?
12-30-2007, 02:59 AM
#11
Three Wheelin'
Join Date: Jan 2007
Location: not where you think I am
Posts: 1,466
Likes: 0
Received 0 Likes
on
0 Posts
suggest you have someone like Roger (who might have several sets of new motor mounts in stock) take measurements and get them to you for comparison???
---Russ
---Russ
12-30-2007, 12:15 PM
#13
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
Stock MM free height is 75mm give or take a "gnats c**k"
A little less when compressed in the engine.
A little less when compressed in the engine.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
12-30-2007, 01:45 PM
#14
The Lady's Man
Rennlist Member
Rennlist Member
Join Date: Sep 2003
Location: south O.C. california
Posts: 10,444
Likes: 0
Received 0 Likes
on
0 Posts
Can someone inform me (less mechanically knowledgable) what the advantage of this is compared to the stock set up? Sounds like a rough ride with lots of vibration.
12-30-2007, 02:46 PM
#15
Instructor
Join Date: Feb 2007
Location: Da Island, mon! (VI,BC,CA)
Posts: 238
Likes: 0
Received 0 Likes
on
0 Posts
solid mounts/ride
FWIW, I have raced a few cars with solid motor & tranny mounts (tho not 928). and some cars are actually quite a bit better than you might expect regarding vibration. I had an 83 celica with 22RE 4cyl 2.4l, and despite the reputation of large 4cylinders for being rough, I never actually noticed it except at idle. Toyota was pretty good at smoothing out their 4's
I would guess that a well balanced engine, in proper tune, would be acceptable as a street car, as long as you didn't have to drive in traffic a lot. Could become annoying on a long road trip, depending on harmonics.
Just my $0.02
Ken
I would guess that a well balanced engine, in proper tune, would be acceptable as a street car, as long as you didn't have to drive in traffic a lot. Could become annoying on a long road trip, depending on harmonics.
Just my $0.02
Ken