Stiffer OM60x motor mounts?
Stiffer OM60x motor mounts?
raysorenson
08-22-2012, 12:21 PM #1After the 5 speed swap into my '87 300d, I see a need for a tighter drivetrain. Are there any aftermarket or OE alternatives to the stock motor mounts?
Anybody here ever play with casting poly?
raysorenson
08-22-2012, 08:41 PM #2Now that I think about it, the diff mounts probably allow more drivetrain rotation than the engine mounts. The diff mounts are very close together on a W124, which means that for a given amount of bushing deflection, the corresponding amount of rotation should be higher than for other drivetrains with diff mounts situated farther apart. In the absence of any aftermarket options for diff mounts, the best plan is to melt or burn the rubber out of stock mounts, clean up the metal and pour in some poly.
Anybody here ever play with casting poly?
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
08-23-2012, 09:01 AM #4Or have some made up from delrin
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
raysorenson
08-23-2012, 01:21 PM #5I'll see if I can dig up a pic of the V8 subframe on the intarweb to see what you're talking about.
(08-23-2012, 09:01 AM)Simpler=Better Or have some made up from delrin
2 problems with delrin,
1, too hard. It would probably rock for a track car
2, you can't cast it, so you would have to trust it to not slip around inside the subframe, which is designed to accept a bushing with a metal sleeve that press-fits in.
I've done some research and found THIS wonderful post on a Scoobaru forum. Great read if you're interested in doing some bushings.
I think I've decided on shore 80A hardness. The above NASIOC post mentions that fresh stock bushings vary in hardness from 60-70A but the W124 rear diff bushings have an air gap cast into them, effectively reducing the overall hardness of the bushing, so my thinking is that shore 80A will be a pretty major increase in stiffness. I'm also thinking about using the left over urethane to fill the voids in some rear subframe bushings to add to their durometer.
raysorenson
08-24-2012, 06:59 PM #6(08-23-2012, 09:01 AM)Simpler=Better Or have some made up from delrin
2 problems with delrin,
1, too hard. It would probably rock for a track car
2, you can't cast it, so you would have to trust it to not slip around inside the subframe, which is designed to accept a bushing with a metal sleeve that press-fits in.
I've done some research and found THIS wonderful post on a Scoobaru forum. Great read if you're interested in doing some bushings.
I think I've decided on shore 80A hardness. The above NASIOC post mentions that fresh stock bushings vary in hardness from 60-70A but the W124 rear diff bushings have an air gap cast into them, effectively reducing the overall hardness of the bushing, so my thinking is that shore 80A will be a pretty major increase in stiffness. I'm also thinking about using the left over urethane to fill the voids in some rear subframe bushings to add to their durometer.
![[Image: SANY1030.jpg]](http://i139.photobucket.com/albums/q316/Ochlockonee/Car%20stuff/SANY1030.jpg)
Diff mounts with rubber removed by soaking in acetone for a few days. The rubber came out with little fuss. Toluene probably would have worked better but it appears that Home Depot quit carrying it. I also poured some in the cavities of W123 and W124 subframe mounts. Hopefully this will prevent my GF's wagon from exploding the instant I install sedan mounts in her subframe.
I'm hoping for minimal NVH issues from the rear diff mounts and that the urethane holds up.
raysorenson
09-03-2012, 04:09 PM #7
Diff mounts with rubber removed by soaking in acetone for a few days. The rubber came out with little fuss. Toluene probably would have worked better but it appears that Home Depot quit carrying it. I also poured some in the cavities of W123 and W124 subframe mounts. Hopefully this will prevent my GF's wagon from exploding the instant I install sedan mounts in her subframe.
I'm hoping for minimal NVH issues from the rear diff mounts and that the urethane holds up.
![[Image: subframe1.jpg]](http://www.w124performance.com/images/W124_subframe/subframe1.jpg)
I see the front pinion mount brace has changed. I can't see what the rear mounts look like, which I suspect to be the source of the majority of the drivetrain slop.
raysorenson
09-09-2012, 08:44 AM #9Ahh... blurry photographic evidence;-)
I see the front pinion mount brace has changed. I can't see what the rear mounts look like, which I suspect to be the source of the majority of the drivetrain slop.
I'm going to see (and report on) how the shore 80A urethane diff mounts do in the 6 cylinder subframe.
raysorenson
09-10-2012, 12:28 PM #11Thank you. That appears to be a big improvement over the I6 subframe/diff mounts. I'll have to keep this in mind in case I run into a V8 parts car.
I'm going to see (and report on) how the shore 80A urethane diff mounts do in the 6 cylinder subframe.
Now the issue is longevity. I'll post as soon as an issue arises. If I don't post, then that's a good thing.
raysorenson
09-28-2012, 12:31 PM #12I just removed new stock rear diff mounts and installed the home made poly bushings. The drivetrain feels much tighter now. It's much easier to drive at slow speeds in low gears without jerking. No notice able increase in NVH and possibly a slight decrease in the low rpm vibration that's more prevalent in higher gears that some might call "engine lugging".
Now the issue is longevity. I'll post as soon as an issue arises. If I don't post, then that's a good thing.
Here's where I got it: http://www.smooth-on.com/Urethane-Rubber...index.html
It looks like I'm gonna try this stuff next in probably a shore 60D.
http://www.smooth-on.com/Urethane-Plasti...index.html
If it's too harsh I can just pop the other ones back in.
![[Image: durometer.gif]](http://www.mcmaster.com/param/inline/rubberfoam/durometer.gif)
Shore 80A may be too soft, shore 60D is up next!
raysorenson
11-12-2012, 11:03 AM #14I used the PMC 780 pourable casting urethane shown in the pics. And, judging by the photographic evidence, I used shore 80, not shore 70.
Here's where I got it: http://www.smooth-on.com/Urethane-Rubber...index.html
It looks like I'm gonna try this stuff next in probably a shore 60D.
http://www.smooth-on.com/Urethane-Plasti...index.html
If it's too harsh I can just pop the other ones back in.
Shore 80A may be too soft, shore 60D is up next!
With the stock diff mounts in there and a manual trans, I would call driveline tension and frequency a flat out mistake. A dump truck would be tighter. The shore 80A urethane mounts were an improvement for a while, then they got a little softer. The springiness became an irritating issue. The stock mounts had air pockets cast into the rubber and were clearly designed to collapse under driveline wind-up. This allowed spongy slop on driveline engagement and torque reversal, but once the diff twisted up and the mounts collapsed, they were virtually solid mounts. The shore 80A mounts that I cast would not collapse and had plenty of spring. Too much.
The 80A mounts looked good when I removed them. I ordered their toughest industrial use poly and it looked as good as it did the day I cast it. No cracking, splitting, chunking or swelling. One thing did happen though. The inner part of the mount was no longer bonded to the urethane and you can now slide them out. Structurally, I don't see this being a problem, the mounts should last indefinitely like this. However, I think this is the reason that the 80A mounts got springier over time. With the inner metal part of the mount bonded to the urethane, there would be shear forces on the urethane that aren't there with the center of the mount just pressed in.
raysorenson
12-12-2012, 06:05 PM #15I popped the shore 60D mounts in today and I like 'em! The frequency of the drivetrain has increased and I don't have that springy herky-jerky thing as bad as before with the 80A durometer diff mounts. NVH hasn't become an issue, noise is not coming through the driveline into the cab. I suspect you could just fill them with hard plastic (60D is almost hard plastic, but not quite there) and you'd be fine since the subframe isn't solid mounted to the body.
With the stock diff mounts in there and a manual trans, I would call driveline tension and frequency a flat out mistake. A dump truck would be tighter. The shore 80A urethane mounts were an improvement for a while, then they got a little softer. The springiness became an irritating issue. The stock mounts had air pockets cast into the rubber and were clearly designed to collapse under driveline wind-up. This allowed spongy slop on driveline engagement and torque reversal, but once the diff twisted up and the mounts collapsed, they were virtually solid mounts. The shore 80A mounts that I cast would not collapse and had plenty of spring. Too much.
The 80A mounts looked good when I removed them. I ordered their toughest industrial use poly and it looked as good as it did the day I cast it. No cracking, splitting, chunking or swelling. One thing did happen though. The inner part of the mount was no longer bonded to the urethane and you can now slide them out. Structurally, I don't see this being a problem, the mounts should last indefinitely like this. However, I think this is the reason that the 80A mounts got springier over time. With the inner metal part of the mount bonded to the urethane, there would be shear forces on the urethane that aren't there with the center of the mount just pressed in.
![[Image: 12885392910171700624180.jpeg]](http://www.ringer-racing.com/images/12885392910171700624180.jpeg)
http://www.034motorsport.com/chassis-com...p-772.html
It has the same unloaded 4" height as the stock motor mounts and mounts with 2 8mm studs. I will not be installing one on the LH side without modifying it as it does not have the tensile strength the stock mounts have. The RH side gets compressed under accel. The only tensile forces the RH side sees is while backing or engine braking.
raysorenson
02-16-2013, 09:14 AM #16I installed an 034 Motorsport "density line" motor mount for a B5 Audi/VW on the RH side. It has reduced the nuisance "trailer hitching" significantly. Vibration at idle is not significantly increased. My S.O. didn't notice anything. I measured a 6 HZ .3g vibration at idle with the stock mounts, I'll measure again with the VW mount after I decide what to do about the LH mount.
http://www.034motorsport.com/chassis-com...p-772.html
It has the same unloaded 4" height as the stock motor mounts and mounts with 2 8mm studs. I will not be installing one on the LH side without modifying it as it does not have the tensile strength the stock mounts have. The RH side gets compressed under accel. The only tensile forces the RH side sees is while backing or engine braking.
Theese guys do engine mounts for merc`s! Make them as hard as you want.
HaavardPYA
05-30-2013, 01:13 PM #17http://www.flenstadtekniske.com/produkter.htm
Theese guys do engine mounts for merc`s! Make them as hard as you want.
(08-22-2012, 09:06 PM)aaa Transplant the v8 subframe. Totally different diff mounting.
that also requires a swap to a larger diff...as I discovered last week... the diff cover is totally different between the small and large diffs...luckily the early 90's 300e has the proper 2.65 ratio in the larger 210mm diff...just had to swap over the input flange to the larger 300D/W126 style...and even more fortunate I was able to find one in a local yard...
I had to rig up an "adapter" between my stock 185mm diff and the V8 subframe...which then pushed my driveshaft about 3/4" too far forward and exacerbated a previously undiscovered missing/deteriorated rubber center support bushing and causing the driveshaft to rattle around and vibrate like crazy... then the local parts stores could no get the rubber bushing/bracket (even on special order) so I had to hit up a part yard to get a used one...
anyway, long story slightly shorter: I finally was able to cobble up enough parts to get me back down to San Diego where I could get the proper diff I needed...
But, the V8 subframe, 400E springs, front brakes (and rears later this week) are in and I should finally be able to take the old beast down for an alignment next week and put my new rims/tires on...
W123 Mods: 4 speed ** manual climate control ** '85 Kalitucky intake ** manual windows & full tint ** Euro headlights retrofit w/bixenon projectors ** 4 brake light mod ** Vogtland 50mm drop front & Lesjofors S600 drop rear springs ** 16" rims ** late w126 brake spindles, rotors & calipers ** full suspension rehab ** Bilstein HDs ** AL129X alternator & 1/0 starter and charging cables ** 300GD clutch/flywheel ** AFCO 80103N radiator & Earl's 41610 oil cooler ** custom block-off plate, remote oil filter & t-stat ** MW IP w/ tomnik's 6.5mm 'Holly' elements **
S124 Mods: 400E Rear subframe ** SL600 Brakes ** Late 300E 210mm diff ** SLK230 6 speed ** 17" CLK rims ** Vented RF Fender ** Facelift Hood, Headlights, and Lower Cladding **
OBK# 62
SurfRodder
06-04-2013, 09:51 PM #18(08-22-2012, 09:06 PM)aaa Transplant the v8 subframe. Totally different diff mounting.
that also requires a swap to a larger diff...as I discovered last week... the diff cover is totally different between the small and large diffs...luckily the early 90's 300e has the proper 2.65 ratio in the larger 210mm diff...just had to swap over the input flange to the larger 300D/W126 style...and even more fortunate I was able to find one in a local yard...
I had to rig up an "adapter" between my stock 185mm diff and the V8 subframe...which then pushed my driveshaft about 3/4" too far forward and exacerbated a previously undiscovered missing/deteriorated rubber center support bushing and causing the driveshaft to rattle around and vibrate like crazy... then the local parts stores could no get the rubber bushing/bracket (even on special order) so I had to hit up a part yard to get a used one...
anyway, long story slightly shorter: I finally was able to cobble up enough parts to get me back down to San Diego where I could get the proper diff I needed...
But, the V8 subframe, 400E springs, front brakes (and rears later this week) are in and I should finally be able to take the old beast down for an alignment next week and put my new rims/tires on...
W123 Mods: 4 speed ** manual climate control ** '85 Kalitucky intake ** manual windows & full tint ** Euro headlights retrofit w/bixenon projectors ** 4 brake light mod ** Vogtland 50mm drop front & Lesjofors S600 drop rear springs ** 16" rims ** late w126 brake spindles, rotors & calipers ** full suspension rehab ** Bilstein HDs ** AL129X alternator & 1/0 starter and charging cables ** 300GD clutch/flywheel ** AFCO 80103N radiator & Earl's 41610 oil cooler ** custom block-off plate, remote oil filter & t-stat ** MW IP w/ tomnik's 6.5mm 'Holly' elements **
S124 Mods: 400E Rear subframe ** SL600 Brakes ** Late 300E 210mm diff ** SLK230 6 speed ** 17" CLK rims ** Vented RF Fender ** Facelift Hood, Headlights, and Lower Cladding **
OBK# 62
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