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What to do- people with solid motor mounts check in!

12K views 45 replies 23 participants last post by  CoolAid 
#1 · (Edited)
Was having issues with Kooks headers clearing my steering column. Specifically vibration against the shaft at idle and in any gear at 1000-1400 RPM and like 10% throttle. Anyway, not the issue, keep reading.

I had it in the shop to see if they could find some room in there so things aren't banging around. They looked at it, basically told me the only real thing to do was put in new motor mounts. Same recommendation from Marylandspeed. So I said fine, I'd go ahead and order the mounts. Picked the solid Ultra mounts. I know I know, solids in a daily driver = :nono: I figured the big jump was going from stock to poly, and poly to solid should not be that big a difference. Plus they were cheaper, and I've seen too many pictures of failed poly mounts, so win win win right?

Shop called today and said they fixed the clearance issue. :facepalm:
So now I have these solid mounts that I don't need. Reading everything I could about them online though I still would like the benefits that they do offer. I already have them, and got quoted only $160 to put them on where they did my headers.

I am not too worried about the extra vibration through the car, as far as physically feeling them is concerned. I have the stock cam so I don't think it'd be too bad. My concerns and questions for everyone with solid mounts are:

1. Has the added strees/vibrations affected the long term reliability of the car? I'm talking over thousands of miles, multiple years. Stuff shaking loose that shouldn't?

2. I think I can deal with the extra shaking. I do not want extra rattles and sounds though. This will definitely annoy me. Feeling it in my ass is one thing. Constantly hearing it is something else. So did interior of the car eventually become a maraca?

3. I haven't found a definite answer regarding the extra shaking affecting our knock sensors. I would think it wouldn't because the engine isn't shaking at all anymore, but who knows. Anyone have this become an issue?


Ok, so all who have lived with solid mounts and like them or had them for 2 weeks and took 'em out, let me know. I'm leaning towards putting them in, as long as 1, 2, & 3 won't (likely) happen.
 
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#3 ·
It took two people 45 mins to change my mounts to the Ultra Poly mounts. That was without a rack. Jacking up the engine, change the mounts, lower engine. $160 to change your mounts is ludicrous. I can see one hour of labor max. A shop that knows what they are doing should take 30 mins or less. I wouldn't run the solid without having a better trans mount.
 
#6 ·
Haha, I'd like it to be that easy. People doing it themselves with everything under there said it takes them about 6 hours, without a lift. I talked to the people at Creative Steel and they said it usually takes 3-4 hours at a shop. Book rate to do mounts with stock manifolds is 2 hours and that's what my quote was.

You can't run solid mounts on the street.. They will cause things to crack over time and are "race only".
O'rly? I've only put 20k miles on mine... when should I expect this cracking to start to occur?... and where?



:rolleyes:
See, that's what I'm talking about. I know convention says do not put solids in a street car. But people are doing it, with what seems like no detrimental effects on the car, only personal preference. There seem to be a fair amount of people running solids on street cars, so I would think someone would say something about issues they have actually run into.

I understand what is supposed to happen and why they are considered a bad idea, but reality seems to be differing.

As far as mixing with trans mounts, I've heard as long as you stay rubber or poly with solid engine mounts either is ok. Just don't go all solid!
 
#21 · (Edited)
Said they just slid the rack over, which is what I told them to try when I brought it in. They didn't believe me until they actually did it.

I can't speak to if they are exactly the same as stiffer mounts for flex but I can say that they drastically dampen torquing. I went thru a lot of intakes developing the SS OTR intake and some of them were very close to the hood. The Stiffy kept them from touching the hood under track condition launches when an engine normally jumps all over the place. The LS2 heads have the same mounting point. In fact I have 243 heads on it now. It has to do where the Stiffy mounts on the body on LS2s.
Cool beans. I'll have to look into this. Helped with shifter feel and throttle response as well? That's what I'm really trying to get after. My shifter is is terribly clunky. I almost have to stop and push it past neutral each shift, or else I feel like I'm beating on it. Anyone want to trade a stiffy for solids then?

solids are surprisingly reasonable on the street...however there will be some vibration into the cabin and you may find female passengers a bit 'hot and bothered' from the vibrations.

if you drive normally you wont notice it past 1500rpm...but round there or lugging the engine it will vibrate pretty badly.
Haha, yeah when I told my gf about these and what it'd do she was not too excited about riding in the car anymore. I don't think she thought it all the way through though...l

So if I try to spend most of my time cruising at 1200-1800 RPMs, other than accelerating, I probably want to look into something else then?

I'd also make sure you go solid trans mount as there is driveline flex in the driveshaft inherently built in via the couplers.
putting solid engine mounts and allowing the trans to flex is asking for something to break, you cant have one thing solidly mounted and the other a flexy mess and expect it not to snap something.

its very easy to modify the stock trans mount to convert it to a solid mount, some plate steel and a welder is all you need.
I've heard both ways regarding this, more saying to keep a rubber/poly mount though. My understanding: the transmission is bolted to the engine, and if the engine isn't moving how is the transmission going to move? Also, with stock motor mounts the engine and transmission were already moving, so wouldn't that be a problem already?

I guess the argument against it is with stock mounts all around the motor/trans were moving in unison. Hold one side still and not the other, one side will flex and eventually break? I wonder how much force is actually being put on the end of the transmission case.

Have you sat in a GTO with solid mounts as it runs through the gears? Sits at a stop light? Gets driven around like a grandma is behind the wheel?

Someone in this thread has.
^^^THIS^^^ I'm not saying people who say you should not put solids in a street car shouldn't post, on the contrary. I just want actual scientific-ish results from people who have actually done it, or at least experienced one and found it to be a deal breaker. Let's keep it civil though, I want good discussion here.
 
#11 ·
Maybe. Nothing a little prune juice couldn't fix.
 
#13 ·
OP, you are in luck. You have an '04 and we can get the Ingalls Stiffy engine torque dampener. I have one and it gives absolute stock idle and cruise feel with dampening of any engine movement under torquing conditions. The best of both worlds. They don't fit '05-'06s. Love mine.

 
#14 · (Edited)
Looks good, does it provide as much resistance to flexing as stiffer mounts would? I'm afraid to ask, what if I have 243 heads on, does that mean I can't use it? Or is the LS2 block in a different place relative to where this would want to mount to?
 
#15 ·
$160 labor sounds right.

80 an hour x 2.

Mechanics make money by beating the labor time.

Tools ain't free
Lifts ain't free
Nor is time

I wouldn't pay 160 either, because it takes me a half hr to slap them in on the ground.
 
#17 ·
solids are surprisingly reasonable on the street...however there will be some vibration into the cabin and you may find female passengers a bit 'hot and bothered' from the vibrations.

if you drive normally you wont notice it past 1500rpm...but round there or lugging the engine it will vibrate pretty badly.
I'd also make sure you go solid trans mount as there is driveline flex in the driveshaft inherently built in via the couplers.
putting solid engine mounts and allowing the trans to flex is asking for something to break, you cant have one thing solidly mounted and the other a flexy mess and expect it not to snap something.

its very easy to modify the stock trans mount to convert it to a solid mount, some plate steel and a welder is all you need.
 
#18 ·
I'll go ahead and say it, you are retarded if you want to put solid motor mounts on anything other than a race car.
 
#19 ·
Happily retarded then.
 
#22 ·
I'm in on this too..would love to hear some more reviews..I won some Poly Mounts in a raffle at a GTO Meet this year and have been debating whether or not to put them in..I have a cam though so I know its going to be a lot more shaky HaHa
 
#23 ·
Solids are like anything, some people like them and don't, preference is fine. But to say they are dangerous or stupid, well that's just ignorant. I can barely tell they are in there. Never has a passenger complained about it shaking (it doesn't) or vibrating (it doesn't). Maybe if your engines ran right you wouldn't notice a bunch of vibrations and shit. :dunno:

I have no doubt by removing some of the "shock absorbing" features out of the equation might put more stress on certain parts, but if we all made decisions based on that logic alone we'd never modify our cars.
 
#26 ·
I have poly MMs and the most notable vibrations are at engine idle (even when clutching in in parking lots, etc) and if accidentally slipping the clutch too much. There might be some vibes at cruising, but my suspension is stiff, so it is hard to tell. I would never do solids.
 
#29 ·
The Stiffy is cake to install. Whatever you do take the advise to match your tranny mount to whatever you do. Solid motor mounts to solid tranny mount or whatever. I did the Window Weld mod to my tranny mount and it mates up very well with the Stiffy. Take a good look at the Ingalls. It is a very good solution and you won't notice any difference in normal driving with it at all but a noticeable difference when you need it..
 
#30 ·
Whatever you do take the advise to match your tranny mount to whatever you do. Solid motor mounts to solid tranny mount or whatever...
That is absolutely wrong. If you mount the transmission solid along with solid motor mounts you will crack your transmission case starting from the tailshaft housing foreward. Even with front and mid motor plates hard core racers use stock rubber mounts on the transmission do to chassis and driveline flex. I did as well for many years racing my Nova in the 5.80 then 5.20 index class.
 
#37 ·
15k miles with solid mounts (engine and trans) with Maggie torque and nothing has cracked. In order for something to crack it has to twist or hit something and neither is feasible unless I go all dukes of hazard on it... Any twist is going to be extremely minute...

What first hand experience do you have with this cracking you talk of? This is the first time I have seen someone feel so strongly in the this regard...
 
#33 ·
Apparently some flushing is required. At least a little plunging. Svede is obviously a very reputable individual and thinks otherwise, and he's not the only one. I have no first hand knowledge, but I do agree that one should stay away from true solid trans mounts. Is my explanation above on the right track, or are there other forces at play here?
 
#34 ·
For the most part, yes. Chassis flex is the main reason for this as there is no chassis that is 100% flex free, but there is some driveline flex as well. Svede is a very good and reputable guy, but the only people I have ever heard that have said to use solid transmission mounts have zero first hand experience with the issue.
 
#44 · (Edited)
As long as your transmission mount gives more than your engine mount, you will be fine. The problem lye's in the fact that when you have body flex (and you will) and your drive-line is 100% fixed, the only way for your drive-line to flex along with the body is for the bell-housing, mid case, transmission case, and tail-shaft housing to bend and flex. This is not something new. It has been known for a VERY long time.

15k miles with solid mounts (engine and trans) with Maggie torque and nothing has cracked. In order for something to crack it has to twist or hit something and neither is feasible unless I go all dukes of hazard on it... Any twist is going to be extremely minute...

What first hand experience do you have with this cracking you talk of? This is the first time I have seen someone feel so strongly in the this regard...
Great... Glad you haven't had any issues yet. Doesn't mean its not stupid wrong.

As for experience. I used to run a 66' Nova in a 5.80 1/8th mile index class. I, at this point hadn't even heard of this issue before. I cracked my power glide case about 30ft off of the line, and spit all it's hard parts on the track. I learned this lesson the hard way. Its up to you how you want to learn it. Good luck! :)

Here is another thread about this same issue that is more recent if you don't want to take it from me. http://www.ls1gto.com/forums/showthread.php?t=434294
 
#40 · (Edited)
Not interested in Miss Daisy stuff. My car already shakes/vibrates/rattles violently from the giant cam and straight through exhaust with circle track mufflers.

If solids have the better performance than solid it is. Shaking/vibrating/rattling more is actually a bonus to me. I enjoy the Parkinsons effect at a stop light while the car belches out fumes of unburnt fuel from its monster lopey overlap. To me, thats muscle car.
 
#41 ·
Shaking/vibrating/rattling more is actually a bonus to me. I enjoy the Parkinsons effect at a stop light while the car belches out fumes of unburnt fuel from its monster lopey overlap. To me, thats muscle car.
I've been looking for a new quote... this wins :D
 
#45 ·
I only read about half of this thread, with that said.

Hinson motor mounts, Nice and solid... great feel after they were installed.
Nearly 100% stock feel.
Only vibration i can get is if i rev it up in N to about 1500 rpm... if im in a gear i get absolutely no added vibrations at any rpm.
 
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