when i accelerate my car shakes at around 4k rpm. fixed my axles and had new wheels and stil lthe same problem but a little reduced. can it be my torn motor mounts? should i buy new stock motor mounts?

 

i doubt its the motor mounts.

usually i would say to have your tires balanced, but you said they're new.. (asuming they spin balance them).. you might want to rotate the fronts to the rear, and see what happens, its just for good measure.. i know some tires cancell out at different speeds, so it could be possible still.

and it being under acceleration, i would guess your drive axels.. but those are new.

3rd, i would look into your susspension bushings. get your car in the air, and use some channel locks, and start jaring some suspension bars around, and check all your bushings.

 

I won't argue against Built B16A, but I would personally say that considering what you have fixed/replaced so far, that it's a good idea to check out your motor mounts.

About six months ago, on my 92 teg, I started getting a vibration anytime I was on the gas, especially noticable at higher RPM, or when on the highway and accelerating moderatly without downshifting from 5th. I immediatly thought axle(s), specifically the inner CV joint. I replaced both axles (and balanced my tires), and it went away. About one month later, the exact problem came back.

I checked out my motor mounts, and the side ones (tranny and t belt side) weren't too bad. But the rear one was trashed, basically ripped in two. This allowed my engine to rotate front/back anytime I got on the gas.

Gave me an excuse to buy these


Innovative Mounts kit for 2nd gen teg. Def worth the money, lifetime warranty. Night and day difference after installing them.

Back to the topic though, after installing them, and replacing both axles again, it's been months and the reoccuring problem of vibrations hasn't come back.

Check into the condition of your mounts

-- Kevin

 

my first gut reaction would have been uneven wear on a certain tire that's accentuated when you're driving faster... but you mentioned you got new tires. like other said, check bushings, check motor mounts

 

Not to jack your thread, but when i get on it and let off the gas real quick i feel like the engine is slamming back at me. Is this normal or could it be a bad mount?

 

today i went to a mechanic to have them inspected the car.. they said it has nothing to do with my motor mounts that causes vibration. they said they are %85 sure i need another axles when i already told them i just had them done a week ago. they also said if i raise my car a lil then the vibration might go off. now im stuck and dont know if i should listen to them and buy new axles and change them all over again?

 

They are saying that bad motor mounts could never cause vibration? Did they even check them? That rear mount isn't exactly the easiest thing to inspect/see...and if they are 85% sure it's bad axles, which you just replaced, what did they say the other 15% chance is?

Say what you want but that sounds shady. Tell them if they are so confident it's the axles, to go ahead and do them. But if they are wrong, make sure they'll be willing to pay/figure out whatever actually IS wrong. I admit that sure, an axle could be bad right out of the box (rare), maybe more so if it's a reman. But as how you described it, it doesn't sound like the problem changed much at all when you put the new axles in.

More info/details on the car. Year, mileage, mods, driving habits (beat the **** out of it or be-nice-to-it daily driver...). I still vote engine mounts, I don't think they even bothered to look at them.

-- Kevin

 

did they check the motor mounts?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b62pteg#2 &raquo;</TD></TR><TR><TD CLASS="quote">They are saying that bad motor mounts could never cause vibration? Did they even check them? That rear mount isn't exactly the easiest thing to inspect/see...and if they are 85% sure it's bad axles, which you just replaced, what did they say the other 15% chance is?

Say what you want but that sounds shady. Tell them if they are so confident it's the axles, to go ahead and do them. But if they are wrong, make sure they'll be willing to pay/figure out whatever actually IS wrong. I admit that sure, an axle could be bad right out of the box (rare), maybe more so if it's a reman. But as how you described it, it doesn't sound like the problem changed much at all when you put the new axles in.

More info/details on the car. Year, mileage, mods, driving habits (beat the **** out of it or be-nice-to-it daily driver...). I still vote engine mounts, I don't think they even bothered to look at them.

-- Kevin</TD></TR></TABLE>
the mechanic checked the motor mounts and said its not possible that the mounts are causing vibration even though it is torn because worn motor mounts only make the motor goes up and down.. not vibrating when accelerating at higher RPMs... now i am stumped thinking if i should buy a new pair of axles or go against them and buy new stock motor mounts?? hmmmmmmmm

 

Think about this. YOur vibration occurs at 4K engine RPM. It does not matter what speed you are going, so it CANNOT be tires, rims, axels, or anything that rotates. These things depend on the speed of the car, NOT the speed of the engne. If you have out of balance rims, you get a vibration at 60mph, not at a certain engine speed.

So this leaves you with motor mounts as the best guess. If it is not that, I would look into if the engine is running "smooth" as it goes past this RPM- it may be roughness in acceleration instead of what you feel.

Just my thoughts. I do not think it can be the items everyone is suggesting, excepth for motor mounts. What year and milage on the car?

 

VTECcnIT -

I think you need to find another mechanic man. I actually started laughing when I read your post, in regards to what he told you.

Now I'm not saying I'm Mr. know it all, but I'm a mechanic at the local Acura dealership, and I went to school for auto tech. And one of my friends, who is also a mechanic (for VW), was here when I read the post. Like I said, we both got a good laugh. You're mechanic admitted to seeing the torn and worn motor mounts, and told you that doesn't have ANYTHING to do with the vibration?!...

Like I said in my very first post, as well as every single post thereafter, find out the actual condition of your motor mounts. If they are indeed bad, check into some new ones. Either OEM, aftermarket, or that quick cheap fix some poeple are doing. And you still didn't answer my question in my last post a bit ago about age/mileage/condition/driving habits of your car.

So yet again, I say, check the motor mounts.

-- Kevin

 

how would one go about checking all mounts and where would one look...im having a similar prob with my car....

 

thanks for reply guys as for my car.. i recently swapped in a 94 JDM b18c fresh motor in my 94 DC2 and the vibration starts coming into play. right after the swap, it felt smooth untill one day my balljoint stripped and was broken down in the freeway. ever since then, my car vibrates under accell.. im getting new motor mounts anyways.. hope this helps.. to the mechanic that replied to my post.. does worn out motor mounts make the car vibrate at high RPM?

 

Cosmo -

Inspect your motor mounts by putting your car in gear, keeping on the brakes, and giving the engine gas. This obviously puts stress on the mounts. To check their condition, simply look how much the engine moves. If your mounts are in good/decent condition, the engine should flex front/back very little. There's not an actual set amount (i.e. like 1-2" or something like that). But there should be little movement. Do this test in both reverse and a forward gear.

Then of course visually inspect the mounts for seperation/rips/tears/deterioration/etc. Also physically feel them to make sure they haven't become brittle/hard. If you find any that are damaged, as I said earlier, your choices are many. Either replace with OEM, or aftermarket. Or buy used, or fill in the old ones (if enough original is there, more info can be found by searching).

IMO, it's best to just replace all at once, assuming your car is older (like mine was). 248k miles hadn't been kind to any of the mounts, especially with my driving. Like I said earlier, gave me a good excuse to get the set in the pic above

VTECcnIT -

Yes, worn out mounts can cause high RPM vibration. Is it the only thing that could cause it? No, but it def can cause it. In my original first post, you'll notice what I said my symptoms were (here's a copy and paste so you don't have to scroll up):

"About six months ago, on my 92 teg, I started getting a vibration anytime I was on the gas, especially noticable at higher RPM, or when on the highway and accelerating moderatly without downshifting from 5th. I immediatly thought axle(s), specifically the inner CV joint. I replaced both axles (and balanced my tires), and it went away. About one month later, the exact problem came back."

Now like I said, given what you've already fixed, motor mounts def seem like a good starting point. Add to that your "mechanic" already admitted that your current ones are in shoddy condition...

Now I'm trying to figure out if your ball joint breaking caused any of this, or if it is behind the vibration itself (due to some sort of other damage caused by the ball joint breaking). At this point though, given all the other info, I am def still leaning towards your engine mounts. Now like I said, even if you replace your mounts, you still might have to through another set of axles on. Again, from my original post, bad motor mounts can cause bad axles, specifically the inner CV joints. This causes vibration (more noticeable on acceleration).

Lastly, and real quick, make sure your engine itself is aligned properly. Knowing now, since your last post, that you did an engine swap, there is a chance that your engine isn't lined up, and therefore not actually sitting straight. This could cause a vibration as a result (or cause the bad axle(s), but I don't see it very often as a cause.

Good luck with everything, and keep me posted. I'de like to know what the problem ends up being. Oh, and if you plan on replacing the mounts yourself, the rear one is a bitch!

-- Kevin

 

thanks for replies b62pteg#2 i will be replacing new motor mounts soon and im hoping the vibration will go away.. and also.. do u think its necessary to raise the 2 front wheels a little so the axles can sit straighter? do u think itll stop vibrating this way?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rtzx9r &raquo;</TD></TR><TR><TD CLASS="quote"> These things depend on the speed of the car, NOT the speed of the engne. If you have out of balance rims, you get a vibration at 60mph, not at a certain engine speed. </TD></TR></TABLE>

like i said.. did we try rotating the front wheels to the back yet?

 

Built -

But your question doesn't make sense. You quoted Rtzx9r, but his statement agrees/suggests checking engine mounts. Because indeed, it occurs at a certain RPM, not a certain speed. Additionally, VTECcnIT goes on to say it occurs under acceleration. Out of balance wheels would cause it happen whenever they are rotating, whether your accelerating at 20mph WOT or at 70mph WOT.

Not to mention the fact his mechanic has already admitted that his engine mount(s) are torn/in poor condition.

Given all of VTECcnIT's posts, I'm still leaning towards mounts. For the sake of it, VTECcnIT, if you want to ahead and please everyone, try rotating the tires front to back. See if this fixes it, and let us know. I said before by no means do I know it all. But the symptoms, and items already replaced/fixed, is basically a duplicate of my problem I used to have.

Oh and VTECcnIT, you asked about raising the front wheels a little? Do you mean as in you have adjustable coilovers, that you can change the drop? If so...I guess technically raising it back closer to stock height isnt going to hurt. That is another thing that can damage axles, is (extreme) lowering of a car. But I've been driving around on 1.5" front 1.8" rear drop for two years now and that never affected my axles. But if you're slammed 4" or something, yes, that could affect them.

-- Kevin

 

trust me.

why do american engines have harmonic balancers? because the engine isnt' balanced? of course its balanced, but at some RPM's it can cause vibration. a wheel can be balanced on a machine and some shops will get it "close enough" within 1/2 an OZ. and clall it good. for the most part, to you, a driver around town, its balanced.

but on the freeway at a higher speed, it will vibrate. ive had wheels vibrate at a certine speed. once a 60, and once at like 75. they were both off very minimally.

like i said.. rotate your tires.. its free, and worth a shot.

 

ok.. we know this is happening at 4K.. is this 4K in every gear, or just 4K in 5th? which would make it a 70, 80 MPH?

i'll agree that if its 4K RPM in every gear, there is something out of balance, either it be a axle, crankshaft, mounts...

if its 4K RPM every gear, i think we can rule out wheel bearings.. it would do it most of the time.

my suggestion on the wheel balance is a RPM range related directly to MPH. so say a 60-70 MPH range. a wheel can be slightly out of balance, even BENT.. and only vibrate in a certin vehical speed.

 

i take it one way or another, we solved our problem?