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Horrible drivetrain vibration


ColdScrip
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This has plagued my restored car since it has been on the road. I don't care what it takes I want this gone.

 

Problem: Excessive drivetrain vibration.

 

Present primarily under two conditions:

1. Low speed high gear: 10MPH-3rd Gear, 20MPH-4th Gear, etc.

2. At highway speeds in 4th or 5th gear: 55+ MPH

 

I have control of the vibration! - For example:

 

1. 10MPH-3rd Gear: If I push the gas pedal down slightly it has some vibration but not much. If I put the pedal to the floor the vibration shakes the entire car to the point you want to pull over immediately. This is rediculous violent shaking.

 

2. This applies through the gears as long as its in a gear that is too high for its speed as shown above (20MPH-4th Gear, etc.)

 

3. At highway speeds in 4th or 5th gear: 55+ MPH : I also have control of the vibration in this situation based upon how much I push the gas pedal down.

 

As a result it seems that if there is a lot of load on the drivetrain (whether its high gear low speed, or the high load of higher speeds) that the vibration is a direct result of the load.

 

Also: if I am going 55+ highway speeds and of course the vibration is there, if I put it into neutral the vibration goes away as the motor returns to idle RPMs.

 

Currently I have swapped out driveshafts and the issue did not change. My clutch was re-used from the previous owner, I do not remember it having springs but it wasn't a 6 puck.

 

Also I noticed that I used my new poly bushings with the old bushings that sits above the large cylinder shaped bushings of the rear subframe. I later learned that only one or the other should be used. As a result they are really smushed and perhaps causing that part of the subframe to be a slight bit lower. Hard to say if it is a slight bit lower let alone if it would even cause this issue.

 

If you guys can follow me through this that would be great. If you tell me to swap trannys and clutches then I'll do it...I just want this gone. Thanks all.

 

Edit: New stock motor mounts, new stock tranny mount, new stock OEM rear diff mounts.

Edited by ColdScrip
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sounds like something is loose. or something is flexing under load to make the driveshaft **** to one side causing the vibration. open the hood, engage the e-brake, give er some gas and slowly let out the clutch.. this will load the drivetrain, only do it for a second or two. have someone watch the engine to see if it cocks to the side or twists in the engine bay. this would be my first step.
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sounds like something is loose. or something is flexing under load to make the driveshaft **** to one side causing the vibration. open the hood, engage the e-brake, give er some gas and slowly let out the clutch.. this will load the drivetrain, only do it for a second or two. have someone watch the engine to see if it cocks to the side or twists in the engine bay. this would be my first step.

 

Sounds like a dangerous test for my hood and the guy in front of it..

 

Love the something loose idea though. Going to check mount nuts and bolts for sure.

Edited by ColdScrip
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a joint almost falling out can cause this , or one so lock'd up it don't want to rotate the drive shaft,, i'd drop the shaft and inspect them,,along with the rear diff mounts

 

any engine vibration will still be there in neutral just reving the engine , unless the trans is not bolt'd to the engine :)

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Driveshaft has new U-joints, also replaced it with another driveshaft just to see and no difference.

 

Checked rear mounts, they are new OEM ones with no issues. (Literally checked them 2 days ago)

Edited by ColdScrip
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Sounds like a dangerous test for my hood and the guy in front of it..

 

Love the something loose idea though. Going to check mount nuts and bolts for sure.

lol, if you use the prop rod and don't let the car move it's not dangerous. almost as if your testing the parking brake. not enough to move the car. It's also the easiest way to test engine mounts. btw, stand next to the car, not in front of it.

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lol, if you use the prop rod and don't let the car move it's not dangerous. almost as if your testing the parking brake. not enough to move the car. It's also the easiest way to test engine mounts. btw, stand next to the car, not in front of it.

 

Makes perfect sense and yes lol don't know why i thought of in front

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10mph in 3rd gear? Am I missing something here? I cant drive my car in any gear under 1.5k rpm, I always keep it at 2k and above. Anything less and I get bunch of vibrations. Now, I'm running all poly mounts and a 6 puck clutch, but either way, I'm pretty sure you are under torquing (I think that's the correct term) and that is causing vibrations.

 

You said it yourself, that this happens when you are in a gear too high for the speed. Correctly if I am wrong, but this sounds normal and happens in every manual car I drive. I'm not sure the cause of it but I will guess the clutch is slipping. I think if you are too low of RPMs for the engine to pass its energy to the wheels and the ground the clutch starts to slip, the engine cant stall and the wheels keep rotating so the weakest link, the clutch, starts to slip and vibrate. This has gotten much worse in my car when I got the 6 puck, now I really cant drive it below 2k or its like sitting on a tumbler.

 

Put the car on jacks or a lift and see if there are any vibrations in each gear at idle with no gas, there shouldn't be any. You can apply the parking brake, give it some gas and see if the vibrations come back. (use a second set of jackstands under the control arm to keep them from sagging)

 

 

As far as highway speeds, my car vibrates are certain speeds as well. But I always thought that was my car and poly mounts where certain speeds amplify the problem.

 

An inline 4 engine is not balanced. A running engine has a gyroscopic effect at certain RPMs. (Correct me if I am wrong) If you are outside that spectrum, the unbalanced nature of the engine will become more apparent. Now, there is a balance rod in the engine but unless it has moving weights on it that counter each RPM spectrum, it can only do so much to alleviate the problem. If you have stiffer suspension, poly mounts or any have removed any factory comfort feature removed, the vibrations be more noticeable.

Edited by Killtodie
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You can't put the car in gear and let the tires turn while jacked up that will throw axle pieces at you they are at too great an angle to spin.

 

Is the differential leaking or does it have oil in it? Push up, pull down on the alxes at the differential and the hub maybe one is bad or a wheel bearing. The torque tube bearing, I had one that was bad and the rust ate up the pinion seal and the pinion bearing was also bad.

 

You might take the tranny pan off and inspect the gears for any chips or pieces missing or laying in the pan.

 

Do your tires have even wear?

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You can't put the car in gear and let the tires turn while jacked up that will throw axle pieces at you they are at too great an angle to spin.

 

 

duur, right. I forgot I can do this with coil overs. Then put some jacks under the control arm to keep them from sagging.

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You can't put the car in gear and let the tires turn while jacked up that will throw axle pieces at you they are at too great an angle to spin.

 

Is the differential leaking or does it have oil in it? Push up, pull down on the alxes at the differential and the hub maybe one is bad or a wheel bearing. The torque tube bearing, I had one that was bad and the rust ate up the pinion seal and the pinion bearing was also bad.

 

You might take the tranny pan off and inspect the gears for any chips or pieces missing or laying in the pan.

 

Do your tires have even wear?

 

Diff has fresh fluid and it does not leak. I'll push and pull on the axles to see if there is a lot of play. All new wheel ebarings on all 4 corners. Torque tube bearing was replaced with an OEM one when I replaced the pinion seal. All 3 diff bearings felt and looked good.

 

Excellent idea about the tranny pan. I can probably take pics too.

 

Tires have even wear in terms of even wear for front set and rear set.

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10mph in 3rd gear? Am I missing something here? I cant drive my car in any gear under 1.5k rpm, I always keep it at 2k and above. Anything less and I get bunch of vibrations. Now, I'm running all poly mounts and a 6 puck clutch, but either way, I'm pretty sure you are under torquing (I think that's the correct term) and that is causing vibrations.

 

You said it yourself, that this happens when you are in a gear too high for the speed. Correctly if I am wrong, but this sounds normal and happens in every manual car I drive. I'm not sure the cause of it but I will guess the clutch is slipping. I think if you are too low of RPMs for the engine to pass its energy to the wheels and the ground the clutch starts to slip, the engine cant stall and the wheels keep rotating so the weakest link, the clutch, starts to slip and vibrate. This has gotten much worse in my car when I got the 6 puck, now I really cant drive it below 2k or its like sitting on a tumbler.

 

Put the car on jacks or a lift and see if there are any vibrations in each gear at idle with no gas, there shouldn't be any. You can apply the parking brake, give it some gas and see if the vibrations come back. (use a second set of jackstands under the control arm to keep them from sagging)

 

 

As far as highway speeds, my car vibrates are certain speeds as well. But I always thought that was my car and poly mounts where certain speeds amplify the problem.

 

An inline 4 engine is not balanced. A running engine has a gyroscopic effect at certain RPMs. (Correct me if I am wrong) If you are outside that spectrum, the unbalanced nature of the engine will become more apparent. Now, there is a balance rod in the engine but unless it has moving weights on it that counter each RPM spectrum, it can only do so much to alleviate the problem. If you have stiffer suspension, poly mounts or any have removed any factory comfort feature removed, the vibrations be more noticeable.

 

The clutch doesn't engage until halfway up the pedal and it really is stiff and feels like its shaking the car when its engaging from a stop. I can however turn the clutch pin by hand so I know its not being held in. Also I thought maybe this is just normal (my main vibration issue) but we have 3 other quests in the family... none of them do this to the extent mine does. it is quite honestly REDICULOUS.

 

Also KTD, I understand the under torquing idea but what about the horrible vibrations in 5th gear past 55+ mph? Obviously it shouldn't be doing it then. This is not normal and I want this to be how the other 3 quests are...in other words it needs fixed.

 

I can floor it in 1st without a clutch slip but I can't pop it in 5th at 30mph and floor it without tons of vibrations and very little torque. I don't see how the clutch can handle the 1st gear pull and not the 5th gear flooring it at 30mph when its just hanging around 2k rpm. Could a clutch even cause this issue?

 

Also like what Indiana said, maybe the tranny is starting to go? Could this be bad tranny bearings? It does like to grind into gears...sometimes even at around 2-3k RPM.

Edited by ColdScrip
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What flywheel do you have? You pulled the inspection plate to see if its loose? Put a piece of hard wire under a bolt and snip off the end at an angle now bent it up to the back of the flywheel and just about to touch and you watch that gap as someone bumps the starter or turns it over by hand and see if the flywheel wobbles. Edited by Indiana
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I'm not sure about the mechanics of under torquing and clutch slipping. Let me see if I can explain it. When you have an engine under torquing, the engine wants to stall but cant because the car is moving forward. The rear wheels cant lock up because there is too much traction on the tires. (I bet if you had the car rolling on bare metal rims and tired to put it 5th at 20mph the engine will stall and the rear wheels will lock up) so how does the clutch start slipping with not enough torque but wont slip when you are slamming it in first? I wanna say this happens because the wheels and the drive shaft and the transmission is rotating at one speed and the engine is rotating at a speed too low to equal the speed of the wheels so because of this difference the clutch starts to slip. There is a LOT of force meeting there and one of them is winning. So the clutch slips, and (hopefully) nothing breaks. Writing this I remember when one of my friends was teaching someone to drive stick in his car, I was in the backseat, every time that person was under torquing he would get really, really mad and yell at em, "stop under torquing, give it more gas! you'll ruin my transmission!" That's the only time he would yell, not for stalling or grinding gears, just for under torquing. Now that I think about it, I see why and how this kinda makes sense now.

 

You say you have new mounts, are they all OEM other than the rear diff?

 

 

 

as for the vibrations past 55, like I said, in my car they come and go. when my car hits the sweet spot of around 80mph the vibrations lesson, they come up again at 95 and around 65 to 70 but almost melt away at 80, its like its at idle. At high speeds like that a lot of other factors can tribute that are not related to your initial problem. Alignment, wheel balance, shaft balance, cross winds, road vibrations...

 

 

And how bad are these vibrations, you seem to be rather annoyed. hard to judge that as it just your opinion and whats loud and annoying and what isnt. My car has a straight exhaust, all poly mounts, stuff suspension and a LOT of wind noise, I'm personally, not annoyed.

 

 

Make a video!

Edited by Killtodie
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I didn't even think of a loose flywheel. I understand your method of checking it perfectly as well Indiana. I am very fortunate for all of these ideas because they make a lot of sense. Thanks I now have quite the list to go through.

 

Its a stock lightened 88 flywheel.

 

KTD, its hard to just describe it since it is my opinion. My dad also rode in it and we both agree it is atrocious. I mean I don't even want to go on the highway because of it and while driving I feel like I have to be in the right gear at the exact right RPM because of this issue. My stock daily driver quest has so much more shifting room and doesn't do anything anywhere near like this car does with its vibrations. I just really have trouble taking "Its normal for your setup" as an accurate answer to all this...When making this thread I knew very well its going to be hard to explain this issue accurately.

Edited by ColdScrip
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I see from your sig that you have poly bushings. What kind of engine and tranny mounts do you have?

 

From what I've read so far, I think you have two issues, one is under torquing and whatever mods you put in are amplifying normal vibrations. Second is something being loose or unbalanced since it happens at high speed.

 

 

Step 1: Make a video, mount the camera on a tripod, dont hold it in hand.

Step 2: Put the car on a lift, make sure the control arms dont sag and see if the vibrations occur as you go through gears.

Step 3: Follow any other suggestions and inspect all your components.

Step 4: If you still haven't found the source, put the car on a dyno, this will eliminate a bumpy road and unbalanced tire/alignment scenario and put stress on your drive train only so any problem there will become apparent.

 

If you can get to a dyno like this

http://www.mustangworld.com/ourpics/News/select4/mikedyno1.jpg

Should be even more helpful.

Edited by Killtodie
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30 mph is no where near 2k rpm,, 5th should never be use'd under 45 mph

 

also is there any vibration when reving in neutral,, and poly mounts suck

is there any shakeing of the rear of the car like rear seat, do the frt seats shake

 

poly mounts is like bolting the engine metal to metal , most can't live with the shake and vibration

 

also has eather drive shaft ever broke a ujoint, Chip broke a ujoint a few yrs back , and the shaft shook the car so bad it was hard to drive , it don't take much to distort a shaft

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No poly mounts. Stock replacement motor mount and tranny mounts and new OEM rear diff mounts. Just poly suspension bushings,

 

I can't seem to mimic the vibration with revving in neutral. I don't think there is enough load on the engine for it to do it.

 

The entire car shakes when this happens. I mean that quite literally. You can feel it mainly in the driver seat but thats only because it is what my body is directly on of the car.

 

Please remember no poly mounts here guys, just bushings.

 

Shelby the driveshaft with new u-joints I am not sure if it ever broke a U-joint as I got it with U-joints in it. However I did try another driveshaft with no change.

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It's the clutch if you ask me. I have a TEP street clutch in one of mine and it does what you describe, all except for the over 50 vibration. It chatters like mad due to the spring steel modifications they do to the Daikin PP. If I try to shift into a high gear too soon, it will shake like mad. My ACT and stock clutch cars do not do it. I know it is clutch related because I had a stock set-up before with no issues other than it wouldn't hold. It is partly due to the Fidanza too, but I ran the TEP on a lightened stock fly and it did the same thing.

I think your clutch has a cheaper spring steel combination that is causing the chatter from stop, and shake when going into 5th under 45MPH. You could have an actual clutch disc spring that is broken too. However, that shouldn't cause the vibration at speed.

You could measure one spot in the inspection cover area, as you rotate a little more and measure again to see if the flywheel is running true.

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i just skipped through this i was having a similar problem i finally found out what was going on

 

took it to the strip last night

shattered a gear in the transmission

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so it was probably loose or something then it decided to break apart
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You can't put the car in gear and let the tires turn while jacked up that will throw axle pieces at you they are at too great an angle to spin.

 

Yes you can and no it wont have any ill affects.

 

That's how I polished my rims. Car on jackstands, suspension hanging not supported, 5 gear and engine idling. The rear was spinning at 30 mph acording to the speedometer. Even gassed it up to 60 and no noises from the drivetrain.

 

 

http://www.starquestclub.com/forum/index.php?showtopic=117781&view=&hl=polish&fromsearch=1

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