I was driving down the highway yesterday doing about 70 and my cars front end starts shaking very bad. This didnt bother me cause it always does this. But on my way home I had the heater on and it didnt shake the whole time I had it on. When I went to turn it off it went back to the shaking. I always thought it was the tires or suspention. Does anyone have any idea why it does this, and if it can be fixed? Thanks

 

umm well I don't have any clue how that could happen. But I will take a shot in the dark with a wild guess.

hmmmmmmmm

For some reason your car is grabbin air and the front end is lifting making it unstable at that speed. But
with the heater going you suck enough air out from under the hood to stop the lifting.

Just a wild speculation.

Try putting speed holes in your hood and fenders.


Though I have found through my years of used cars. Front end vibrations at 70-100+ is usually fixed with new rims. As most had 15-20 year of someone else driving and pot holes to get out of shape.

 

Check your tranny fluid...(while parked, warm, and running)

 

the air gets sucked in from in front of the windshield... not engine bay, or everyone that has even so much as an oil leak could not drive the car for the smell...

 

How would the tranny fluid do this? Not saying you're wrong just curious. I've never heard of this being the cause.

 

if the fluid is horrifically bad, it can cause slipage, which if anyone has ever tried to power through a locked converter at part throttle can attest to the shaking.

 

I think your just trying to hard to get something going but.........

your saying air doesn't flow under the car? So my air dam doesn't grab air and force it through my rad, to cool my car, instead of going under the car?

and I did say

Just a wild speculation but my best gues for a car that loses front end stability at only 70 +.

I think you need some sugar though.

 

I was not tring to start anything, I was addressing that you said that with the heater on, the extra intake of air with it being on effected the underhood movement of air.
It does not, so I pointed that out.

And I can say that my 92 was damn stable 90+. No front end lift, to weaving, no drifting. Nothing but rock solid.

So, yes air does flow under the car. And the air damn only protrudes about 2 1/2" of the availible 5-7" there. So it does not make a huge difference in diverting air, unless you are traveling at a very high rate of speed.

But for propper cooling it is most certainly needed.

No back to the topic at hand.
Can you possible give a little more info?
Like maybe lift the weight off the front tires and check the ball joints, tie rods, wheel bearings, pitman arm and so forth.

 

Thanks for the info so far. I will check the tranny fluid tomorrow and let you know.

As for all this, Unfortunaly this is my first car and im kinda learning as I am going. With that being said I really wouldnt know what to look for. Is there an easy way to tell if these parts are bad?

I always thought it was my front struts. I was also told this. So I got new shocks/struts and its no better if not worse. So my theory is out the window.

 

Trust me...I had a g/f who ran her car out of tranny fluid. The damn thing started shaking like a *****. I thought the damn engine was gonna blow...it felt like the wheels were attached with string it was so bad.

Do you notice a loss of power in any certain gear or feel "dragging" that feels like the brakes might be engaged even though they aren't?

When you check the fluid...just make sure you do it with the engine hot, car in park and idling. If you check it when the car's not on, it could show that's its fine, even if its critically low...so check it while it's on. And since it's your first car...be careful of the belt while the car's running.

Oh yeah...and do you have any noticable leaks under the car?

 

I have never seen them shake from running out of fluid.They usualy just stop working. Only time I ever had a front end jump around was from a broken motor mount. It ws sort of coo las the car did a one sided wheelie.

 

OK...
Jack up front end with a real jack and support on jack stands.
Leave keys in ignition, and the steering wheel unlocked.

Go to the front wheels and put hands at 3 and 9 position.
Move back and forth pushing in on the 3 and 9 position.
This is testing the steering components.
You are are looking for excessive movement of the wheels. If you can move the wheels and they turn before the steering wheel there is too much play.
Either have someone turn the wheel like decribed above, or have them watch the tie rod ends and other suspension parts. If you can visably see slack, and give as the wheels are turned, there is too much play.

Now put hands at 12 and 6 position.
Try to move the tire on that axis. If it moves, your ball joints are bad.

Now put hands at 2 and 7 position and move on that axis.
If it moves then, your wheel bearings are bad.

You can also go to a place like sears, or plaza tire or the like (A national chain) type place and ask them to check it for you.

 

have you had the tires balanced or checked to make sure theres no runout or bad belts?

 

I just got done checking the tranny fluid. The amount that is in there is good. It is a golden brown color, is that still good or should I change it?
Now that you mention the slippage I think I've felt some. It feels like it should shift but it just stays in that gear and cant reach the next gear. Is that what that is?

About the tires, no ive never had them checked. When I bought the car it had fairly newer tires on the rally rims, and the stock had older tires on them. The same problem with both sets.

Would they check these when they inspect a car. I just had my car inspected not even 5 months ago.

 

That is bad fluid. It should be a bright blood red color.
Depending on how many miles it has, I would not change or flush it. Sometimes that does more harm than good with high mileage tranies. I would start looking for a core /junkyard transmission to have rebuilt.

typically, no they would not.
They would check the brakes, and related hoses (or should).
Just go to a GOOD shop and ask to have the front end checked.

Trans slipage, is when the engine suddenly revs while in gear but you slow down. What you seem to be discribing is the trans holding gears, which can be caused by bad fluid.

 

Gumby> Believe me...having tranny fluid issues can cause violent shaking...you might not have seen it...but I have and it will scare the h3!! out of you when it happens.

grimmcs> You can check the front-end yourself by following v6sucker's advice...but once again, I would lean tranny. Find a decent tranny specialist and have them do a diag on it for you. Also, you can ask for more tranny advice in the Transmission forum. It might be worth it to post over there and see what the "experts" think.

 

I was going to go to Cottman and have their free check done. After that I'll let you know if anything is/was awry.
Also I was reading in the tranny section and someone said that they had the same problem and it was their driveshaft. I have an aluminum driveshaft sitting in my basement and I was thinkin about putting it in and seeing if that might help if the tranny isnt the problem. Any thoughts on if it could be the driveshaft.

 

It can be a number of different things, and yes that is a suspect/cause.
If it has thrown the weight, or gotten any dents, it will be a RPM sensitive shake, meaning it will get worse the higher the RPM's you go. Through with its position, it will feel like your butt is vibrating...
Out of balance wheels are the same way, the faster you go, the worse it gets.

 

you sure you didnt check the oil by mistake?

 

Yeah I'm sure. Oil is on the driver side and tranny is on pass. side.

 

I would say not to eliminate anything with the drive train until you checked it, so the shaft could definitely be the culprit. I've known some of the new trailblazers to have vibration issues at high RPMs due to out of balance driveshafts...and the oldest one of those is only 4 years old.

Also, oil can be checked cold. Tranny has to be checked hot, with the car on and idling in park. It will (can) show full if the car is hot, but turned off even if you are more than a pint low. So just to ask (and not to be a jerk or anything), you did check it hot, with the car on and idling in park, right?

Also...you said it didn't happen with the heater on. Hmmm...makes me wonder if the tranny is over heating. So obviously it changes either when the fan is on...or when you are taking heat off the engine. Does it happen when the A/C (or "cold" vent if you don't have A/C) is on? Does your engine overheat or get hot? If your tranny is getting hot is it maybe a tranny cooler issue or a radiator issue...but I would need someone smarter than me to get into the nitty-gritty details.

Questions highlighted in BOLD for readability.

 

Yes the car was running. I warmed it up than checked.
I eather have it all the way on hot or cold. When its on cold its turned off seeing how my a/c doesnt work and I dont want hot air blown at me. My engine gets close to the red line that the fan turns on and it cools off very quickly.
Now this is just a thought so feel free to shoot it down.
Could it be that I have a problem in the ball joints, tie rods, wheel bearings, or pitman arm like V6sucker had said and when I was coming home they were in such a position that it was working correctly. Than after a while it just went back to normal and my heater has nothing to do with any of this. So in all that my question is can those parts not work one minute and than work the next?

 

It could be all of those things...and more (motor mounts, clogged cat/exhaust, etc)...tons of things cause vibration/shaking; however, if it truely does stop when you have the heat on, I have a hard time believing its a front-end/steering/wheel problem.

Can you confirm that it "always" goes away when you have the heat on...or was it just a coincidence that one time?

Also any idea what shape your motor mounts are in?

John

 

im gonna say that your heater has nothing to do w/ the problems youre explaining. its gotta be coinsidence. your heater has nothing to do with your drivetrain or steering/suspension. the only way you would feel anything from the heater would be if the blower fan has a bearing going out or something, but that wouldnt cause what youre describing. id say, get the front end checked out, check wheel balance, and get a tranny flush. start with the cheapest thing first.
actually, just jack up the front and check it yourself. wiggle both wheels from side to side, check for looseness. then grab the top and bottom of the tire and wiggle back and forth, check for play. if theres anything, start there. if not, then have your wheels/tires balanced and checked for any sort of runout at all. then have a trans flush done, and maybe even after that a filter change, itll either do wonders or soon after, roach the trans. but if its that bad, youre gonna need a trans soon anyway.

try that and let us know

 

Just to clarify the reasons I thought it might, stressing the word might, have something to do with the heater is the following. This summer I drove on the highway mabye six times and it would shake like crazy everytime, driving to and from location. One time of all the times Ive driven on the highway it dosent shake and my heater was on. I turned it off and it shakes again.
I never drive on the highway so I havent tested this to far in depth. Now that I know what could cause it I will check/fix the possible problems and test it. I will get back to you all to let you know if it was the steering or tranny. Thanks for all the help.

 

one thing to be aware of==> anytime a car is moving at any speed things vibrate. at certain speeds (68-71 in my 2.8) all of these things vibrate in harmony, or at like frequencies. this can result in the whole car shaking a bit (your dashpad will especialy wiggle around)

but if you speed up to get past the "harmonic point" the vibration will cese. you may want to try this as it sounds like that might be it.


if that proves not to be the case i would REALY recomend doing v6suckers suspension check. when i replaced my front wheelberings ALOT of vibration ceased as well as wandering (at freeway speeds) i had not even noticed i had. hell, its just a good idea to do it if it has not been done recently. the berings are pretty cheap too.

good luck.... this reminds me, i need to get some new wheel bearings for my new GTA

 

Something Xoph said just triggered my brain.

do you have any lose body parts? What kind of condtion are your doors in?

I need two new doors peroid but my drivers sdie door the top 2-3 inches of the door skin had come lose. Over 50mph it felt like my left front tire was out of balance. I blamed it on my rotor as the caliper locked before and got it cherry cherry hot last year.

till one day I had my arm out the window and felt that it was the door skin making the whole left front vibrate. Only took a glop of silicone to pin it down.