Pecuiliar vibration

[vex]

has cropped up in the last two days. I've been trying to isolate it, but it very hard to tell where the vibrations are based off of. I do not really feel it until I get above 40MPH and it seems to be oscillatory in nature. This leads me to believe that it's speed based and so a thrown weight, or something to do with the suspension and not the engine forward.

This seems to be confirmed when I free rev in neutral. I don't feel any increase in vibration similar to when I'm traveling at speed.

I am however still a little concerned with it as I don't feel any vibration under 40 at all. Vibrations also don't appear if I accelerate quickly to 40+. Which leads me to think that it's in the transmission/differential area.

Is there any other tests I can preform in the meantime to narrow the possibilities down?

[RETed]

If you're trying to isolate it to a certain tire, rotate your tires front-to-back.


-Ted

[vex]

If you're trying to isolate it to a certain tire, rotate your tires front-to-back.


-Ted

Easier said than done. Front tires and rear tires are not interchangeable.

[RETed]

Got a spare?
Change them out one by one after taking test drives in between?


-Ted

[vex]

Got a spare?
Change them out one by one after taking test drives in between?


-Ted

Darn you Ted. You keep giving me good ideas on things I can't do!

I'm trying to isolate it a little more than either the tires/suspension and more along the lines of isolating it by function: Engine, Transmission, Differential, tires/suspension.

I don't get vibration, or at least the vibration subsides a little when I engine brake and speed is above 40. I feel the vibration comes around from the rear up through the chasis eventually feeling it in the steering wheel. At 40+ I start feeling it in the seat.

I have a few things to check, and will hopefully have the car up in the air this weekend to double check the bottom of it.

[classicauto]

Wheel bearings likely.

How old are the tires/rims? I would jack up the car, check all the wheel bearings and if they're tight have the wheels balanced - then go from there.

[RotaryDiagnostics]

Put the car on stands and run through the gears while watching the drive shaft. Could be a damaged/out of balance drive shaft or worn "U" joints.

[TitaniumTT]

You might even be able to see the u-joints. But the @ speed test is a good call

I had a similar vibration recently as well. It popped up on the first test drive. I could've sworn it was the wheel bearings as they had been fucked with by the previous owner that I got the 5 lug swap parts car from. So I swapped the wheel bearings. Vibration persisted. I blamed my friend for giving me a bad TII driveshaft. So we swapped that out. Still there, now I'm pissed to the point of seeing red. I had swapped in the Torsen and set the backlash myself so I knew that was good. I rebuilt the axles so those should've been fine, so in a fit of rage we swapped my rear end out. Vibration gone. The vibe must be in the pinion area. Seemed OK when I checked it out, the spermburper that sold it to me said it was in great shape, I guess I can't complain too much becuase I got an entire TII rear end, subrame, arms and a few spare axles for $200.

Anyway, check the driveshaft, axles and wheel bearings. Worst case it's in the diff. Mine is going to KDR to be repaired/setup next week.

[WE3RX7]

^ Diddo, I say driveshaft or dif itself... have you playing with your new found power too much lately?? :)

[vex]

I don't think so... No hard launches, not in the boost all that often or for very long as I don't have a system in place to tune for positive pressure. It's definitely from the transmission out as I still get vibration when off power and rolling. I also find that the vibrations subside a little bit when I get the car warmed up.

I'll be checking the drive shaft today. I know the diff was slightly worn when I installed it... It may infact be time for a rebuild of it. Though I can't say for certain. If I had my bore scope here, I'd drain the fluid and check out the inards for wear. From what I can tell the bearings still seem fairly firm with no play.

Oh yeah. Funny story yesterday. I was doing some trouble shooting yesterday and put her in boost (Vibrations seem to subside to nill if I get weight off the front--yet to check the front bearings as I haven't had time). Heard the blow off valve for the first time and thought it was the greatest sound in the world. So I put her under boost again in hopes of hearing it... all i hear after about 2 seconds in boost is "Pssssssssssssssssssssssssssssshhhhhhhhhhhhhhhhhhhh hhhhhhhhhhhhhhhhhhh." The car then stutters to off. I popped my first coupling! Actually my idle control recirculation line popped off. :lol:

[TitaniumTT]

Lifting the front usually makes the vibration worse if the problem is in the front end somewhere

[vex]

http://www.fostertire.com/tcm_vbrt.htm

Some helpful information. Seems likely that I may have some tires out of balance.

Anytime the seats and floor of your car vibrate when you are traveling over 35 miles per hour have the transmission mounts, front drive axle shafts and drive shaft checked. This can even be caused by a faulty vibration damper. If nothing can be found that would cause the vibrations check to see if the exhaust system is making contact with the chassis. Also, check for broken or loose clamps. When your car vibrates only when you are traveling at high speeds this is usually a sign that your tires are out of balance. Although some amount of vibration is normal in the dash and especially on transverse engine front drive cars, if the vibration becomes a rattle you will need to check your panels and brackets. Press your hand over the area on the dash where the noise is coming from. If the noise is eliminated or reduced you will need to tighten the retaining screws. If this still doesn't stop the noise, loosen the panel and slip a sheet of rubber under the panel before tightening the screws. Wind noises can usually be traced to bad weather stripping. Tape the window shut and if the noise stops, have the weather stripping replaced. If the noise does not stop check the grille to see if you have a broken section. You can test this by taping the section and driving the car. If the noise stops you will need to have the grille or grille section replaced. Do not leave the tape on the grille since this could cause your car to over heat. A whine under the body of your car could indicate that the rear axle or front drive final drive unit is faulty. Have them checked and serviced by a professional mechanic.
http://www.allsands.com/potluck3/troubleshooting_udr_gn.htm

[rx4ur7]

Do you feel it in the steering wheel or your butt? If steering wheel it will be in the front. In you butt, engine back.

U joints possible but usually they will show through out the range. Check for bad tire, shifted belt. Bearings usually do not cause vibration unless they have really gone bad and you will hear them then. Check half shafts and installation.

Rear bearings and rear you can get a good idea of any bearings by listening to them with your stethoscope. Long screw driver will work, as will a length of fuel line.

[vex]

Do you feel it in the steering wheel or your butt? If steering wheel it will be in the front. In you butt, engine back.

U joints possible but usually they will show through out the range. Check for bad tire, shifted belt. Bearings usually do not cause vibration unless they have really gone bad and you will hear them then. Check half shafts and installation.

Rear bearings and rear you can get a good idea of any bearings by listening to them with your stethoscope. Long screw driver will work, as will a length of fuel line.

That's the thing... I feel it in both. It's literally shaking the entire chassis--pretty sure it's from the rear though.

[lcrotaryracer]

I have the same vibraton. it started light then made the car shake so bad where i dont drive it any more.

[rx4ur7]

Whole car shake OK. If it were a stock vehicle never worked on I would first go U joints. Trans mount can cause issues, as can rear diff mount. Although rear diff mount was usually the complaint that the rear was trying to come out from under the car on take off.

If the clutch has been replaced, loose flywheel, loose clutch cover, broken clutch cover especially if it was a rebuilt unit.

60mph is the usual range for tire or wheel related vibrations. And you can usually know if it is front or rear by steering wheel or seat feel.

U joints should be obvious. You could remove the driveshaft and see if the shake goes away. If it does, driveshaft or rear. If it does not, motor, clutch, trans.

I have had a vehicles come in that had clutches done at a quick clutch place or just a general shop that had flywheel clutch issues. One the flywheel was loose, one had missing bolts on the clutch cover.

I had issues with whole car shake in the GT car, a bit unnerving when going through turn 12 and 13 at PIR in Phoenix. Needed to have the split driveshaft installed, once I did that I could run flat out through them. Then it was just - hope the Goodyears stick, and never cross that white line at the apex.

[misterstyx69]

Check the motor mounts.
also the transmission mounts.
is this a Swap or was another engine PUT in?..Could it be that someone didn't tighten a mount up??.

[TitaniumTT]

If it is the u-joints make sure and cut the driveshaft away and save the yoke and the flange to use as a plug for the tranny. You'll never have to drain the fluid again...... unless you need to change it

[vex]

Vibration is defiantly coming from the rear of the car. And it's not based on RPM or Speed, but load. Go figure. (Vibration will happen at any RPM and any Speed, but will not occur when engine braking) I'll try to find some time this weekend to get the rear in the air and check everything out. I'm thinking some mounts went out.

[TitaniumTT]

Mounts or bearings in the diff

[vex]

Mounts or bearings in the diff

Yeah, I'm thinking it's one of the mounts in the diff. I'm getting a "clink" everytime I shift between 1/2/3'rd. Just behind the driver seat. Makes me think it's the front mount, but doesn't rule out the rear diff mounts either. I don't want to rebuild the diff until I'm back in blacksburg and moved into my new place.

[vex]

Diff mount has come loose and the nuts are no where to be seen. Anyone know of the correct thread pitch for the nuts? Would be very helpful.

[vex]

I found the source of the vibrations. The front U-Joint has seized on me. I'm going to be putting it back together and since I don't have a U-Joint or anything that I can replace it with on hand I'm going to drive it like that until I order/receive a new drive shaft for replacement.

[classicauto]

Last year before DGRR I had my driveshaft rebuilt locally. New u-joints (greseable) and balanced for around $200.

Wouldn't hurt to hit up some local driveline shops, may save some coin and be further ahead :)

[vex]

Trouble is it's saturday. I'll look up some shops and see if they are able/willing to do it local to culpeper/gainesville. As it stands now, the drive shaft is out of the car and I can't get the F'ing sub frame back in. I can either mount the subframe or mount the rear diff mounts. But I can't do both. It's starting to tick me off a little bit.

[vex]

Well, I got the new drive shaft installed. Total cost came in just under 300 shipped to my door. I would have had a drive line shop fab me up one for install but... well... they wanted close to 500 for it. On top of that they didn't install one of the bolts for my exhaust I came to find out when I took it in the first time. Looks like I'm off to get another stainless steel metric nut and bolt+washers. sigh....

Anyways like I was saying: I installed the new drive shaft. OMFG! It's like a completely different car. None of the weird noises that I just assumed were my cars natural noises, no more harsh vibrations that I attributed to road deformations and my hard suspension. It's a completely amazing feeling. It makes me want to fix the rest of the car up and get it looking and feeling just as amazing as this.

I still plan on cutting off the old drive shaft spline portion so I never have to drain tranny fluid when I pull it. But my brother-in-law doesn't have an oxy/acet torch I could use to make short work of it. Which leaves me little recourse right now (unless WE3RX7, do you has any tools I could use to chop it up?)

I still have a vibration in the rear of the car, but it's very minute and I think it's from the rear being out of alignment. I'll take it in to fire stone on sunday (if they're open) and see if they can't do an alignment for me (I do have a life time alignment thing with them).

And since I swapped drive shafts, it's amazing hitting boost. So smooth with none of the noise I used to associate with it and none of the vibrations either. :D

[classicauto]

Good job :)

Also even a hack saw would be fine to chop off the yoke. Just might take a couple minutes.

[TitaniumTT]

Yup, I was going to say hack saw. I would havce a hard time choosing between my oxy/ace torch and the plasma though :D I'm a tool whore :rofl:

I felt the same way when we hunted down my vibration to the rear itself. Swapped it out and the car was silky smooth..... quite awesome actually. I know that elation well