After getting to drive my 68 for awhile, I noticed that between 35-40 mph, I have a bad front end shake. It feels like the whole front end is shaking from left to right. Once out of the speed range, the car seems to drive fine. Inorder to figure it out, I've already: had the car re-aligned, re-balanced the tires, and swapped the front tires to the rear. The vibration is still there. I am running subframe connectors (not sure if they could cause it, wouldn't think so), and the entire car has been rebuilt. My tires and rims are brand new, Cragar S/S, and Firestone INDY 500s. I'm thinking it is the front coctail shakers. The rears appear to be in good shape, although I've never taken them out to see if they have fluid in them. The fronts have been removed, and the drive's side is solid, but the passenger side had to have a new bracket welded on, and had sprung a leak. We welded a new bracket on, but were careful not to overheat the canister, and then refilled it with ATF. I didn't know how full it should be so I just guessed.

Any thoughts here? Thanks

I can say with confidence that it's not the cocktail shaker. I've driven a few 1st gen verts that didn't have them and they do not shake. Any surface rust inside a brake drum or on a brake rotor will cause this. The 'sad but true' fact is that if you don't drive your car much you will be plagued with this problem.

No cocktail shakers here, either. I think they were designed to control dynamics from road bumps. On a smooth road they won't do anything. I had a bad shake over 50 mph that turned out to be a severely out of balance brake drum. I welded on a piece of bar and cured it. My case seems to be fairly unique, though. But it's a thought.

Yah, it just about has to be a rotating part. If you are sure your wheels and tires are balanced then there's not much left to look at.

In a different RWD car, I've had vibration at 50-60 MPH caused by worn out front wheel bearings.

just a guess ,but have you checked your drive shaft? might need balancing...

All parts are new, including the drive shaft. The front and rear are Disc brakes. Fronts off of a 71 lemans, and rears out of an 81 TA. I'm looking for a set of wheels to try and swap, inorder to rule out the wheels and tires, but haven't found any yet. I'll have to check the front rotors, maybe I need to have them turned, eventhough they are new. Could it be a motor mount, or something like that also?

Thanks,

I would check those wheels real close. Look at the surface that goes against the hub. See if there is anything that would make it mount slightly crooked.

Do you have a disc master or do you have the drum master with your retrofitted disc brakes? If you have the drum master on discs, the drum-type residual pressure valve could keep the pads against the rotor. This would cause even the slightest rotor run-out to cause vibration.

Cragar SS's? Are they the Uni-mount type?...the ones with the elongated holes?

If these type aren't mounted just right, they will vibrate...but at higher speed.

Could it be a torque converter issue? I had problems with a Ford Crown Vic. The converter went bad. Between 50-55MPH, it felt like you were running over a cattle grate.

LOL, Greg, I had issues with Cragar SS unilugs too. So bad, in fact, that I traded them for a set of American Racing steel wheels that ran much more smoothly.

Were your wheels and tires balanced on or off the car? If off the car, wheel centering may be an issue.

The wheels are Cragar Uni-lugs. Once I find a set of rims to use for a test run, I'll rule those out. I'm in Maine, and haven't found anyone yet to borrow a set for a test run.

The car has 4-wheel discs, and a 4-wheel disc master. I guess I'm going to have to try and check the entire front end until I find the issue. Nice to know it shouldn't be the cocktail shakers, but they would atleast be an easy fix.

Thanks

Another thought, I recently had a bad plug wire on a car that caused a shake at speed - an intermittant connection that was only at about 30-35 mph, then cleared up. The wire was able to vibrate at a low frequency at a certain engine rpm and cause a misfire. The wire resistance was about double the other wires, then had the open circuit when wiggled while testing with the ohmmeter. Replaced the wire and the shake was gone. Of course the shake was only under power.

The car was just finished but I didn't have time to do a shakedown run because the owner wanted his car for a cruise night. May also be related to your fuel smell! Worth a quick check at least!

Rommel, is the vibration on one side, or just from the front end?All ball joints, bushings, and linkages are new? Does your steering wheel also shake?

If you swapped the wheels to the rear, the vibration should have followed if related to the wheels/tires.

Vikki, wheels were balanced off the car. I bought a pair of SS's with the correct bolt pattern in 15" for the rear. No problems there. If I know I'm going for a longer cruise at highway speed, I mount the rally II's. Smooth as glass.

Vibration can be a real pain to track down. I have replaced (because they needed it) tires, ball joints, tie rod ends, center link, control arm bushings, springs, and swapped the drum master cylinder to a disc master cylinder, balanced the wheels/tires, had an alignment done and rechecked, checked for bent rims and runout on tires and rims, and yet I have a 45-50 mph mild vibration. It does not affect ride or handling but it is enough to be perceptible. As it is felt through the seat and floor rather than through the steering wheel, I believe it is probably a drivetrain/driveshaft vibration. The u-joints are the factory nylon-sealed parts and undoubtedly are due for replacement. We put a couple hundred miles on today, and a hundred Dream Cruise weekend, so it's not an intermittent issue.

I wouldn't run a hard plastic Firestone tire on my lawnmower, let alone on my car. No, the issue goes way back before the tire blowout deal. That was just a case of I told you so showing up a number of years later.

You said new tires, but do you mean new a few days ago when you started driving the car, or new 2 years ago when you parked the car? If you let it sit on the tires, they have flat spots, and they are destroyed.

There is also an issue called load blance, and it would be typical of a Firestone product: The tires will static/bubble balance, but when operated under a load. That could be the issue more than flat spots because of the problem in one speed zone. Again, flat spots can be the issue because the problem goes away after 45 because centrifigual force irons out the flat area. Then again, I'm only guessing that the problem goes away above 45 because you didn't say whether or not it irons out above 50 mph.

It's a safe bet that it isn't the brake components because there is a good chance that they brakes would pulsate. If I were dealing with the car, one sure bet would be that the firestones would be in the s/can, and that would solve that aspect on tire troubleshooting.

Let's pretend that I loved firestone tires,a nd I could not find a donor set of tires. (Even in Maine--I hanged out every summer in Rockport--you should be able to find a borrowed set because there are a bezillion 14's or 15's that will bolt up.) If I couldn't, it's a toss up of whether I would get would get 4 used tires that held air, mount/balance them, or replace the tires.

If the tires are brand new, as in being bought a few days ago, they should have a warranty. Oh yeah, that's right--they're firestones.

The problem occurs between 35-40mph, it may be occurring outside that range, but I can't feel it. As for the vibration, it is in the front of the car, and through the steering wheel. The steering wheel shakes with the front end. You can see the entire front nose clip shake from side to side. Most of the steering components are new. Pitman Arm, and centerlink are originals. Also I'm using a new Steering box a newer fast ratio box.

I'll be looking for tires over the next week or two, I'm going to be doing some traveling so I'll be a bit busy. As soon as I get a chance to swap, I will and I'll let y'all know if the problem still exists.

Thanks, I can always count on the members here!

Food for thought. Nothing like a drive in the vert to get the brain 'wheels' turning. I've got Firestone tires on my vert. Not because I picked them, because they were given to me and I'm cheap. They are like new and I can't throw them away. One has a flat spot. Why just one? Because it's the one that had a slow leak. It's the one that sat around with 5 pounds of air in it until I got around to airing it up. It's on the drivers front.
With all this in mind, I realized you can tell the difference between a flat spot on a tire and other problems with vibrations. A flat spot makes the car shake up-and-down, not side-to-side. Side-to-side must either be a bent wheel or miss-aligned rim. This is easy to check with the wheel on the car. The expert way would be to use a dial indicator and find out if the wheel is spinning true. A way to do it if you don't have an indicator would be to jack the car up so the wheel can spin. Take anything stationary that you can move close to the wheel. You could use a 2x4 with a spike sticking out. Nail the two by four to the wall or something heavy with the point of the nail very near to the edge of the rim. Spin the wheel and see if the distance between the nail point and the wheel stays constant. If it does then you have a straight wheel. I think it's possible that you could get a bent wheel balanced and have the side to side shimmy.

Correct, but the shop doing the balancing should have mentioned a bent rim or rim runout. The reason I asked if the wheels were balanced on or off the car is that sometimes the center of a wheel will be tight on a hub and prevent good seating; this will show up if the wheels are balanced on-car as a wobble but won't show up if the wheels are balanced off-car.

Since the brake system is new and aftermarket, checking runout on the rotors themselves would be a good idea.

Merv's Quote; "It's a safe bet that it isn't the brake components because there is a good chance that they brakes would pulsate."

Good point. Also, A severe 'tow out' front end alignment could cause this too.

My Quote:"I would check those wheels real close. Look at the surface that goes against the hub. See if there is anything that would make it mount slightly crooked."
The indicator or '2x4 with nail' test would highlight this problem.

I recall reading about wheel caused vibration issues a while back on Camaros.net. The problem was with wheels that are located on center by the studs instead of by the center hub. Granted these were used wheels, probably with worn mounting holes. Just for grins, jack up each wheel and spin it by hand and watch. Who says a brand new wheel has to be concentric?

The reason a master can cause this issue is there is always a small amount of rotor run out and this run out will normally kick the pads back into the caliper. If the master cylinder holds pressure against the shoes (say it was a drum master) , the rotor can't kick the shoes back so they will drag each time the rotor high spot passes. The high spot won't be high enough to cause brake pedal surge but it is enough to cause vibration if the pads can't retract. It would be typical for this vibration to be worse as the brakes heat up. It's a long shot. I would look at the rotating assembly again first.

It probably won't help, but you could try torquing the wheels like you would a cylinder head. With my Fords, I'm used to that procedure because the tire shop impact wrench method warps the junk Ford rotors right away.

Front end vibration shouldn't be ignored. It puts the front end parts under increased stress so parts will wear out quickly. Maybe you can find a specialty shop that will look at balance and runout issues while on the mounted hub. Before computers told monkeys where to add weights, they would spin problem wheels mounted on the axle at speed. There are transducers that can be mounted at each axle to isolate which one is the cause.

Check the wheel bearing torque too. Loose bearings will make the car ride like a worn shopping cart. If they were overtorqued, they may be damaged now. There is a sweet spot for these bearings which Amervo described in great detail a while back.

Slotted holes combined with a universal hub is what made unilugs so bad to work with. You have to spin each lug nut in a crisscross pattern until it just contacts the fully seated rim, then spin the rim and snug, in a crisscross pattern, each nut a little at a time. If you do this, you may get a good position on the first try. If not, you can get a shimmy or bounce in a straight line and it's time to loosen them all and try again. You can watch for runout without any special tools, you need only a stable point of reference to watch as you spin the wheel. The edge of the rim should rotate as a perfect circle, and so should the edge of the tire with no weight on it.

Then check a reference from the front; the wheel should not appear to weave in and out while spinning. If it does, dismount the rim and check the rotor. If the rotor has runout, be sure the inner bearing race is fully and squarely seated.

I have found that many wheel bearing vibrations change when turning, and caliper/brake hardware vibrations are felt through the brake pedal when not braking and change when braking.

I too have a mild vibration at 35-40 which feels as it comes from the rear or driveline.
Nothing is felt through the steering wheel. No difference when braking or rolling in neutral. Tells me it has to come from the driveshaft og anything "behind" it....?

The wheels and tires are new, and haven't sat, so I'm sure there are no flat spots. I like the idea of checking Rim run out, and checking the rotors. I do have a dial indicator and I'll give it a shot. Unfortunately it will be a couple of weeks before I get a chance. I'll pass the results asap.

Thanks

Okay, but rotor runnout is not the issue. Runout of the rotating assembly is what I would look at first since balance has been checked already. A square tire can be balanced. A square tire won't ride too nicely. It may seem a weird question, but are your tires round? Rotor runout is only a vibration issue while cruising when the calipers are stuck. Stuck comes from being rusted (old and wet) or stuck comes from a wrong master application. Otherwise, rotor runnout shows first in the brake pedal during stops.

Since you have brand new wheels, I would not let much time pass while the manufacture is on the hook to make this right. In fact, on the off-chance that your new wheels don't mount up true, I would get something signed with return receipt off to them in the mail asking for support on this issue. These are expensive parts. You can't pass them on to someone else if they're no good.

The same is true with the brand new tires, with which the tire store has an obligation to you. If time passes, neither vendor is responsible and you eat the costs out of pocket.

Vikkie makes some interesting points about unilug. I had not heard of a universal hole. I though the holes were supposed to be precise to the application. If there is a mounting procedure for unilug, try this next.

The reason I suggested checking the rotor for runout is to determine whether the face of the rotor where the wheel mounts is true, and whether the center hole is concentric. At this point, checking the rotor's braking surface is not critical. A third problem that I have seen is the inner bearing race not fully/squarely seated, so when the rotor and bearings are mounted on the spindle and tightened, the bearings push and pull as they rotate. One test for this is to have the wheel bearing nut just shy of contact, then spin the wheel while tightening the nut a degree at a time. If you feel the nut feeling snug and loose while turning it, check the bearings and races.

To check tire roundness, jack up the control arm so that the tire is just skimming the floor. Spin and watch the clearance below the tire.

Here's an interesting article about unilugs.

http://www.alanhorvath.com/54chevy/cragar_washers.php

Vikki, I did some investigation about the unilugs when I got them, and verified that I had the proper washers (centered). The techs at Cragar told me they had to be finger balanced through the lug holes, because the center hub is not truely centered. Problem is most shops don't have the proper 5 finger balancer for these wheels. As you noted, it is difficult to tighten these wheels up so the run true on the rotor, thus imagine trying to do that on a balancing machine, with a universal lug balace kit.

I'll let you know what I find about the run out on the wheels and tires.

Thanks

That is an interesting link Vikki. It sounds like the place to start.

Hansi, your problem is probably "Ice", let it defrost some.......lol

Oh get lost!!:-))
I drove 500 miles last weekend to the annual North-Norway amcar meet. South across the arctic circle. The return on sunday me and Knut went top down all the way! And that, my friends, is somewhat of a sensation up here! 16-20 centigrades and clear skies!!
BTW; the vert won 3rd overall prize, only beaten by a "new" 56 custom chevy and a 14 days old Corvette.

I understand there is balance equipment that is able to balance under a simulated load. I've never seen one. If you have any old tire shops around, they may have an 'on the car' spin balancer.
When I first started out busting tires, the only option to bubble balance was a spin balance. There is a machine that spins the front wheels at speed. You would then add/subtract and position the weight accordingly. On the back wheels (non-posi)
you would simply prevent one rear wheel from turning, and run the car in gear to spin the tires one at a time. On posi-rear, you have to take one tire off and then the other. I still think this is a better way of balancing, but with the free standing & easy to operate balancers, this is an art that has gone by the wayside. It would allow you to determine which wheel or wheels the problem comes from.

That´s the thing Greg.
Back in ´84-86 I was an apprentice and we had this little "scooter" which would spin the tires at the car, and then strobe at it to tell where to place the weights. I haven´t seen them around in many years now. They definately have their advantages.

Update on Front end... I checked the wheel bearings they seemed to be loose, so I replaced them today. No change, still have vibration. I removed the front cocktail shakers, 1 at a time, and both just to rule them out... No change. Hoping to get a set of rims/tires this week to rule those out. More to follow.

Thanks.

I would consider Bronzebirds torque converter suggestion.

I would consider Bronzebirds torque converter suggestion.

You can say that again

...maybe try keeping it in first or second gear at the speed where the vibration is felt.

Does it happen just prior to a gear shift? If you maintain that speed, does the vibration continue?

I don't have a lot of expertise with fixing or rebuilding engines and transmissions but I'm an old guy who has driven a whole lot of miles. I have felt a bad torque converter shake a car at a specific speed. Once a good mechanic diagnosed it and replaced it, it ran great again.

The car has a Tremec TKO 600, so not the torque converter, but that is one I'd never thought of. I am finding out that there are a multitude of items that can cause a vibration/shake a specific speeds. I'll keep trying...

OK, I finally had a chance to work on the car (Just moved to Rhode Island). I spoke with Summit racing, where I purchased the Cragars, and they will take them back. I bought a set of American Racing TTIIs, 17x8s up front and 17x9.5s in the rear, with 235/45/17, and 255/45/17s. After replacing the tires and wheels; no more vibration. Until I actually did it, I had a very hard time believing it could be the wheels/tires since I swapped the rears to the front, and still had the issue. I was running the Cragar SS unilugs, and Firestone Indy 500s. The tires were from 2 different stores, and 2 different sizes. I must say from my experience, I would tell anyone to stay away from the Cragar unilugs, and if you are running them... buy a new set of wheels, and get rid of the Cragars. My car drives like a completely different car. It handles like a dream, and I'm not afraid of pushing it like I was with the other wheels. I know that the 17s, and lower profile tires have added to the handling, but man what a difference!!! Thanks to all who provided advice!