Fox T-Bird/Cougar Forums

Hey Guys,

Just got my car back from the garage today with new Mastercraft G/T tires put on and my mechanic, Mike Jr., is concerned about the cars steering vibration at cruising speed of 45 mph or so. It was his first time driving the Cougar following the tire swap. (the tires are perfectly balanced and feel better than the previous tires, they're not the problem here)

However, his dad, Mike Senior, who also worked on my car over summer (did a complete brake overhaul after I bought it), said it was "normal" for "80's Mercuries and Fords" to have a bit of wobble/hop.

So that's two different isolated opinions from two very good mechanics. Mike Jr. suspects the driveshaft to be causing the vibration. Bend driveshaft? bad u-joint?

What do you guys recommend I do? It isn't too severe; it smooths out below and above 45 mph, feels strong on 1st and 2nd gear pulls. But if a new U-Joint or something affordable/simple can cure the problem, it's worth getting fixed now I would assume.

Suggestions? Mike Jr. wants me to drive the car and call the garage back. I may have them take 30 min on Monday to inspect the driveshaft.

Thanks,
Chris :bowdown:

Is the steering wheel shaking from side to side or up and down? If it's side to side it's a front wheel/wheel balance issue on the front tires. If it's up and down you should also feel it in the seat/floor/see it in the rear view mirror. If that's the case it can be a rear wheel/wheel balance issue, a driveshaft issue, or a differential issue.

Ill check tomorrow but i think its usually side to side.  If i grab the steering wheel closer to 12 o clock the shaking lessens

It could be up and down too though,  lol. I need to check tomorrow...

Also worth mentioning (I read on Coolcats i think) that the slight "bump'lurch feel" when letting off the throttle is also caused by driveshaft u-joint problems.

I get that "lurch" when letting off the throttle in 4th gear around 45mph.

Punt your car in drive then pop it in reverse with your foot on the brakes. If it makes a loud thud, you need u joints.

A thud everytime...

U joints are quick and easy. My first time it took about 5 mins. Before you actually do it, crawl under the car while it's in park and jack up the rear wheels, use jackstands of course. Then you can physically grab the driveshaft near the ujoints and feel them for play. A little is okay, alot is bad. Once fixed there will be no play. It's not fun loosing a ujoint. I lost the front yoke out of the trans when I downsiftes on the freeway to pass a semi

I recommend you remove the driveshaft, marking the pinion  to driveshaft as it shoopuld be balanced. You will need snap ring pliers, a large c clamp or rent the tool and a 12 point 1/2" or 13mm for the rear driveshaft and some thread lock for those bolts. The tbird ujoint did not fit mine, I ended up ordering one for a 87 gt and it fit fine. Good ujoints are greaseable  and will last longer.

I used duralast (autozone) gold and forgot to grease them. I only replaced one and didn't have a problem. It's not much harder then changing spark plugs. With tools and parts on hand, you could probably do it start to finish in 30 mins, maybe an hour your first time.

I forgot to mention the trans yoke seals in fluid. When you remove it it might just drip, it might gush out. Have a rag and drain pan ready just in case. Once rear wheels are off the ground, put it in neutral to turn the driveshaft.

Always use jack stands and make sure tires are chocked properly before crawling under a car, and do a bounce test.

Thanks Haystack for all the infomation; however, I'm not a wrencher at all! My mechanic is literally down the street and they are extremely precise and do a superb job; they are well known here in CT and are sometimes booked three weeks ahead. They enjoy working on muscle cars and have done a great job on this cougar since I had gotten it in June. I don't think they will bill me badly for changing out some u joints ( I hope not, I'm 24 and in college and my step dad is about to have a stroke because of the work this car has needed). It has mostly been with parts susceptible to mileadge i.e. brakes, tires, lubricating etc

Now that you have mentioned yoke seals and fluid, I have been noticing small drips beneath the car that don't appear directly beneath the motor, I wonder if that's also from the driveshaft.

Another possible cause:

http://www.foxtbirdcougarforums.com/showthread.php?39205-Vibration-shakes-steering-wheel-up-and-down-Speed-related-Pinion-bearing

Darren

Yeah but in my case it was hella violent :hick:. I think most of the issue was from trying to shove the power of a healthy 306 through what was basically a stock 7.5" rear with 3.73 gears and a Traction-Lok.

I'm betting the OP has a u-joint/driveshaft balance issue or a wheel balance issue.

Perfectly balanced or perfectly road force balanced??

The car's wheels with the new tires seems to performing great; the ride is better than it was before (having the old tires and balancing readjusted twice before). The wheel does indeed shake in a twisting manner as it always had i.e. clockwise and counterclockwise when cruising, especially on shiznitty roads around 1800rpms. I don't get any unusual sounds other than motor and tires, and lurches when changing gears (lurching being the torsional force on ujoints under throttle?) 

Even with the wobble, it is not severe at all, passenger doesn't really notice; I just want to get all the problem squared away... I'm bringing her in on the 8th to get the driveshaft inspected so we can see once and for all.

Other than the cars' minor imperfections, I do love the stupid thing. I'm happy I have it. I also got the Reagan-nomics Silencer out of the fender with the help of my twin, definite difference in sound and maybe a little more torque or "placebo".

The reason why I asked that earlier is that maybe one of your front tires might be a little out-of-round. That would only show up with a road-force balance, not with a regular spin balance. I'm going thru sort of the same issue with my black bird but I also have to change out the worn shocks and struts and get it re-aligned. Good luck and hope you get it figured out. Oh and my blue bird, when I first got it and put new goodyear eagle aquatreads on it, was smooth riding up to it's red-line.......:evilgrin:

Sorry this is a really old picture

Side to side movement is definitely a wheel balance/bent wheel/alignment issue. If the wheel was vibrating up and down and you could feel it in the seats then it would be a driveshaft/rear end issue.

If nothing else it sure looks good sittin' there!!!

I really don't know if I like 87 or 88 XR7's better....so much winning everywhere.

Try rotating your wheels from front to back and see if that changes anything. That would show up a bent wheel.

+1. Try this first.

I'll have my mechanic try rotating the wheels around to find the culprit/s; he suggested rotating the rims the day I had the G/T's put on. I think the ride is defenately a result from both the front end and an old ujoint. Thanks for the advice.

However, none of this stuff prevents me from treating every stop sign and red light as a staging lane...

Post when you find out what fixed it, mine does the same thing.

I'll give an update after they inspect.

Tree the you-know-what outta them!! :burnout:

Cause: Bent right rear Rim.

How do I intelligently go about picking up a new 10-hole mustang rim without being fooled into getting another bent rim? Should I get it checked by a garage the day of?

I got 4 10 holes off Craigslist for $50 and another 4 for $75 with good tires a few years later.

Check local ads, Craigslist, online classifieds ect. If there is slight rash its usually okay, and one of the four should be good if ya end up with 4.

+1

Buy a set local for cheap and use the best one. Keep the rest as spares.

FYI: http://www.ebay.com/itm/15-Ford-Mustang-Thunderbird-Mercury-Capri-Cougar-1985-1986-1987-1993-/231760578130?hash=item35f601c652:g:j8QAAOSwc3ZUmuL9&vxp=mtr

Sounds good, Thanks