Bent axles?

[BCompy]

Ok boys your help is needed once again. I have a vibration in my car that has been narrowed down to bent axles. Tires have been balanced ,front end aligned, tires have also been removed and replaced with another complete set and what feels like a high speed shimmy continues. My Cobra specialist feels the rear axles are bent.( I am prone to performing the rare donut if there is absolute safety and a camera is present, juvenile I know , but I was sheltered as a child and not allowed on rollercoasters.)
Any way I digress. Ford no longer makes axles for the 79 rear end. I would need to replace the carrier and other odds and ends and that seems cost prohibitive. Does anyone know what other year Mustang differentials fit under the Classic. I am think of swinging a new third member rather than rebuilding what I have.
All advice is greatly appreciated. I have had two different front end shops go over the car and they can't find anything wrong. Ball joints , rack, tie rods, all tight, no broken welds, yet this shimmy comes on at about 65mph and planes out smooth at seventy . Can't feel it in the stick and vibration occurs if the clutch is in or out ,or in neutral.

[Double Venom]

Bent or not bent, that is the question.

I'm going to turn yuu into a "skid mark" expert, the fun way. Find some clean concrete, a long flat driveway works real well. Thirty to forty feet is plenty.

Now make sure you do have plenty of room to stop! Pretty important info here You can see where were headed.
Point it straight and try to keep it straight when you pop the clutch. Get a good burnout, if you can get 3,000 rpm out of it the better, about 20 feet long.

Now, walk the marks. You should easily see the tread marks. I mean "see and read" the pattern, not just two wide black marks.
If you have a bent axle you will easily see the "inboard" lines and possibly the very outer edges, will have a defined "squiggle" to it if the axles are bent. If they are and you're good at it, you might even pick up a "repeat cycle".

If they're straight, minus the lateral side to side movement, then, nope, no bent axles.

Or, if you want to do it the old fashioned way, just put a magnetic dial indicator to the axle and check them that way.

DV -- Any body seen any loose chocolate chip cookies around?
Help support the Fling, buy your raffle tickets!

[BCompy]

Thanks Ed but we did it the old fashion way with the magnet and gage. They are slightly out . Which way I don't know. I just got the manual out and realized the rear should be out of at least an 86 not a 79. I probably can get axles for that year,there are no tags to tell me what year the differential is.Any hints of what else to do?

[Double Venom]

Darn! I like the "fun" way to do it myself. Replacement axles are easy to get. I think, not sure but 88's all the way to 92's are the same. After that you get into the GT rear ends. a little bit wider but they will still bolt in without mod's. But... watch the wheel off-set, don't want you to end up having to buy new wheels!

DV - ????

[dscott]

If this is an 8.8 rear then the Motorsports axels will work. They cost about $225 a pair and come with the drums. The part # is M-1126-A.
Don

[CobraEd]

If you feel it more in the front of the car, maybe the driveshaft is bent or welded out of round, or just out of balance.

You indicated that you replaced tires, but what about wheels, maybe they are out of round.

Ed

[BCompy]

I took a complete set of rims and tires from a buddy with a FFR. Still had the shimmy. Also rotated the driveshaft 180 degrees,no change. I swear the sensation is coming from the front ,I feel it mostly in the steering wheel but cannot find anything wrong there. I am going to do the axles just to eliminate them.
I do love this car but this is getting to me!

[CobraEd]

Rotating the driveshaft does nothing. Jack up the back of the car and run it in gear and then watch the driveshaft to see if it wobbles. If it does, it was not welded straight, or is bent. Even if it looks good, bring it in to a driveshaft shop to check the balance, it might have thrown a balance weight.

Ed

[BCompy]

Recipe for a smooth Cobra= One Flaming river rack, one full four wheel alignment, re-balance all four wheels, new Moser axles,throw out all four tires and replace with new, take all four wheels and tires off and replace with friends wheels and tires,

Then and only then don't listen to the experts, take the goddam driveshaft out because it couldn't be that! Have it balanced and new universals put in for a wopping 100 bucks and now smooth as glass.
One tall Jack Daniels to go please!

DV I too love this car but is does test me!

[Double Venom]

BCompy,
What doesn't drive you nuts...makes you stronger!

Did you ever narrow it down to a single problem?

DV

[BCompy]

DV it was a combination of the front tires( Bad Belt) and bent or out of balance driveshaft. When I put my buddies complete set of tires and rims on my car I neglected to ask him if his car had a shimmy. Of course it did but it didn't bother him. So my car still shook but I didn't think it was the tires. I now have Goodrich 245 r 15s on the front and 295 r15 Drag radials on the rear. I think the drag radials ride like crap and am looking forward to getting rid of those too when time and funds permit. Right now I am just going to enjoy the car.
Thanks for everyones help I can now enjoy the season.

Long Island Cobra Run 1 coming up. (to the track?)

[Jack21]

B,

No matter how good you think you are, in all their simplicity, these things will humble you at times. Hang in there!

The first warm summer night over the Robert Moses will make it all worthwhile.