Spitfire Bad vibration in rear of '71 Spit

[spit71]

Some of you may remember my first post last week regarding my EBay purchase of a 1971 Spitfire that was advertised as "running like a top". I have now gotten the car running quite well, as far as the engine is concerned. Mostly through the good advice found searching this forum, I was able to correct the black smoking super rich idle, and stalling. In addition, it is amazing what a fresh tank of gas can do. I think maybe this car has been parked for a few years. The more I drive it, the better it gets.

My next project needs to be the wicked vibration I get above 45 MPH. It is almost certainly in the rear drivetrain. It is so bad, you have to slow down. I hear no clicking as though it were a U-joint. There is no clank or crunch when going from reverse to forward or vice-versa. Under power or coasting, nor braking, makes any difference.

I am afraid that it may be the differential. I can hear it while driving. It sounds like a bowling ball on hardwood. Could the differential cause a vibration? I should mention that I just discovered that 2 of the wheels have no weights on them! I do not believe that this could cause the vibration that I am experiencing, but it would be nice if that is all that it is.

The car is really sweet until 45 MPH. Any suggestion or WAG's would be appreciated.

I am still on my honeymoon with this car. It can do no wrong, in my eyes. It's quirks are still cute. If I have to buy a rearend, I will. Because She's Worth It.

 

[myspitfire]

Check and tighten ALL the DRIVESHAFT FLANGES.Flanges on the 2 drive axels & the flanges on the main drive shaft.The bolts on the flanges do have a tendency to work loose & cause a noise like that.They ALL should be tightened with a torque wrench.But i at the moment don't know the torque setting...........Also it may be that the balance weights on the driveshaft fell off.They are needed to keep the shaft running true.Otherwise if the noise is not a clicking or a clunking its not the u-joints or rear axel bearings.
This may be helpful...ask for MORE advice here..this forum is a GREAT place for answers
Ken&WhiteLightning(restored 1500 1979 Spit)I'll bet you a dollar & a donut its the flange bolts.

 

[tdskip]

Does it go away over a certain speed?

You might want to get the wheels balanced since it is cheap, easy and needs to be done anyway.

 

[spit71]

I had not considered the flange bolts, Myspitfire. That would be pretty sweet if that was the problem. My previous spitfire 20 years ago had one of the flanges come loose to the pont that only one bolt remained and the flange spun on that one bolt. The car bucked like a clown-car across a parking lot. (thank god it didn't happen on the freeway). I will check those tomorrow.

Tdskip, I haven't gone fast enough to see if the vibration goes away at higher speeds. The fastest that I have driven this car is about 65. The vibration becomes frightening. It feels like something will break.

 

[piman]

Hello Spit71,

I endorse Tdskips advice to do the wheel balance first, the next likely source of vibration is a dive shaft universal joint, you don't always hear them. Unless a drive flange is almost dropping off it is unlikely to cause a vibration. (Nor is it likely to be the differential)
However the 'sweet until 45' sounds very like an imbalanced wheel(s)

Alec

 

[DrEntropy]

Viewed from the rear, how do the wheels look? Perpendicular to the ground?

 

[frankenstang57]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]The fastest that I have driven this car is about 65. The vibration becomes frightening. It feels like something will break. [/QUOTE]

Not a tire balance problem. The vibe will go away eventually with a balance issue. If it keeps getting worse as speed increasess, it's one of two things; a bad tire or a bad U-joint on the axle or driveshaft. I'd check there before balancing tires. (worked at Discount for 3 years, spent the last two as the go-to-guy for ride issues) If it isn't loose bolts, but a U-joint, here's a # to cross for new at about 1/2 of what BV charges, made in the USA, and has grease zirks!

 

[tr6lover]

i agree with frankenstang, sounds like an axle or driveshaft issue. on the spit i had before it had the same vibration at 35mph and up and after taking apart the axles and changing u joints it turned out to be a bent driveshaft. put the car in the air and run it in gear and look underneath to see if the driveshaft is wobbling. it should turn straight, otherwise its bent or has a bad u joint or possibly the yokes where the u joints go are 180 degrees out of phase. if thats the case you could take the u joint apart and flip the yoke.
Randy

 

[piman]

Hello Frankenstang,

"The vibe will go away eventually with a balance issue",

How?

Alec

 

[frankenstang57]

If it's a balance problem you should be able to drive through it. I'm not a rocket scientist(but a space system data anylist...)that's the way it works. Tire balancing problems are more fluid than mechanical, and just go away with speed. Your tire may not be touching the ground any more, but your ride should smooth out with speed. Shaking like you describe like I said is probably mechanical. Tires will only shake so far then goaway. Tires out of balance usually don't shake until 60-65mph, and eventually go away. Like I said, check your U-joints.

 

[piman]

Hello Frankenstang,

i'm sorry, it is not that simple. Out of balance forces increase with speed, they may come and go (remember he said it comes in at 45mph, but he also said that he hasn't gone past 65mph) as resonant frequency plays a part. As you say yourself, "the tyres may not be touching the ground", that is not a good situation.

While I agree that it could be a worn universal joint (quite a common problem with Triumphs) the point he made about that there are no balance weights rings a bell. I've never had a car that didn't need balance weights on the wheels. Even if that is not the cure the wheels ought to be balanced.

Alec

 

[myspitfire]

I don't think its a ujoint or you would get a progressive click,A clunking is obviously a rear axel issue,BUT definatly a balance issue.....a whine at road speed is most likely a differential issue.Having said all that IT IS A SAFETY ISSUE.Or you'll drop a drive shaft or the axel will wear through & break(axel bearings)and loose your car in a ditch.
Ken & WhiteLightning
PS;but then it could be a wheel is out of round caused by curbrash

 

[spit71]

Thank you everyone for the great advice. Frankenstang, I appreciate the photo of the u-joint with part number, that should help alot. If it doesn't need U-joints now, I'm sure that it will.

As I said before, I hope that it is a tire balance issue at least partially. It is probably a combination of issues. I have absolutely no history with this car, so a bent drive shaft is completely plausible.

 

[spit71]

OK, I fixed it this evening. I bought a floor jack today and lifted the rear of the car and all appeared fine and tight. No noises while spinning tires or anything. I then lifted the front end and noticed the passenger side wheel had ALOT of bearing play in it. I removed the wheel and bearing hub and the castle nut was TWO TURNS out from finger tight. Now the car snorts right past 60.

Awesome.

When I returned home the brake on the front drivers side was smoking. I'll look into that later.

Question: Should I replace the front bearings? Does it damage them to be run so loose like that? It seems fine now.

Thanks all.

 

[Andrew Mace]

Hmmm...shoulda thought of that solution, since I experienced a very similar problem a few years back with the Herald...and solved it the same way.

I suspect it's worth taking a very close look at those bearings and related bits, including the stub axle, to make sure there was no damage. At least, you can repack the bearings; at worst, a new set isn't that expensive compared to what a failure might cost. /bcforum/images/%%GRAEMLIN_URL%%/frown.gif

 

[piman]

Hello Spoit71,

was there a split pin in the nut?
If so I suspect a bodge fix to cure a dragging brake, due, probably, to a seized piston? Does the car pull under braking, it sounds as though it should?

Alec

 

[spit71]

Andrew, I think I agree and will replace the bearings. I worry about PO workmanship now that I have had the car for a couple of weeks and have made some interesting discoveries.

Piman, yes there was a split pin in the nut. I guess the PO didn't set it correctly. Or is it possible that wear would have resulted in this much play? The grease appeared new and very clean.
The wheel that I found smoking was the drivers front, not the passenger front that had the loose castle nut. The car does not pull under braking, and the smoke did not smell of brakes. My previous post clearly states that the brakes were smoking, and I feel that that was an error on my part. I assumed it was the brakes, but after further consideration, I must admit that there was no brake smell. I think I need to check and see if the driver's side castle nut is too tight. This might the cause the whole hub to get too hot, right? Sorry I am changing my story after you were nice enough to offer your advice.

 

[piman]

Hello Spit71,

That's OK; well when you strip it down will tell you about wear. Too tight is as bad, possibly worse than too loose with these taper bearings. I've read that they can seize (When too tight) and shear the stub axle, very dangerous, obviously!

Alec