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Vibration

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M

MCS

Jedi Warrior
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Hello,

I have a vibration that is driving me crazy. It seems to be bad around 55mph. It is felt through the drive tunnel, I keep thinking it is driveline related. I have pushed and pulled every part on the car a hundred times over. The car is very tight, everything is brand new.
It might be the dat210 trans I recently rebuilt. This was my third trans I have rebuilt so maybe I missed something. I replaced all bearings, purchased a complete kit from rivergate. The trans works great no shifting problems. Does seem slightly noisy my neighbor reminded me that it will never be as smooth as my late model mini cooper s. Yesterday I had the prop shaft balanced, that helped a little I think.
My question tonight. I stuck my dial indicator on the outside of the rear drums; the run out is aprox 30 thou, wondering if this is too much. I then did the same on the front, the hubs have run out of 20 thou. Again wondering if this is too much.
The tires and rims are all 2 years old. I have had them balanced twice, each time by a different shop.
Thanks Phil
1966 Mk3 Sprite
 
no help with the brakes, but, I've noticed that a lot of the time vibrations seem to be traced to a bad motor mount
 
thanks JP,
they were new last year, I have tried to pry on them, hard to get at, I have had the motor out so many times maybe they are torn, they look ok.
Phil
 
General rule, steering wheel and cowl is front, seats and floor is rear.
On your runout.......have you checked the runout of the axle?
Put the wheel on, check the edge of the rim for runout.
Bent axle, bent wheel can do it.
The wheel rim edge will show it up best.

On other makes, I have run across bent companion flanges that can cause the driveline to act out-of-balance.

You check that up on jackstands.

Neutral, block one wheel, have an assistant roll the unblocked rear wheel while you hold a tyre crayon against the floor or a brace, and approach the driveshaft.
It will mark the shaft on the side it is out (if any).
At least you will know.

If you're feeling it in the floor, could be rear mount, probably not motor mounts.
 
Thanks TOC,
Wed mornining I will check wheel run out.I will look for my neighbour and test the driveshaft as well
I am using the rivergate trans mount it is new and tight
thanks Phil
 
Phil, if you need an extra pair of hands, I have to be in Puslinch a little before 1PM. I can scoot by your place. PM me or call 647-348-0879 or johnpetersmit "at" gmail.com
 
Hey JP,
Thanks for dropping by. I really appreciated the time you spent helping me source my vibe issue. Going for a drive with me and discussing the vibe goes along way to isolating the problem. I hope our tentative plan for Monday works. I promise a good lunch, no KD. In the mean time I will dream about swapping your wheels with mine and driving my sprite vibration free.
Cheers Phil
 
TOC
I checked rim run out the range is 25 thou to 45 thou, nothing extreme. The driveshaft is out 8 thou. Great ideas but not the problem.
Did not remove the half shafts, not ssure how to check them.
Phil
 
Phil;
A couple of questions;
Is this a new driveshaft and was it balanced before use?
Are the "U-joints" very flexible when not in the car? By this, I mean, do they move freely, (no binding), in all directions?
I live in Tillsonburg, and am a Licensed Technician.
If this problem persists, send me a PM and I'll help out, if you would like.

Dave :savewave:
 
MCS said:
TOC
I checked rim run out the range is 25 thou to 45 thou, nothing extreme. The driveshaft is out 8 thou. Great ideas but not the problem.
Did not remove the half shafts, not sure how to check them.
Phil
Click to expand...

Half shafts you need the load on the suspension, so jack stands under the carriers.
Roll and check as before on main driveline.
U-joints can do this also, as indicated.

Axle bearings are tight, no end wobble of wheel and tyres discernible?

Bearings okay?

Roughness can be checked by touching bearing carrier and spinning tyre.

Was the .008" runout on the driveshaft measured in the car or on the lathe?

In the car also finds bent companion flanges.
Especially if you undo the shaft after marking, rotate 180 degrees, re-install and recheck.
If the marks stay roughly in the same place, it's shaft runout.
If the move to the other side of the shaft, it ain't the shaft.
 
O.k, What TYPE of vibe is it?

Is it what I like to call "machine" vibe (vibrates at engine or driveline speed) or "road" vibration? (@ road or wheel speed, about the same frequency as an out of ballance washing machine).

Does it lessen with engine load? (notice I didn't say engine speed).

Does it come in @ 55mph, go away as you get faster and come back in at 70, then go away if you go faster? ( usually wheel balance)

Does it come in at 55 and get worse as you go faster? (something bent, bad tire)

Can you feel it in the streering wheel?

(o.k, you can feel everything throught the wheel, does it shake?)

Does it gett better/ worse as you turn the car from side to side? (load and unload each side of the car.)

Any itching/ burning, that sorta thing????

I have a machine vibe throught the tunnel and shifter. I'm convinced I have a sagging tranny mount.
 
Hi Dave,
Thank you for the offer. I think I am getting closer to my silk smooth sprite.

The driveshaft is original, the u joints are new and the yoke is also new. I took it to Niagra Drivetrain they balanced the driveshaft, said it was way out, needed two ounces of weight, that did help a bit.
The radius Links I installed today also helped, see my new post. The vibration now is most noticeable at 50-55mph, the front fenders shake up and down, very little vibration is felt in the steering wheel.Not sure what happens at higher speed maybe Friday afternon I can zoom up to 401 and go a little faster
My next step is to swap tires and rims on Monday
Thanks Phil
 
Hi Kellysguy,
Thanks for your input,

I think most of your suggestions have been looked at. The shake is now coming from the front, loads make no difference. I hope to try swapping tires/rims on Monday

I did notice that most of my tunnel vibes disappeared with the radius links, nice welcome improvement
Phil
 
Ah.
Front wings jumping....I'd be looking at front wheels for runout.
I didn't see you'd done fronts.
And, out-of-round tyres, or a belt separated (usually a lump or a squirm in the tread).
Front bearings loose?
Tie-rod ends okay?
Rack mounts?
You would not believe what odd behaviour worn, loose or oil-soaked rack mounts can create.
 
If you don't feel like waiting till monday, swap the front to back and see if anything changes. This would be a good time to look for the ply separation mentioned above.

usually load will make a difference on out of balance, bent componants or ply separation, but I'm starting to lean in that direction.
 
Phil - check your PM
 
See you Monday

We can do the wheel swap and see if the problem goes away. JP want to pratice his Nascar tire change procedures out. Turn the heat on and lock the beer up.

Cheers

Mark
 
Hey Mark. Lots of heat no problem, bring yur shorts. My new heater is working great. Should I have lunch ready for your arrival? JP’s wheels will be the perfect medicine I need.
I finished my Winners Circle tapered bearing install tonight. I also had the two front tires rebalanced, one was ok and the other was out 2 ounces. Out for a quick test as I had a family outing tonight. I think it is an improvement, hard to tell how much the fenders shake, it was very dark. Will go for a ride in the morning. At this rate my sprite will be as smooth as a 7 series BMW
See you Monday
Phil
 
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