possible causes of car shake at 70 mph

Hey guys
I am trying to eliminate causes of shaking of the car at speed.l I had the wheels balanced a week ago and it is a lot better. the steering wheel has a jiggle to it but the shaking is thru the whole car with the targa roof oscillating/ rattling. it starts at about 50 mph and doesnt go away.it doesnt get a lot worse at 70 but is more noticeable
I might try to get a dynamic balance of the wheels as in an on car balance if possible but i suspect the following culprits..
Gearbox/engine mounts.. The car recently passed road worthiness and bushes/tie rod ends cant have been defective.
thanks for any input
Nick

Anything that rotates... bad CV joint, bad wheel brg, warped brake disc, bent rim... are a few possibilities...

A dynamic balance may mask the problem...

SteveC

Hey Steve

Good to hear from you. I did email you 5 or 6 days ago but there were bushfires up your way so I figured you were busy.
The brakes are new and i dont get shimmy when braking.
So i figure the tripodes, bearings. One of the rims did need 100 grams to balance but bob jane didnt mention anything re bent rims .. mind you they where flat out.
Would engine mounts gearbox mounts be a possibility?
I suppose i should get the bearings cv joints then shouldnt i?
Thanks again Steve. I hope all is well
Regards
Nick

Hi Nick,

I typed out a reply to your email, but my overplayful cat decided to mess with the computer power leads plugged into a four way powerboard and turned me off before I pressed send :-( and just ran out of time to reply again...

Bushfires were closer to Perth in the hills, pretty bad too, we had 60/70km/h winds that day and over 100 homes got destroyed/damaged in just an afternoon/evening... started by sparks from an angle grinder by a guy fixing his box trailer!!

It would be nice if you could isolate the shake to front or rear... that would eliminate a few possibles... 100grams is a lot... I would be looking at the rims... know anyone with another fiat that you can swap rims/tyres with for a quick drive and see what happens?

SteveC

hey

I hear 60 percent of the houses that went up was because the swampy air con pads caught fire thus starting the fires. I will beg borrow or steal a rim... there is the spare but the tyre isnt so hot.. I will try that first Steve
Thanks again

Tires and wheels

I agree with trying to isolate the front or the back.
Having been doing tires for the last 21 years I have seen a lot of things.

If the vibration is in the steering wheel, then the problem is usually in the front tires.

Conversely,if the vibration is in the body of the vehicle, it is usually in the rear of the vehicle.

Swapping the tires from front to back is an easy way to find out if its the tires/rims. If the vibration moves from the body to the wheel, or vice versa, then it is most likely a tire/rim problem.

If a tire/rim takes 100g worth of weight, especially a 13" rim, then that is the most likely culprit. If you are able to watch the balancing being done, watch the surface of the tire as the wheel spins, relative to the floor or other stationary object, look for up and down and side to side movement. If there is a lot of movement, then watch the flange(edge) of the rim against something stationary and see if it is moving U/D or S/S.

Sometimes you can have a high spot in both the rim and the tire, that when lined up, can cause vibrations without there being any tire problems. Sometimes this can be corrected by spinning the tire 180deg on the rim (or 90deg, or 270deg.) to find the best fit. We refer to this as "Match Mounting". Newer balancers can do this for you. If this does not work, then mostlikely tire or rim replacement is in order.

When this is not an option, place the worst wheels/tires on the right side of the vehicle, especially on the right rear. There it will cause you the least about of annoyance. (Although it will still annoy your struts)

If initally, moving the tires from front to back does not produce any big changes, then there could be something mechanical, which is mostly beyond my area of expertees.

Well, hope that helps, off to work, my tires and my tyres await.

Lancia beta rims

Thanks for the timely advice.
Due to budgetry constraints could anyone advise if lancia beta rims would fit the xe. i once had them on my 124 and all they needed was one extra spacer.. i realise they are different cars but if i could fit l4 inch rims to the car i could get better rubber as there isnt much out in 13 inch land any more and i could manage that right now
Nick

duderduderini said:

?...could anyone advise if lancia beta rims would fit the xe.

Click to expand...

Hey Nick,

I ran with Beta wheels for about half a year. I recall it taking two spacers in the front. Looking back, it was probably kinda dumb, but it was an interesting experiement and a cheap one.

Hope that helps

John O.

imagumby said:

Having been doing tires for the last 21 years I have seen a lot of things....If the vibration is in the steering wheel, then the problem is usually in the front tires.

Click to expand...

Well, I've been chasing a steering shake for 3 years and the only conclusion I have is that the Sumitomos I've been buying just aren't round, because the CD30s they are mounted on are absolutely true.

I'm coming down to Winston in May to visit my three kids at School of the Arts (I went there, too). Maybe I can schedule some time with you tire shop to help me figure this out. If nothing else, perhaps I head back to DC on new rubber. I kinda don't care what tires anymore, just as long as they are round; it sucks having a sports car I can't drive comfortably over 65.

John O.

As already covered, basically anything in the suspension/steering/rotational parts can cause a shake. My rabbit was doing at this at 61 up to around 71 and smooth at 75 and the cause/s were several: 4 bent rims, worn tires (uneven), bad tie-rod ends (one didn't even have a retaining nut), bolts holding shocks to carriers were loose, and lastly The springs and struts were toast (bad alignment is a give-in here). So yeah the ride was shaky and a bit scary when it was time to turn the wheel,...so to say that the switch to "new" wheels and tires, 4 wheel alignment, 2 tie-rod ends, new suspension and tightening everything made a difference is a severe under statement. GL :thumbsup:

PS: the 40mm drop provided by the new parts was a plus!
Before:
After:

I had a shake similar to yours

and it turned out to be not only the plastic bushing on the passenger side, but also a bad tie rod end. Raise the front and try to move each tire left to right. There should be no slop whatsoever between the two wheels.

Remember, these guys are down under...

imagumby said:

When this is not an option, place the worst wheels/tires on the right side of the vehicle, especially on the right rear. There it will cause you the least about of annoyance. (Although it will still annoy your struts)

Click to expand...

I don't know how to "double quote", but someone also mentioned the steering rack bushing on the "passenger" side of the vehicle.

My point being, both of those references may be backwards for a RHD drive car such as they have in Australia. Easy (when you live in the US) to forget there are anything but LHD X's, but this is a world-wide forum.

Pete

JDExSquid said:

and it turned out to be not only the plastic bushing on the passenger side...

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Plastic bushing??? The only plastic bushing I'm aware of is in the radius rod mount. Can you be more specific?

Here's the thing, This problem has travelled from one X, my Black&Tan '86, over to my new all black '86. I mean, I've literally eliminated an entire car as a variable. Which leaves the wheels and tires, they are the only constant at this point, and I'm nearly certain the wheel, as I noted above, are perfect. Tires.

John O.

That's what I was talking about, Pete!

There's a plastic bushing on the long side of the steering rack that will harden, crack, and disintegrate. Wears tires out.

how old are your tyres? could be warped tyres

roadbox said:

Hey Nick,

I ran with Beta wheels for about half a year. I recall it taking two spacers in the front. Looking back, it was probably kinda dumb, but it was an interesting experiement and a cheap one.

Hope that helps

John O.

Click to expand...

Hi John
Could I ask why you thought it to be dumb?...
I will go over the car when I have the time and check all bolts nuts etc.... the tyres are relatively new in that they have lots of tread.. I still suspect as has been surmized that the rim which needed 100 grams balancing is the culprit. The budget doent stretch to 15 inch rims right now but i might be able to score lancia 14 inch rims which I could do
Thanks for all the advice
Nick

So if not 14 inch rims what exact offset and width for 15 inch rims

Hey guys
I see a 195/50/15 pretty much matches the 175/70/13 for gearing etc.
There is a mob in South Australia which do the Mini lite and they do rims for the X but I am concerned re tyre rubbing and legality.
What offset should one specify and is 195/50/15 going to fit?
Thanks

JDExSquid said:

There's a plastic bushing on the long side of the steering rack that will harden, crack, and disintegrate. Wears tires out.

Click to expand...

I'll take a look.

Thanks.

John O.

My apologies..

Pete Whitstone said:

I don't know how to "double quote", but someone also mentioned the steering rack bushing on the "passenger" side of the vehicle.

My point being, both of those references may be backwards for a RHD drive car such as they have in Australia. Easy (when you live in the US) to forget there are anything but LHD X's, but this is a world-wide forum.

Pete

Click to expand...

My apologies, Pete is perfectly correct. Putting the bad wheels/tyres as far away from the driver would have been the correct way to phrase that. Even then it is still only a temporary fix.

I also ran the rims off my '75 beta coupe on my '79 x-1/9 just cause I liked the 14" rims better, but due to the rims Positive offset compared to the more neutral offset on the X, (coupled with a lack of spacers and short wheel lugs) it ended up looking like the Delorean in Back To The Future 3 when they modified it to run on the rails......

and JohnO, just let me know when you are gonna be around and we will set something up. It will be nice to see an Italian car in my shop again. Last 2 I was were an 2007 Maserati Quattroporte(sp) and a clean 1984 Biturbo.

As for Tyre diameter....
The original 165/70r13 is appx 22.13in - total diameter
the more common 175/70r13 is appx 22.68in
a 185/60r13 is appx 21.73 (smaller than the original)
a 195/60r13 is appx 22.2 (closest to the original)
I found a BFS v rated tyre in a 165/65r13 which is 21.42 (smaller still)

Ideally If you can find a decent 15" rim with the 4x98 pattern and around a 0-10mm positive offset, the 195/50r15 is 22.72(same as the 175 13's) since most 15's will be wider (7'commonly), you might need a more neutral offset to keep it away from the interion components. Test fitting is the only way to really know.

Back in "The Day" i used to run some Keystone aluminum rims and barely fit a p215/50r13 BFG Radial T/A in the wheelwell. (rubbed up front on hard turns and in the rear out fender when hitting speedbumps and such)

I digress........
(hope somone found this helpful)

15" 4/100 wheels are cheap and plentiful...

and 4/98 to 4/100 hub/wheel-centric adapters can be had for less than 200. A 195/45/15 works well too.