[kishoryk]

Hello Gurus,

I recently purchased Alto Lxi and drove it for about 1000km. Only modification was that, I've got the original tyres replaced with Tubeless ones and I think slightly larger. Dealer did this before the delivery of the new car itself.

So far, running, comfort level is all fine as expected, mileage front too, no complaints. Gear shifting, clutch operation, pick-up are all fine.

Only problem is that, car wobbles/shakes when the speed is between 65 and 75 kmph. This shaking gradually stops when I exceed 75 again and probably only once (very momentarily) I noticed when I did between 90-100 (I know I should not exceed say 80 for a new car but tried this just once). This shaking starts as I approach from 60 to 65 kmph and peaks at 70. It's somthing like you are riding on a very bumpy road. But there are no problems like loss of control, or any shaking with steering or car pulling to sides or problems with braking.

Initially I thought problem could be with wheel alignment. I reported this when I did the first service. I was told that the wheel alignment is corrected. I did see the report and found some differences between "Before" and "After" values, though did not understand the meaning/impact of these differences. The engineer told me, there will not be any more shaking of sorts. I immediately tried about 65kmph and found to be okay, though I did not feel totally comfortable. On the way back from the service station, while filling in the petrol, I wanted to get the air pressure checked. Noticed that tyres are actually over filled. Reco was I think 30psi for Alto, but each tyre showed something like 34/35. Not sure, if this over pressure alleviated the problem. I got this air pressure back to recommended levels of 30 psi in all 4 wheels. Again, I find this shaking back when I drive more than 65kmph speed. (Did not try the upper limit).

Now, Gurus, please could you suggest, what could be the issue here? It's wheel allignment again? wrong tyre pressure, or problem with engine itself?
(I don't think it's problem with engine, because, even when I disengaged the gear, meaning driving in neutral, this shaking does not go).

Thanks much in advance.

Regards,
KK

[dinar]

Check if the wheels are balanced after the tire installation.get this done, it was not, you'll find the weights on the rims to be sure if it was done, and also the dealer charge for the weight if not for labor.

[condor]

@KishoryK, whenever you check the car for existence of the problem (till the problem is resolved), Do Not Forget to check the tyre pressures. Pick up a guage from an accessories shop if you dont have one.

[amit_mechengg]

kishore,

i had faced a similar problem in alto. the engine being 3 cylinder has some wobbling. it happens peculiarly at speeds of 60-70 on a plain road, i.e not on slopes or something. i have observed it happens when the engine is almost at rpm where there is constant speed and the engine is almost in no load condition.

if the tyre is the issue the car wobbles at all speeds. try at 80-100 once safely somewhere.

ask the maruti people to check the engine mounts and ask them to check the steering dampers too.

[Sankar]

Originally Posted by amit_mechengg

kishore,

i had faced a similar problem in alto. the engine being 3 cylinder has some wobbling. it happens peculiarly at speeds of 60-70 on a plain road, i.e not on slopes or something. i have observed it happens when the engine is almost at rpm where there is constant speed and the engine is almost in no load condition.

if the tyre is the issue the car wobbles at all speeds. try at 80-100 once safely somewhere.

ask the maruti people to check the engine mounts and ask them to check the steering dampers too.

Amit, the engine is a balanced unit eventhough it's three cylinder mill. If it were an unbalanced unit it would probably self destruct before you experience any wobbles. But if your car has worn out engine mounts then it might cause a wobble, but not while you cruise on the highway.

KishoreK check the tyre pressure, and get the wheels balanced again if necesary. Inbalanced wheels WILL cause a wobble at certain speeds and the wobble might go away after certain speeds.

[SirAlec]

Its definitely wheel balancing problem.

And can we please recommend alloys along with tubeless.?

[BaCkSeAtDrIVeR]

I think this is a case of harmonic vibrations.

[anupmathur]

In a new car, it could only be wheel balancing causing the problem you have described.
Do get the wheels balanced.

For sure its the balancing problem. The speeds between 65-75 (as you metioned) helps to achieve the natural frequency of the structure due to which resonancy occurs and thus the shaking. If you move higher, the normal frequency does not match with the natural frequency of the structure so resonancy does not occur.
You might not understand the concept if you haven't studied waves.

And being honest you dont even need to understand that. :P Just get you wheels balanced (not just aligned) and everything will be fine.

[Jaggu]

Originally Posted by SirAlec

Its definitely wheel balancing problem.

And can we please recommend alloys along with tubeless.?

Originally Posted by BaCkSeAtDrIVeR

I think this is a case of harmonic vibrations.

Get your wheel balanced, so that it wont get into a harmonic vibration mode with your springs. 100 Rs job.

[vinit.merchant]

I had faced similiar issue with Santro between 80-90 on Highway.
Stopped at a tyre shop near the pump and asked to check the Rims.

There was a Rim bend, which I got done and the car is running well now.

Check whether the rim is bent. It happens sometime on Indian roads, when you tend to hit a big pot hole.

[rjstyles69]

Originally Posted by kishoryk

I recently purchased Alto Lxi and drove it for about 1000km. Only modification was that, I've got the original tyres replaced with Tubeless ones and I think slightly larger. Dealer did this before the delivery of the new car itself.

Folks what if it is a wrong upsize ? Kishore why don't you post the tyre size, you can get it off the sidewalls . Generally the number would be like 165/60/R13 .

Apart from this I can only think of a wheel alignment issue which needs to be addressed if your upsize if correct.

[rohan_fonseca]

His has got to be if stock replacement i.e. tube to tubeless, 145/80/12. Get balancing checked at a tyre shop instead of MASS for an unbiased opinion.

[kishoryk]

Thanks for all your responses. Wheel Balance did not strike to me. Will check that out tomorrow.

Originally Posted by rjstyles69

Folks what if it is a wrong upsize ? Kishore why don't you post the tyre size, you can get it off the sidewalls . Generally the number would be like 165/60/R13 .

My wheel size is 155/70/R12. Is this a problem?

Originally Posted by vinit.merchant

Check whether the rim is bent. It happens sometime on Indian roads, when you tend to hit a big pot hole.

No, for sure, it's not a dent with rims. I noticed this problem the very first time I reached 65kmph and till then it was just a simple drive here and there.

[VJ_MAVRICK]

Originally Posted by kishoryk

Thanks for all your responses. Wheel Balance did not strike to me. Will check that out tomorrow.



My wheel size is 155/70/R12. Is this a problem?




No, for sure, it's not a dent with rims. I noticed this problem the very first time I reached 65kmph and till then it was just a simple drive here and there.

Correcting you KishoreK its the tire size that is 155/70/R12(stock size might have been 145/80/R12) and not the Wheel which i presume is a stock wheel.
For tubeless it is better to run them on alloy wheels (13 " with 5j rims) and defnitely it would be wheel balancing problem.