Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 2nd November 2008, 21:50   #1
Rai
BHPian
 
Join Date: Feb 2008
Location: Bangalore
Posts: 82
Thanked: 6 Times
Default Fiat Petra - Brake Vibration at High Speed?

Hell Gurus,

Today I was driving down to Bangalore from Mangalore in my Fiat Petra 1.6 ELX, 2004 which has around 54,000 KMs on Odo. After KushalNagar, The Roads were was excellent and I was cruising at 120+ KMs speed.

But when the speed is high and when I press brake lightly I get heavy Vibration in the Vehicle. The Vibration is heavy in Steering. I asked my Passenger and he too felt the Vibration all over. Everybody in the vehicle feel the Vibration like Grrrrrrrrrgrrrgrrrr. But the Vibration goes off if I press the brake hard.
I think something is Not ok here. Can you guys suggest whats going on.

Regards
Rai
Rai is offline   Reply With Quote
Old 3rd November 2008, 13:41   #2
Senior - BHPian
 
trrk's Avatar
 
Join Date: Feb 2004
Location: Alleppey, Kerala
Posts: 2,113
Thanked: 12 Times
Default

Hi,

> But when the speed is high and when I press brake lightly I get heavy
> Vibration in the Vehicle.

Your front discs may be warped.
trrk is offline   Reply With Quote
Old 3rd November 2008, 16:28   #3
BHPian
 
tadukuttan's Avatar
 
Join Date: Mar 2006
Location: Bangalore
Posts: 241
Thanked: 22 Times
Default

Quote:
Originally Posted by Rai View Post
But when the speed is high and when I press brake lightly I get heavy Vibration in the Vehicle. The Vibration is heavy in Steering. I asked my Passenger and he too felt the Vibration all over. Everybody in the vehicle feel the Vibration like Grrrrrrrrrgrrrgrrrr. But the Vibration goes off if I press the brake hard.
I think something is Not ok here. Can you guys suggest whats going on.

Regards
Rai
The brake disks overheated from you driving a bit fast. And that caused them to warp. Sometimes, after it cools down, it will come back to it's flat shape. Do you get the vibrations when the disks are cold also?

It is better to replace the disks once this happens, the other option is to give it for machining, where they will remove the irregularities(thickness will decrease, causing even more overheating). The service center will know what to do. It is quite a common problem.
tadukuttan is offline   Reply With Quote
Old 3rd November 2008, 23:48   #4
BHPian
 
RedMM340's Avatar
 
Join Date: Apr 2008
Location: on the move
Posts: 459
Thanked: 23 Times
Default

Your brake rotors are likely warped.

Remove them and have a machine shop grind them on a lathe. This will make them flat and eliminate the vibes. I would also do the rear drums.

Machining the rotors will NOT cause more overheating.

Don't bother with an authorized service center, as they will only try to sell you 2 new rotors.
RedMM340 is offline   Reply With Quote
Old 4th November 2008, 01:54   #5
Senior - BHPian
 
nitrous's Avatar
 
Join Date: May 2004
Location: UAE/Lon/Madras
Posts: 6,966
Thanked: 282 Times
Default

Brake discs' life is usually measured by the thickness and the scoring.
The friction from the pads overtime reduce the thickness of the rotors and the uneven scores formed over usage.
The manufacturer usually specify a minimum thickness needed for the rotor. If its below the value, you need to replace the rotors. I've had this experience in two cars and the easiest and most sensible solution to me was replacement of the discs.
Remember to replace the rotors in pairs and its recommended to replace the brake pads as a set too.

For reference, an original MGP esteem brake disc cost me Rs.650.

Last edited by nitrous : 4th November 2008 at 01:55.
nitrous is offline   Reply With Quote
Old 4th November 2008, 08:55   #6
BHPian
 
RedMM340's Avatar
 
Join Date: Apr 2008
Location: on the move
Posts: 459
Thanked: 23 Times
Default

The cars is stated to have 54,000 k.m., this means it is on its first or possibly 2nd set of front brake pads.

It is HIGHLY unlikely that the discs are worn down to the point that they cannot be resurfaced. The minimum disc thickness is usually stamped somewhere on the disc, and of course that should be measured prior to machining. Problem is that not too many service centers will have a caliper or a micrometer to do this measurement.

Again, my point was that if you take the vehicle to an authorized service center, they will typically try to sell you a new pair of discs rather than resurface the existing ones, since that would be much easier for them.
RedMM340 is offline   Reply With Quote
Old 4th November 2008, 12:52   #7
Senior - BHPian
 
nitrous's Avatar
 
Join Date: May 2004
Location: UAE/Lon/Madras
Posts: 6,966
Thanked: 282 Times
Default

I partially agree,Gaurav.
But, the cost and the competence of the lathe machinists here plus the requirement of new rotors in the future(if he's planning to keep the car for long) would just make replacement sensible,right now.
nitrous is offline   Reply With Quote
Old 4th November 2008, 18:02   #8
BHPian
 
RedMM340's Avatar
 
Join Date: Apr 2008
Location: on the move
Posts: 459
Thanked: 23 Times
Default

I had my Palio front discs and rear drums turned for about Rs.300, and the machine shop did an excellent job.

Another reason that I would recommend machining of the discs/drums is that they have been temperature cycled many times and subsequent warpage will be less likely.

New discs might actually have a higher chance of warpage if they go through a high temperature cycle.
RedMM340 is offline   Reply With Quote
Old 3rd December 2008, 19:04   #9
Rai
BHPian
 
Join Date: Feb 2008
Location: Bangalore
Posts: 82
Thanked: 6 Times
Default At last took my Petra for Brake Service

Hello All,

Atlast today I could get some time and I took my Petra for Service at Tata Dealer in Bangalore.
I asked them to have a thorough Check on the Brakes. Plus I also asked them to do general Check.
For last 10 months I have never done any General Check-Ups (Because I didn't had any Problems) and felt guilty today and asked them to do a thorough General Checkups also.

Well, this is what they found and fixed today.
1. Front Brake Disks were not clean (warped? as mentioned in this
query above) and they did facing (they suggested not to go for
new disks as still life is there in the current disks).
2. One of the Cylinder of Rear Brake was Leaking and they replaced
Cylinders of both wheels.
And service mechanic told me that probably it was leaking for long
time (Infact around 4 to 5 mnoths back I had a query in this forum
that my Brakes seems to be weak).

3. AC Belt was split into 2 belts, but still in same position and working.
Replaced it.

I also wanted a Driver Side Electronic/Electric Rear-View Mirror. But it was out of Stock. Mine is Broken after Autorikshaw guy tested its strength.

I was really surprised that after 10 Months I had only these issues in Petra.

Other issues I had in my Petra sofar (after owning it for almost a year) are as follows.
* Changed the Drive-Shafts
(I wouldn't call this as a regular Service since this happened due to my stupididty of driving in Shiradi Ghat to Mangalore).
* Starter Motor Service at around 48K KMs on Odo.
* UnderBody Plastic/Fibre Cover Broken. But No issues with that.
* Broken Fuel Cap Cover (remotel operated Cover)
(Broken by Petrol Bunk Boy. Again No problem here. Lock is Broken)

What do you say guys..... Am I spending too much on this Car?.

Comparing to Diesel SUVs I owned earlier/now, this is much much lower.

Your Commens Please
Rai is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
FIAT PETRA Power Steering problem and FIAT India's responsiveness! rishi_kapoor Long-Term Ownership Reviews 13 13th June 2009 09:09
vibration in OHC beyond 110km/h speed weejai Technical Stuff 7 20th April 2009 13:08
Fiat Petra - Normal or High Performance Petrol ?? mchulet Technical Stuff 3 2nd June 2008 17:58
Fiat Petra - BRAKE - is it weak? Rai Technical Stuff 9 13th May 2008 00:24
Mag wheels for Petra High cost?? shbhrao Tyre & Alloy wheel Section 2 18th July 2006 17:37


All times are GMT +5.5. The time now is 04:49.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks