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Vibration when braking

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braking
4K views 9 replies 4 participants last post by  z06tim 
#1 ·
First, this story is about a Mitsubishi Outlander 2011.

I am posting here from two reasons: once, I am not visiting Mitsubishi forums :)
and secondary it is probably a general car issue, not necessarily related to brand.

So to begin, I have changed the rotors and pads (used some ATE) because the previous ones
were worn - but they worked normally, no issues. This was done 5 months ago.
All went fine, no problems.

Two months ago I took the car to dealer for regular maintenance and also had the brake fluid changed.
My fried took the car straight from the service and she has done a 600 km trip on that day.
When she arrived home, I took the car and immediately noticed some noise from the front. Stopped, and checked the wheels.. The front right wheel was holding only on ONE BOLT. All other 4 bolts were loose. Luckily the wheel did not come off while she was driving causing whatever could have happen.
So I have just tighten the bolts and thought we are lucky and that's it.

But it was not IT.
On the next trip out of the city, on the highway when I pushed the brakes at ~ 140km/h the car started to treble like hell. Stopped, checked wheels - all fine.

Went back to the service and I told them about the problem. I did not mention the bolts being lose one month ago, because I did not imagine that could be the issue, I thought that I just bought some cheap plastic ATE discs.

They said brake discs have been deformed, and I need new ones. (those discs were still under warranty, almost new). Bought new discs (and pads!) according to their advice (OE parts), took the car on the highway - exactly the same!
Back to the garage, and now I told them about the loose wheel story, because I figured it might have something to do with all this, the measured the brand new discs with a dial gauge for lateral runout (with discs mounted on the car) and said its "25" (I suppose 0.25 mm or 2.5 mm?) on the front right, and "6" on the left wheel (the second one being within the normal limits according to them).
So they pointed the wheel hub is deformed, as the discs are brand new.
I bought a second hand steering knuckle + wheel hub + bearing assembly from a 50,000 km Outlander, put it on the car - SAME VIBRATION AT BRAKING.

Measured the new disc on the car again with the replaced knuckle assembly and new discs on, 10 on the right wheel, 6 on the left one.

The suspension and steering has been checked 100 times already, all fine except for the upper strut mount (on the right!) which also makes a clonk noise on uneven roads. But I know about this one for a while, and the brakes were fine before. Could this cause the vibration on braking? (maybe the wear on it got much worse lately)

Wheels have been balanced.
Inner and outer tie rods, replaced.
Shock absorbers checked on the stand, perfect condition.
ARB bushes and link rods replaced.
Lower arms - perfect condition.
No errors coming from the ABS unit
The only fault in the suspension (not resolved yet is the right upper strut mount).

At this point the mechanics have run out of ideas.
Today they are gonna put a caliper form another Outlander they have in the garage, and if it's still the same I don't know what to do - and suppose they don't know either.

I can only connect this problem with the last service before it started, when they replaced the brake fluid, and delivered the car with loose bolts on the front right.
Driving 600 km (at speed!) with a loose wheel has probably damaged something there - but what ?
I could only think about the discs, pads and wheel hub (all replaced and not problem not fixed), and maybe the caliper which will be done today.
Could it be related to the brake fluid replacement not done properly (air inside)?

Symptoms described:

The car brakes fine at any speed for the first time (when cold)
After a few brakes, it start trembling when braking at speeds over 120 km/h.
It vibrates harder as the speed increases.
After more brakes applied, when they get hot, it vibrates even at 80 km/h but not so hard, and at lower frequency.
Also when the breaks are hot, when I apply constant power on the pedal at low speed, it doesn't break constantly, the braking power slightly fluctuates (but not on the same rate as the wheels turn).
At 50 km/h the braking power fluctuation rate is around 1 second (although I keep the same pressure on the pedal).
There is no vibrating (feedback) from the pedal. It feels normal, only the car and the steering wheel are vibrating.
And when there is no braking, the card runs normal, no vibrations.

So, what is it? :)
 
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#2 ·
This is a tricky one. Your following observation seems odd, in that vibration only occurs when braking, but not through the brake pedal.

"There is no vibrating (feedback) from the pedal. It feels normal, only the car and the steering wheel are vibrating.
And when there is no braking, the card runs normal, no vibrations"

Due to this i would guess that the brake discs are more than likely OK, and your mechanic was mis-interpreting that as the problem. Anyway you have eliminated that problem by changing discs and hub.

Assuming you don't have a problem with the wheel balancing, or any damage to a wheel. Have you tried swapping fronts to back? Can you tell if the vibration originates from the front?

I would have thought if there is a problem with a brake caliper it would show up on a brake force test as out of balance, and the car would pull to one side when braking.

I would be focussing more on that right upper strut mount you mention.

i would also suggest checking your drive shafts for damage, as perhaps you may have an issue with an out-of-balance drive shaft. This could have been there for some time, but only becomes noticeable as other components age, or under certain conditions, such as when you brake.

I would expect there to be more vibration issues at certain speeds with an out of balance driveshaft, without braking. Have you noticed anything odd, such as weird footwell vibrations, or passengers complaining of feeling a bit sick?

I hate these sort of problems. I hope you solve it.
 
#3 ·
Got a similar problem with my mx5
- changed calipers, brake disks, brake pads, tyres, wheels
- inspected multiple times, including when shocks replaced and full geo

Vibration through steering wheel after a few hard braking sessions.

Starting to suspect ball joints, tie rods, CV joints, etc although there's nothing obvious :(
 
#4 ·
There are almost no noticeable vibrations in the car while running. Only when the brakes are applied.
Maybe a very small awkward feedback in the steering wheel I change lanes for example at speed.

And definitelly no, or very very small vibration in the brake pedal. The whole car trembles, so the pedal all together. But the pedal itself is not pulsating.

What I ha e managed today - I put all 4 wheels from another Outlander and 75% of the problem was gone!

So there is definitelly a problem with at least one of the wheels. I will put the winter tires on Monday and also check the rims for any issues.

With the other wheels there is still some vibration left when braking, but somehow different and much less severe.

I have also ordered both upper strut mounts and their bearings.

So after doing the tyre change, rims check and upper strut mounts on Monday, I wi also have the mechanic put the dial gauge on all discs again with me beside him :)
 
#9 ·
The tolerances between a good and bad tyre are minute. I tend to go for budget tyres on the Mondeo. The last set I had put on the Mondeo were on the rear. I noticed an immediate change in the handling when pressing on....I could feel the rear of the car almost sliding about as there was so much lateral movement in the tread block. I shifted the tyres to the front but that brought up a new issue in that suddenly first I was unable to get one of the wheels to balance up correctly (I used the balancing machine at work). I've never had an issue with balancing on this machine before so I knew the tyre was at fault. Said tyre also caused the car to pull quite severely to the left. Once the tread had worn away a little I swapped the tyres back to the rear. With the tread blocks worn a little the tendency to feel loose at the rear had gone, and with the know good tyres back on the front the car was steering correctly once again.
 
#10 ·
Glad you solved it.

These sort of issues really highlight the importance of the condition of tyres, and as Mymatemarmite says budget tyres may come with more compromises even from brand new.

Was there any obvious damage or abnormal wear on the tyres on your Outlander? Were they run-flats?
 
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