[hvkumar]

Chronicles of a 261,000 km old non-crde Scorpio:

I thought when I changed the rear brake cylinder kit, my Scorpio's brakes will work better. They didn't.

Then I discovered a leaking feed pipe and I gloated that I can return to the 140s again confident with the stronger brakes. That did not work out too.

Brake pads were changed, rear brake cylinders were inspected and found OK.

It must be bald tyres, so I changed over to not-so-new Yokos. Braking still felt as though I was on a tight-rope.

Ah ha, I said, when engine oil leaked from the alternator and fouled up the vacuum pump, starving the brake booster and fading out brakes. I threw a party the night Bosch collected a handsome fee from me to change bearings, seals, stators, etc. That was a premature celebration!

Brake oil was replaced, brake lines bled.

My brake booster have already been changed, along with the master cylinder once before.

I found the vacuum pump oil feed pipe leaking, the washers were changed and the leak fixed.

Checked the pressure tank for any obvious leaks, found OK.

Brake pads are not too old, they don;t make any squealing noises when brakes are applied.

What happens?
I apply brakes.
Pedals go in OK, braking is mild, but brakes bite in only when the gap is miniscule.
And when it engages, it is with a screech almost, and I have to watch my back so that the guy behind does not crash into me.
Pedal play is normal, but braking action is delayed and minimal.
I pump the brakes long and hard and I found the same hardness returning to the pedal as I faced when I had the brake booster, vacuum pump and belt problems.

The next theory I am looking at is - could the brake calipers be retracting the brake pads slowly, and the resultant jam is causing the hardness and failure of brakes. In other words, when I engage my brakes, it works the first time, but on continuous engagement, the brake pads get stuck to the disc and do not spring back. I am able to "unlock" the brakes when I moved the car forward and backward.

Net result is - I am unable to predict braking action, on occasions I found the brake pedal suddenly turning hard, especially if pressed hard, indicating that either the vacuum or hydraulic pressure is not sustaining or else the brake pads or shoes re getting locked up.

Solutions, anyone?

[SS-Traveller]

^^ Were your front caliper kits replaced?
Edit: What brand of brake pads are you running on?

[hvkumar]

Originally Posted by SS-Traveller

^^ Were your front caliper kits replaced?

Never. Do you think they could be causing the problem? I suspect the springs there may be gone, and am planning to check that next.

Brand of brake pads - don't remember, but I think it is the standard TVS one which the ASCs stock.

[SS-Traveller]

Originally Posted by hvkumar

Never....
Brand of brake pads - don't remember, but I think it is the standard TVS one which the ASCs stock.

Check for wear and corrosion in the caliper pots, replace kit if no corrosion/wear seen, or at most replace the pair of calipers. Turn the discs, and put in a fresh set of pads - that should solve the issue of late/erratic brake bite.

[SPIKE ARRESTOR]

Originally Posted by hvkumar

And when it engages, it is with a screech almost, and I have to watch my back so that the guy behind does not crash into me.

I agree with SS. Do the wheels lock? In most cases this is a result of a faulty caliper mechanism (improper retraction). I believe you have changed wheel cylinders so that rules out improper retraction of the wheel cylinder pistons up to some extent. The screeching noise can also be due to faulty liners (dirty / greased). Does this noise come during cold starting on an early morning?

Spike

PS- Have you checked the wheels and tyres after a long run? Do they become hot?

[kaushik_s]

Originally Posted by n.devdath

Pretty usual actually. If your car wanders to a side even when you are not braking, it is the alignment of the wheels and if it wanders only when braking, get the brakes checked. Their bite is not even on all the wheels.

Unless the pull is very severe and your use is within the city, you could leave it till the first service as well, if you do not have the time or inclination to get it done immediately.

Originally Posted by SS-Traveller

You probably need a wheel alignment check, with adjustment of the caster angle.

Thanks for the response. Will get it checked today..
Today the demo service advisor came home to give the demo and I was telling him about the issue. He suggested me to take the vehicle to service center. According to him it looks like an alignment problem but they will check the brakes also.
The pull is severe in case of speeds more than 80 and hard braking only as I can feel whole car is pulling towards left side. For normal braking it's as normal as it should be.
I'll probably take the vehicle to the service center today and get it checked.

[PRADEEP KUMAR]

Kumarji,
Have a feeling it could be the brake booster which is palying up the issue.
tx

Note from the Team-BHP Support Team: Please avoid quoting an entire large post. It inconveniences our small screen & mobile readers.

Thanks.

[hvkumar]

Originally Posted by SPIKE ARRESTOR

I agree with SS. Do the wheels lock? In most cases this is a result of a faulty caliper mechanism (improper retraction). I believe you have changed wheel cylinders so that rules out improper retraction of the wheel cylinder pistons up to some extent. The screeching noise can also be due to faulty liners (dirty / greased). Does this noise come during cold starting on an early morning?

Spike

PS- Have you checked the wheels and tyres after a long run? Do they become hot?

No, the wheels do not lock, but the brake pedal remains hard for a few seconds.

Yes, both the wheel discs are not very old. The rear brake cylinder kits have also been changed. I do not have any instances of swerving which can happen if any one wheel brake pad/shoe is jammed. Yes, the screeching (mild) may be because of the dirt. I did not notice it specifically in early morning.

I did check the heat in the wheel cylinders, did not find anything unusual, although I suspect that there is a little more heat than normal in the rear wheels. Yet to open up and check though, planning to do so.

Pradeep Kumar, it is logical to suspect the malfunctioning of the brake booster. But I have my doubts on that because typical brake booster failure means the pedal remains hard all the time whereas in my case, it works most of the time in normal circumstances. The brake booster (and the master cylinder) has also been changed once, so what I have now is less than 1 lakh kms old. Nonetheless, I will do the brake release-engine start-brake pedaling test to ascertain if the tell-tale symptoms of brake booster failure occur. Another reason why I am unable to check out the brake booster problem is that I do not have a stand-by booster for trial testing purposes, I have to buy a new one (and that is an expensive proposition), which is not viable unless I am sure that is the cause.

[kaushik_s]

At The work shop now. What predicted to be a normal alignment problem turned out to be a fix for caster/camber alignment and something called shim or sim, not sure what the exact word is. Already 2 hours and it might take some more time it seems.. Just hoping that the problem will be solved..

[kaushik_s]

^^ Problem still not solved :( The pull become less after the alignment but is still present and can be felt. They've also checked the brake pads and calipers. Have to leave the car again at the workshop tomorrow or day after. Not sure what the problem actually.

[n.devdath]

Which workshop? Gimme a shout if you need any help at SKS. Did they check for brake adjustment on all the 4 wheels?

[kaushik_s]

Devdath, thanks for the offer to help. This one is Sireesh Auto workshop. They checked the front brakes only today not the rear as it was getting late already. They've asked me to drop the vehicles at workshop but I was not comfortable keeping it there for night (I never keep my cars on service centers overnight). Also their senior mechanic was not present today and they said he will be back day after and so decided to to take it there again on Wednesday.

[n.devdath]

Originally Posted by kaushik_s

This one is Sireesh Auto workshop.

Ok, here is a RED Flag. Keep AWAY from Sireesh. Any outlet of theirs. All my friends have had their worst experiences there.

[kaushik_s]

Originally Posted by n.devdath

Ok, here is a RED Flag. Keep AWAY from Sireesh. Any outlet of theirs. All my friends have had their worst experiences there.

Oops, that's bad news. I've just bought the vehicle from them. So I guess for the initial period it'll have to go there only. But I'll definitely keep a tab on what's going on. Normally I'll be with the vehicle if it goes for service anyway.
BTW, can you please tell me what are the issues your friend's have faced? That would help me while dealing with them.

[SS-Traveller]

Originally Posted by kaushik_s

...a fix for caster/camber alignment and something called shim or sim, not sure what the exact word is.

It's a shim [http://en.wikipedia.org/wiki/Shim_(spacer) ]. M&M supplies standard thickness shims specifically to adjust the caster and camber angles. But what were they taking 2 hours to do the job for? You're probably unfortunate enough to get an incompetent/newbie mech handling your job.

Originally Posted by kaushik_s

Oops, that's bad news. I've just bought the vehicle from them.

Not necessary. There's no compulsion for you to service the car from the same dealer who sold it to you. Any M&M dealer will do it, as well as honour warranty.

Originally Posted by SPIKE ARRESTOR

I agree with SS.

I wonder - this must be a world record, to run a pair of brake calipers without kit change / caliper replacement for 2.61L km!!! Spike, you want those calipers for a museum or for the R&D people to take a look at?