pulling to the left when braking hard... what to check...

[davido140]

pads and disks all checked out fine at serviced 200ish miles ago, but pulling has gone from slight tug to biiig pull when braking hard. What should I have a look at? Bleeding the whole system was the only thing I could think to do.

Cheers

[GreenV8S]

I assume tyre pressures all correct, and nothing obviously wrong in a visual check of the suspension and quick prod at the major components.

Given that, most likely one of the callipers is sticking, next suspect would be worn suspension bushes allowing the suspension to flex under braking.

[davido140]

Wouldnt a sticky caliper pull all the time?

didnt think about suspension. I have never actually taken the time to look underneath the TVR, can I visually inspect the bushes if I jack it up?

Its still on original shocks at 43000 miles, could one be on the way out? (good excuse for nitrons)

[Biggriff]

put money on a seized caliper. Take it off and push the pistons back gently. Leave rags around the reservoir as this can overflow.

I have seen (so called) main dealer serviced cars where the calipers are seized solid and i'm not just talking about TVR's.

R

[davido140]

which side would be siezed? the left (as its pulling to the left)? or the right (siezed open and not working properly ?)

Sorry for dimbo questions...

anyone know the torque setting I should use on my wrench when putting the calipers back on? or just do em as tight as I bloody well can?

edit: thanks for the quick help by the way.

Edited by davido140 on Saturday 28th July 17:47

[GreenV8S]

The most likely calliper problem is the slider sticking. This will mean that only one pad is being applied to the disk which puts nasty unequal loads on everything. If it's being doing this for a while then it will show up as uneven pad wear. When the callipers are serviced, the sliders should be cleaned, checked for wear and greased. But who's to say it happens every time?

ETA: Sorry - I'm assuming single pot sliding callipers here, as used on the earlier models. I don't know if the Tuscan uses the same sort.

Edited by GreenV8S on Saturday 28th July 18:04

[davido140]

ok, we have officially reached my kwik-fit knowledge of brakes. I can change pads and bleed 'em. Buggered if I know what a slider is!!

[GreenV8S]

davido140 said:

ok, we have officially reached my kwik-fit knowledge of brakes. I can change pads and bleed 'em. Buggered if I know what a slider is!!

The classic calliper is the sort rigidly bolted to the upright with pistons on both sides.

There's a much cheaper sort called a floating calliper which only has a piston on one side (usually the inside). The calliper is attached to the upright by a couple of sliders and the body of the calliper extends over the top of the disc and holds the outer pad. Hence when the brakes are applied the piston pushes the two pads together, the disc is trapped in the middle and the whole lot is free to float sideways to ensure that equal pressure is applied on both sides of the disc. They're much cheaper than classic double sides callipers, and are common on production cars. This is the sort used on the S series, Griffith, Chimaera etc as standard.

The sliders wear and can get gummed up with burned grease and brake dust. If they jam, the calliper can't move sideways so the pressure than should be applied to the outer pad, isn't. Sometimes they jam on so the outer pad rubs against the disc and overheats.

[davido140]

GreenV8S said:

davido140 said:

ok, we have officially reached my kwik-fit knowledge of brakes. I can change pads and bleed 'em. Buggered if I know what a slider is!!

The classic calliper is the sort rigidly bolted to the upright with pistons on both sides.

There's a much cheaper sort called a floating calliper which only has a piston on one side (usually the inside). The calliper is attached to the upright by a couple of sliders and the body of the calliper extends over the top of the disc and holds the outer pad. Hence when the brakes are applied the piston pushes the two pads together, the disc is trapped in the middle and the whole lot is free to float sideways to ensure that equal pressure is applied on both sides of the disc. They're much cheaper than classic double sides callipers, and are common on production cars. This is the sort used on the S series, Griffith, Chimaera etc as standard.

The sliders wear and can get gummed up with burned grease and brake dust. If they jam, the calliper can't move sideways so the pressure than should be applied to the outer pad, isn't. Sometimes they jam on so the outer pad rubs against the disc and overheats.

ahhhhh.... thank you! that makes sense. Come to think of it, doesnt the Tuscan have floating calipers on the rear? off a granada or something IIRC?

edit: just to confirm, the tuscan has "classic" callipers on the front so stuck sliders is not my problem?

Edited by davido140 on Sunday 29th July 10:20

[GreenV8S]

davido140 said:

edit: just to confirm, the tuscan has "classic" callipers on the front so stuck sliders is not my problem?

Problem could be at the front or rear. If you feel a pull on the steering wheel under braking that would suggest it's at the front. If the car just seems to wander sideways it could be at the rear. It'll take a while for uneven pad wear to be noticeable but if this has been happening for a while it's worth checking all the pads to see if you can find any clues. Something else you can try is check for heat build-up. Go for a gentle drive and confirm that all the brakes are cool afterwards. Then go out and work the brakes very hard for a few minutes. The fronts should get hot quite quickly and be the same temp on both sides. The rears will heat up less but still be the same on both sides. Ideally measure using an infrared thermometer but you may find it is really obvious if one side is red hot and the other isn't. Better hope that shows where the problem is, because the next step would be to start investigating the callipers which will involve significantly more time and expense.