Brake disc change
Discussion
Hi everybody! , planning a trip to Stresa in Italy later this year, before we go I will get the v8v serviced, but it could do with new discs, not impressed by dealer quotes to do this work, so have ordered new front discs, new front pads, total cost, about £430.... Not bad.
The workshop manual says that the calliper bolts must be renewed, because the old one can break!!! Surely this is a load of old b
ks???....any advise would be appreciated !
The workshop manual says that the calliper bolts must be renewed, because the old one can break!!! Surely this is a load of old b
ks???....any advise would be appreciated ! The cap screws in question are quite meaty and made of high tensile steel, so weather they would break is a moot point. As I remember the torque settings are quite high. I would imagine the reason for replacement is more to do with the threads stretching due to heat and tension, thus possibly compromising the torque settings if reused. Four cap screws aprox £2.00 per pop not a huge amount in the grand scheme of things.
Whenever the subject of pad and disk replacement comes up for discussion most of the spanner men will say no big problem, I would agree, that is if the vehicle has had loving care and attention when serviced. I found the biggest problem when replacing the discs and pads (front and rear DB9) was removing the pad retaining pins as some of them had seized in the callipers. If a bit of copper slip has been used on them when last fitted there probably would not have been a problem. Unfortunately I ended up having to drill the pins out (amazing what you can do with a Dremel) even though I had turned up a dedicated pin punch so as not to damage said pins, replacement pins only come as a set.
It would be worth making sure the pins will come out before you get to a point of no return.
Whenever the subject of pad and disk replacement comes up for discussion most of the spanner men will say no big problem, I would agree, that is if the vehicle has had loving care and attention when serviced. I found the biggest problem when replacing the discs and pads (front and rear DB9) was removing the pad retaining pins as some of them had seized in the callipers. If a bit of copper slip has been used on them when last fitted there probably would not have been a problem. Unfortunately I ended up having to drill the pins out (amazing what you can do with a Dremel) even though I had turned up a dedicated pin punch so as not to damage said pins, replacement pins only come as a set.
It would be worth making sure the pins will come out before you get to a point of no return.
A lot of early models 1993 - 2005 have had caliper bolts break off when undoing.
It could be something to do with bi-metalic reaction rather than weather corrosion.
When I last tried mine the end of the thread that's visible was very clean.. I brushed them to make sure and used releasing fluid and let it soak in there for a few days, adding more each day.
When the time came they were a real "git" to free off and then when turning creaked at every turn.
Upon coming half way out they then siezed completely, I had to then wind them back in and prey that they eventually come out when needed.
The effort required to turn the bolts was A LOT, flexing a 600mm hard bar in the process.
So, new bolts? "ALWAYS"
The do go in very tight on the threads so I guess a small amount of copper slip (trace amount) to prevent future siezing would work. Once torqued up they won't be coming out on their own, that's for sure.
It could be something to do with bi-metalic reaction rather than weather corrosion.
When I last tried mine the end of the thread that's visible was very clean.. I brushed them to make sure and used releasing fluid and let it soak in there for a few days, adding more each day.
When the time came they were a real "git" to free off and then when turning creaked at every turn.
Upon coming half way out they then siezed completely, I had to then wind them back in and prey that they eventually come out when needed.
The effort required to turn the bolts was A LOT, flexing a 600mm hard bar in the process.
So, new bolts? "ALWAYS"
The do go in very tight on the threads so I guess a small amount of copper slip (trace amount) to prevent future siezing would work. Once torqued up they won't be coming out on their own, that's for sure.
Thanks for the replies, will source new bolts, get a nice breaker bar and some WD40,, one other question, according to the workshop manual, torque setting is something like 22 ft lbs + 90 degrees? I am assuming this means, turn through another quarter turn after reaching torque setting?
Quick update, have posted this elsewhere in this forum
Started caliper and pad change at about 3.00 pm, had many work related phone calls, and a bit of Steak and Chips, finished at 6.15 pm....... Result!!!
Caliper bolts no problems, pad pins no problems, disc screws no problems.....discs wre very stuck though, first one took 30 mins of hammering to shock it loose, second one I squirted some GT85 in screw holes, 10 minutes later it came off with a few taps, had to clean up both hubs, they were quite rusty, applied copperslip so next time will be easier. Oh, and when the servicing garage tells you your pads are 70% worn, they could be telling a porky, I was told a year ago mine were 70% worn, and may not last till next service, well, since then i did 12000 miles and one track day, when I compared new pads with old, I would say the old ones were LESS than 50% worn !!!
Started caliper and pad change at about 3.00 pm, had many work related phone calls, and a bit of Steak and Chips, finished at 6.15 pm....... Result!!!
Caliper bolts no problems, pad pins no problems, disc screws no problems.....discs wre very stuck though, first one took 30 mins of hammering to shock it loose, second one I squirted some GT85 in screw holes, 10 minutes later it came off with a few taps, had to clean up both hubs, they were quite rusty, applied copperslip so next time will be easier. Oh, and when the servicing garage tells you your pads are 70% worn, they could be telling a porky, I was told a year ago mine were 70% worn, and may not last till next service, well, since then i did 12000 miles and one track day, when I compared new pads with old, I would say the old ones were LESS than 50% worn !!!
Edited by Ikebaddog on Friday 5th July 20:00
Out of interest, how much are new bolts and pins? I can't imagine they're much in the context of the overall job cost? On safety items like this, I would want to know they were new.
As for the dealers remarks...I think they have to tell you when they're down to a certain level. But maths and percentages aren't usually their strong point IME and I suspect the warnings have more to do with commerciality than safety. I've gone for thousands of miles beyond getting "advice" on brakes and tyres with zero degradation in performance.
As for the dealers remarks...I think they have to tell you when they're down to a certain level. But maths and percentages aren't usually their strong point IME and I suspect the warnings have more to do with commerciality than safety. I've gone for thousands of miles beyond getting "advice" on brakes and tyres with zero degradation in performance.
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