Seized Bolts, Stripped Threads…. Brembo Brake Calipers.
The factory fitted Brembo brake calipers on all 2001> Impreza STi models are a good bit of kit. They perform well when fitted with choice upgrades to the discs and pads, and bled through with decent brake fluid will tolerate a fair amount of hard use on the road or a track before starting to protest and fade…
However, they can be extremely troublesome to work on, when it comes to changing the discs, or even just bleeding the brake fluid. – Caliper mounting bolts regularly seize up when trying to remove them, and sometime snap, or they can just pull all the thread out of the caliper body, leaving them requiring remedial work and thread repairs before they can be refitted. What originally started out as an hour or two job to replace discs and pads can easily turn into a bit of a nightmare if you’re not prepared for it…
A pair of front calipers that i had to remove today didn’t want to play ball…. A combination of heat, penetrating oil and some serious persuasion managed to coax three of the mounting bolts out relatively intact, but the fourth just locked solid and promptly snapped.
Once removed, the caliper was put in the vice, heated up, and a bolt extractor used to remove the remainder of the offending bolt
An M12 Timesert Kit was waiting on standby – This is an invaluable piece of kit if the threads in the caliper are destroyed. It allows you to drill out the damaged thread and tap to a larger diameter, then countersink and fit a solid steel insert with a thread-forming tap, which locks itself into the caliper body. This is the only practical solution to renewing a damaged thread, and is better than new, as you are then fitting a steel bolt into a steel insert, which is a lot less likely to seize up again.
On this occasion, the Timesert kit wasn’t needed, and once the broken bolt was removed, all the remaining threads could be cleaned out with a tap, and all bleed nipples removed, threads cleaned, greased and refitted.
New discs, pads and braided lines fitted, bled through with Motul DOT 5.1 fluid, and ready for action….
If you like to have your replacement brakes fitted or just need some of the threads repaired on your brake calipers, feel free to get in contact with me…
Dave "ginola" Norris
i had FB tuning carry out a disc and pad upgrade on my factory brembo’s and 2 of the 4 mounting bolts stripped the aluminum threads in the Brembos, despite every precaution being taken. This was repaired by Rich with steel inserts in no time at all and have had no issues since. The next time any of my brembo’s need to be removed I will be taking the car back to FB Tuning.
Tracy
It may be a good alternative to try the “v” angled thread files. The angle is 60% degrees so it is similar to the angle on Inch, Metric, Pipe, Male, and Female Threads. The files are basically round and they work great in restoring internal and external threads.