ISF rear calipers

[RichGS11]

Hello all,

Yesterday my car went in to be steam cleaned underneath, rust treated and rewaxed. In the process there were the usual issues of snapped bolts and corrosion on the CAT pipe, etc, but nothing hugely abnormal and damaging price wise. The only issue that has come about as a result is that the rear caliper bolts are siezed up. The steel bolts won't budge from the calipers regardless of what the mechanic has tried and as such I'm looking into options.

As far as my mechanic views it, I can either purchase a new set of calipers (or used), or remove the bolts potentially stripping the threads inside the caliper, then re-threading them with inserts. My mechanic is very switched on and knows his stuff, and right now this is not an urgent job as the rear discs are healthy, but as he rightly says, to removed the discs I will need to address this at some point in the future.

So my questions are.....

Has anyone come across this issue and how did they address it?

Do the GSF, ISF and RCF share the same rear calipers?

Does anyone have any other suggestions?

Thank you.

[ColinBarber]

The IS-F has different brakes to the GS F and RC F (which share the same brakes).

Not sure what else to suggest other than a squirt of penetrating oil every day for a week and then remove using a decent impact wrench.

[hockeyedwards]

Took a week of spraying penetrating fluid once in the morning and once in the evening into a few seized bolts on my LS400 before they came off. A few on my dads mk1 golf required heating and then 'cracked' with a decent socket and bar. For one on the LS we had the car up on quik-jacks, one of us laying on the floor pulling down and one above pushing down as we could only fit medium sized socket and bar into available space.

I'd keep trying every few days, take worst case scenario of needing to replace the calipers - anything less than that is a victory and if you are in no immediate rush, patience might save you some £££.

[RichGS11]

Thanks guys. I will try that trick for a few weeks and see what happens. Any specific fluid you suggest?

[hockeyedwards]

7 minutes ago, RichGS11 said:

Thanks guys. I will try that trick for a few weeks and see what happens. Any specific fluid you suggest?

What can only be described as some ancient beaten up old can that could only be found in the depths of my fathers garage and sworn by through the generations! 😆

I've honestly forgotten its name but I had never heard of it before, will report back if I remember.

[ColinBarber]

40 minutes ago, RichGS11 said:

Any specific fluid you suggest?

I've currently got this WD-40 one:

https://www.halfords.com/motoring/engine-oils-and-fluids/lubricating-and-penetrating-oil/wd-40-specialist-fast-release-penetrant-250ml-366317.html

 

Seems to do the job ok but not as good as the one in my father's old garage that was 20+ years old. Halfords do a 3-in-1 penetrating oil which I'll try when I run out of my current can.

[hockeyedwards]

11 hours ago, ColinBarber said:

Seems to do the job ok but not as good as the one in my father's old garage that was 20+ years

Amen. 😆

[RichGS11]

Thanks gents. I shall get some and start applying it and see what happens in a week or two.

[GS300h2014]

Be aware WD40 is not the best rusted bolt fluid to use in my opinion. In fact Car Mechanics did a comparison test published here:

http://www.bilthamber.com/downloads/penetrating-oils-2.pdf

Results gave GT85 (8 out of 14 for performance), Plus Gas Formula A (8/14) Bilt Hamber Ferrosol (8/14) but WD40 (5/14)

'Obviously we couldn’t do a penetrating oils test without having this household name in the group. But, somewhat predictably, WD-40 cannot quite cut it against the dedicated automotive brews. Part of the reason for this is the very reason that WD-40 has become such a big-selling product: its incredible versatility. Just reading the tin identifies diverse applications like polishing brushed metal surfaces, preventing slugs from climbing plant pots, and even cleaning crayons 
off washable surfaces. Another great bonus of the product is the simple fact that practically everywhere sells it. And, in all reality, compared to our fully dry ‘test control’ bolt, WD-40 did reduce the loosening torque and it certainly made it easier to spin the bolt out – just not anywhere near as effectively as other products here.

 

[Killysprint]

Plus gas used to swear by it- years of skinned knuckles and bruised hands working on old minis and dolly sprints attest to its effectiveness.

[RichGS11]

Well I have been advised to find a garage with an induction heater as they're the best way to generate intense localised heat for bolts such as this.

So I have a few options it seems.