83SC front caliper bolts

wolds · wolds's Garage

Well now I'm in a bit of a pickle. Ordered caliper rebuild kits from PMB along with the ribe bit that is used on the caliper bolts. I soaked the nuts well and with the use of a lot of heat I was able to disassemble 3 of the 4 calipers without issue. The last caliper which is one of the front calipers I am having trouble getting apart. I managed to shear off the bit in the bolt in the first bolt I tried. I got the piece of broken bit out, but I managed to damage the socket of the bolt. Eric from PMB already told me that the bolts are not available, but I thought I'd check to see if anyone has been hoarding away a few. This is the larger M9 bolt, but uses the small ribe bit which makes it problematic to take apart. Warren

kodioneill · kodioneill's Garage

You should not separate the caliper halves very dangerous to do so. Buy rebuilt calipers. I sent you a pm.

Eric_Shea · Eric_Shea's Garage

Myth.

James Brown · James Brown's Garage

i think he meant to say that if you don't have the parts, than don't take them apart. there should be a lot of these bolts laying around, even buy a old caliper for parts. a trick i always use is turn the nut and hold the bolt, the least torque is on the nut side.

Eric_Shea · Eric_Shea's Garage

I don't think he meant to say that, but that is a better answer.

wolds · wolds's Garage

Thanks guys for the info. Eric at PMB sold me two used bolts so I'll be OK. It was my own stupidity that I stripped the one bolt out to begin with. I'll post some pictures when I get my parts back from t he plater. He's doing my calipers, backing plates, e-brake parts and all my nuts and bolts.

Walt Fricke · 01-12-2013, 10:13 PM

Eric - why would anyone want to bother with taking an A or M iron caliper apart into two halves? Isn't that just asking for trouble with no reward? Can't you do any fixing which is economically reasonable with the thing assembled, but pistons and fittings and seals (other than the ones between the halves you have to do this disassembly to reach) out?

Mine from '77, rode hard and often put away wet, seem to work fine, through a couple of seal replacements, and a change to stainess pistons, with the normal brake cleaner squirting and blowing of air to get it all out as part of the deal.

wolds · wolds's Garage

I went into this rebuild knowing that it could happen and had called Eric to order seals and the ribe bit. I knew up front that if I screwed up a bolt that this could happen and it did. After going over the project with Eric I chose to continue as I was willing to take that chance. Working on these calipers is not rocket science. For me,the end product will be worth the risk taken. Warren

Eric_Shea · Eric_Shea's Garage

Walt, to do it properly you have to half the calipers. See my other post in the caliper rebuild thread:

Rebuild Calipers - DIY? or Buy Rebuilt?

There's absolutely no trouble to be had taking an M-Caliper apart. The only issues we've seen with A-Calipers are the extremely poor design of the fastener itself. The M-Caliper is a perfect comparison:

M-Caliper - M8 fastener with large Ribe R8 head. Never a problem with this combination.

A-Caliper - M9 fastener (NLA) with a smaller Ribe R6 head. Recipe for disaster. It also has a taller 14mm nut.

The size nut and shaft on the M9 fastener is too large for that smaller R6 head, especially when you add years of heat and corrosion.

Beyond that, splitting caliper 1/2's is a myth. I've never had a caliper 1/2 leak issue to speak of in ten years.

Without prepping the rust issues that occur around the bore seal, you'll be doing that job again soon. Stainless pistons or not. Sounds like you've already done it a couple of times.

Tip: for those about to enter Warrens world; do not use an impact wrench on the 14mm nuts and do not attempt to turn the fastener with the Ribe bit. Use a 14mm deep well on a long breaker bar so you can "feel" what is happening with that fastener. Use the Ribe R6 bit to simply "hold" the fastener. Any attempt to turn the fastener with the bit vs. the nut will result in a broken bit. You should hear a snap as the nut comes loose. If it is being stubborn - STOP. Use a MAPP torch or, better yet, acetylene if you have it. Get that nut hot, tap it and try again. These are the most stubborn fasteners out there beyond the troublesome 930 or other Brembo aluminum on steel fastener issues.

Say hello to Kathy. Hope to see you guys again soon.

wolds · wolds's Garage

As Eric suggested, have MAPP gas on hand. I do now. I went out and bought a MAPP/O2 setup from Lowes. I'm guessing it will be $70.00 well spent.