Am I using the right bolts?

[Duvel78]

Hi guys,

I'm almost working day and night on the GLT for the BKV in UK... It's horrible, I just wanted to repair the struts, finally I also removed the engine so I can check and replace more... I hope it will be done for the meet!!!

Quick question: I made a full restoration of the spare front struts I had (new coating, springs...), they look very fine now... I also replace the whole brake system etc etc... I got new bolts from Volvo for fitting the new brake discs, the last available bolts in Belgium... But of course the bolts for the calipers on the struts are NLA. I really want to change them (rusty and not really looking good)

They are quite specific ("100" reference" on it + a kind of Tensilock head). I got from a supplier something different, he said it was nearly the same and perfect for the brakes. I would like to have your advice. What I got is:

Make: SQUF
Reference: D961 M12X1,25X30 10.9 TPBT S 5

They are a bit shorter (2mm), it's 10.9 (strong enough?) and they don't have any Tensilock.

What do you think? Can I use the new bolts? Here crappy Blackberry pictures

The old ones:

The new ones:

[Nimminz]

Mac's your man for this one,

I'd be thinking of using a washer aswell as the new bolts aren't flanged head but I'm no expert

[Duvel78]

Well yes, it's my biggest worry, the absence of flanged head...

[volvodspec]

will be fine but only with a chemical locking (Loctite 243 in this case) on the bolts, as mr Nimminz says; also use a washer or you'll damage the coating/paint on the calipers.

[Duvel78]

Thanks for the point of view. In fact the head of these bolts isn't in contact with the caliper, it comes directly on the front strut (rear).

It can be a very warm environment, is Loctite really ok for this?

[mac]

Ah yes - the caliper carrier bolts (the ones through the strut eyes and into the carrier body - not the calliper to the carrier)

Long and hard have I searched for these- no luck so far - at least not with all the OE features (32mm length, serrated flange head, min.10.9grade).
Firstly the markings '100' - this is equivalent to 10.9' next the serrated flange head - this combines locking and load spread.
If you can source bolts long enough then provided you use a "thick" washer (2mm) and appropriate thread locking (there are loctite products quite suitable) then a "normal" (hex) head bolt will indeed be fine.

As you have found Aymat, the easy one to find is 30mm - already 2mm short BEFORE you add a 2mm washer - now you're 4mm short - no!, I would not use them! Go for next preferred length up - ie. 35mm. ( you may need to run an M fine tap through the carriers to clean out the last bit of thread in the carrier bores - they are not always fully threaded through.)

Mac.

Ps Aymat - I can supply M10x1.25 x25 index caps crews (to secure discs to hubs) in grade 12.9 (see my boltshop at the BKV.

[Duvel78]

Mac, you surprise me everyday This is exactly what you describe... OE bolts are 32mm long and they have a serrated flange head. I didn't know that 10.9 the same was as 100, very interesting to know.

Well yes, impossible to find a bolt with the same specs, I asked to a lot of industrial suppliers, no chance to find it.

I'll follow your advice, I won't use the 30mm long bolts I got today, I'll buy the 35mm and I'll use a 2mm washer. Do you recommand a specific washer type? All details are welcome so I can directly buy the right one!

(nice that you can supply the bolts for the disc on the hub, I'm interested!)

[mac]

Aymat - nothing specific on washers except - steel, thick, ie. 2mm or so. ( due to the fairly high torque loadings I would not use a "std. "thin" washer).

Use a quality thread locker - loctite 243 should be fine (it's working range goes up to 180degC) - if you're really worried about brake temperatures (if you are an "enthusiastic driver") you could go for loctite 278 (which also has a higher breakaway torque).

If you need any more disc to hub screws I will have supplies at the BKV.

Mac.

[Duvel78]

Mac,

I followed your advice, I bought the same bolts but 35mm long, I have washers too and Loctite.

Back to work on the GLT this evening / night, I nearly don't sleep anymore

[SteveP]

Good effort Aymat! It will be worth it!