My grandson managed to lose the front caliper bolts from his 1985 Volvo 240. GRRRR. I bought that car new & he's now tearing it up, but that's another story. Can someone tell me what the size of the bolts that hold the caliper to the spindle casting? Thanks.
Marlin

eeuroparts is showing the genuine 975546 M12x35 bolt in stock, possibly just meaning available from a distribution warehouse. ipd is showing it as avail to order. It’s also shown avail on foreign sites like scandix. When searching for Volvo p/ns you should omit the -3 check digit suffix. Fitment is listed in Volvo parts catalogues as 1988-on 240 w/Girling front calipers (which all were).

Genuine Volvo parts sites are showing this as a flange screw with a partial threaded shank, which is what I vaguely recall is original. As long as it’s grade 10.9 so it can be suitably torqued without stretching and long enough to fully thread then I wouldn't get too excited about the shank or the flange (I'd suggest a flat washer if there's no flange, but for calipers you don't want to encourage movement). A drop of thread locker is called for, but I never bother, one winter of salt corrosion will more than suffice.

The odd Volvo dealer parts & service may still have a couple in old stock as they technically weren’t supposed to be re-used, although I'm sure most shops did. I’d suggest approaching a friendly bone yard and see if they’d be willing to sell just a couple bolts. A good Volvo indie may even have a couple spares in a box. Pleading innocence because your son lost them may help.

Local fastener distributors will generally want to sell you a box full as it will likely be a special order. McMaster-Carr has the flanged screw under p/n 98093A756 in qty 10. A quick search under that p/n suggests it may have been used in some Ford and GMC, so you could always try those parts houses, but I wouldn't get my hopes up of anything in local stock. Fastenal has the bolt under various p/ns depending on finish and quantity, including individually, but doesn't appear to carry the flanged cap.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

These are what Volvo provides with replacement rotors. Grade 10.9


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Art Benstein near Baltimore

If you don't pay your exorcist, you get repossessed.

I have a 1989 245 DL and have to remove the front brake calipers to do maintenance on the brakes, bearings, and front suspension. The Volvo Parts Book list the front bolt as 975546-3 and describes its size as M12x35. You show a different size of M10x32 for the 1985. I called my Volvo dealer who told me the Volvo replacement part is no long available. Do you know what the thread specification is for the M12x35 bolt? Is it 1.0 or 1.25 or 1.5 ?

Sounds like we've converged upon a Grade 10.9, M12x1.75, 35mm long screw like this one from McMasterCarr https://www.mcmaster.com/90180A647/ (or PN 90854A229 if you prefer your zinc coating yellow chromate flavored instead of blue dye).

But I'd like to back up a moment and inquire Walter as to why you're replacing the fasteners? That these screws are so hard to track down suggests that most folks simply reuse them with a bit of threadlocker.
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XC60 / Odyssey

Will, I think I can answer the question for Walter or Ellenbrick.

In the aftermarket repair guides, designed for all levels of experience, there are warnings to not reuse "single use fasteners." No such warnings could I find in the factory service manuals, but Bentley, one of the many we 240 owners use, has this instruction step in the section "To remove and install front brake caliper" shown on page 510-6: "4. Remove the two caliper mounting bolts and discard the bolts. See Fig. 13."

I always did as you suggest until Volvo must have acquiesced to the legal dept. and began to include replacement bolts with their discs. What else would I do with them?
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Art Benstein near Baltimore

"I been in the right trip but I must have used the wrong car." -Dr John

Ahh, I admit I was puzzled when you referenced new bolts arriving with rotors. I get it now.

I wouldn't know about such things, I usually buy the cheapest aftermarket parts I can find. Even when they come with fasteners I will only sometimes use them as they're often cheesy looking compared to the Mother Volvo originals.

My knowledge of metric and international fastener standards is severely lacking but presuming that the M12 10.9 screw is roughly equivalent to a 7/16" grade 8 fastener (M12 is a little bigger diameter, same material strength, 150ksi), then each of those screws should be good for about 6 tons. Unlikely that they would be compromised during use or even ham-fisted maintenance.

Have a great day!

-Will



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XC60 / Odyssey

"I wouldn't know about such things, I usually buy the cheapest aftermarket parts I can find."

I have always done the same until I've established some sound proof the knockoffs are inferior, such as with the donut rings that hold up the exhaust silencer and a couple other rubber parts. I enjoy testing things so I can let you all know what to look out for.

In the case of brake rotors, I've used Zimmermann and Brembo, mostly Brembo, until I found a few years ago the blue box rotors are now competitively priced. I mean competitive! $38 vs $34 for the cheapest of the aftermarket. Of course they are made in China, but I do not equate that with poor quality as some do by knee-jerk. Check out this current offering from FCP.

https://www.fcpeuro.com/Volvo-parts/240/Brake-Discs/?year=1991&m=20&e=914&t=5&b=6&d=34&v=11
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Art Benstein near Baltimore

A bargain is something you don't need at a price you can't resist.

I didn't realize this started as an old thread by another poster so you won't get an email alert to my reply of a few minutes ago further down. I was also just thinking, if you want to save money and are not in any kind of rush then you can order a couple of the proper flanged M12 x35 10.9 fasteners from China on aliexpress for under $7. That's all without having to drag your butt off your chair, delivered right to your home mail box by USPS, including shipping, exempt from customs brokerage and duty, plus a full no-quibble money back guarantee if it doesn't arrive in 60 days. I've bought odd fasteners that way on many occasions when I'm not in a rush. Some were metric fasteners I couldn't even source from McMaster. It would cost me more than $5 in gas just to go to a local fastener store to find they don't carry anything close. I can see a bunch of you rolling your eyes when you see China, but just where do you think these fasteners are being made and just where do think the likes of Volvo and McMaster get them? They come from the exact same factories, just by way of these massive small item distribution centers and taking advantage of ridiculously cheap international small packet delivery rates.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Sorry, the different size I showed was my error. The correct bolt, whether for an '85, an '89, or any other Volvo 240, is as you found, M12 x 35mm long with a thread pitch of 1.75.

I think your Volvo dealer could find this bolt if he tried a bit harder. The new rotors are still being shipped with them. I learned from one dealership parts man that all the older RWD parts were cleared out of their inventory to be ordered from Volvo GCP (Genuine Classic Parts) or some such separate company if necessary.

It is interesting to see the images offered by eeuroparts, ipd, skandix, etc. when searching on 975546, show flanged bolts with no unthreaded portion or threadlocker. The bolts shown below are what you will likely find on your car, and what come new with genuine Volvo rotors.


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Art Benstein near Baltimore

"Never trust the work of the last guy, even if you're the last guy"

Hi Art. The original Volvo spec for the front caliper bolt on a 1985 240 w/Girling (any -1987) was actually a slightly shorter flanged M12 x 31mm 10.9 bolt (p/n 947328), but a 35mm bolt as spec'd for 1988-on w/Girling (p/n 975546) should of course fit fine, worst is going to be a bit of exposed thread to get rusty.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Thanks Dave,

Looking at the parts fiche, you're right in identifying the part number change which I've always associated with the initiative to reduce weight. The flanged bolts needing wrenches other than 19mm (14 in my recollection) have only surprised me on the rear calipers thus far. My experience, which includes 77,79,83,84,89,90,91,and 93 240s has me only finding the pictured bolt without flange and smooth shank on the front calipers. IPD's picture for 947328 reflects my experience, as does this mess of caliper bolts I've removed or replaced.

When I posted about the '85, I made my own measurements to add to the pic, which were not correct in 2018. Parts fiche describes them as M12 x 31mm. Ellenbrick's question was about the pitch, which is standard M12 pitch 1.75.

Either style bolt will do the job for all years of North American Market 240s which I'm pretty certain all used Girling on the front. Also, I believe the flange you find on the 975546 and some recent replacements for the 947328 is there only to save weight while maintaining the same clamping. So, in the end, it makes no difference to safety or function whether Ellenbrick uses the 975546 or the 947328 bolts shown below.


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Art Benstein near Baltimore

"No news is good news until you need to know the news" -Tonya Stevens

Thank you very much for your responses. Sorry I've been working throughout 2020 on the street delivering vehicle parts to shops in NYC. Most mechanics I've asked have told me they simply reuse the bolts on the vehicle with threadlocker. Happy healthy New Year to All!

As I understand it, the reason not to reuse "single use bolts" is that you can only reach the correct fastening torque once. This stretches the bolt slightly and once stretched there's no going back.
Reusing these bolts, even with threadlock, is not the best practice, but unfortunately quite common and I may have done it myself on occasion.

Hi,

Interesting statement you made.
“ As I understand it, the reason not to reuse "single use bolts" is that you can only reach the correct fastening torque once.”

I would say it “As I see it.”
I’m not sure where or whom came up with single use bolts to begin with, except NASA!
They are or were working with almost an unlimited budget, back during the “race” to the moon!
I know I’m a result of some of that industry from time to time!

My budget and mostly anyone else’s in our lifetime race events, do have a budget!
That is except with the printing machines of our own Treasury!
These notes, that hold the country together, are being over torqued in ridiculous amounts!
The people in our country have been weaken, in this germ “war” and the “fare” of the past year! It’s attacking our American belief in common senses!

With that said, a lot of their stuff went only one way to space or into an ocean, so that makes them a one time use fasteners!
You are correct in that a bolt gets stretched and there are yield points of the material to be mindful of.
This is why we make instruments to show us these limits.
One is our torque wrenching methods.
Now the number of times a material can be taken up to its limit or past, is up to testing it and certifying that material. This is the result of learning how far you can push “things!”

On brake calipers versus engine head bolts are two completely different applications!
On engine heads, you have repetitive vibrations from combustion and the heating and cooling associated with all that!
Brake calipers are subject to heat and cooling but no where near that of engine head bolts!
Common sense says, the forces are lateral to the bolts diameter and not in tension beyond the stretch set with a wrench.

Now guess what, you can use head bolts twice according to engine designers. They have built far more different engine designs than brake calipers but engineers learn and watch each other all the time to keep their jobs.
There become a respect value but not always earned if each doesn’t take the time to learn the details but will do things because it seems right.
The word “safety” runs in the back of their minds and “covering ones butt” runs in between the ears as well!
So with that, I will say that both an engineer and a technical writer has put forth the information in manuals to put the “monkey” on someone else’s back!

I don’t see that these bolts, used on the calipers, are having any special markings and I’ll bet do not have certificates supplied by the manufacturers. Grade nine, is like NASA stuff!
There are made but are exclusive to racing applications.
Not like “most” of out everyday “factory production” and boxed “as head bolts,” that are reused at least once.

Thread locker or snubbers started out as a “nylon pellet” placed in a hole made in the thread with an end mill. They were called one time use pellets along with “ Nyloc” brand nuts!
Before that, aircraft and other critical items, made by man, were hand wired through the head of the fastener, above the stress point of the neck, of course. The method is still used in some cases of extreme environments.

How many miles or years should head bolts last, on a Volvo? We are all working on that answer!
The worry with them is, “I don’t want to have to this again for a long time!”
It becomes, Not safety, but preservation! (:)

I have a box of those, set aside, but no “new”caliper bolts!

Phil

About bolts strenth, I remember 30 years ago I had my two young sons breaking bolts held in a vise.

I wanted them to learn where is the reasonable point where they could tighten 1/4, 5/16 and 3/8 inch low grade bolts, and break them. At their age they assumed metal was unbreakable. This helped a lot when they started working on their cars.

About caliper bolts I can say I always re-used the original ones or took used bolts to replace the damaged head due to over torque. I also never had a caliper come loose during my 52 years driving Volvos (since 1967).

But I agree calpers are critical pieces that no one, nor specially a garage want have problem with a client. I see why they tend to over-tighten our wheel nuts, giving us trouble putting the spare wheel.

Given the fact that these bolts cost me around 2 to 3 euros a piece I am happy to replace them whenever I replace the calipers (and that is very rarely). There are so many things far less critical to safety that cost far more that I can't justify it to myself not to spend that tiny bit of extra money on new bolts.

Hi,

I don’t have any of my calipers available to research your question but a bolts body of that 10mm diameter does seem a bit small for a front caliper application.

If you have the other side of calipers take one of those out and match it up by laying the thread pitches together side by side to match.

FYI
A lot of stores have thread sample testers and carry grade 5 bolts or higher, if needed.
I believe 10.9 is our grade 5
Most stores stop at 8 or five marks and are there for a farming tractors implements.
Most bolts on cars are a grade 5 and will have 3 line markers raised on the heads top face.
Grade 2 has no markers and are like butter in strength but that’s standard hardware.
Higher grades will have three or more lines, so the number two is a “given” and is a cheap way out of not having to strike the head. It saves cost and allows more room for identification purposes on other bolts.

From my experiences,
If you see a bolt head with line’s enough to go all the way around in a circle, now you are talking about special grade bolts!
They can even come with trace certificates back to a batch of manufacturing specialty.
NASA. Military, and highly sophisticated projects! Big DOLLARS!

Phil

“ I believe 10.9 is our grade 5”. Not correct. Closer to grade 8.