PotatoMafia
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- #1
Does anyone know the torque specs for the front and rear rotor mounting assembly and the caliper assembly?
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Torque specs for front and rear brake rotors / assemblys
- Thread starter PotatoMafia
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PotatoMafia
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are those brake bolts really 1 time use or send em with blue loctite?
if so can anyone reference the part numbers for them?
if so can anyone reference the part numbers for them?
Thraxbert
Well-Known Member
The bolts marked one-time-use are torque-to-yield (TTY) fasteners. I would do some Google searching on this topic and decide your level of risk for yourself.
Suffice it to say: once removed, they will never hold at the correct level of torque again, as they've been permanently stretched by the tightening process. TTY bolts improve the consistency and durability of the clamping force, and require fewer bolts in a given area to secure XYZ thing. They also require less maintenance, because you don't have to retorque them -- the stretchiness/springiness/yield of a TTY bolt takes care of that problem for you. If things shift, stretch, or compress a little bit, a TTY bolt will still hold at the same torque.
But the downside is that the yield/stretching is permanent and weakens the bolt. It cannot again reach the specified torque or holding power. Retorquing it to spec could cause it to break, or it could shear in service, or the clamping force could fatigue out and come loose in service.
Do lots of people reuse TTY bolts? Yes they do. Should they? No. But can they? Maybe, maybe not. It depends on the application. You alone must be the judge.
Suffice it to say: once removed, they will never hold at the correct level of torque again, as they've been permanently stretched by the tightening process. TTY bolts improve the consistency and durability of the clamping force, and require fewer bolts in a given area to secure XYZ thing. They also require less maintenance, because you don't have to retorque them -- the stretchiness/springiness/yield of a TTY bolt takes care of that problem for you. If things shift, stretch, or compress a little bit, a TTY bolt will still hold at the same torque.
But the downside is that the yield/stretching is permanent and weakens the bolt. It cannot again reach the specified torque or holding power. Retorquing it to spec could cause it to break, or it could shear in service, or the clamping force could fatigue out and come loose in service.
Do lots of people reuse TTY bolts? Yes they do. Should they? No. But can they? Maybe, maybe not. It depends on the application. You alone must be the judge.
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PotatoMafia
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just trying to make sure i get the right part, is 90118WA651 the correct part number for the rear caliper bolt that needs to be torqued to 110NM?
Tsuki8
Well-Known Member
Very nice, which site is that?As far as I am aware:
90118-WA630 x2 for front caliper to hub (70 lb-ft), and 90118-WA651 x2 for rear.
Much easier to use than the clunky new Toyota ones.
Thraxbert
Well-Known Member
https://partsouq.com/en/catalog/gen...bN35ib2Nbcm4Sc0JIAAAAAgGepZw==$&vid=0&cid=&q=
Much better than Toyota's parts diagrams, indeed. I discovered this website a few years ago when restoring a Suzuki Jimny, and I've been using it for my all my cars ever since. The Toyota official diagrams are especially vague and poor, and sometimes the dealer-provided parts websites don't even agree with Toyota.com. And sometimes it's Toyota.com that's wrong! It's madness.
MoreIceTea
Well-Known Member
As far as I am aware:
90118-WA630 x2 for front caliper to hub (70 lb-ft), and 90118-WA651 x2 for rear.
Huge thanks for confirming the part number! Toyota did a terrible job on marking this bolt as #7 on their diagram, with a confusing description. I was suspecting 90118WA651 is the right part number but struggling to find anywhere clearly points it out.
tracer bullet
Well-Known Member
Edit: I see 17Nm in the top of the first drawing posted in post #2. Never mind the below unless you're really bored.
**************
BMW TIS shows 17Nm for rear caliper, aluminum, painted (oddly specific, I'd think it just matters aluminum or cast iron, but unpainted aluminum is the same value). I would reasonably think the front is the same.
My approach is basically an 1/8 turn or so past finger tight. I know to go light, and my method seems to work (no leaks, no broken bleeders or stripped calipers) but this is the TIS on it. I haven't tried my 1/4" low force torque wrench on it but this feels kind of high to me. Maybe not, the oil drain plug is 25Nm, it's not too bad and this is less. I'd still err on the low side. Finger tight for me is using the 1/4" ratchet, twisting with like 3 fingers way up at the head of it and off the handle.
I know the question was > a year ago but if anyone wants a #, that's it per BMW anyhow.
baagel
Well-Known Member
FYI, 90118-WA630 works for the rear as well if you are removing the entire rear caliper from the hub.
I know it's mentioned that these are allegedly TTY bolts, but the fact that there's no angle after the torque spec in the manual makes me unsure. It's probably fine to reuse the bolts (former tech I talked to also expressed the same opinion). I had already bought some replacement bolts anyway so I used new ones when replacing my rotors.
I know it's mentioned that these are allegedly TTY bolts, but the fact that there's no angle after the torque spec in the manual makes me unsure. It's probably fine to reuse the bolts (former tech I talked to also expressed the same opinion). I had already bought some replacement bolts anyway so I used new ones when replacing my rotors.
i3igpete
Well-Known Member
Did a quick google search and the results landed where i kind of expected. Honestly, i was hoping to either be terrified into never reusing, or reassured it was bullshit.
"On the Reuse of Bolts Which Have Been Torqued to Yield" by Dal B. Lee, Joseph Foyos et al. https://digitalcommons.lmu.edu/mech_fac/46/
- The First Cycle (Installation 1): The bolt stretches exactly as intended into its plastic range, achieving optimal clamping force. Permanent deformation occurs.
- The Second Cycle (Installation 2 / First Reuse): The bolt successfully reaches the torque-plus-angle specification without breaking. However, data logs show a distinct loss in clamping force.
- The Third Cycle (Installation 3 / Second Reuse): Some bolts begin to experience necking (visible thinning of the bolt shank) and fail.
- The Fourth to Fifth Cycle: In almost all standard automotive TTY fastener studies, the bolts suffer catastrophic tensile fracture (snapping) or complete thread shear before or immediately upon reaching the final angle specification.
tracer bullet
Well-Known Member
I've kind of gotten to where - since I replace brakes so rarely, and I save so much money DIY'ing it, why not spend the few extra $'s on new bolts "just in case" they are right about them. I don't advocate pissing away money for no reason, but occasionally I subscribe to the "just in case" theory.
SJ-Ray
Well-Known Member
I'm in the boat one time reuse is ok.
It would be interesting to have a percentage of clamping force loss with the first reuse.
I probably have to change rotors next year and will use new bolts, since i don't know if the previous owner, or a workshop did anything to the brakes before and reused them - so better be safe.
It would be interesting to have a percentage of clamping force loss with the first reuse.
I probably have to change rotors next year and will use new bolts, since i don't know if the previous owner, or a workshop did anything to the brakes before and reused them - so better be safe.
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