Torquing aluminum bolts

[Jazzbass]

Just curious if some of our more engineering-inclined members can see a problem with my plan here:

I need to replace 4 cylinder head bolts in my E90. I have a 2006 330i with the N52 engine - Al head, Mg block, integral cast timing chain cover. The 14 main head bolts are steel, but the 4 auxiliary bolts in the timing chain area are Al. These bolts have a bad reputation for breaking - rumor is BMW over-torqued them in 06. The head of the bolt snaps off, falls into the engine, and if you're lucky doesn't get caught in the timing chain and just falls into the sump. I have my valve cover off to replace some broken valve cover bolts (same issue - over-torqued Al bolts broke) and am thinking of preemptively replacing the Al head bolts now before they break as well.

Torque spec on these bolts is a two stage thing - first to 10 N-m, then 90 degrees. So if you were installing new you would tighten all the head bolts to torque spec in sequence, then go back and tighten 90 degrees also in sequence. My plan is to simply remove each of the Al bolts one at a time, replace with new, torque to spec and then 90 degrees. Then move on to the next.

This seems like it'd be OK since all the other bolts are torqued and I can't see why it'd be a problem, but sometimes I assume things like this and SMD comes on and post "Oh yeah, it's well known that you can't do it like that. Your car's going to explode any moment now" :lol:

[smdubovsky]

LOL. Your plan makes sense to me.

[ducatithunder]

The only thing I would add is if your using a torque adapter then make sure you do need calculations. But it sounds like your using a socket so no worries.

[Jazzbass]

The only thing I would add is if your using a torque adapter then make sure you do need calculations. But it sounds like your using a socket so no worries.
Shouldn't be necessary. Torque wrench with e-torx socket (because BMW) attached directly for the initial torque and then a standard torque angle gauge for the final 90 degrees. Neither change the effective length, so no changes necessary.

43261

[ducatithunder]

Yeah I mean this type of torque adapter ... I have to use them to torque my intake bolts as there is interference unless you disassemble the entire intake.

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQwZw411V8K6HaOCA98WnavtWQC8OlGV LxogONx5GcyI3Isd5u_

http://www.cncexpo.com/TorqueAdapter.aspx

btw I like that deg indicator.

[Lupin..the..3rd]

btw I like that deg indicator.

x2, who makes that one? BMW engineers love the "+90 degree" stuff.

[Jazzbass]

x2, who makes that one? BMW engineers love the "+90 degree" stuff.
Snap On sells them for $90 each: http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=634907&group_ID=675249&store=snapon-store&dir=catalog

but I got mine from Pep Boys for $10 and it's exactly the same as this $13 OTC one: http://www.amazon.com/OTC-4554-Drive-Torque-Angle/dp/B003UMRXSW/ref=pd_sim_auto_4?ie=UTF8&refRID=13J3P74Q7NH3ADP9KY2Y

There really is nothing to this thing - the "socket" part is basically just short a 1/2" extension, so no moving parts between your ratchet and the socket. I suspect that Snap On wants $90 for one for the same reason Ferrari wants $5000 for a clutch disk - because they can.

The only advantage to the Snap On is that they make it in 3/8" drive. The $10 ones I've only been able to find in 1/2" drive. A $5 adapter seems to solve that problem, though.

[Trak Ratt]

Yeah I mean this type of torque adapter ... I have to use them to torque my intake bolts as there is interference unless you disassemble the entire intake.

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQwZw411V8K6HaOCA98WnavtWQC8OlGV LxogONx5GcyI3Isd5u_

http://www.cncexpo.com/TorqueAdapter.aspx

btw I like that deg indicator.Me 3!

Snap On sells them for $90 each: http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=634907&group_ID=675249&store=snapon-store&dir=catalog

but I got mine from Pep Boys for $10 and it's exactly the same as this $13 OTC one: http://www.amazon.com/OTC-4554-Drive-Torque-Angle/dp/B003UMRXSW/ref=pd_sim_auto_4?ie=UTF8&refRID=13J3P74Q7NH3ADP9KY2Y

There really is nothing to this thing - the "socket" part is basically just short a 1/2" extension, so no moving parts between your ratchet and the socket. I suspect that Snap On wants $90 for one for the same reason Ferrari wants $5000 for a clutch disk - because they can.

The only advantage to the Snap On is that they make it in 3/8" drive. The $10 ones I've only been able to find in 1/2" drive. A $5 adapter seems to solve that problem, though.
Going to have to get some of that boy-o!!!

[hoophead]

Here's a more expensive Stahlwille version that I use:

43262

[VaSteve]

Shouldn't be necessary. Torque wrench with e-torx socket (because BMW) attached directly for the initial torque and then a standard torque angle gauge for the final 90 degrees. Neither change the effective length, so no changes necessary.

43261

That thing is cool. I had to torque the head on my 944 like that. I just eyeballed it. First was like 30 and then 90 degrees. I thought it'd be easy. 90 degrees. No, that got tight.

[Vicegrip]

I am so far behind the times. Here I have been using a little plastic kids school set protractor and a sharpie. (AKA a "bluntie" in my shop) Run to torque then make the degree mark lines on something nearby to go by.

[cmartin]

That's advanced in my book.

Jazz - that degree gauge is over the top.

[Vicegrip]

That's advanced in my book.

Jazz - that degree gauge is over the top.Hoopheads is the shizzle too. No stigma of low skilled build there. I have to admit I do like well made tools. They add to a job well done rather than simply work or at worst cause issue.

[smdubovsky]

FWIW, The baller tools are the SnapOn "techangle" torque wrenchs.

[hoophead]

FWIW, The baller tools are the SnapOn "techangle" torque wrenchs.

I've been eying those for a while - I have a plain "tech" that is awesome. Seems like every other bolt on Audis is torque-angle, and a lot of them in places where you can't get the angle fixture into. Then I have to fall back on the sharpie technique.