[JB20DGM]

I'm going to be replacing my starter on my 2006 N52 and have all the parts. I looked at the instructions in the Bently manual and it has the torque spec as 20nm + 180 degrees for both starter bolts. But from a few other places I am seeing that the long bolt is the 20nm + 180 degree, and the short bolt is 20nm + 90 degrees...was this just an update by BMW at some point and the latter is correct? I guess the latter could take into account the additional stretch that happens with the longer bolt vs the shorter to give a more even final torque loading between the two bolts?

[The Nightman]

It's possible that Bentley is incorrect? TIS also says 20 Nm +180° for the longer M10x85 bolt and 20 Nm +90° for the shorter M10x30 bolt

[JB20DGM]

Originally Posted by Guy Fieri

It's possible that Bentley is incorrect? TIS also says 20 Nm +180° for the longer M10x85 bolt and 20 Nm +90° for the shorter M10x30 bolt

Wouldn't be the first time a manual was wrong. I'll go with what TIS says...last thing I need it to sheer a bolt off. Thanks.

[Suvorovo]

If you haven't finished the job, PM with your VIN. I'll check the Specs in ISTA+ for you after work.

I suspect start bolts torques are the same across models, but sometimes there are slight differences depending on the type of bolt used on your particular model.

[PhaseP]

Originally Posted by JB20DGM

Wouldn't be the first time a manual was wrong. I'll go with what TIS says...last thing I need it to sheer a bolt off. Thanks.

I remember Bentley manual had the torque spec of idler pulley bolt that goes on to the alternator torque wrong. They had an errata web site where they were publishing correction there. But that site is not working now.

All that said, when I had replaced my starter, it was hard to fit in a wrench for the bolt that is on the firewall side for me, let alone a torque wrench. So hadn't bothered with torque wrench on those bolts.

Sometimes gutentight is guten enough.

https://neologisms.rice.edu/index.php?a=term&d=1&t=7455

[Brian86]

Doesn't the the starter use steel screws? Guten-tight is perfectly fine on steel.

The aforementioned idler pully is a steel screw going into a steel housing. That joint is much more forgiving to either under or over tightening. Not likely to have caused anybody nightmares.... Now... the big spring-loaded tensioner... That's one you don't want to get wrong.

If they are aluminum, I would err on using the two different angles. the longer bolt will need a larger amount of strain to achieve the same joint clamping force... all things equal.

Unfortunately it's best to have an 'experienced touch' with aluminum fasteners as well... because the books are incorrect often enough to cause one to have a really bad day.

[Brian86]

When I did my transmission.... I literally have no idea how tight the four(?) aluminum screws holding the bell housing to the block are.

Trying a precise angle torque while laying under the car doing a dragonfly situp into the center tunnel, with three feet of extension flexing in a precarious arrangement that keeps falling off...

Fully admit on those fasteners I went with 'gut-feel-lowball' guess... but 60k later the transmission is still on there.

[JB20DGM]

Originally Posted by Brian86

Doesn't the the starter use steel screws? Guten-tight is perfectly fine on steel.

I believe the N54 ones are steel, book just lists a straight torque for those. The N52 ones are definitely aluminum bolts (can see the blue paint on the factory bolts and the replacements are aluminum).