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Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 10:57 am
by MrPT
Hi,
Been looking for torque values for the rear diagonal chassis brace bolts. Does anybody know?
I've got a bit of a clunk at the rear, so just checking rear ARBs, struts etc, one at a time. Pretty sure it's the KW shocks - they are only one click from full "soft" at the moment - but thought it worth checking the braces while she's up in the air.
Cheers!
P.
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 11:02 am
by Smartbear
Hi, reading this made me wonder if the z4m suffered from the diff mount becoming detached as the z3m/m3 have been known to fail?
Rob
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 11:09 am
by VRSteve
MrPT wrote: ↑Sun Sep 17, 2017 10:57 am
Hi,
Been looking for torque values for the rear diagonal chassis brace bolts. Does anybody know?
I've got a bit of a clunk at the rear, so just checking rear ARBs, struts etc, one at a time. Pretty sure it's the KW shocks - they are only one click from full "soft" at the moment - but thought it worth checking the braces while she's up in the air.
Cheers!
P.
Can't find values for them on TIS
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 11:33 am
by Scooba_Steve
The lower ones that meet at the diff?
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 11:54 am
by VRSteve
Smartbear wrote: ↑Sun Sep 17, 2017 11:02 am
Hi, reading this made me wonder if the z4m suffered from the diff mount becoming detached as the z3m/m3 have been known to fail?
Rob
No
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 1:34 pm
by MrPT
Scooba_Steve wrote: ↑Sun Sep 17, 2017 11:33 am
The lower ones that meet at the diff?
Yep.
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 3:07 pm
by Scooba_Steve
MrPT wrote: ↑Sun Sep 17, 2017 1:34 pm
Scooba_Steve wrote: ↑Sun Sep 17, 2017 11:33 am
The lower ones that meet at the diff?
Yep.
From TIS:
51 71 482 is the process, don't drive without them fitted. The nut is the one in the middle, screws at each end.
51 75 5AZ: Replace screws
59 Nm + 90 degrees
51 75 7AZ: Replace nut
24 Nm
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 8:39 pm
by MrPT
Scooba_Steve wrote: ↑Sun Sep 17, 2017 3:07 pm
MrPT wrote: ↑Sun Sep 17, 2017 1:34 pm
Scooba_Steve wrote: ↑Sun Sep 17, 2017 11:33 am
The lower ones that meet at the diff?
Yep.
From TIS:
51 71 482 is the process, don't drive without them fitted. The nut is the one in the middle, screws at each end.
51 75 5AZ: Replace screws
59 Nm + 90 degrees
51 75 7AZ: Replace nut
24 Nm
Nice one, thanks Steve.
Looks like it's the same procedure for loads of models. I'm taking the "don't drive without them fitted" to mean they don't do nothing and are worth re-torquing every few years!
Torque spec for rear underbody chassis braces?
Posted: Sun Sep 17, 2017 9:34 pm
by Scooba_Steve
Welcome, ref is only so you know I'm not guessing! I think they're always worth a check, though after 6 months if they don't work loose I doubt they would.
Torque spec for rear underbody chassis braces?
Posted: Tue Oct 03, 2017 11:12 am
by MrPT
Well, the "Screws" are definitely single-use. Sheared @ 30Nm!
Just a heads up to anybody who wants to try this. The car is parked up now while I get a replacement bolt/screw.
Torque spec for rear underbody chassis braces?
Posted: Tue Oct 03, 2017 5:19 pm
by Steve84N
Almost certainly been off and overtightened before as I've had mine off at least once with no problem.
Torque spec for rear underbody chassis braces?
Posted: Tue Oct 03, 2017 7:42 pm
by GuidoK
^with mine at least 20 times
But they are stretch bolts and the more you use them the stiffer they get. So be sure not to use that 90deg if you have used them multiple times.
I do it mostly by feeling, but its usually around 30-45deg
Maybe I'll change all underside bolts sometime.
But if it shears at 30Nm, something is wrong.
Torque spec for rear underbody chassis braces?
Posted: Tue Oct 03, 2017 11:27 pm
by MrPT
Ok, cheers fellas. That’s actually reassuring - probably should have lefty loosey’d before I righty tightey’d.