So I’m either lucky or screwed. I decided to change the manual gear box fluid and flush the clutch and brakes. Everything went well until reassembly. I guess there are many different posts about torque specs for the bottom pan and chassis links and I must have read the wrong ones. I thought the bolt specs were 48 foot pounds for all but the forward ones and that they were 65 foot pounds.
Well one bolt snapped as I was torquing but it didn’t break in half, so I got it out. It seems like the bolt gave but the nut may be fine. I put the still good bolt in the nut hole and torqued down to 48 and it seems good.
Would you all just get new bolt and count yourself lucky or would you do more? I’m also trying to figure out if I should get 2 new bolts or just one and leave that one in there just incase it’s on its last leg.
Also, what’s the worst that can happen? Nothing catastrophic while driving if it strips as I drive?
thanks.
not mistaken some of those are torque to a certain level and then 90° but that may be a later 981 I’m thinking of
Bolts are cheap. Is just order new ones.
All that stuff back there contributes to the rigidity of the subframe and can take some pretty large loads
I guess it can’t take 65 foot pounds though. Seemed low specs for these bolts.
I’ll get new ones.
What size bolt was it? And grade (marked on top of the head)? There are general guides for bolt-torque-spec's based on size/grade. It's worth learning those. I had a
BMW
motorcycle where I was doing the clutch. The pressure plate assembly bolted up to the flywheel with about 12 bolts. ALL the manuals gave a torque spec for the bolts - and when I torqued the bolts to that spec, the heads started popping off. Come to find out - this particular engine -
BMW
changed the size of the bolts from an M12 to an M10 - grade/8. Torquing to the spec's in the manual, which were based on the M12 bolts over-torqued the M10 bolts causing them to fail. Luckily this happened before final assembly, and I ended up using new M10 bolts, torqued to the spec for an M10 bolt. Never had a problem with it - once done right.
Point being - it's a sanity check if you look at a bolt and think to yourself "That can't be right..."
I’ll have to look, I just ordered 2 more from the dealer.
Hex - Head Screw 10X45.
Part Number:
99907203101
Supersession(s):
999-072-020-09; 999-072-031-09; 99907202009; 99907203109; 999-072-031-01
A handy chart to hang on the garage wall:
The bolt head should indicate the grade.
Thanks for the help. I got the bolts in yesterday and everything went well. Guess I dodged a bullet with that one.
