Transmission Brace Stripped Bolt

tcw · 06-09-2013, 06:57 PM

So I was putting the transmission brace (brace to car body bolt) back on and before torquing was snugging everything back up with a ratchet (3/8 ratchet so not too much effort). Well as I was tightening one bolt it went from relatively hard to easy all of a sudden and I knew it was stripped. I believe it was already weakened from an impact wrench in the past. Regardless, my question is:

Is the metal thick enough to be drilled out and Helicoiled? I assume so since it is supporting the back end of the transmission.

Looks like the bolt is M8X22-8.8-ZNS3 from realoem (http://www.realoem.com/bmw/showparts...06&hg=22&fg=10). Now I just need to find the Helicoil equivalent.

Also since putting everything back together whenever I hit a bump I hear a clicking or rattle and I assume it is from this corner of the brace bouncing a little. If I find the equivalent Helicoil I will link it here for future reference.

Edit: It looks like M8 is the diameter and 22 is the length, I assume 8.8 is the yield rating. Helicoil has M8X1.5 course and M8X1 fine thread. Does anyone know if this bolt is course or fine? Maybe that is hidden in ZNS3...

Edit2: Appears "ZNS3: means that the bolt is coated with a corrosion-resistant coating" so no dice there. Does anyone know the pitch?

Dave W. · 06-09-2013, 09:03 PM

I don't know the thread pitch offhand, but if you have good eyes and a metric ruler you can count the number of threads over one CM. Otherwise I can check tomorrow.

tcw · 06-09-2013, 09:51 PM

I read somewhere that most BMW bolts are 1.25 pitch so I think I am going to buy the kit tomorrow and test it. If you are able to get the pitch before hand then I will order whatever you ID it as.

Thanks for the help.

Dave W. · 06-10-2013, 04:33 PM

You were right, the thread pitch is 1.25
torque is 14 ft-lbs.

tcw · 06-10-2013, 05:57 PM

Quote:

Originally Posted by Dave W.

You were right, the thread pitch is 1.25
torque is 14 ft-lbs.

Thanks for the info! I bought the thread repair kit today (and now I know it will work) and will be using it tomorrow. I'll update with results.

tcw · 06-11-2013, 12:19 PM

Turns out I didn't need the thread repair kit. Luckily I stopped by the dealership this morning and picked up a new bolt in case the threads were damaged on it.

Dave W. · 06-11-2013, 08:12 PM

Oh it was just the bolt! That's a lucky break, haha.

That's why I already gave the torque spec, it's one of those bolts that feels like it should be tighter since it holds up the trans, but it's still a small bolt so it only gets 14 ft-lbs.

06-09-2013, 06:57 PM	#1
tcw Captain 53 Rep 748 Posts Drives: 2008 335i Join Date: Jan 2012 Location: Atlanta, GA iTrader: (2)	Transmission Brace Stripped Bolt So I was putting the transmission brace (brace to car body bolt) back on and before torquing was snugging everything back up with a ratchet (3/8 ratchet so not too much effort). Well as I was tightening one bolt it went from relatively hard to easy all of a sudden and I knew it was stripped. I believe it was already weakened from an impact wrench in the past. Regardless, my question is: Is the metal thick enough to be drilled out and Helicoiled? I assume so since it is supporting the back end of the transmission. Looks like the bolt is M8X22-8.8-ZNS3 from realoem (http://www.realoem.com/bmw/showparts...06&hg=22&fg=10). Now I just need to find the Helicoil equivalent. Also since putting everything back together whenever I hit a bump I hear a clicking or rattle and I assume it is from this corner of the brace bouncing a little. If I find the equivalent Helicoil I will link it here for future reference. Edit: It looks like M8 is the diameter and 22 is the length, I assume 8.8 is the yield rating. Helicoil has M8X1.5 course and M8X1 fine thread. Does anyone know if this bolt is course or fine? Maybe that is hidden in ZNS3... Edit2: Appears "ZNS3: means that the bolt is coated with a corrosion-resistant coating" so no dice there. Does anyone know the pitch? __________________ 2008 335I E92, AW, VFF700, 18" Forgestar F14, M3 front/side, M-tech rear, AMS IC, H&R Touring Cup Kit suspension, HID AE, ER Charge Pipe & Synapse BOV, CIC Retrofit, Quafie, DSS, Defiv Lockdown, SPEC 2+/Steel SMFW, Walbro 450 Last edited by tcw; 06-09-2013 at 07:05 PM..
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06-09-2013, 09:03 PM	#2
Dave W. Lieutenant 5 Rep 538 Posts Drives: Porsche 951, 1992 Eagle Talon Join Date: Apr 2012 Location: SF Bay Area iTrader: (0)	I don't know the thread pitch offhand, but if you have good eyes and a metric ruler you can count the number of threads over one CM. Otherwise I can check tomorrow.
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06-09-2013, 09:51 PM	#3
tcw Captain 53 Rep 748 Posts Drives: 2008 335i Join Date: Jan 2012 Location: Atlanta, GA iTrader: (2)	I read somewhere that most BMW bolts are 1.25 pitch so I think I am going to buy the kit tomorrow and test it. If you are able to get the pitch before hand then I will order whatever you ID it as. Thanks for the help. __________________ 2008 335I E92, AW, VFF700, 18" Forgestar F14, M3 front/side, M-tech rear, AMS IC, H&R Touring Cup Kit suspension, HID AE, ER Charge Pipe & Synapse BOV, CIC Retrofit, Quafie, DSS, Defiv Lockdown, SPEC 2+/Steel SMFW, Walbro 450
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06-10-2013, 04:33 PM	#4
Dave W. Lieutenant 5 Rep 538 Posts Drives: Porsche 951, 1992 Eagle Talon Join Date: Apr 2012 Location: SF Bay Area iTrader: (0)	You were right, the thread pitch is 1.25 torque is 14 ft-lbs.
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06-11-2013, 12:19 PM	#6
tcw Captain 53 Rep 748 Posts Drives: 2008 335i Join Date: Jan 2012 Location: Atlanta, GA iTrader: (2)	Turns out I didn't need the thread repair kit. Luckily I stopped by the dealership this morning and picked up a new bolt in case the threads were damaged on it. __________________ 2008 335I E92, AW, VFF700, 18" Forgestar F14, M3 front/side, M-tech rear, AMS IC, H&R Touring Cup Kit suspension, HID AE, ER Charge Pipe & Synapse BOV, CIC Retrofit, Quafie, DSS, Defiv Lockdown, SPEC 2+/Steel SMFW, Walbro 450 Last edited by tcw; 06-11-2013 at 09:54 PM..
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06-11-2013, 08:12 PM	#7
Dave W. Lieutenant 5 Rep 538 Posts Drives: Porsche 951, 1992 Eagle Talon Join Date: Apr 2012 Location: SF Bay Area iTrader: (0)	Oh it was just the bolt! That's a lucky break, haha. That's why I already gave the torque spec, it's one of those bolts that feels like it should be tighter since it holds up the trans, but it's still a small bolt so it only gets 14 ft-lbs.
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