Blower snout bolts are torque to yield - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

robrocketanski · 05-16-2017, 02:04 PM

The snout bolts are one time use. Does everyone just reuse them?

E. Bryant · 05-16-2017, 10:12 PM

The bolts for the spare blower in my office are M8x1.25, class 9.8, without any sort of obvious necking-down of the fastener shank. This is a bit of an oddball class so I can't find specs in the standard tables, but class 8.8 bolts should be torqued to 18.75 lb-ft, and class 10.9 bolts should be torqued to 27.75. The Lingenfelter instructions specify 20 lb-ft for torquing the "front cover" (snout) bolts, so you should be more than safe (this torque level should not cause the bolts to yield).

I reuse the bolts, FWIW.

robrocketanski · 05-17-2017, 05:58 AM

20 lb ft is the torque spec from GM. I was curious what people have been doing. If everyone reuses them then I am sure it will be fine.

There is a torque sequence too.

Thanks

E. Bryant · 05-17-2017, 08:21 AM

GM has lately called for the replacement of many fasteners, despite providing bolts that are not designed to yield and torque specs that are not high enough to yield the fastener. I'm not sure why; maybe they make a lot of money on replacement bolts, or maybe they're tired of paying additional labor to technicians who rattle the same bolt in and out several times until the head and/or threads are wiped out.

I will also say that the recommendations in the factory service manual are generally there for good reasons, and any deviation should be carefully considered on a case-by-case basis. GM may charge excessively high prices for replacement fasteners, but it's still generally cheaper than extracting broken bolts from expensive parts (or worse, as would be the case for a fastener failing in-use). If in doubt, follow the manual!

zman1969 · 05-18-2017, 07:26 AM

20 ft lb is torque spec? I'd use them again and again even Chinese bolts cant be torqued that tight and survive repeatedly

its like, Do you want Fries with that? cents add to dollars and on and on

05-16-2017, 02:04 PM	#1
robrocketanski Drives: ZL1 Convertible Auto Join Date: Apr 2015 Location: Macomb, Michigan Posts: 330	Blower snout bolts are torque to yield The snout bolts are one time use. Does everyone just reuse them? Attached Images __________________ LS3 intake and throttle body, Huron Speed Products twin turbo with 6265 oil less turbos, and 3" header back, JRE smooth cam, ID1300, Fore dual 450lph pumps with MSD voltage booster, A6, 305/45/17 MT Street R

05-16-2017, 10:12 PM	#2
E. Bryant Gearhead Drives: 2012 ZL1 Join Date: Jun 2014 Location: Michigan Posts: 252	The bolts for the spare blower in my office are M8x1.25, class 9.8, without any sort of obvious necking-down of the fastener shank. This is a bit of an oddball class so I can't find specs in the standard tables, but class 8.8 bolts should be torqued to 18.75 lb-ft, and class 10.9 bolts should be torqued to 27.75. The Lingenfelter instructions specify 20 lb-ft for torquing the "front cover" (snout) bolts, so you should be more than safe (this torque level should not cause the bolts to yield). I reuse the bolts, FWIW. __________________ 2012 Chevrolet Camaro ZL1 M6 - JRE 650 RWHP kit, AFCO heat exchanger, JPSS V4 aero, Z28 wheels for the twisties and Weld big-n-littles for the dragstrip. 11.193@128.13 in 515' DA

05-17-2017, 05:58 AM	#3
robrocketanski Drives: ZL1 Convertible Auto Join Date: Apr 2015 Location: Macomb, Michigan Posts: 330	20 lb ft is the torque spec from GM. I was curious what people have been doing. If everyone reuses them then I am sure it will be fine. There is a torque sequence too. Thanks __________________ LS3 intake and throttle body, Huron Speed Products twin turbo with 6265 oil less turbos, and 3" header back, JRE smooth cam, ID1300, Fore dual 450lph pumps with MSD voltage booster, A6, 305/45/17 MT Street R

05-17-2017, 08:21 AM	#4
E. Bryant Gearhead Drives: 2012 ZL1 Join Date: Jun 2014 Location: Michigan Posts: 252	GM has lately called for the replacement of many fasteners, despite providing bolts that are not designed to yield and torque specs that are not high enough to yield the fastener. I'm not sure why; maybe they make a lot of money on replacement bolts, or maybe they're tired of paying additional labor to technicians who rattle the same bolt in and out several times until the head and/or threads are wiped out. I will also say that the recommendations in the factory service manual are generally there for good reasons, and any deviation should be carefully considered on a case-by-case basis. GM may charge excessively high prices for replacement fasteners, but it's still generally cheaper than extracting broken bolts from expensive parts (or worse, as would be the case for a fastener failing in-use). If in doubt, follow the manual! __________________ 2012 Chevrolet Camaro ZL1 M6 - JRE 650 RWHP kit, AFCO heat exchanger, JPSS V4 aero, Z28 wheels for the twisties and Weld big-n-littles for the dragstrip. 11.193@128.13 in 515' DA

05-18-2017, 07:26 AM	#5
zman1969 Drives: 1969 R/S Z28 302 m20 Endura Join Date: Sep 2009 Location: DFW Posts: 432	20 ft lb is torque spec? I'd use them again and again even Chinese bolts cant be torqued that tight and survive repeatedly its like, Do you want Fries with that? cents add to dollars and on and on __________________ 1969 RS Z/28 302 1969 Firebird LS6-6 speed TA clone 2015 Zl1