| Author |
Message |
James Selevan (Jselevan)
Member
Username: Jselevan
Post Number: 730
Registered: 6-2002
| | Posted on Wednesday, August 27, 2003 - 8:38 pm: | |
Bill and James - thank you. I did clean and grease the bolts. Perhaps I over stressed them.
I will remove all 4 of the suspect members and replace. Thanks.
Jim S. |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 511
Registered: 5-2001
| | Posted on Wednesday, August 27, 2003 - 8:28 pm: | |
James,
My GT-4 WM also shows 7 Kg*m for the shock bolts, so your number looks good. I suspect this is a dry torque. Are you using an oil or anti-sieze to lube the threads? If so, you may be overtightening them. If a bolt won't hold the torque, then the threads are damaged and the bolt and nut need to be replaced or something is plastically deforming. |
James J. McGee (Dr_ferrari)
Junior Member
Username: Dr_ferrari
Post Number: 168
Registered: 7-2002
| | Posted on Wednesday, August 27, 2003 - 8:02 pm: | |
James,
I think I would remove the bolt and inspect the threads on both ends, Maybe as you say at one time they were stressed and now the threads are weak.
Best regards, Jim |
James Selevan (Jselevan)
Member
Username: Jselevan
Post Number: 729
Registered: 6-2002
| | Posted on Wednesday, August 27, 2003 - 7:59 pm: | |
Bill, Jeff, David, et. al., thanks much. All of your comments confirm my thoughts which are that the bolt was ready to fail. It is a plated original equipment bolt. The previous mechanic working on the car may have over stressed it.
How about the lower front shock mounting bolt, also to be at 7 whatever, that does not seem to tighten. There is a spacer between the vertical anti-sway bar and the suspension member. Is this spacer digging into the rubber bushing of the vertical anti-sway bar member? Or is this bolt also failing?
Jim S. |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 509
Registered: 5-2001
| | Posted on Wednesday, August 27, 2003 - 7:54 pm: | |
James,
You might want to also take a good look at your torque wrench. Ever have it calibrated? By the way, the metrology guy at work confirms that properly calibrated, beam type torque wrenches are more accurate than click types. |
Jeff Green (Carguy)
Member
Username: Carguy
Post Number: 478
Registered: 10-2002
| | Posted on Wednesday, August 27, 2003 - 7:52 pm: | |
James...are these bolts new, and are they zinc plated? It could be a case of hydrogen embrittlement. If so I whole-heartedly agree with Jeff Ryerson's comment about them breaking now versus on the road. |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 508
Registered: 5-2001
| | Posted on Wednesday, August 27, 2003 - 7:51 pm: | |
OK, let's be careful here. Mt GT-4 workshop manual lists torque (or moments) in Kgm units. That is: Kg*m, or kilogram meters. So
1 Kg*m = (2.2 lbs/1 Kg)*(1 ft/0.3048 m) = 7.22 ft *lbs
and
7 Kg*m = 50.5 ft*lbs |
David Feinberg (Fastradio2)
Member
Username: Fastradio2
Post Number: 298
Registered: 4-2002
| | Posted on Wednesday, August 27, 2003 - 7:45 pm: | |
Jim,
The torque figures expressed in the BB WSM are indeed kg-m. The problem is...as you've likely discovered in the past is that there are numeous errors. When all else fails, or the bolt snaps, common sense and/or a torque-bolt size chart work well.
FWIW, I called Ferrari concerning a problem I was having with pulled nuts on the diff covers. I was purchasing OE studs and nuts, yet the nuts would strip when torqued to the WSM spec. Their response.."Use a lower torque figure!"
Regards,
David |
jeff ryerson (Atheyg)
Member
Username: Atheyg
Post Number: 409
Registered: 8-2002
| | Posted on Wednesday, August 27, 2003 - 7:45 pm: | |
Jim
The GT4 manual specifies 8kgm fixing suspension forks to chassis amd 7kgm shocks, even if you overtightened the bolts should not have failed, they did you a favor by breaking now vs ? |
Barney Guzzo (Trinacria)
Member
Username: Trinacria
Post Number: 414
Registered: 8-2002
| | Posted on Wednesday, August 27, 2003 - 7:40 pm: | |
Maybe whats wrong is my math thinking. I will look it up tonight when I get home. Obviously 4.2 lbs does not seem correct which is why I thought there was a misprint in James's book (I should really know this off the top of my head). Ill write back in a few hours. |
James Selevan (Jselevan)
Member
Username: Jselevan
Post Number: 728
Registered: 6-2002
| | Posted on Wednesday, August 27, 2003 - 7:36 pm: | |
I appreciate everyone's conversion. I have numerous conversion tables and calculators. However, I assumed that the WSM meant 7 decaKg or 7 KgMeter - as it only states 7 Kg in the torque specification. I believe that a suspension bolt holding the shock absorber would require more than 7 foot-pounds of torque. Am I wrong?
Any Boxer owners with a WSM that can look at the torque specs at the back of the book and interpret for me?
Thanks. Jim S. |
Jeff Green (Carguy)
Member
Username: Carguy
Post Number: 475
Registered: 10-2002
| | Posted on Wednesday, August 27, 2003 - 7:33 pm: | |
Barney....I hate to disagree with you, but torque is a functoin of force at a rotational distance. If you are tightening a bolt with a lever that is 1 meter long and you are pushing with 7kg of force at the end or 1 meter away, to excert the same amount of tightening force only 12 inches away would require a great deal more force than 4.2 ft-pounds. It could also be looked at like balancing a teeter-totter, with one side 1 meter away from the folcrum and the other side a foot away from the folcrum. It takes more weight on the shorter side to balance out the weight on the longer side. Does this make any sense? I'm just rambling here. |
Barney Guzzo (Trinacria)
Member
Username: Trinacria
Post Number: 413
Registered: 8-2002
| | Posted on Wednesday, August 27, 2003 - 7:30 pm: | |
1 kilogram/meter = 2.01 foot lbs per meter
or
.67 per foot
Something must be wrong.
70 kilograms/meter would be about 47 foot pounds |
Barney Guzzo (Trinacria)
Member
Username: Trinacria
Post Number: 412
Registered: 8-2002
| | Posted on Wednesday, August 27, 2003 - 7:27 pm: | |
1 kilogram/meter = .67 lb/ft
That means 7Km = 4.2Fp |
Tom Jones (Ferrarioldman)
Junior Member
Username: Ferrarioldman
Post Number: 144
Registered: 6-2002
| | Posted on Wednesday, August 27, 2003 - 7:20 pm: | |
Sorry, I ment Kg, not Km.
tj |
Jeff Green (Carguy)
Member
Username: Carguy
Post Number: 474
Registered: 10-2002
| | Posted on Wednesday, August 27, 2003 - 7:19 pm: | |
James...is that 7Kg per meter of torque? If so that's about 50.6 foot-lbs. The key question is the denominator...or length. If it's meters you did okay and something is wrong with the bolt. If it's a value less than a meter then you may have over-torqued it. |
Tom Jones (Ferrarioldman)
Junior Member
Username: Ferrarioldman
Post Number: 143
Registered: 6-2002
| | Posted on Wednesday, August 27, 2003 - 7:19 pm: | |
7 Km is only 50 ft. lbs. 1 km. = 7.233 ft.lbs.
tj |
James Selevan (Jselevan)
Member
Username: Jselevan
Post Number: 727
Registered: 6-2002
| | Posted on Wednesday, August 27, 2003 - 7:11 pm: | |
I am installing new shocks on 1983 Boxer. During the installation of the front shocks, I snapped the bolt that holds the steering hub to the lower A-frame - the outboard bolt that holds the spacers for wheel alignment. The manual calls for 7 Kg torque - which I interpreted to be 55 foot-lbs. In addition, I continue to turn the nut on the lower shock bolt without it tightening to 55 pounds. I suspect it is about to go. This bolt mounts the stabilizer on the front lower A-frame. There is a spacer that appears to be sinking into the rubber bushing of the vertical stabilizer mount.
What am I doing wrong? Help greatly appreciated.
Jim S. |