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Diving in 911
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New 964 rod bolts
Couple questions for the masters here. I have a new set of oem rod bolts. Gave them to my machine guy to rebuild the rods. I’m certain he didn’t do the 90’s. Are they good to go or do they need to be replaced after being torqued to 15#’s. Again, new …newer run. Also, are the rod bolt nuts single use?
Is there a stretch length spec? Couldn’t find one. Thanks!
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1976 911s Special Edition Turbo bodied IROC tribute 2002 911 Carrera C4S 1971 914 1.7 Tangerine 1989 964 Coupe/1992 964 Cab 1987 928s4 Granite Green / 1986 951 |
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03-02-2023, 09:07 PM
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PCA Member since 1988
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Look up the torque spec for the rod bolts. IIRC, it's about 42 ft-lbs, but since this is critical, don't trust my memory. If your machine shop only torqued to 15 ft-lbs, that's well below the torque spec, so don't worry about it.
Late Edit: I was thinking about the ARP bolts I use, which use a straight torque spec. Good thing not to rely on my memory!
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! Last edited by PeteKz; 03-03-2023 at 09:35 AM.. |
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03-02-2023, 10:57 PM
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Registered
Join Date: Oct 2008
Location: Nash County, NC.
Posts: 8,471
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Realize, there are two different Carrera rod bolts in the system
The originals and later 12.9 stamped on the top. The original spec was 15 ft# and 90 degree swing. The 12.9 is 15#, 90 degrees and another 90 degrees. Bruce |
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03-03-2023, 04:29 AM
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Diving in 911
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Quote:
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03-03-2023, 06:11 AM
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It's a 914 ...
Join Date: Jan 2008
Location: Ossining, NY
Posts: 4,696
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You might want to ask the machinist - did he really rebuild your rods without torquing them? This would result in improper clearances. He must have torqued them.
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03-03-2023, 08:33 PM
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Diving in 911
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Ya, I’m convinced I need to buy a new set…..or every noise I hear will instantly be a broken rod lol. I’ll paint these heads red and save them as dummies. Thanks folks! Appreciate it.
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03-03-2023, 08:53 PM
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PCA Member since 1988
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Often the machine shop will use the old bolts to torque the rods for sizing so that the new bolts are not torqued. Ask if that’s what they did.
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03-04-2023, 03:17 PM
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Registered
Join Date: May 2004
Posts: 874
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Quote:
The correct way to install new bolts is to measure the lengths before installation so that when they are loosened the same length can be measured. Never should old bolts be used to rebuild the BE of the rod unless the same bolts are used again. The bolts that will be used in the build have to be used when rebuilding the rods. Hence, if the bolts were torqued to the factory spec, you are good to go. The rods should not have been rebuilt unless the bolts were torqued to the factory spec. There is no given factory stretch for these bolts that I know of, unless the shop has done these before and found one of their own based on the torque value. There is a known name for the syndrome you are experiencing. Its known as "old lady with a new table". |
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03-06-2023, 05:35 AM
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Warren Hall Student
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I know this thread is a couple years old but I thought I would mention that the Porsche Service Bulletin states 10.5# plus 90 degrees and then an additional 90 degrees for the later 12.9 bolts.
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06-10-2025, 09:59 AM
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Garage full of it
73' Porsche Targa
