Question about connecting rod bolts
11-09-2005, 10:48 PM
#1
Burning Brakes
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Question about connecting rod bolts
My engine (actually the whole car) is apart, the engine was apart for a valve job when I purchased the car, while it is appart I figured might as well get 964 cams, hf-s turbo etc. since I am making the upgrades I also got raceware studs,nuts and washers. In one of the other threads you mentioned that the connecting rod bolts were the weak point in the engine and that they could be changed without splitting the case. OK now that I have the bolts they are raceware bolts. do they need to be indiviually weighed? and the instructions say measure the bolt stretch instead of the torque. Can this be done with the crank still in the case? Also one last question the pistons are still connected to the rods do I neet to pull them off of the rods to do any of this?
11-09-2005, 11:42 PM
#2
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No, you can not use the stretch method while the case is together. It will have to come apart to get the gauge on the rod. ARP and some others offer to settings, one for TQ/loosen /TQ/ loosen/TQ method and one for stretch with the gauge. I prefer using the gauge as I feel it is more accurate, but the ARP swears the other way works as well. They have 25 years plus in the industry. You will need to remove the Ps and C'/s to gain access.
11-10-2005, 12:41 AM
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ok thanks!! the instructions also listed the torque/loosen method but recomended the stretch method as the preferred way. Do I need to weigh the bolts or are they already matched, they are raceware brand.
11-10-2005, 02:11 AM
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Ken a recommendation is to send the rods out and have them reconditioned. Give the machine shop the bolts and they will resize the big end and torque the bolts to the correct value. You wrist pin bushings will also be replaced/honed.
11-10-2005, 03:07 AM
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It only has 40k miles on it you sure it needs it ? besides since hurricane wilma took out the wifes car she is driving my 911 , I need to get this thing done. i'm right now on the hairy edge of still being able to afford the paint, It's being turned into a slant nose and I have already welded in one of the rear ducts and have the hole cut for the other. So I'm coming up on the do I finish it or buy another car to drive while I save up to finish and listen to the bitching the whole time decision. besides I am getting tired of looking at that shiny new turbo and cams in the box.
Last edited by kens911; 11-10-2005 at 03:26 AM.
11-10-2005, 10:33 AM
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Yes, if they are out have them checked. It is very unwise to place them back in. It only takes a couple of overevs to create an issue. For the time/cost which is small it is not worth bypassing it. Have them sent out with the bolts and cleaned up. I would bet that they are not perfect.
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11-10-2005, 10:43 AM
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no pics yet will try to take some this weekend unless i have to work. it's an all steel kit from NRautomotive, the ducts fit very well it came with cardboard templates and measurements. My only regret was the fact that the car came with a set of slant nose fenders along with the stock ones, so I got only the vents and rocker panels from NR now i'm having to scrounge parts missing from the lights kit(bushings wiring harness etc.) plus the fenders were banged up some so they require straightening and fitting. Now for the Engine The rods are not out, what would it cost to pull them and send them out? i'm assuming then that also means new rod bearings,bushings, probably main bearings too since the case would be split. I was just planning on replacing the bolts without splitting the case.
Last edited by kens911; 11-10-2005 at 11:00 AM.
11-10-2005, 12:57 PM
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Ken, you do NOT need to split the case to get your rods out of your engine. When your mechanic pulls them out send them out to be resized. If you need help with that task email me..
11-10-2005, 10:04 PM
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I'll be the one pulling them out I was just wondering how much it is to get the rods resized, and what additional parts will i need conrod bearings bushings, anything else?
11-11-2005, 01:54 AM
#13
Ken
To give you the whole run down on the Rods, here's what should be done.
Make sure you supply the new bolts when rebuilding the rods and give the machine shop 2 Piston Pins.
First have them straight checked. This shows up if any are "bent" and if either the 2 bores are not at 90 drgrees to the rod beam.
Then have them magnufluxed. no point in repairing cracked rod.
Then the CC lenghts should be checked. this way if any Rods are longer, then when or if the Caps are dressed, the beam can be done if needed. Or the pin bushing can be bored to suit.
Have the Pin bushings Pin fitted to your Pins. If you are going to do any racing, running more clearance is often a good thing here.
Make sure you supply the machine shop the bore sizes and the clearances you want to run.
Then have the machine shop measure the stretch of the bolts and record the torque numbers to achieve the required stretch. Then when you replace the rods, torque to those specs'. Ask the machine shop to supply yuo the grease they used when doing the Bolt work.
Have the Rods shot peened. If you need a spec for this, shot size, shot type, pressure, etc, ask them what they recommend. If in doubt, email me and I will find out what is common and forward this to you. There are many mil spec's on this work.
Then make sure they are clean. Shot inside the engine is not a good thing.
This would rebuild the Rods correctly. The costs stated earlier would not include 1/3 of what I have suggested, so expect a higher cost if you wish to rebuild them properly. Unfortuntely, alot of Rod rebuilding never covers the work required, only enough to make them look good. If the 2 bores are not parallel, all sorts of problems can occur. Bearing wear, Piston skirt and Cylinder wall failure to list a few. A good engine starts with good machining I'm reminded of often. If you need any help here, email me. I can suggest a really good racing engine builder who build Porsche engines, who do their own machine work inhouse and who's level of work is at the highest.
To give you the whole run down on the Rods, here's what should be done.
Make sure you supply the new bolts when rebuilding the rods and give the machine shop 2 Piston Pins.
First have them straight checked. This shows up if any are "bent" and if either the 2 bores are not at 90 drgrees to the rod beam.
Then have them magnufluxed. no point in repairing cracked rod.
Then the CC lenghts should be checked. this way if any Rods are longer, then when or if the Caps are dressed, the beam can be done if needed. Or the pin bushing can be bored to suit.
Have the Pin bushings Pin fitted to your Pins. If you are going to do any racing, running more clearance is often a good thing here.
Make sure you supply the machine shop the bore sizes and the clearances you want to run.
Then have the machine shop measure the stretch of the bolts and record the torque numbers to achieve the required stretch. Then when you replace the rods, torque to those specs'. Ask the machine shop to supply yuo the grease they used when doing the Bolt work.
Have the Rods shot peened. If you need a spec for this, shot size, shot type, pressure, etc, ask them what they recommend. If in doubt, email me and I will find out what is common and forward this to you. There are many mil spec's on this work.
Then make sure they are clean. Shot inside the engine is not a good thing.
This would rebuild the Rods correctly. The costs stated earlier would not include 1/3 of what I have suggested, so expect a higher cost if you wish to rebuild them properly. Unfortuntely, alot of Rod rebuilding never covers the work required, only enough to make them look good. If the 2 bores are not parallel, all sorts of problems can occur. Bearing wear, Piston skirt and Cylinder wall failure to list a few. A good engine starts with good machining I'm reminded of often. If you need any help here, email me. I can suggest a really good racing engine builder who build Porsche engines, who do their own machine work inhouse and who's level of work is at the highest.