Camshaft Sprocket Assembly - Rebuild Question
01-25-2016, 01:25 PM
#16
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There are no pins in the 993's series - but the 95's and some 96's had the indexed sprockets, but the inner sprocket is not there. The bolt on the sprocket is holding it in place relative to the camshaft. Just leave it alone. 
Cheers,
Mike
Cheers,
Mike
01-25-2016, 02:11 PM
#17
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So there is no need to put the pin back in place (Just in case it ever was...) ??
I read some time before here in Rennlist someone telling that there was no pin too in his '95 with multi-hole sprocket and he was sure That no one had got his fingers in it before...
My Indy says there should be a pin there to prevent the slight movement between the sproket and the cam that can cause a miss timing.
My sprocket is like this:
01-25-2016, 02:31 PM
#18
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is that picture your car? It has the inner sprocket which was not part of the 993 engines (from what I know - maybe very early european cars might have left overs from the 964). Do you have the inner sprocket as well?
There has been some talk of slippage after Porsche went to just the bolt holding the sprocket in place - and I retrofitted back to the pin system when I rebuilt my 96 993 engine. However, if the car is running fine and has been for years I do not see why you would retrofit the pin system.
Cheers,
Mike
There has been some talk of slippage after Porsche went to just the bolt holding the sprocket in place - and I retrofitted back to the pin system when I rebuilt my 96 993 engine. However, if the car is running fine and has been for years I do not see why you would retrofit the pin system.
Cheers,
Mike
01-25-2016, 02:39 PM
#19
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Actually the vernier adjustment toothed sprocket with the pin fitting in the cam gear hole is the original design of the cam drive going back to the first 911. The part numbers for the cam gear and toothed flange still start with "901", the numeric moniker for the 911 before Peugeot sued them over numbers with a zero in the middle.
A bit of axial play is normal, but make sure the thick washer has its bevel facing away from the gear.
Stomski Racing makes great tools for setting up vernier drives for both cam timing and sprocket offsets, I use:
http://www.stomskiracing.com/product...ing-socket-set
http://www.stomskiracing.com/product...alignment-tool
http://www.stomskiracing.com/products/digidix
A bit of axial play is normal, but make sure the thick washer has its bevel facing away from the gear.
Stomski Racing makes great tools for setting up vernier drives for both cam timing and sprocket offsets, I use:
http://www.stomskiracing.com/product...ing-socket-set
http://www.stomskiracing.com/product...alignment-tool
http://www.stomskiracing.com/products/digidix
01-25-2016, 02:52 PM
#20
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Actually the vernier adjustment toothed sprocket with the pin fitting in the cam gear hole is the original design of the cam drive going back to the first 911. The part numbers for the cam gear and toothed flange still start with "901", the numeric moniker for the 911 before Peugeot sued them over numbers with a zero in the middle.
Cheers,
Mike
01-25-2016, 06:24 PM
#21
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is that picture your car? It has the inner sprocket which was not part of the 993 engines (from what I know - maybe very early european cars might have left overs from the 964). Do you have the inner sprocket as well?
There has been some talk of slippage after Porsche went to just the bolt holding the sprocket in place - and I retrofitted back to the pin system when I rebuilt my 96 993 engine. However, if the car is running fine and has been for years I do not see why you would retrofit the pin system.
Cheers,
Mike
There has been some talk of slippage after Porsche went to just the bolt holding the sprocket in place - and I retrofitted back to the pin system when I rebuilt my 96 993 engine. However, if the car is running fine and has been for years I do not see why you would retrofit the pin system.
Cheers,
Mike
My question is if it is necessary to time the cams if I remove the hexagon bolt that secure the sprocket into place or can I just remove the bolt, insert the pin and torque the bolt again without changing the camshaft position? And if yes what should be the procedure and tools needed.
It is not possible to insert the pin without removing first the bolt. That's the point.
01-25-2016, 07:33 PM
#22
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no you do not have to remove the camshaft - but you do need a few things, including the specific tool to hold the camshaft in place while you torque the bolt back on. There will be residual pressure on the camshaft to move, so if you want to come close to your original timing, ideally you would pull all the rockers and spark plugs so the camshafts and crankshaft are free, and then use the tool to hold the sprocket in place while you undo thenut, then put the pin in, and then retorque it back. You need to check the timing afterwards! via the standard mechanism by measuring the lift, which should be 1.00mm. DO NOT SKIP THIS STEP!!
There is a entire procedure involved, including keeping the chains tight by removing the chain tensioners. See my web site for some guidance on how to do this:
http://pcarworkshop.com/index.php/Ca..._timing_Part_I
and
http://pcarworkshop.com/index.php/Ca...timing_Part_II
Cheers,
Mike
There is a entire procedure involved, including keeping the chains tight by removing the chain tensioners. See my web site for some guidance on how to do this:
http://pcarworkshop.com/index.php/Ca..._timing_Part_I
and
http://pcarworkshop.com/index.php/Ca...timing_Part_II
Cheers,
Mike
03-31-2016, 08:20 AM
#24
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Cam Parallelity help
not sure if anyone can help me here but I ran into a sang. I put new cam housing/o-ring/ cam gaskets on and when I check parallelity My left cam is way off. It is set too deep. When I took it apart it had two shims on each cam and now the left is so deep with 6 shims it is still not right.* Here is the bonehead disclaimer. I bought a hungarian cam holding tool off ebay and it would not quite line up with the cam gear so I gave it some taps with a hammer to try to tease it in. I finally had to file the cam tool to get it to fit. The only thing I can think of is I drove the flywheel side bearing cover back a couple mm and that is letting the cam slide back too far. Is that a possibility? Any other suggestions would be appreciated.
03-31-2016, 11:46 AM
#25
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Not sure what you mean by a "cam holding tool" - is that a copy of the cam alignment tool that holds the cam in place on the back side of the engine for the timing alignment? (BTW, I use the old method of measuring the lift at TDC)
Some light tapping should not displace the camshaft that much, but it depends on how "hard" is your tapping. The cam runs against a thrust surface to hold it in place against side forces, you may need to take the cam back out and check for damages on those faces.
Did you check the alignment btw on disassembly? that is sometimes good to do, then you know what the engine was like going in.
Cheers,
Mike
Some light tapping should not displace the camshaft that much, but it depends on how "hard" is your tapping. The cam runs against a thrust surface to hold it in place against side forces, you may need to take the cam back out and check for damages on those faces.
Did you check the alignment btw on disassembly? that is sometimes good to do, then you know what the engine was like going in.
Cheers,
Mike
03-31-2016, 07:15 PM
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Thanks for the reply Mike,
I didnt have the cams out of the car that is the strange part. I only took off the cam housings and replaced the gaskets and put it back together. By Cam tool I mean Special tool 9191. But mine came from SIR tools.
When I took the gears off there were two shims on each side. The right side is back in perfect alignment with two shims. The left side is way out of alignment (cam too far in the engine) even with six shims under the left cam. This is the side I tapped
My taps bordered on hits. Any other suggestions would be great but I think I may have to pull the cam out and check it over.
I didnt have the cams out of the car that is the strange part. I only took off the cam housings and replaced the gaskets and put it back together. By Cam tool I mean Special tool 9191. But mine came from SIR tools.
When I took the gears off there were two shims on each side. The right side is back in perfect alignment with two shims. The left side is way out of alignment (cam too far in the engine) even with six shims under the left cam. This is the side I tapped
My taps bordered on hits. Any other suggestions would be great but I think I may have to pull the cam out and check it over.
03-31-2016, 09:10 PM
#27
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solved.
Thanks again Mike. To my embarrassment I had the left cam gear on backwards and that was the difference in my parralelity. Thank god! Switched the cam gear around and I am back in Business.
03-31-2016, 10:22 PM
#28
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Just a single point of reference and, in general to agree with all Mike said. I have an early 95 that had both the toothed inner sprocket with key and the holed outer. When I added my RS cams all I needed to do was add the pins... I would have gone the whole route to the 964 pined shaft if I needed to just to have a positive lock between the chains and the cams.
03-31-2016, 10:53 PM
#29
Burning Brakes
No. I have an earlier 1995 993 in which Porsche must have been using up their old 964 parts. The camshaft has the woodruuf key and the cam sprocket is of the 964 design. The only thing missing from this config is the dowel pin (which I bought). So in essence I am back-dating to the 964 timing method to avoid having to buy the expensive newer style timing tool cam locks (RUF does this on all their 993's).
Thank you. I am going to push on and accept this as normal - the movement is almost imperceptable. I am now in the process of measuring the parallelity of the intermediate shaft with the sprocket faces. This is a b*t$h as I am using a straight edge and a micrometer and am getting variances of up to 2mm where the max allowed is .25mm. I have yet to figure out why - perhaps the small numbers involved combined with my pre-historic tools are generating this. I may have to buckle and buy the expensive tool.
Interestingly, when I took it apart there were only 2 shims on either side whereas the manual suggests 3 for the left and 4 for the right upon rebuild. What did you find in doing yours and did you end up adding more shims than the 2 original?
Thank you. I am going to push on and accept this as normal - the movement is almost imperceptable. I am now in the process of measuring the parallelity of the intermediate shaft with the sprocket faces. This is a b*t$h as I am using a straight edge and a micrometer and am getting variances of up to 2mm where the max allowed is .25mm. I have yet to figure out why - perhaps the small numbers involved combined with my pre-historic tools are generating this. I may have to buckle and buy the expensive tool.
Interestingly, when I took it apart there were only 2 shims on either side whereas the manual suggests 3 for the left and 4 for the right upon rebuild. What did you find in doing yours and did you end up adding more shims than the 2 original?
Hi,
I have the tools you need to check parallelism. I have the Stromski tool that holds the straiight edge, and I have the proper straight edge. PM me if you would like to borrow the tools.
12-29-2016, 06:55 PM
#30
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My early 95 (flange plus drive gear style) had two shim washers each side when I disassembled. Reading Porsche tech manual it emphasizes getting gears parallel (not sure how shims would affect that unless they are referring to left and right gears) and that normally 4 shims are required... Anyone can help me figure out what to look at/measure to determine if i need more shims on re-assembly. Reading this thread looks like I need yet another fancy tool. Anyone that can help?
Thanks,
Thanks,
