Vorsicht

I just finished installing both camshaft sprocket assemblies on the camshafts and there appears to be a very small amount of movement of the camshaft in a forward/backward motion on both (less than 1mm). The nuts are torqued to spec. It's very small, but I am able to pull the shaft out a bit and then push it back in. Is this normal?

Any help is greatly appreciated as I am in the middle of this right now.

Thanks!

e3photo

It seems like I remember a slight movement. It has been a while since I did my rebuild, so I was hoping someone more knowledgeable would chime in.

Ed Hughes

Are you talking about the entire assembly, or the sprocket in relation to the cam?

Vorsicht

It is the entire camshaft/sprocket assemby. If I put one finger on each end of the cam I can produce this tiny movement. I can not push the inner or outer sprocket down any further over the woodruff key.

dgmattingley

Did you back date to 964 sprockets?

Ed Hughes

My recollection on my 911 motor, was that there was probably .25mm of in/out "slop" on the cam assemblies. At least that is what I think I see in my mind. It makes sense, since the cams "float" in the cam tower journals.

Vorsicht

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?

Ed Hughes

I believe I reused shims as they were, and was in spec.

NineMeister

Slight axial float on the camshaft is normal; when setting up the camshaft offsets I normally push the camshaft as far back in the housing as it will go (away from the timing chain end) before taking the offset measurements.

The end float is the result of the difference in thickness of the thrust bearing (the round aluminium end cap held on with three M6 screws) and the machined step on the crankshaft; a machined face of the cam and the inside face of the chamfered washer (fitted first onto the cam, followed by the shims, the hub & the sprocket) are the actual thrust faces. There is no adjustment, so what you have is what you get.

Vorsicht

Thank you Mr. Nine.

Regarding the sprocket face to layshaft alignment the numbers I am using are 43.27 (plus 'a' dimension) compared to 4-6 measurement (plus 'a' dimension). And for the 1-3 side Im using 98.07 (plus 'a' dimension). Are these correct?

'a' dimension is from the layshaft to the far side of the straight edge.

I seem to be getting an unusally high delta on both sides ranging from 1.5mm to 2mm. This is with the original 2 shims. Do you ever come across wear like this? What wears? I am re-using all the original parts and had the camshafts re-conditioned.

Mike J

Same for me, and I checked it with the proper alignment tool.

My notes tell me that 6-10 thousands is allowed for axial play.

What tool are you using to make sure the straight edge is at a perfect 90 to the layshaft to measure the offsets? I used one of these:



Cheers,

Mike

Vorsicht

Thanks Mike, I have been using your great website as a guide. It's probably the tool I'm using and/or The Loose Nut Behind The Wheel (me).

The tool I am using is a standard 36 inch straight edge with a 1/4 inch lip for the 90. It is far from perfect. I was hoping to avoid the $100 tool as I am using it only once. I suppose I could just buy one and resell but then I would have to wait to receive it and I really want that rrm rmm sound soon!

Mike J

You are trying to take a pretty accurate measurement so you are right, you may be picking up variances using your method, but it should still be in the ballpark. I also borrowed the tool since I used it for about 10 minutes when I verified.

I would not be so worried except your count of spacers is not what we expected. Has this engine been taken apart before?

Let me check my notes on what measurements I got when I did the engine - don't remember off-hand.

Cheers,

Mike

Vorsicht

I am the second owner. Got it at 60K, now 96K. This is the first time it has been apart as far as I know.

From what I have read it is not uncommon for both sides to be found with 2 factory installed shims. The perplexing part of this is: if (and it's a big if) my measurements are correct what could possibly cause 2mm of 'wear'?

Anyway, I just re-read the manual and there appears to be a fudge-factor. Here is the quote. Note the first word:

Anyone in the bay area want to lend me their alignment tool?

PITBULL964

Hello guys,

I was changing timing chain gaskets on my '95 C4 due to an oil leak when I saw that there was no pin to lock the sprocket neither in the left and right camshafts.

So I am thinking right now to put the locking pins in to place but I am not sure if when I pull off the hexagon head bolt and washer that hold the sprocket in place, timing will mess up.

The thing is that I belive the car was never timmed and engine has not been ever done before. IMHO the car runs great, just some oil leaks as many others, so if I had to do timing I would live it that way with no pin.

Any help is welcomed!