View Full Version : "wobble" cam gear mod! @$#%^

11-16-2009, 05:13 PM
The only things reused are the block, head casting and the CAM SHAFTS...

-Not sure if anyone remembers, but nearly a year ago when I was planning out this build, right up through the final assembly, my plan has always been to get it built, up and running on stock cams, then step it up to 3658's, 3652's or whatever once I have some info to go off of (as in "what the motor wants") but also for ease of getting it running and tuned on SEM.

Well, this may be the reason I ate up my new AGU (shaed) valve cover last month!

Turns out the cam gear wobbles like a bitch! clearly noticable when the motor is running.
I finally put a dial indicator on the cam gear and turned the motor by hand, and guess what? I have .02" of out-of-round not niceness.
I think my exh. cam is bent. anyone else have a hypothesis of what could cause a cam gear to wobble?

most importantly, is this bad enough that I shouldn't run it until I can replace my cams? or should it be OK as long as I keep it under 6k as I have been so far, and keep the run time limited to short logging runs UNTIL I can afford a new set of cams?

any thoughts, opinions or advice are greatly welcome.

11-16-2009, 05:43 PM
id say if you cam was messed..it would either be leakinig out the seal or youd have some other mechanical issues...id say that its most likely just the gear thats screwed..grab a another one and slap it on and check again

11-16-2009, 06:15 PM
.02" is quite a wobble. i cant find anywhere where audi specifies the roundness of the cam gear, i would assume any wobble is bad though. are you sure the gear is properly seated and torqued with a new bolt to 48 ft-lb?
if you put on a new, perfectly round, gear and it still does this, then its your cam that is bent. if you run bent cams, you can screw up the cam journals and turn your head into a boat anchor.

if its the gear that is bent, just replace it. if you dont you could throw the timing belt, or put unnecessary forces on the cam caps/journals/other things. i probably wouldnt run the car until its fixed.

did the cam gear contact the valve cover? what was the damage done to that?

11-16-2009, 06:18 PM
Wouldn't it be rather difficult to actually bend a cam?

11-16-2009, 06:24 PM
^^^maybe not if you accidentally over torque the bolt on the end for the gear.

11-16-2009, 06:32 PM
Wouldn't it be rather difficult to actually bend a cam?

that's what I'm thinking...
My cam gear is brand new, as is the bolt, and I torqued it properly. Unless I got a bad part... I don't know.
I'm really wanting to check the gear against the cam, but I don't see an easy way to do this.

Anyone have any ideas?

As for the possible causes of this, front end collision keeps coming to mind[confused]
carfax didn't reveal anything, but that doesn't mean it was never hit, nor does it mean that the motor I presume to be the original motor didn't actually come out of another B5 that died in a fiery crash.
The wobbling of the cam gear is dead certain, and I would really like to know if it is the cam or the gear itself.
Since the motor is assembled, I can't figure out how to check the actual nose of the cam, as to do this I would have to be able to remove the gear / timing belt, and doing so would render it so I couldn't turn the cams over to check!

I hope someone smarter than me will offer up a suggestion, because I would REALLY like to know exactly where the problem is, and I'd really like to figure that out without pulling the head off.

If I HAVE to, I guess I will. I haven't went this far with my build only to leave something to chance... -At least I have ARP Head studs [up]

11-16-2009, 06:45 PM
the bolt would break before you bent the cam. i dont know how you would bend a cam, maybe if you snapped a timing belt with some inconnel valves or something you could get it to twist like a helix slightly. though it should be very apparent on the cam journals if it were that out of spec.

i would lean more towards the gear not being seated or being bent. it would be much easier to put some force, perpendicular to the axis of revolution, on the gear and torque it out of roundness.

EDIT: i have a new OEM cam gear you can borrow if you want, you pay shipping and i wont charge for the borrowing. i can put it on our coordinate measurement machine at work and guarantee its dimensions.

11-16-2009, 06:50 PM
A bent cam is ..unless you've broken a timing belt with those cams in (even then..highly highly unlikely) My money is on a messed up gear.

Ghost beat me to it^

11-16-2009, 07:06 PM
The cast iron on the stock cams are a lot more likely to crack than bend. I would have to put my money on a messed up gear as well

11-27-2009, 04:35 PM
and you would be correct... my cams are fine. they are within a half thou...

the cam gear on the other hand is, -let's just say NOT round. -at all. (not even close)

As you can well expect, Int. Engineering is taking care of this. (I can't express how happy I am with Pete and IE. He's just the best parts supplier and best guy I have EVER dealt with and that's out of any platform I have ever wrenched on.)

I've got a few questions though, and I was hoping to sort some of this out as I wait for a new cam gear to arrive.

First, Does ADVANCING the cam gear tighten or widen the LSA?

Second, what is the RIGHT way to go about determining the maximum safe advance / retard for my particular motor? I know I could feasibly adjust the gear to nearly the point of piston/valve contact, then back that off a little, but isn't there a more scientific method for this?
and then is there a way to determine an approximate ideal setting for my cam gear, or is this simply trial and error?

Thanks for any help!

Anyone else here running a Eurospec cam gear?
I'd be interested to know if I just got a bad one, or if it is par for the course when it comes to Eurospec QC?[confused]
OH! one more thing, I had to reduce the OD of the washer on the OEM cam gear bolt in order to make it fit the Eurospec cam gear. is this normal?
Kinda makes you wonder if Eurospec tests anything out before offering it up for sale to the public though, eh? friggin wierd... although so is a lot of the other charming little issues I have run into with this build! God knows I've had more than my fair share[race]

11-30-2009, 12:57 PM

12-06-2009, 09:33 PM
I'm back in business[drive]

Pete at Integrated Engineering came through once again, and sent me a new cam gear as well as a new stock crank pulley and all my wobbling is GONE.

I'm talking UNBELIEVABLY smooth running now.
I had gotten used to all the vibration, since it has been like this since the first time I fired it up a couple months ago, but now that the crank pulley and the cam gear are no longer wobbling hideously, it runs smoother than it did before I built it. simply awesome!

Thanks Pete! [wrench]

I'll try to pull some datalogs in the next few days and post 'em up.

12-06-2009, 09:36 PM
You got the AEM running?

12-14-2009, 02:38 PM
You got the AEM running?
It's been runing on AEM and nothing BUT AEM for some time now.
is my most recent tuning and logs.
It's running better and better each time I spend a couple hours working on the tuning, but I'm still a long way from where I hope to be with this build...

There are just SOOO many areas to setup and tune, and remember, I have started out with a blank slate as far as the tuning goes!

Since no one has ever installed this EMS on one of these cars, there are certainly no "Maps" "Base Maps" or otherwise CONFIGURATION files to DL[o_o]

It has been a long and ardous process just to get it to fire up and run, but as my current logs now show, it's getting much better!

Once I have it running smoothly enough that I feel it's feasible to make a 50 mile trip to Port Charlotte, I plan on making an appointment with a tuner at this place:


anyone here ever heard of them?[confused]