So my car just stopped working, as in the front 3 banks stopped firing...well burning gas. There is spark and everything. So i opened up the timing case and i found that my cam adapter broke. The cam adapter on the intake cam broke. The screw used for the adapter broke not the actually spacer. I'll post up some pictures soon. I'm going to contact stephen max to figure out how this could have happened.

 

It happened to me to (not with stephen max's adaptors).

 

what did you end up doing to fix the problem? i mean if there are problems with these adapters...people should know and something differently should be done to them to ensure that something like this does not happen again. my car has been down for weeks due to this problem

 

I still say drilling the cam is the best way to go.. Better to have stress on the cam than a dowel pin.

 

well i'm screwed....finally took out the adapter and took a look and it looks like the dolley just broke out of the hole that it was screwed into. winter's here and i don't have a car this is great.

 

If you can find the screw and put it back in, get it welded in and it shouldnt pop out.

 

this thing got wedged out of the hole that it was screwed into...pictures are below...sorry about my dirty finger nails :-X

 

i could get it welded on but the thing is that this shouldn't have happened in the first place...

 

how does the adapter look in the rear banks?

 

i have not have a chance to take them out and check yet...but i think they're fine. just hat this one came loose. and fudge up everthing. My cam gear is slightly damaged also.

 

going to get a new spacer and maybe a new gear put in and get back on the road?

any damage to the timing chain?

 

no damage to the timing chain...dude i already got my cam drilled once. and now i got spacers and spacers are screwed....i'm not about to pay for new spacers that was suppose to be working.

 

Do this....


Get new dowel pins... and remove the pins from the adapters and use the adapters as a spacer.

 

cams not drilled :-X

 

So, drilled cams would be better at far as not breaking? Does anyone drill the cams?

 

Tilleys99 does.

 

My '97 (w/ 3.5 swap) is in "the shop" right now b/c the front-bank secondary tensioner failed (don't know why). Anyway, they have the OUTER timing cover off right now. I purchased, and am using, StephenMax's cam adaptors. Should I have to shop perform any preventative measure(s) b4 reassembling everything? After paying this shop a significant amount of money, I'd like to ensure that nothing else happens. Glad I stumbled upon this thread...

 

Sorry to hear man. When i first looked at the spacers the screw looked kind of flimsy and i wondered if it would hold up to the forces it would be subected to.

It would be best if they were welded in, but the adapters are aluminum and it would be pretty hard to do.

 

Nismology, please read the post above yours. I wouldn't mind finding a machine shop to create some made of steel or ??? What do you think? Not trying to hijack the post, BTW.

 

The stress of turning the cam is always on the dowel pin. It's just better if the dowel pin is the OEM pin rather than a screw.


I say keeping the VTC and not having to modify anything is the best way to go.

 

I dont mean to go off topic in this thread, but you really need to check your PMs Biggs...

 

Who do you mean by "you" and "your"?

 

Sorry about that. it's fixed.

 

The idea of the adapters would work good.. as long as it doesn't come apart like Bigg's adapter did. A one piece adapter would work best. And no using screws.

 

So...maybe I should find a local machine shop that is willing/able to machine one-piece adaptors out of (aluminum?/steel?)...just to be safe?

 

Did you torque the cam sprocket bolts to spec?

The torque is transmitted from the sprocket to the cam in two ways.
1) friction between the three faces sprocket/spacer/cam from the clamping force created by the bolt preload

2)Shearing force across the dowel pin(s) (set screws in this case)

Failure mode was low stress, high cycle fatigue as evidenced by the very small area of ductile tearing left on the bolt fracture face. The fatigue crack would have initiated at the root of one of the threads.

It is hard to tell looking at the pictures whether the relatively "soft" aluminum started to deform at the surface prior to crack initiation or not. If that is the case, then the loading on the setscrew would have changed from almost pure shear to a combination of shear and bending which would have expedited the fatigue process.


To make a long story short:

1) Threaded fasteners should never be loaded in this manner if at all possible
2) The spacers should have been made from steel and dowel pins used. Obviously a more expensive assembly, but considering the consequences, I would say it is cost effective.

 

well like you said given the circumstances these cam spacers are vital to the 3.5 swaps. So, the best design to prevent failure would be a material that can handle more stress.

 

every thing was tighen to spec. It looks as though the screw just bent and then came loose. you can see that the other screw, which is still in tack on the adapter, has no damage at all and are holding up just fine. maybe there was a defect in the one i got? or maybe because this screw was long and therefore could not hold up like the shorter one.

 

Biggs, how long have you been running the 3.5 swap with the spacers? How many miles?

 

i only had it for 600 miles. I went to pickup a camera from a local maxima guy and the car failed one me 45 mins away from my house. Had to get the car towed home.

 

That is really really odd man. I've been running the 3.5 swap for over 4k miles with stephen max's spacers. Haven't had any problems.

It looks like there was some play between the cam and the sprocket with all those scrape marks on there. Are you sure you torqued those bolts down well enough?

 

i torque them down well enough...like i said...maybe it's just this one adapter that is defective. look at the other side and it looks fine. and the motor only spins one way...why is there damage to the screw on the other side...

 

the picture of the screw of what seems to be left of the thread at the point of breakage is not acutally what it seems to be. It's actually the thread being pushed inwards and then protruding up making it seems as though that's where it broke. I could not find the other "half" of the screw...it was there...

 

The light grey part of the setscrew fracture surface is the fatigue portion. You can even see the clamshell shaped markings originating back to the initiating point (at about the 5'oclock position the way you are holding it).
The stretched out part is just the final ductile failure zone where the cross sectional area was no longer sufficient to support the applied load.

All the markings on the one side of the spacer are from the broken setscrew being dragged around as the sprocket continued to turn with a stationary cam for a few revolutions as the engine stalled.

Of course there were no markings on the other side of the spacer as the setscrew was still intact. Therefore there was no relative motion,

 

I am assuming that the people with drilled cams and regular aluminum spacers are using proper dowel pins. They will be fine as long as the sprockets are torqued on properly. There are no threads to serve as initiation sites for fatigue cracks.

For those that have cam adapters of the same type as used in this thread, it is a different story. Don't think that because you have 10K or 20K on your adapters that you are homefree. Fatigue crack initiation can take millions of cycles to occur and they can grow very slowly in a low stress field.

 

so what does this mean for everyone with this spacers? i mean everything was tight down to spec i mean how can we go about making sure that this will not happen to anyone else? make the adapter a "one piece" thing and not like the way it's now?

 

have you spoke with stephenmax yet? Lets wait for his responds first and see what he says. If this becomes a more frequent problem rather than just a freak thing then something should definitely be changed.

 

i send him a pm already...i hope this is just a fluke....all my other ones are doing fine...except for this one...

 

Eng92 is pretty much saying that everyone is screwed at this point.

 

A one piece would be idea, or use a equal length solid piece of solid tube, and get it welded in place. diymaximakid gets his adapeter pieces welded in for extra strength.