Camshaft gear alignment

[RX8SE3P]

I recently sold a guy the two camshafts from the rear of my K8. So not the disty side of the engine, the back.

He broke one of his cams and needed another. He also seems to have chipped his other cam too. I sent my cams to him after carefully removing (followed manuals closely with bolt order etc). He's reporting that he can't get mine to line up at all. He sent some pics. I'll post them here for people to see. If anyone can spot anything let me know.

He also said he can line up his chipped cam with my other cam but not line both of mine up.

Pics below...

http://users.adam.com.au/kakarot/Pic1.jpg
http://users.adam.com.au/kakarot/Pic2.jpg
http://users.adam.com.au/kakarot/Pic3.jpg
http://users.adam.com.au/kakarot/Pic4.jpg
http://users.adam.com.au/kakarot/Pic5.jpg

[MrMazda92]

That ring on the end of the gear isn't identical to the gear itself. You can not physically space it evenly on all sides, so it won't appear to line up properly, this is completely normal.

I had this exact same concern, and it's honestly not a problem.

[Ryan]

Thats the point of the friction gear. If you didn't mark them on disassembly, you need to take that big nut off the end and re-align the teeth on the friction gear to match the cam at the factory paint mark.

[mazda915]

yea it wont line up on the floor or on a table it only aligns up on the head , it is kinda hard and tricky to put them both in but the intake should be placed on first then the exhust it is a little hard and will need some force and a little pressure then the cam go right in , make sure the cam is aligned first . just takes time and a few messing around with also just becareful

[marcdh]

Camshaft Friction Gear - Between the two camshafts are drive and driven gears with 55 teeth each and a friction gear with 56 teeth. The friction gear, superimposed on the driven-gear by spring force, was designed to be free from backlash with its extra tooth. The friction resulting from this structure absorbs fluctuations in drive-gear rotation, effectively suppressing gear rattle noise. In addition, tooth flank precision is optimized through simulation techniques to eliminate gear engagement noise.

http://www.tsentraal.ee/mx6/engine/SAE920677.htm

It has an extra tooth, when you put it in the head it will be fine! Just make sure you align the dots. I recommend the revised edition of the FGS and nut if you're in there. As Ryan says, on occasion they can be a bit awkward if the nut has been off.

[RX8SE3P]

Thanks for all the info guys, I never removed the friction gear assembly and also took the cams out very carefully, so would it be safe to say that the FG shouldn't have moved?

[MrMazda92]

If the nut is tight, I would say yes, but it's not terribly difficult to line it up. You marked your cam timing prior to pulling the cams right?

[RX8SE3P]

Well I'm positive that it's tight (don't have the cams anymore btw, they are sold) so I highly doubt it moved.

[MrMazda92]

Did you mark the teeth on the cams prior to pulling them?

[RX8SE3P]

No, it never said anything about that in the MX-3 manual and I've rebuilt my ZE before without doing that. Just lined the dots up, which are marked for general location and that was that...

A friend of mine did the friction gear replacement too, to reduce noise etc and he said the nut was a b---- to get off...

Out of curiosity have you had the gear move, if so what did you do?

[MrMazda92]

The nut is definitely on their securely. As long as it was lined up properly there shouldn't be an issue for him then

[RX8SE3P]

Cool, appreciate all the help. Hopefully he can get the cams in soon.

He told me he is doing it with the engine in the car, which would be a challenge!

[MrMazda92]

That is the hardest part, to be honest.

[davmac]

I agree that the friction gear spring nut is not likely to loosen and let the friction gear (the thin one with extra tooth) move out of alignment - but maybe in shipping? I don't know how, but I'm guessing that this is the problem. Personally I would loosen the friction gear nut, push the E and I cams together so the marks on the back match and then mark and retighten the friction gear spring nut. This is exactly what I did when I replaced the friction gear spring to the new style.

The friction gear spring nut is 46mm but it was easier to find a 1-13/16 socket that will work. If you have a very large adjustable / crescent style wrench that will also work. A 3rd option is to stand the cam up in a vise and use the vise to hold the large friction spring nut and use a large wrench (27mm or adjustable) on the flats of the camshaft to loosen the nut.

Helpful links related to friction gear spring:
Excellent writeup at this site
On MX6 site with pictures of the camshafts removed
Ryan also did an excellent writeup where he did the friction gear spring replacement without removing the camshafts - excellent but doesn' t really apply here.

[Ryan]

This guys best bet is to install the cams in the head, however they align, install a few caps, and hten rotate the cam with a big wrench and seei f hte factory marks align.

If not, he needs to loosen the FGS nut (1 1/4? 1/8? 32mm?) align the teeth around the factory mark, adn then reassemble.

They can't be broken like this, its not like he needs a refund.