Off-center Rockers

[Dano 1]

Hi all, new guy here with my first post. I had a timing belt failure on my new to me '88 325 convertible (totally my fault, CHANGE YOUR TIMING BELT), bent all exhaust valves and a couple intake valves so the head is getting a complete rebuild.

On reassembly I found the intake rocker shaft to be slightly bent, (~.010" of runout, enough to not assembly without butchery) so I ordered up a new, aftermarket, shaft from Bav Auto (Vaico brand).

Everything assembled really smoothly until I got the shaft all the way in and located properly for the retainer plate. Once I clipped the rocker retainers in place all of the rockers are about .060" off-center to the valve and cam lobe. I triple checked the shaft orientation with large oil holes down, the cam is properly seated and all of the exhaust side lifters (with the OEM shaft) line up perfectly.

Overlaying the bent OEM shaft the grooves in the new shaft appear to be improperly located relative to the large groove for the retainer plate. Has anyone ever experienced this with aftermarket rocker shafts? My assumption is this is out-of-spec for OEM but maybe Vaico has wide open tolerances?

I don't feel great about running it as-is, the cam is original and while not worn excessively the lobe is polished and the new rocker now straddles the polished area and the un-worn portion of the lobe, which I imagine would cause irregular wear on the new rocker pad. The eccentric is also correspondingly misaligned with the valve stem which means it's not making full contact either. I appreciate people's thoughts, thanks!

[SkiFree]

I hate to be the bearer of bad news here......

Backstory:
About two years ago, rocker shafts were not available new anywhere (both the BMW parts system and the aftermarket parts system). At the time I was responsible for product development at a company and approached one aftermarket manufacturer about having more shafts made.

As per the norm for a project like this I sent a few factory sample shafts along with an agreement for a minimum order. What happens in situations like this is that the manufacturer will approach other suppliers and say something along the lines of "We are going to be doing a run of these, do you want in?" Unfortunately they did not send a sample back for a final inspection/test as requested (this is shockingly common in today's aftermarket. Call it an undo amount of trust placed in CAD/Scanning Technology coupled with keeping development time to a minimum. As you can imagine, when the batch came back, I found what you found.
However, at the same time BMW had separately contracted more shafts to be made and those turned out to be completely kosher. Given my relative little control over the situation, I simply turned to using the OEM shafts. Unfortunately the miss-made shafts have now permeated just about all aftermarket suppliers (both brands, and the parts networks that sell those brands).

If enough people complain from various sources, then the parts networks will independently of one another pull them from their shelves. Over time the shafts will filter out of the system. For now your best bet is to go OEM BMW.


Cliff Notes & Info:
2) That batch of shafts was made a little bit off. They will "function" but I wouldn't run them on my car.
3) Buy the OEM shafts for a perfect replacement shaft.

-Andrew Adams

https://www.r3vlimited.com/board/showthread.php?t=403163

[Dano 1]

Awesome info, if not the answer I was hoping for. Somehow I missed that thread when I did some searching so thanks for digging it up.

To Bav Auto's credit they are over-nighting a new shaft to me to see if it was an isolated problem but by the sounds of your story the new one will be the exact same. Just adds more credibility to the adage that there's no replacement for OEM!

[TobyB]

(Vaico brand)

Did it say Made In China on it?

In past years Vaico was ok, but my experiences this year have all been poor

t

[digger]

Febi used to make shafts to ?

[ForcedFirebird]

Febi used to make shafts to ?

They have been NLA from all my sources for the past 1.5-2yr or so, but ye, Febi was always the brand they carried.

[SkiFree]

They have been NLA from all my sources for the past 1.5-2yr or so, but ye, Febi was always the brand they carried.

Yes, this is also my experience.

Toby, they are definitely chinese made. The Vaico 6-bolt guibos are great. Other bits.... have started to become "hamberg technique"-esque.

Dano, no worries on not finding that, it was a PM I wrote the OP of that thread.

[Dano 1]

Small update for anyone interested, I received another Vaico shaft from Bav Auto (again props to their sales folks) and it appears to be exactly the same as the one I have.

Interestingly when I compared my bent OEM unit to the Vaico it appears that the rocker locating grooves are only out of spec relative to ONE of the larger end grooves.

According to my logic, and correct me if I'm wrong here, but theoretically I could run the Vaico shaft on the EXHAUST side which would use the oppose large groove for the retainer plate to the INTAKE side. I would have to swap my OEM exhaust side shaft to the intake side but since my rockers are all new I wouldn't think there would be any weird wear issues. Of course I could also do the 'right' thing and order up an OEM unit, I'm just ready to get this thing back together.

The Vaico unit is made in China, I won't open that can of worms but just as a general reference this is not a German made part.

[Dano 1]

Small update/follow-up: I go the replacement Vaico shaft from bav auto (again awesome customer service) and it was, in fact, identical to the first one I ordered. This lines up with SkiFree's account of the situation in that it is a widespread issue among aftermarket inventory.

After inspecting my bent OEM shaft and the new one, I figured out that the rocker location notches were only out of spec relative to one of the end retainer plate notches. Seeing that I have one good OEM shaft I simply moved the OEM shaft from the exhaust side to the intake which allowed me to reverse the Vaico shaft orientation and everything lines up perfectly.

Now this isn't exactly the ideal solution, in a perfect world I would have returned both and just ordered an OEM replacement. My main hold-up was not wanting to wait multiple more days, pay for expedited shipping, and postpone the whole job even longer, so I made do. This also only works if you're replacing only one shaft and ALL the rockers. If any parts are being re-used I would not recommend moving OEM parts around in relation to each other.

Moral of the story, there's no replacement for OEM and Bav auto rocks!