CXFA Balance shaft installation

[gonze]

Hi all
I am currently rebuilding my CXFA engine that has two balance shaft’s built into the engine block. I have not been able to find any information as to the position they need to be in when I install the crank shaft. When the block is upside down on the engine stand the shaft‘s rotate to the heaviest side facing the floor. I just want to be sure I don’t need to position them in anyway before bolting everything together as they connect directly to the crank shaft.

I have the VW engine build manual but the only reference it makes to the balance shaft’s is on an exploded engine block diagram simply states this diagram does not cover engines with balance shaft’s!

Any help would be greatly appreciated

 

[mmi]

Not really helping but the following can be found in 2022.11 edition of Workshop Manual (but not in the earlier editions - e.g. in 2019.03)

 

[gonze]

Thank you for helping, unfortunately the link or picture I’m unable to see.

I have the 2019.03 workshop manual

 

[Dellmassive]

pic not working . . .

 

[Paynewright]

No linky for me either….just a box and a question mark. Doesn’t do anything clicking on the box or ?

 

[mmi]

Thanks for reporting - indeed, nterestingly the picture is missing when I'm not logged in but when I'm logged in I do see the picture (on Windows Firefox, Edge, on Android Chrome, T6Forum App, Firefox).

Anyways, a new try below - any better????

 

[gonze]

Thank you for adding the picture again.

I’m a bit stumped as what to do now though

Might have a Google for VW engine builders and ask the question. I don’t imagine the refurbed engine companies online use harmonic testers on there blocks.

 

[bluezie]

If you look at - VW Self Study Program 564, page 9 there is a diagram of the balance shaft set up.
I'm guessing VW set these up dynamically, so there is no specific precise timing that all engines have, they may be all a few teeth different. If you didn't mark the gears when dismantling, I fear the dynamic timing will be lost. You might get it somewhere near from the picture, or there may be a basic setting that VW starts with before fine tuning. This is probably what engine builders use if they've lost the timing.
There are probably specialists that build racing engines that have the kit to balance it properly.

 

[gonze]

It would appear I have messed up in an awkward way. Have spent hours this morning looking for companies that undertake engine harmonic balance setup and finding nothing other than crank balancing

 

[gonze]

I have not been able to find any information or advise on setting up the balance shafts.

Has anyone deleted them from the system? I will have to leave them in place as they will be very difficult to pull out as they are pressed into the block but I can have the splines removed the crank gear that connects to the balance shafts.

I would guess the engine will sound and run like the standard transporter engine?!

 

[bluezie]

Depends if the crank is the same or balanced differently, but it will run all the same, just might be a bit more vibration.
I once worked on a LPG forklift engine, which also had 2 block mounted balancer shafts, one didn't work as it was belt driven and the belt had snapped, but no unwanted vibrations, although they are a very slow revving engine in LPG form.

 

[gonze]

The only illustrations found for the shafts are the two below. I know they are not Haynes manual illustrations but both show the shafts with heavy side down and crank in high position for pistons 1& 4.

Do I take a gamble and install in that position? I’m really not keen on deleting the shafts in case the engine runs very badly.

I just need to find that one person that has dismantled one and has a photo!!

 

[reidman]

Hi Gonze, I wish I was the one person with the photo you mentioned, but unfortunately, I did the same as you! I didn't mark the position before dis assembly. I know its and old thread but what did you do in the end? I am currently looking at their functionality to see if there is a logical std position for these things relative to the piston positions.

 

[gonze]

I did a lot of research and spoke to a number of VW mechanics and came to the conclusion to remove them rather than take a gamble on the placement as it was more likely to cause issues. I've done circa 10K miles and the engine runs perfectly with no strange vibrations etc. I removed the idler wheel between the crank and the balance shaft on one side and the other I cut the toothed wheel off the end of the balance shaft but left the shafts within the engine block.

 

[reidman]

Thanks Gonze. Good to know there is no noticeable difference with them removed after some time, it does sway me to think this would be the least risky option of the two having the benefit of your experience, glad it worked out for you without this knowledge...it was quite a risk!

It does make some sense though that they should be as per the pictures above. The weights moving in the opposite direction to the downwards moving pistons, twice per crank rev, but this sounds too simple to set up and therefore doesn't match with the workshop manual warning. I think I will research a bit more before making my decision. Thanks again

 

[reidman]

With the number of CXEB engines approaching higher miles and the issues becoming more evident and needing reconditioning, I figure this may get asked again soon, so I will put some stuff on here as I reach my conclusion to hopefully help. This video is useful for understanding the balance shaft setup and function and ties in with the pictures of the balancing shaft's weight down with the pistons 1 and 4 at top dead centre.

I am slowly being convinced balance shafts may all be set up the same for inline 4 engines relative to position position, maybe someone knows differently? And the resetting could be straightforward if this is the case. I cant fathom the reason for the workshop manual warning yet, maybe it is a question of suitable access to perform the task.

 

[Skoda_Petw]

Hi All,

I too am also at this point about to Rebuild my CUNA but unable to find any information on balance shafts timings. I left the short block disassembly to the machine shop and did not mark the original position which the shafts were in. I only have 4 more days I can afford in the garage with my current torn down engine.

I'm hoping to hear back from Darkside as I'm a customer and they have removed and installed balance shafts in their videos. Hopefully they will give me some advice if not I will have to delete them.