Stihl 076 AV conversion to 3/8 - trouble

Hopefully some of you 076 owners will see this and have some advice.
This discussion was started on "084 versus 090 versus 076".
I bought a Stihl 076 AV powerhead and wanted to convert it to 3/8 for milling. Being new to milling and big saws I had no idea what I was getting into. Thanks to the guys on the other thread here is what I have so far:
The parts are from Bailey's and everything seemed fine until I put the chain on and it won't move. When forced by hand it comes out of the drive sprocket. It looks like the sprocket and bar are not properly aligned but why?
I checked everything for spurs and visible problems. The drive sprocket moves fine until the chain goes on. I took it apart several times without results. Could the oil pump be sitting too high - didn't take it out.

Oregon Power Mate Rim & Drum System for Stihl 050, 051, 075 and 076
Drive Sprocket Rim (Standard Spline) 375-8 Tooth
36" Carlton Premium Sprocket Tip Bar (36-57-B3104-PS)
WoodlandPro 33RP Ripping Chainsaw Chain

Here are some pics:

Great pics, phred45. That helps a lot.






in this photo, the rim appears to be aligned with where the bar would be.


I have a question, not intended to insult your intelligence, but I have to ask just to be thorough, and not to overlook anything.

Your new Carlton bar came with a 404 nose sprocket. As we discussed before, it is necessary to remove the 404 nose sprocket and install a 3/8 nose sprocket on the bar, instead. Did you do that ?

Thanks Mntgun,
Don't worry about insults. May be a few years down the road I might lift an eyebrow. Right now anything is possible. I do costomer service for computer programs and when I get those "nothing works" calls, my favorite is to check that it's plugged into the outlet. You'll be amazed how often the problem is that simple.
Actually Bailey's offered to put the 3/8 sprocket nose on for me no charge, I thought that was nice. Your question is very legitimate, they did send the 404 sprockets and chains but ( that's why it all took so long) the nose has 3/8 written on it. The rim is sitting just slightly higher than the bar. Bobl has asked to get some better pictures with the chain and bar on so I'll do that tonight.

phred45 said:

the nose has 3/8 written on it.

Click to expand...

OK, sounds good, we can rule that out.

Once again, I am stumped.

Spline rim float?



Looks like the oil pump drive cogs are holding the spline rim up in this picture.

The spline rim should be able to float between the clutch drum and the dust shield freely to find it's happy place in line with the bar. Bar thickness can vary so the spline rim system uses the slop here like a spur gear allows the chain to slide on the gear to line up with the bar.

On outboard clutch style husky's the spline rim can slide over the oil pump drive cogs. Is the rim even close to sliding over the drive cogs in this case? Something else holding it up?

srcarr52 said:

Is the rim even close to sliding over the drive cogs in this case?

Click to expand...

I agree, I think it's pinching on the oiler drive. I had a similar issue converting an 045AV from spur to rim - the rim setup needed a different oiler drive washer, which has the profile of the splines cut into it and fits over the splines on the drum to engage it. The old spur one just used a little metal pin which fit into a recess in the spur sprocket. Maybe you're having a similar problem and need a new oiler drive system to match as well? I don't see a separate part on the IPL though.

Brmorgan said:

I had a similar issue converting an 045AV from spur to rim - the rim setup needed a different oiler drive washer, which has the profile of the splines cut into it and fits over the splines on the drum to engage it. Maybe you're having a similar problem and need a new oiler drive system to match as well? I don't see a separate part on the IPL though.

Click to expand...

You may be right, however ....... if I understood Phred45 correctly, the saw was already set up for a rim when he acquired it. All Phred45 did was install a new drum and a new rim.

That's why I'd like to see the old parts sitting next to the new parts, to see what changed. Or then again, maybe it was incorrect when he acquired it.

OK then. I must admit I've not been following that other thread terribly closely.

I think the rim drum is not designed to fit that oiler setup and is not being allowed to sit down far enough on the crank. Because the drum isn't down over the drive tabs, the rim can drop down onto them because its larger ID will fit over the washer's collar. This would cause problems, I'm sure. Another possibility is that with the drum sitting out too far, when the clutch is spun onto the crank, instead of it bottoming out on the shoulder at the end of the threads, it pushes on the drum, pinching it against the oiler.

oil drive

Simple I have the same saw either you drive the oil pump with pins or the tangs (sqaure things on the oil pump gear) not both if the drum has the square notches ditch the pins and all will be fine. Unless somebody knows different I think I am right because it works.

Matt

Thanks guys,
Unfortunately I threw the old parts away, thinking I was all set to go. When the saw came it had a 404 rim sprocket. Since I didn't have a bar for it, I never got to run it. So I figured I may as well change the whole thing over to 3/8. When finally all the parts arrived the chain wouldn't move. The square lugs from the oil pump gear hold the rim up too high. At least that is what I think. The manual calls for another rim on the 075 but i don't know if that is the same for the 076.

To avoid having to change the oil pump system (not cheap) can I go with a 3/8 spur sprocket instead?

I'm going to the dealer here in a couple of hours to see what they have to say. However, I have little hope for that, they aren't too friendly and don't deal with big saws as a rule. Mostly a lawn and garden type dealer.
Will let you know what they say.

phred45 said:

To avoid having to change the oil pump system (not cheap) can I go with a 3/8 spur sprocket instead?

Click to expand...

I'm guessing whatever clutch drum you buy has to be compatible with your oiler, and apparently not all oilers and drums are compatible with each other. That may hold true whether the drum is the rim type or the spur type.

I feel bad enough for recommending the new clutch drum that didn't work. Well, the description said it would fit the 076. It probably does, if you have the right combination of parts.

If the dealer doesn't have answers, you might try posting on the chainsaw forum. There's more traffic over there and one of the 076 owners may be able to educate us and post pics, part #'s, etc..

Also, you might try explaining the problem to Grande Dog and see if he knows anything.

Some pics I found on the bay.

Here's a drum that appears to slide over the oiler lugs. Does your drum look like this ?


A spur drum that slides over the oiler lugs.


Here's an 076 drum that appears NOT to slide over the oiler lugs.


Aha ! ! ! Here's the answer. Apparently the 076 requires a SPECIAL rim, which naturally costs more money. The special rim slides over the oiler lugs.


Here's the ebay link.

The seller claims the rim part # is 0000 642 1215.

That rim does appear to fit your oiler lugs, however, there is still a question of whether your clutch drum fits your oiler lugs, since you have not posted a picture showing us that side of your clutch drum

Hope that helps. Again, I feel bad for giving you inaccurate advice about the clutch drum and rim from Baileys. I wasn't aware that 076 drums were so complicated.

rim sprocket

well if they wont help you maybe I can my saw has oregon drum #22262 and rim sprocket 22270 and is 404 but any rim including 375 which is 22273 will fit . The drum and rim sets are 22262x for 404 and 22271x for 375.
All you should need from your old parts is the pump cover.

Matt:greenchainsaw:

076 stihl said:

well if they wont help you maybe I can my saw has oregon drum #22262 and rim sprocket 22270 and is 404 but any rim including 375 which is 22273 will fit . The drum and rim sets are 22262x for 404 and 22271x for 375.
All you should need from your old parts is the pump cover.

Matt:greenchainsaw:

Click to expand...

That's helpful, but does your 076 have the rectangular oiler lugs like phred's ?

I believe Phred does have the 22262X drum from Baileys.

If I was at home In Oz I would have been able to go down to my shed and look at my 076 and sort this out back at post one.

Come to think of it i'm pretty sure mine has the special sprocket with the indents it the inside rim.

yes it does

:biggrinbounce2:Well, I'm back from the dealer. Pleasant surprise there. They have a new guy in the shop, much easier to talk to. As you guys already figuered out, I had the wrong parts. They had the right rim at the shop and it fits nicely over the luggs. The rim has notches like the e-bay picture Mtngn shows. However, the chain still doesn't ride smoothly, it makes clicking sounds in the rim/drum area like there is something in the way. They think that the drum also needs to be replaced with the correct part ($46 for the kit-outch). Hopefully that will fix it. Unfortunately the dealer said it would take 2 weeks to get them in. I may have a closer look at the e-bay ones.

076 Stihl, I first ordered the 3/8 kit from Bailey's and they sent the 22262 for the 404. So I called them and they said all I needed to exchange was the rim and they sent the 22273. Neither of the rims had the notches for the square lugs eventhough they show the Stihl part number the same as the e-bay rim. I also think that the drum should have been changed to the 3/8 because the part number is not the same. I really don't know what went wrong. Like mtngn said, they looked like the right parts and the pictures on Bailey's are not useful.

So Mtngn, don't worry, have a beer . It's way too hot to work outside any way. Besides, even though frustrating, this is quite a learning experience. I suspected I didn't know much, now I know.:biggrinbounce2:

phred45 said:

:biggrinbounce2:Well, I'm back from the dealer. Pleasant surprise there. They have a new guy in the shop, much easier to talk to. As you guys already figuered out, I had the wrong parts. They had the right rim at the shop and it fits nicely over the luggs. The rim has notches like the e-bay picture Mtngn shows. However, the chain still doesn't ride smoothly, it makes clicking sounds in the rim/drum area like there is something in the way.

Click to expand...

Some clicking is normal with new chains and sprockets but sometimes it's the wrong chain-sprocket combo. Assuming this is OK generally if you squirt some extra bar and chain oil onto the chain and run it for a few minutes it will smoothen up. Make sure you sort out your drum issue first.

Wow my rims have the notches actually 3 of them sort of weird but two on both line up with with the drive dogs. I do have old parts because I bought mine from cheap chainsaw parts and the boxs look like they are 10+ years old LOL. I really appreciate the heads up if I buy new stock I will make sure I have the bridgeport set up to mill those pesky notches! Thanks for the info!

Matt

phred45 said:

I also think that the drum should have been changed to the 3/8 because the part number is not the same.

Click to expand...

The drum should be the same regardless whether a 3/8 or 404 rim is used.

Yes, I realize Oregon gives them different part numbers.

Is Bailey's going to take the drum back, since it didn't fit ? Does the Baileys drum not have the notches for the oiler ?

Anyway, I'm glad you're making progress. It's been educational for me.