Husqvarna 372 big end rod bearing replacement.

[Den]

I see quite a few videos of builders splitting cases, and replacing crank bearings. But can't find any videos of someone separating the connecting rod from the crankshaft on a 372 XP. I think quite a few of the builders might be replacing bearings and seals everywhere except the big end rod bearing.
Can't remember if someone said it has to be heated and pressed off, or if there is a different procedure?
Anyone ever done this, or know of a video of it being done?





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[ballisticdoughnut]

I wouldn’t trust a crank if it were pressed apart and put back together again. If it needs a rod bearing it needs a crank.

 

[Den]

I wouldn’t trust a crank if it were pressed apart and put back together again. If it needs a rod bearing it needs a crank.

Yep, I wondered about that ballisticdoughnut.
Additionally, if someone wanted to put a Farmertec crank/rod combo in a saw they intend to use daily for work, I'm not sure I'd trust that either.
Isn't there also Neotec aftermarket crank/rod combos for Husqvarna 372 saws?

 

[idiotwithasaw]

Without precision tools and expertise it would be almost impossible to get it back together true and balanced. As stated above if it's bad then replace the whole thing, otherwise roll on.

 

[Den]

Don't know of any cheap alternatives to OEM Husqvarna assemblies, other than Farmertec, or maybe that Neotec. I'll have to research Neotech.
Know of any other manufacturers?

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[ballisticdoughnut]

Yep, I wondered about that ballisticdoughnut.
Additionally, if someone wanted to put a Farmertec crank/rod combo in a saw they intend to use daily for work, I'm not sure I'd trust that either.
Isn't there also Neotec aftermarket crank/rod combos for Husqvarna 372 saws?

If your needing a crank, you could probably find a good used one here or on eBay.

 

[Tomos770]

Without precision tools and expertise it would be almost impossible to get it back together true and balanced. As stated above if it's bad then replace the whole thing, otherwise roll on.

When I was a teenager.....I had one old mofa (moped) wich I (&my father was my mechanic) was constantly improving/porting/ect....

I can still remember how my father changed that big end bearing and crank with nothing more then bench vice, hammer and a piece of (flat) glass/window.... <----- he tested if crank is even with that glass (flat surface!)

Mofa is still running......ported!

 

[The Shooters Apprentice]

Yep, I wondered about that ballisticdoughnut.
Additionally, if someone wanted to put a Farmertec crank/rod combo in a saw they intend to use daily for work, I'm not sure I'd trust that either.
Isn't there also Neotec aftermarket crank/rod combos for Husqvarna 372 saws?

I’ve run a few other the farmertec saws and no complaints with bearings of any kind yet. The cranks are a bit softer though.

I believe Hyway has cranks as well.

 

[lloyd786]

When I was a teenager.....I had one old mofa (moped) wich I (&my father was my mechanic) was constantly improving/porting/ect....

I can still remember how my father changed that big end bearing and crank with nothing more then bench vice, hammer and a piece of (flat) glass/window.... <----- he tested if crank is even with that glass (flat surface!)

Mofa is still running......ported!

I did this on our yz125, worked out fine. You need the v blocks on the glass to test the crank for true. I think if you get it very very close it will run itself to true in the first few minutes.

 

[giver]

One of my first jobs was working in a motorcycle shop and we changed rods a bearing on 2 stroke bikes and scooters never had a problem.
Always use machinist v block and precision straight edge though

 

[Den]

One of my first jobs was working in a motorcycle shop and we changed rods a bearing on 2 stroke bikes and scooters never had a problem.
Always use machinist v block and precision straight edge though

I suspect this one 372XP I'll be working on, has a good crank and rod... just bad bearings. I know of a couple machine shops that are pretty good. Think I'll ask them how much to perform said task.
Brings up the question... why don't manufacturers simply put removeable rod caps on chainsaws? Sure they run at high rpm, but one would think the components used would stand up to the stress and not break or vibrate loose. Then again, manufacturers might figure that a rod separating from the crank at such a high rpm might cause a catastrophic breakage which could injure the operator. Thats all I can figure.


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[giver]

Probably more for vibration and rotating mass I would imagine. If your crank has bad big end bearings I would think the rod and crank pin would probably be damaged also.

 

[giver]

I think it would almost double the weight of the rod with bolts and a removable cap, I t didn't matter much on the older saws that only turned 8-9000 rpm but closing your throttle butterfly at 14-15000rpm with that much mass still spin would cause a lot of lean conditions.
Just my thoughts

 

[Den]

Probably more for vibration and rotating mass I would imagine. If your crank has bad big end bearings I would think the rod and crank pin would probably be damaged also.

Now I've got the bug to start working on these 372XP saws, just need to make the time !!!

 

[halfmile]

I wouldn’t trust a crank if it were pressed apart and put back together again. If it needs a rod bearing it needs a crank.

Yamaha might take issue with that.
Also Harley-Davidson

 

[jltrent]

Usually a bad big end bearing will destroy the saw. I bought one that the cylinder/piston was bad as a bearing got lose and knocked a hole in the case also. If that is the problem get the best OEM one you can find cause when they go they do a lot of damage. The 372xp looked to be low hours from appearance. The piston was nice and smooth except were the bearing destroyed it.

 

[Tomos770]

I did this on our yz125, worked out fine. You need the v blocks on the glass to test the crank for true. I think if you get it very very close it will run itself to true in the first few minutes.

I dont have those V-blocks....tnx for an idea Will buy them....

Father just tested that crank....if both round halves are rolling properly on that glass.....plus if you position crank on that glass and you point battery light on one side....you can see if crank is uneven if ray of light is not the same on both halves (gap is not the same then)

 

[Cantdog]

Yamaha might take issue with that.
Also Harley-Davidson

Well...........HD cranks are not pressed together but are held together by large nuts, keys and tapers....not a straight press fit.

Regardless.... this question comes up on here every year or two and has been debaited to death. No mfgr of modern saws provides big end bearings, rods or any other part of the crank assembly seperately so the parts needed are not available through dealers. This is not a time machine....or a rocket...it is a tiny. low cc chainsaw with tiny parts that have to move unbelievably fast.......ponder......at 13,000 rpm that piston must reverse direction 26,000 time a minute. Note also that when things that are designed with an interference fit, like the crank pin in a saw crank, that every time you press it in or out the interference fit becomes less due to the stretching involved in an interference fit. It is doable if you are clever enough.......but really??.....is it worth it??? Just get a new or used crank.........or do what most do...simply swap all your good parts to a used, but in good condition crankcase with a good crank and git 'er done....leave rocket science to those that do that ****....it's a chainsaw remember......go cut wood......

 

[halfmile]

Well...........HD cranks are not pressed together but are held together by large nuts, keys and tapers....not a straight press fit.

Regardless.... this question comes up on here every year or two and has been debaited to death. No mfgr of modern saws provides big end bearings, rods or any other part of the crank assembly seperately so the parts needed are not available through dealers. This is not a time machine....or a rocket...it is a tiny. low cc chainsaw with tiny parts that have to move unbelievably fast.......ponder......at 13,000 rpm that piston must reverse direction 26,000 time a minute. Note also that when things that are designed with an interference fit, like the crank pin in a saw crank, that every time you press it in or out the interference fit becomes less due to the stretching involved in an interference fit. It is doable if you are clever enough.......but really??.....is it worth it??? Just get a new or used crank.........or do what most do...simply swap all your good parts to a used, but in good condition crankcase with a good crank and git 'er done....leave rocket science to those that do that ****....it's a chainsaw remember......go cut wood......

Street Glide 1450 cc.....pressed:

 

[Cantdog]

OK.......I stand corrected....the late models from the twin cams forward are pressed together.....however from 1999 back to the beginning (nearly 100 years) they were as I stated.....nuts and tapers