Preventing Thread Damage to the Lower Filter Cover Bolt



47 replies to this topic
  • grayracer513

Posted April 20, 2008 - 09:42 PM

#1

Most of us are maybe a little too familiar with the fact that the lower oil filter cover bolt tends to strip the threads on either the bolt or the case, or both. As many of us also know, the reason for this is that Yamaha decided to put a drain passage for the oil filter well in the bike, and have the oil run through the threads of this bolt. The metallic debris that the filter keeps out of the engine internals settles in the drain hole on top of the bolt threads between services, and ends up being ground through the threads and running out through this hole, doing unpreventable damage on the way out. Unless you clean the threads thoroughly, you end up with metal chips chewing on them again on the way back together.

The drain hole is just inside the filter cover, next to the oil feed hole from the pump (arrow below)

Posted Image

The passage intersects the threads here (arrow)

Posted Image

To put a stop to this silliness, I took a a #15 drill (.180") and ran into, but not through, the drain passage. If you don't have a number drill set, and most don't, use an 11/64" (0.172") instead. I drilled to a depth of about .170-.200". Use care. The drain passage is about .120", so the drill will want to bite and dig.

Posted Image

Then, I inserted a 3/16" steel bearing ball (.187") into the hole, and drove it in until the ball was roughly flush with the top of the hole. I then staked over the hole with a center punch to add insurance against the ball backing out.

Posted Image

I did this with the right engine cover off during a water pump rebuild. It could be done with the cover in place, but you would want to take steps to prevent chips from getting into the oil feed hole next to the drain or in the holes below the filter well, and of course, to avoid dropping the ball bearing into the feed hole in the well. BTW, loose balls like this are readily available at any decent bicycle shop.

In drilling the hole, there should not be any real problem created if the passage were to be drilled though entirely, because the ball cannot move down into the bore farther than the bolt. But it makes a better job of it when the ball has a step to stop against. A piece of tubing over the drill can be used to stop it from going deeper than you want.

If doing the mod in place, cover the feed hole and the oil passage next to the threaded hole on the cover flange with tape after cleaning the surface well enough for it to stick. Plug the threaded hole with a greased Q-tip to stop the chips from falling through the hole while you drill. Clean out what you can while the swab is still in place, then unscrew the swab.

Once this is done, the lower filter cover bolt should behave as does any other 6mm bolt.

Note: The diameter of the drain hole starts at 3mm (≊ .120"). I did not try tapping the ball into place without counter boring the hole, but it may work.

This mod has also been done with a threaded plug, but that seems way more complicated than necessary.

  • Ga426owner

Posted April 21, 2008 - 04:55 AM

#2

GreyRacer - thanks for posting this. This hole has been a PITA contention point for me all along from 98 - 08. I see no value to this hole other than quickly wearing out the threads and eventually the destruction to the bolt itself. I have been plugging this hole myself but your method looks preferable.
Seems to me, some company a few years ago also sold a product to plug this hole up also, but I like the DIY stuff.
thanks :thumbsup:

  • DPW

Posted April 21, 2008 - 05:30 AM

#3

Another thanks for posting this. I have been thinking of ways of plugging that hole before and now there is another option.

Ga426owner, how have you been blocking the drain?

What I was going to try and was just to clean the oil filter area/cavity and use something like J-B Weld to seal the hole

  • KJ790

Posted April 21, 2008 - 05:33 AM

#4

I have a couple ways of protecting the threads that have worked in the past. A q-tip with a little grease run in the hole before putting the bolt in helps, as does spraying contact cleaner in the hole to flush it out. Running a tap through the hole quickly before putting the bolt in also does wonders.

  • grayracer513

Posted April 21, 2008 - 06:01 AM

#5

I have a couple ways of protecting the threads that have worked in the past. A q-tip with a little grease run in the hole before putting the bolt in helps, as does spraying contact cleaner in the hole to flush it out. Running a tap through the hole quickly before putting the bolt in also does wonders.

All true, and all good practices, but the point of this is to make all of that unnecessary. Besides, none of the cleanup operations you can do after the bolt is removed do anything to prevent wear and galling from the debris that settles in the drain while the bike runs between oil changes, and attacks the threads as the bolt is removed.

  • SUnruh

Posted April 21, 2008 - 08:57 AM

#6

i see a few flakes of aluminum from the pressure plate on my EFM no-stall autoclutch, but that is about it. i think once on my 01 i felt the bolt go in a little tight, backed it out, checked it and put it in fine.

now on the original drain of the 01 (dec '00), that was pretty horrid. but 2 oil changes and have never had debris in 7+ years now.

agreed it is an *odd* design. if anything the hole should point more towards the bolt head and not get near the threads. if the drain was still used.

  • grayracer513

Posted April 21, 2008 - 10:40 AM

#7

agreed it is an *odd* design. if anything the hole should point more towards the bolt head and not get near the threads. if the drain was still used.

In principal, being able to drain the filter well without removing the filter has some appeal, but I'd rather it were executed differently.

In the first place, I don't like the idea of draining the dirty oil from the filter well back into the primary case, and the use of a cross hole instead of a simple drain plug opens up the whole thread damage issue.

Besides, the truth is that the well drain doesn't really drain very well, and I don't change oil without servicing the filter in any case.

  • Ga426owner

Posted April 21, 2008 - 12:18 PM

#8

Another thanks for posting this. I have been thinking of ways of plugging that hole before and now there is another option.

Ga426owner, how have you been blocking the drain?

What I was going to try and was just to clean the oil filter area/cavity and use something like J-B Weld to seal the hole


I installed a Timesert into the threads that were eaten away (over time)by all the metal particles. The Timesert's design keeps anything getting in the threads.

I like your thinkin Grey....less maint is better IMO.....unless you clean out the threads everytime.....you are damaging threads

  • Aka.Goose

Posted April 22, 2008 - 08:45 PM

#9

Yeah, I like your method...I'm going to do it...Also, Gray, it's going to take a few weeks before I can afford the Hinson clutch kit, so I have time to tinker...What other simple DIY "longevity" mods do you recommend?

  • projected

Posted June 20, 2008 - 05:06 PM

#10

I just did something similar, but I used part of a 3/16" X 1/8" aluminum pop rivet.

First I removed the head or collar of the rivet (not sure what to call it), this left an aluminum ball on the end of the rivet shaft. I cut the shaft off about 1/4" up from the ball. I inserted the shaft end first into the offending hole and tapped on the ball with a punch until it was flush with the case. The press fit was tight enough to make me feel comfortable, plus gravity is on my side in this situation so I can't see it coming out.

Doing it this way I didn't need to drill a hole. I remembered reading this thread a month or so ago but couldn't remember the specifics. I totally forgot that you drilled in order to use the ball bearing. While I was doing this I thought you had just used a ball bearing that was a press fit into the hole. It wasn't until I was done that I looked up the thread to confirm that I realized I did it differently.

Anyway I can't think of any reason not to do it this way, hopefully no one else can either.

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  • grayracer513

Posted July 03, 2008 - 08:45 AM

#11

Having now done the third oil change since doing this to both bikes, I could not be happier with it. The lower bolt comes out and threads back in as smoothly as the one above it every time, with no cleaning or chasing of threads. :thumbsup: :p

  • Kasjok

Posted July 03, 2008 - 09:34 AM

#12

I have done 2 oil changes with this "mod" and I have the same emotion.

  • SPLATT

Posted December 05, 2008 - 05:38 PM

#13

I think using a stud and nut would work as well and keep the ability to drain the filter but I do like Grayracers fix it looks factory.

Steve

  • grayracer513

Posted December 09, 2008 - 06:12 AM

#14

I think using a stud and nut would work as well and keep the ability to drain the filter but I do like Grayracers fix it looks factory.

Steve

A stud would prevent the thread damage problem, but it would eliminate the drain "functionality" of the drain port the same as blocking any other way. The problem is that it would not register the cover as the OEM shouldered bolt does, and the oil ports could become misaligned slightly.

OK! I had to break down and use a hel core. Does this hole lead back to a gear? and after you punch out the end of the core will that pice damage the engine? any way the bolt back in.

Yes, the inboard end of the threaded hole leads directly into the primary gear case. When using a Heli-Coil, the tail of the coil must be retrieved, or the coil inserted with the engine cover removed, or you run a risk of damaging any number of things, including the oil pump drive gears.

  • gjones

Posted March 11, 2009 - 05:26 AM

#15

Awesome suggestion Gray. I had this situation just the other evening when changing the oil. I haven't ever seen a valid reason for the drain bolt myself unless you want to wait 30 minutes for it to drain. By the time you get the drain bolt out and get the others ready to come out you can remove the cover and capture what little oil is in the cavity anyway.

  • FinchFan194

Posted March 11, 2009 - 07:44 PM

#16

What about cleaning it up really well and using epoxy to seal it off or JB weld or something like that how do you think that would work Grey??

  • grayracer513

Posted March 11, 2009 - 08:07 PM

#17

What about cleaning it up really well and using epoxy ... or JB weld...??

When it's this easy to do it right?

The ball costs less than the epoxy, takes less time to install, and the bike is ready to ride immediately; no cure time.

  • finthat

Posted March 24, 2009 - 06:28 PM

#18

Since I already have the whole thing in pieces on my bench that is going in for sure.

  • icon27

Posted March 29, 2009 - 10:18 PM

#19

Where do you get the ball bearing for this mod????

  • travisn

Posted March 30, 2009 - 04:39 AM

#20

I peeled one out of a head tube bearing from an old bmx bike.

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