Socket head cap screw torture

[jimbob1960]

Just did my first airhead tune up, including oil/filter change....read all the advice, had extra shims, 2 piece filter, new white o-ring, etc, etc. The hex head bolts were not an issue coming out, but goodness, that upper M6 socket head? How much engineering went into designing the frame/engine relationship so that on a good day, if the planets align and you hold your mouth right (and have a small enough pair of needle nose to grab the outside and make 1/128th of a revolution...), one can BARELY get the thing out. No wonder people cut these o-rings!
To add to the amount of sample data out there, my oil filter "factor" was about 3.9 MM. The o-ring that came out (with 1 shim, and the paper gasket in place) was just barely flattened on one side, more so on the other. Replaced the shim with a new one, and removed the paper gasket from the stack...had observable "rebound" on the cap with the fasteners drawn down to within a few thou of the cover being seated. The old shim was beat up, and didn't look like the new ones. Kinda looked homemade. It mikes about .25 MM, where as the new one was .3 MM. No leaks, and the oil pressure light went out within three seconds of starting to crank.
JimBob
-----------------
1980 R100RT
1978 SR500
1971 Rokon RT-140
(and my wife's Honda Airblade in Saigon)

 

[robsryder]

When I purchased my first airhead (an 88 R100GS) I paid the BMW dealership mechanic extra to let me watch him replace the oil filter. I wanted to know the "trick".

Turns out there is a tool called a ball-end allen wrench that is very useful in removing the hard-to-reach socket cap screws. Below is a link to a set of these tools which are available from Sears. Snap-On and others have similar offerings.

http://www.sears.com/shc/s/p_10153_12605_00992486000P?prdNo=6

 

[20774]

Nominal depth is 3 to 3.5mm in which case you would use one shim, no gasket. At nearly 4mm, a second shim would add some needed compression the o-ring. Check the o-ring next filter change...if you the o-ring looks more "square" the next time, that's a good sign.

 

[jimbob1960]

Thanks for the link! I have a 6" ball end allen (Snap On) in the big tool box in storage back in Houston. I have to admit, I did this with the crash bar and fairing in place. If I had not been such a lazy sod, it probably would have been simpler. I guarantee, when I get Eva back to Texas, I will be turning a few M6 socket heads down to a smaller OD on my little Atlas lathe. Not likely my lazy tendencies will lessen when I get home!

 

[krpntr]

Difficult screw placement?

Whats wrong with a hex-head cap screw? That's what I have. No torture, no pain, just an open end /box wrench or nut driver.

 

[jad01]

Whats wrong with a hex-head cap screw? That's what I have. No torture, no pain, just an open end /box wrench or nut driver.

I kind of agree- I switched mine from hex-head to allen head when I was converting a bunch of the engine and frame bolts to stainless a few years back. They look neat (if you're lookin'), but I think the allen head screws on the oil filter cover are a pain and will likely switch back to the hex-heads next oil/filter change...

 

[lmo1131]

How much engineering went into designing the frame/engine relationship

6M socket head screw, head height; 6mm [0.236"]
6M hex head screw; head height; 4mm [0.156"]

but I think the allen head screws on the oil filter cover are a pain and will likely switch back to the hex-heads next oil/filter change...

funny the difference 2mm [0.079"] can make... .

 

[jimbob1960]

I think unless it was really short, a hex head would be a real challenge in the upper bolt hole. Not so much from a height perspective, but from a diameter perspective. The perimeter of the head is touching the frame tube for the last few turns (on my RT, anyway...). I am going to look into it though, especially the length. I have always heard that if a bolt has much more than 1 x the diameter engaged in the threaded hole, it has about all the strength it will get, and screwing it in further does not help much. Not sure if that applies with a steel bolt and an aluminum casting. I think a slightly turned down socket head will be the hot set up, but I am also going to experiment next time and see if there is room for an M6 set screw. Might be room to Locktite one in there and use a nut on the cover. If one were to put those in all three holes it might reduce the chance of cutting the o-ring.

 

[krpntr]

Somthin different down thar

What you were saying did not ring a bell with me, so I took a look at mine. I have an '82 R100T. There's acres of clearance between the bolts and the frame on my bike. So ignore anything I say. Whatever works for you. Good luck.

 

[44006]

Perhaps someone messed about with the spacer washers between the engine
and the frame on the subject bike.

How does the trans output end line up with the center of the swing
arm driveshaft opening when swing arm is centered in the frame?
Is the shaft running in the center of the opening as it should?

 

[jimbob1960]

Certainly possible (I have seen some seriously bizarre stuff on old bikes...). No evidence of any crash repair, all the S/N's match. On the face of things, I would wager everything is as it came out of Spandau. But in line with what you are saying, the relationships look a bit different than the pictures I have seen online. So, now I am not sure at all! Have not had any of the aft end components off except the rear wheel. Once the snow flies here in Calgary, I plan on a bit deeper maintenance. Maybe then I can figure out the situation.

 

[44006]

Easy assembly mistake by the unknowing to leave out spacers that may
or may not drop off the engine when it is removed or moved for tran service

see sketch

 

[guenner]

I couldn't find the specs for the spacers for a 1980 R100RT. On my 1988 R100GS the front left spacer is thicker than the other three by 3mm (~1/8"). So there's another chance for the wrong offset.

/Guenther