Topic: CB350f oil pan bolt Mystery?

[Dos]

Hello,

I had to replace my oil pan/sump and foolishly did not keep track of the bolts!
I discovered that one of the bolts threading became thin. It’s hard to explain but the neck of the bolt became thinner with the threads.

I thought maybe this was from over tightening but I looked online and saw an ad for a cb350f oil pan with the bolts included and one of them was also thinned out.

I also have a snapped off bolt and have no idea how to get it out.

 

[Nurse Julie]

Never noticed that, I thought all the sump pan bolts were the same part number and  6x40 flanged bolt  🤔🤔🤔

[willbird]

https://i.ebayimg.com/images/g/YQUAAOSwQ3Rj86mb/s-l1600.jpg

If this is an example of what you are talking about above ??

Most threads on bolts are created by a process called thread rolling. A tool that has thread shaped rollers rolls a straight round part into the required threads. When this happens the diameter gets bigger due to the metal being displaced.

The normal bolts we see I am guessing they actually make the portion to be threaded smaller so that we end up with a bolt that does not have that "necked down" appearance maybe.

The first picture here kind of illustrates it.
https://www.topti64.com/2017/07/28/rolled-threads-vs-cut-threads/

[HondaMan]

Normally, to remove such a broken-off bolt I will first soak it (usually overnight) with penetrating oil because it is likely to be corroded in place, which caused it to break while attempting removal.

Overnight, I'll go to the hardware store for a set of broken-bolt-extractors (often called "E-Z Outs"), and get a couple of drill bits of the appropriate size, like 1/8" to center-drill the broken bolt, using a new, sharp drill bit, then 3/16" to open up the top end of the hole a little more to fit the extractor. You'll need a tap-handle, too, to hold the extractor.

Then, the next day I'll drill the center of the bolt about 1/4" deep, then widen the hole at the top with the 3/16" drill, then heat the case at the bolt with a torch (propane might wrk, MAPP gas works better) to help things along, and then attempt to twist it out.

If this approach fails then you must drill the full length of the bolt (don't drill thru the case into the bottom of the engine, or it can weep oil later on) with the 1/8" drill, then successively larger step-drill sizes until the threads can either be broken free with an EX-out, or you have drilled the whole bolt away and are left with just its threads, which must be picked out. Then run a tap (#6mm x 1mm) into the hole to clean up the threads. If they are excessively damaged, then you'll have to drill the hole a little bigger to install a Helicoil insert, or the like.

[Dos]

For some reason I cannot drill anything into this bolt. I have an ez out but I can’t even get it in deep enough because I can’t drill into the bolt. I’ve snapped acouple bits off already

[Dos]

Ah okay thank you !

https://i.ebayimg.com/images/g/YQUAAOSwQ3Rj86mb/s-l1600.jpg

If this is an example of what you are talking about above ??

Most threads on bolts are created by a process called thread rolling. A tool that has thread shaped rollers rolls a straight round part into the required threads. When this happens the diameter gets bigger due to the metal being displaced.

The normal bolts we see I am guessing they actually make the portion to be threaded smaller so that we end up with a bolt that does not have that "necked down" appearance maybe.

The first picture here kind of illustrates it.
https://www.topti64.com/2017/07/28/rolled-threads-vs-cut-threads/

[rluser]

For some reason I cannot drill anything into this bolt. [ ... ]  I’ve snapped acouple bits off already

I do not envy you this miserable position.
Chuck loose in drill?  Some other equipment failure causing exessive runout and overloading a small bit?

[Don R]

 If you have access to a mig welder I'd weld a washer through the center hole to the broken bolt and then maybe a nut. Often it takes a few tries but usually works.

[dave500]

carefully with a sharp centre punch or pin punch,knock it in the undo direction,you can get lucky,if its not bottomed out it shouldnt have any load on it with the pan removed,you might bit by bit turn it enough to get vise grips onto it?

[newday777]

For some reason I cannot drill anything into this bolt. I have an ez out but I can’t even get it in deep enough because I can’t drill into the bolt. I’ve snapped acouple bits off already

Are you trying to do this with the bike upright on the stand? Or is your motor out on the bench/floor?
If you are trying to do it in the bike, on the stand, then lay the bike over on the side on a shop blanket on the floor for easier access to the busted bolt, left side down so it lays on the alternator cover(gas tank off the bike!)

Do you have the capability to mig weld on the washer and nut as was mentioned? That is the best way especially if you have busted off drill bits or extractors in the busted bolt. The heat from the weld helps lossen the threads so it unscrews easier. A local welder that knows how to do this would be helpful if you can't.

As Mark said, if threads are messed up then an insert will be required to repair the threads. Time-serts are better repair than helicoils.

[Dos]

The bike is on its center stand.

I was at it with a drill bit and punch for hours and I really made it bad…
This seems like a nightmare now haha

I couldn’t even fit the drill under at a 90 degree angle..

I’ll see if I can get a welder, I snapped the bolt off with the old oil pan in and there was actually no weeping or leakage on that side so I’m thinking maybe I just leave it alone?

Both everything and leave it.

[Kelly E]

My first step for a broken bolt or stripped head is use the left handed drill bits. The last time was on the 78' KL 250. I had to drill out 13 siezed case cover screws. Every one of them started to unscrew and came out just before the head popped off. 

[HondaMan]

My first step for a broken bolt or stripped head is use the left handed drill bits. The last time was on the 78' KL 250. I had to drill out 13 siezed case cover screws. Every one of them started to unscrew and came out just before the head popped off. 

Now, THERE's a novel idea!
I'm gonna get me a set of those bits. As many of these engines as I rebuild (with broken-off bolts in them), that could save considerable time?

[Dos]

Ah yes! I have a drill that can spin counter clockwise so that could work!

[newday777]

Ah yes! I have a drill that can spin counter clockwise so that could work!

Drill at slow speed once started into the bolt/screw so that the bit can grab the screw at the slower speed and back the threads out.

I remember starting working with my dad's drills back in the late 60s, he had old metal cased Craftsman drills, with no reverse, then in the 70s he bought a newer drill that had reverse. I didn't learn of left handed drill bits until mid 2010 working on a GL1100.