R60/5 Drive Shaft Filler Plug Stripped

Hello Everyone,

On the newly acquired R60/5 (1973) when I checked the drive shaft fluid, I removed the top bolt (not an allen hole) and saw a piece of metal attached to the threads on the plug/bolt. When I tried to tighten, it started spinning.

If it were the bottom I'd be more concerned - wondering if I could either find a longer bolt or use a little red or blue loctite to hold it in place between maintenance cycles.

Otherwise, I could remove FD, take it to a machine shop and get it re-tapped for next size up or heli coiled.

Open to suggestions.

I would have it tapped for a bigger plug. "Normal" taps have a tapered nose and would hit the pinion shaft before completing new threads. But you can get a short, stubby tap that will work. A machine shop can do this in a few minutes if you bring them the final drive.

If you want to take the bike around the block or a little further you could always wrap a couple turns of Teflon tap around the plug and reinstall it for a temporary fix. After all its on the top and you may find other little things going on with the bike during your test rides that could be fixed while the threads are being straightened out.

If you have the mechanical ability and tools to remove the final drive and swing arm to take it to a machine shop you should be able to fix it yourself by simply removing the final drive and either helicoil or time cert it or go to a bigger plug all together. Just pull the final drive and be real careful not to bottom out your tap or insert on the drive shaft bell.

Thanks, Guys

Just thinking ahead as this will be a Spring project - hopefully a machine shop can get a larger metric "bolt." This approach is the "do it right" way - thanks again.

[QUOTE]But you can get a short, stubby tap that will work. [/QUOTE]

Referred to as , a "bottoming tap". Do it right Ken. Pull the FD (it's only held on with four nuts), take it to a [I]real [/I]machinist, and have a Helicoil, Keensert, or other "proper" thread insert installed. OEM plug, and crush washer will work forever.

[IMG]http://www.projectsinmetal.com/wp-content/uploads/2011/02/Taper_Plug_Bottoming_Tap_Types-300x154.gif[/IMG]

[QUOTE=Lmo1131;840662]Referred to as , a "bottoming tap". Do it right Ken. Pull the FD (it's only held on with four nuts), take it to a [I]real [/I]machinist, and have a Helicoil, Keensert, or other "proper" thread insert installed. OEM plug, and crush washer will work forever.

[IMG]http://www.projectsinmetal.com/wp-content/uploads/2011/02/Taper_Plug_Bottoming_Tap_Types-300x154.gif[/IMG][/QUOTE]

Thanks for the terminology. I knew what I was trying to describe (I own a couple of them), but certainly didn't know what the correct name was.

Another option is to get a 'clean-up' tap, which is essentially a taper tap with the same threads as the plug. The threads are then cleaned and any deformed threads straightened or re-cut. An aftermarket thread repair plastic (I think Permatex makes one) is then applied to the damaged threads.

I mention this because the problems with new threads are that the hole needs to be drilled out. This leads to concerns over aluminum shavings getting into the gearbox and (sooner or later) causing problems. Usually, a tap can be packed with grease to catch any metal chips. However, it's almost impossible to catch all the drilled hole chips (in my experience anyway).

Which is not to say the drive can't be flushed after drilling and tapping. Plenty of kerosene and shaking would likely work. But, there is always that chance of a stray metal chip getting in the bearing or gears with the only real way to eliminate that being dismantling the final drive before repairing the threads.

Ultimately, it's the owners call. But, barring the same ham-fisted guy who managed to strip the threads out having another try, cleaning up the threads with plastic reinforcement should work. Note that the plug needs to have clean threads. If it were the lower plug then a helicoil would be better (but then, metal chips would not fall into the drive during repair). Good luck!

Edit: after thinking about this a bit more, and seeing how the plastic thread repair works, it would be better to remove the drive, put it in a fixture inverted and use a helicoil type repair. The problem with the plastic is preventing any from dripping down into the differential during repair. As such, the same basic problem with metal chips is still there with the plastic.

Cleaning the threads and wrapping them with thick (mil-spec) teflon tape as noted earlier will work until the threads can be repaired.

As I was reading your thread, I started thinking, why couldn't the drilling be done inverted? Of course, not by me - I'd screw it up for sure. Thanks for your suggestions!