Exhaust Nut Wrench for 1971 R75/5?

[jimmiejag]

Doing research for an upcoming retoration of my 1971 R75/5 and have found a number of special wrenches for removing the finned nut that holds the exhaust pipes to the heads. I anticipate some struggle getting a nearly 50 year old nut free so I think a special wrench would be valuable to prevent breaking the cooling fins off the exhaust nut. The Enduralast nut seems to be the least expensive one I have found so far. It is used in conjunction with a breaker bar or similar tool.
Any recommendations for/against this particular tool?
Any other exhaust nut tools I should consider?
TIA,
Jim

 

[khittner]

I have an exhaust nut wrench that I got from San Jose/Luftmeister a couple of decades ago---cast iron, and gets the job done. The key is to not force a recalcitrant nut off with a lot of torque or whacking--that's a surefire way to an expensive exhaust spigot repair. If it's resisting removal, stop and cut the nut off before you strip/ damage the soft threads on the cylinder head. There are lots of threads and online video tutorials on methods, penetrating lubes to use, etc.

 

[20774]

Jim -

The Enduralast part is EXNut-Wrench758? That certainly would do the job...the only thing that I wonder about is the contact patch from the wrench to the exhaust nut fins is small. I have one that I probably got from Capital Cycle when they were all the rage in the early 1980s. Their item id is Item Id: 180600 but it costs $60. It does have a wider contact patch on the fins. Would make me feel better.

I'm sure you've read or will hear to be cautious about taking this apart after all these years. I did a top end on my /7 about 3-4 years ago. Since I absolutely effed up the header threads on one side right after getting my /7, I didn't hesitate to cut the exhaust nuts off right off the bat. Picture shows what I did. I think it saved my bacon.

You should use a good penetrant like AeroKroil and let it soak for days, using hot-cold cycles with a heat gun or something to help the penetrant soak in. Even then, once you start to turn the nut, if it moves and then stops, you're on the verge of galling the head threads. You will have to definitely cut the nut off.

 

[kinterridge]

Northwoods Airheads has the tool for $30 and replacement finned exhaust nuts. If I can't get them off with his tool and penetrating oil I cut them off, much less expensive then taking the threads away.

 

[ebeeby]

Doing research for an upcoming retoration of my 1971 R75/5 and have found a number of special wrenches for removing the finned nut that holds the exhaust pipes to the heads. I anticipate some struggle getting a nearly 50 year old nut free so I think a special wrench would be valuable to prevent breaking the cooling fins off the exhaust nut. The Enduralast nut seems to be the least expensive one I have found so far. It is used in conjunction with a breaker bar or similar tool.
Any recommendations for/against this particular tool?
Any other exhaust nut tools I should consider?
TIA,
Jim

Might as well buy the correct tool - you will need it again.
I bought one early on and have used it 4 or 5 times in 15 years.
Also, you will want to get a nice jug of anti-seize as you will need some whenever you remove the exhaust nuts to renew the paste to prevent having to use a hacksaw in the future. You will also need some anti-seize for sparkplug threads.

 

[jimmiejag]

Good Info, Thanks

I appreciate the above responses. They will be helpful in my project. I wasn't aware how easily the head can be damaged by forcibly removing the exhaust nut.
Danke,
Jim

 

[chunk]

If they are seized this might help.

 

[69zeff65]

If they don't pop loose don't force them

They can be sticky but if they don't pop loose with about 40 ft lb of effort you may want to go directly to cutting the finned nut. If they do come loose but fight with more than about 25 Ft lb I would consider cutting the finned nuts. I had to cut them off my Barn Bike '69 R 69S because it had sat in a bad environment since 1975 and they would not budge. I used a Dremel with heavy duty cutting wheel and made two cuts 180 degrees apart and split the nut with a coal chisel and few taps with a small hammer.

 

[ccolwell]

At Tom Cutter's advice, I used a mix of ATF and acetone on my R90S. Applied it twice a day for a week or so. After a bit of propane torch, the nuts popped off my R90S quite easily. I'm quite sure they hadn't been touched 38-40 yrs at that point.