Exhaust finned nut removal
 

I need to remove both exhaust finned nuts so I can replace push rod tubes. They havent been removed for years so I dont even want to attempt to unscrew them. what would be the best way to cut them off - using a dremmel drill cutting tool of drilling a row of perferation holes along the width and finishing off with a chisel? any ideas? cheers, mark

I thought mine would never come off, when I bought the bike it was clear that they might never have come off since they were first put there..

However surprisingly enough after keeping the threads soaked in penetrating oil for a week, and heating them a little bit, they both came off very easily, using the right tool and a couple of gentle taps with a mallet.

(obviously if they don't unscrew easily then your original idea is the best one)

I also had a little hacksaw ready, a dremel would clearly be much better, the metal is actually quite soft so a careful cut and a couple of whacks with a chisel should be enough to break them off......in a worst case scenario

Hope this helps.

ciao.

Don't even attempt to unscrew them! my 100/7 had not been touched for years, the nuts appeared to be unscrewing nicely, they were with the thread no longer attached to the cylinder head but well embedded in the nut thread! When I had to remove them on my R80gs i took no chances and cut them off/chisled without even showing them the spanner, new exhaust nuts are far cheaper and less agrrevation than having new inserts put in the head, as well as having new nuts anyway, put plenty of copper slip/gold grease on them and if you can remember or can be bothered just make sure they 'run free' and even regrease at every semi major service.

I'd always try and get them off the way they were designed to come off before resorting to cuts and chisels. Remember that any serious damage to those threads will make the head useless, if you deform them with a chisel its almost impossible to get the fin nuts to go back in.

Its easy enough to make up (or have one made) the tool needed to unscrew them.

The BMW tool looks like a big open ended spanner with three studs that go into the fins.

A pair of Stilson wrenches at 90 degrees will also do the job. If you use Stilsons you need to put hardwood wedges between the fins to increase the number of fins that take the torque.

Having a 1m length of pipe over the spanner ends helps to increase the leverage, you'll probably find that they come loose quite easily with a long lever.

Use plenty of penetrating oil and try some spray CO2 to contract the fin nut as well.

Not the case.
The chap who "unleaded" my 78 R80 heads also machined down the damaged exhaust threads & fitted some really nice brass threaded sleaves, pinned to stop them turning.

Also I've seen some clamps (can't remember where! German manufacturer I think) that are split with a pinch bolt, designed specifically for damaged threads.

I also read about those a while back but I can't find the link. Motorworks sells something similar :

Motorworks - BMW Motorcycle Spares - Products **R45/50/60/65/75/80/90/100 (2 valve)

Rubbish - I've removed hundreds of exhaust nuts over the years just by hitting with a sharp bolster. the metal is as soft as cheese, and two good hits and they're split and then they simply unscrew.
Never had any damage to the thread on the head. It's cheaper destroying the fins than damaging the thread on the heads.
Once the new ones are fitted loosen them off and lube with copperslip once a year.

Thanks everyone, went for the hacksaw and chisel option - came off no probs.

Walter Price's exhaust nuts worked great
 

I had buggered up the threads on my R100GS before our big trip and ended up buying Walter Price's exhaust nut replacements. Cheaper than getting the threads repaired but more importantly, I can take off the exhaust using only an Allen key. Definitly a plus when in the middle of nowhere! Here is a link to his website:

BMW V2 Airhead Exhaust Clamp repair

BMW assembly paste will keep them from siezing for many years. I recently bought a 89 mod R80GS with very low milage and were the first person to remove the exhuast after they were installed at the factory. They came loose with only a light knock of the exhuast nut wrench.
On two occasions have I seen copperslip been used and within 6 months from fitting the exhuast nuts they were siezed in place and damaged the threads on the cylinderheads in the process of removing them. DO NOT USE COPPERSLIP! and do not loosen them every year to make sure they are fine, this only increase the risk of damage.
Apply assembly paste, part no. 18 21 9 062 599, to the thread of both the nut and cylinderhead and leave them allone till the next time it become nessasary to remove the exhuast system.
Make sure the threads is clean and free from old and hardened lubricants.

"On the two occasions I've seen Copperslip used...."

I've owned a BMW R100/7 for about ten years and cut the finned nuts off when I first had the bike. Using new nuts I loosen the nuts every year and coat the threads with Copperslip. They've NEVER EVER SEIZED in ten years, OK?

Do you have the proper tools ?
If not.
- Get them.

When you have the bike on the central stand it will tip over towards you when you try to unscrew the right nut, and you will lift the bike when you try to remove the left nut.
>>This is normal.<<

If you feel hesitant - cut the nuts!
Be careful not to damage the threads though.

Riding in salt and sleet will get these nuts stuck real bad -;)
When the nuts oxidize stuck - you will ripp the threads if you attempt to unscrew them!!! And to fix such damages is far more expensive than just cutting the nuts.

When you reinstall these nuts - do lubricate them, generously, with Omega 99 (or equivallent 1000-1200'C paste). I know people recommend cupper-slip/paste, but that will not last even one winter in the salt and sleet (+/-0'C to -8'C).

Lubricating, and heating prior to an attempt to losen the nuts - is an obvious precaution (I have never done it though).


# # #
DO NOT use poly-plier(? english term/word?), chissel, or any "inventive" gadget - in such a case you do better by cutting the nuts!

ONLY Use the proper BMW "claw" or a fair pattern -:)