Forks. How to undo those top nuts???

[dwire]

Two things I'll note in this thread as it seems appropriate it be here for the time...

1) I have the parts coming to make up a "real" torque relief bar set-up for these bikes and once I receive them will spend an afternoon fashioning it and then post pictures, specs documentation and the like for everyone to enjoy such a nicety.

2) Plenty here have mentioned and I will paraphrase, "Tighten those nuts as tight as is humanly possible..." While I have not looked at the torque spec that different BMW resources state in a while, in NM or FT/LB (often there were silly errors in their conversions...) but would like to mention something as subjective as "Tight as is possible" is NOT the way to go and only leads to why this thread started - someone unable to remove nuts that were unnecessarily tightened as tight as someone else could get them.

When the tool has been finished (doubtful I will have it plated first, but...) we can have a technical discussion with regard to what torque is truly necessary on those fork tube nuts. If you want a head start on what I'll discuss from an engineering standpoint, start Googleing things such as "fastener clamp force" and as well, study up on hardness and a bit of metallurgy. Once you understand the absolutely tremendous amount of clamp force that can be exerted by a fastener and how and why a nut and thread actually hold something together (elongation of the bolt, fastener, or in our case the fork tube end and as well in cases such as this special application, both elongation of the nut and deformation of the upper triple-tree plate) you will be prepared to understand that there is a torque value that is reasonable, correct and of no need to exceed for this application...

Food for thought and I will start a new thread on all of this once I get the materials in and produce the special tool for the job and complete its assembly, testing, photography and documentation.

[ME 109]

My bmw manual states 88 ft. lb. for the top nuts on my '81
That torque isn't to make sure the nut doesn't come off, it's to try and get that damn front end a little stiffer.

I'd weld the buggers to the top plate if I could. That'd stiffen things up a little.
But that would be foolish. Too many kangaroos over here.

[Roy Gavin]

San Jose still makes billet top yokes for everything but my G/S.
The make aligning the forks a lot easier.

[Ken in Oklahoma]

I have the parts coming to make up a "real" torque relief bar set-up for these bikes and once I receive them will spend an afternoon fashioning it and then post pictures, specs documentation and the like for everyone to enjoy such a nicety.

While I haven't had any problems loosening or tightening those fork nuts (yet) I'm looking forward to seeing what you come up with.

Then I'll see what I can come up with to improve it!


Ken (Just kidding. Honest!)

[dwire]

My bmw manual states 88 ft. lb. for the top nuts on my '81
That torque isn't to make sure the nut doesn't come off, it's to try and get that damn front end a little stiffer.

I'd weld the buggers to the top plate if I could. That'd stiffen things up a little.
But that would be foolish. Too many kangaroos over here.

As is mentioned below, there are aftermarket billet tops made for most of these applications. Once you all understand the forces involved in this application, you'd likely find your MIG, TIG, or stick welder of no use in keeping the front end properly aligned...

Duane or others that have/do worked on hundreds to thousands of these would be able to weigh in on whether or not the triple-tree's top plate is simply inadequate - I myself have not found that to be the case, yet my sample group consists of - - - > 2 motorcycles! I would tend to think one could only benefit by a more rigid top plate, but have only experienced personally front end alignment issues as a cause-and-effect situation, like your poor kangaroo...

88 ft. lb. of torque sounds quite reasonable. Last time I put somewhere in that region if I recall and that was quite easy with my half-inch long-throw quality torque wrench. "As tight as I could have gotten it" with my long armed click wrench could have easily approached or exceeded the force required to not only hit the failure mode of the top nut, but would most likely have deformed the top plate as well, for I easily could have met or exceeded 140 ft. lb. with my set-up - near twice the spec.; which in ordinary engineering practices is usually quite close to the failure mode region. God knows it would be tough to damage the threads on those tubes, but at least my nuts are not made of all that hard of material and would likely be approaching failure up there.

One thing is certain, if there were no failure/damage issues and I sold the bike to someone that was a user here on the forum and they went to remove them, they would have started the very same thread here... <G>

[dwire]

I have the parts coming to make up a "real" torque relief bar set-up for these bikes and once I receive them will spend an afternoon fashioning it and then post pictures, specs documentation and the like for everyone to enjoy such a nicety.

While I haven't had any problems loosening or tightening those fork nuts (yet) I'm looking forward to seeing what you come up with.

Then I'll see what I can come up with to improve it!


Ken (Just kidding. Honest!)

Thanks Ken, you've always had a great sense of humor! No worries, you, in advance have my permission to start improving the device even now before the materials for its production have been received here... LOL!

[ME 109]

As is mentioned below, there are aftermarket billet tops made for most of these applications. Once you all understand the forces involved in this application, you'd likely find your MIG, TIG, or stick welder of no use in keeping the front end properly aligned...

Just kidding about welding things up

A billet top plate no doubt helps the situation.
A perfect fitting (is that possible?) after market fork brace also contributes to reducing twist.
The 81 oe triple tree is very strong but it can twist.
A billet top plate can rotate (very small amount) around the centre steering head nut.
It all adds up.
Our best weapon to fight bmwobbleyou is perfect alignment.

One thing I've noticed over the years when sitting still on a fully loaded for touring RS, is that turning the bars left to right in quick succession results in the most awful feeling of flexibility throughout the whole bike........

I believe the so called 'heavy' snowflake front wheel offers a good amount of stability through gyroscopic effect.
I can't help but wonder about the increase to stability from an even heavier front wheel.

Having said all this, that same 'loaded for touring' RS behaves beautifully at speed through the mountains.
Similar to racing a Kenworth, ya just don't want to have to do anything in a hurry. Like stopping.

My experience comes from, wow let me think, er 1 bmw.
So take this into account with regard to the above speel.

[dwire]

I am in complete agreement and I know of no man that wants to end up in a tank slapper on their beloved BMW - or any bike for that matter. I knew you were kidding with regard to the welding, but my point was simply that any weak link in the front suspension with regard to alignment, tremendous torque on those nuts would be of no assistance in that area. There is tight enough and then there is too tight. Even without failure, ask me or anyone else who has had someone tighten their lug nuts to about 150 ft. lbs. and see how aggravated (and as well passionate) they will get on the subject. Pulling an axle because a stud broke during a routine removal did nothing further or nothing less in securing one's wheel to the vehicle. <G> If disk brakes were involved in the latter, expect a high probability of a warped rotor as well - all for no benefit at all.

I have no doubt that anything that can be done to make the front end suspension more solid and help keep the geometry correct and consistent is a good thing, particularly on the short wheel base bikes that I have in past and do now own. Without testing, or consulting a professional such as Duane who knows, I have no real idea if a perfectly aligned (or as close as is humanly possible) OEM front set-up is inadequate and would benefit from any of the available aftermarket parts. Thus far, with really no more experience in the matter than yourself (and never fully loaded for touring!) correct alignment seems suitable to my bikes. Stupidity such as when I once forgot to tighten the axle nut, well that makes for the only time I truly was both scared and baffled at the same time by one of these old bike's performance, handling, maneuverability and very much so safety! The thing was 110% unpredictable - turns I gritted my teeth on and hoped I did not either run off the shoulder or into the other lane and a pebble made it feel like it was going to go into an oscillation that might end in hospitalization... Thankfully, I pulled over and realized the error in my ways... Lesson learned - - > THE HARD WAY. (OK, I didn't wreck it or anything... LOL)

[Roy Gavin]

If you are worried about tank slappers you should also check for wear on the swinging arm pivot pins.
the RH pin on my paralever GS was 4 thou " worn at one side, the LH not so much.
The OEM pins seem to be loose in the bearing, and the bearing has started turning on the pin.

Moteren israel have slightly oversize pins at a sensible price, which should cure the problem.
Just got to remember to hold the bearing in place if I remove the pins so I dont pull the bearing apart..

[daz]

Future, did you get your grout cleaned up and did you get your nuts off. Sorry about that. Keep us posted.