Brake fluid, helicoil & drive line play newbie questions

[richardak]

Took everyones advice and changed out the brake fluid on my "new to me" 83 R100RT. Seriously, it looked as if had never been replaced as it was very dark with some sort of film floating on the surface of the fluid and didn't want to come out of the bleed screws. I ran a lot of fluid through both of the systems until the fluid came out clean and the brakes now feel much better. The pads look new so I'm surprised this maintainence item was never addressed.

When checking the valve lash and rocker sideplay, it seemed odd that one of the valve covers had red rtv on both sides of the gasket. Odder still was the use of a locknut on the center stud. I discovered that the threads for the center stud in the head were pretty trashed. Is a helicoil an acceptable repair or is there a better or other preferred method?

How much play should there be in the driveline? While turning the engine to TDC, I had the trans in 5th and kind of rocked the rear wheel back and forth. The play seemed excessive to me at about 15-20 degrees of rotational play at the rear wheel. Is this about right? If this is excessive, where should I start looking? Replaced the final drive and tranny oil and it looked very clean (as in recently replaced) so no clues there.

Thank you in advance.

[20774]

As for the center nut, see this thread...a number of options were discussed. The correct way is to helicoil or timesert it, but I would try the "easier" approaches first, and when/if they fail or you have the opportunity to remove the head, then do the helicoil/timesert.

http://www.bmwmoa.org/forum/showthread.php?t=22335&

As for driveline play, having some is typical. I don't really know how much is OK. Have you removed the wheel and lubed the final drive splines? You might want to take a look at these splines and see how badly they might be worn. If they're worn to a point rather than being squared off, then you'll need to consider a replacement of the splines...there are places that do that. Clean things up and apply a thin coating of Honda Moly 60 paste...this seems to be the accepted, easily obtained, spline grease. You might look this over for more information (probably more than you want to know!!) about the final drive and seals.

http://bmwmotorcycletech.info/rearwhlsplines.htm

[Polarbear]

They have been notoriously a weak stud, ever since I can remember and have been redone by a large number of folks here, no doubt. You can return to the original stud fix with helicoil arrangement and all will be fine. I DID NOT. I simply "cut" new larger threads( a bit larger than the original stud size) and continued with a larger "bolt" in place vs. the factory stud setup! Works better, imo. You must size the bolt to fit proper through valve cover and lengthwise also. My valve covers took a larger bolt diameter, than what the original stud was:). Its simply stronger now, with a larger bolt in there and I "absolutely" use an anitsieze paste every time it comes out, when it goes back in:). My ride is a R100/7,'78...Randy13233. PS; the rtv is not required on the valve cover gaskets, but you may find the gaskets(when new) a bit tough to break in. The gaskets are reusable for "years" if care is taken removing the covers. AND, be sure the gaskets go back on exactly as they come off, as they become imprinted on the heads and covers and the two sides are different, especially around the center stud/bolt. Look see! Happy Trails:usa

[richardak]

...
Have you removed the wheel and lubed the final drive splines?
http://bmwmotorcycletech.info/rearwhlsplines.htm

Thank you for the suggestion, I guess I have a project for tomorrow. I am thinking of going ahead and pulling the head and installing a helicoil. It looks like an easy enough project.

[sumran]

In addition to inspecting spline wear, you may want to check the rivets that attach the final drive assembly to the cast wheel. Mine had a new spline cup installed, but the rivets were not done properly. They enlarged the holes in the cast whell to the point that the rivets were not secure. It was fixed with some special bolts, but could have been dangerous if it had broken during use.

[lkchris]

They have been notoriously a weak stud ...

What they have been is a too short stud.

Everyone should replace with the latest part number.

[richardak]

In addition to inspecting spline wear, you may want to check the rivets that attach the final drive assembly to the cast wheel. Mine had a new spline cup installed, but the rivets were not done properly. They enlarged the holes in the cast whell to the point that the rivets were not secure. It was fixed with some special bolts, but could have been dangerous if it had broken during use.

Fortunately, all is well. The rivets are tight and the splines are all in great shape. Cleaned and regreased the axle and the splines and put the wheel back on. Thank you for the tip.

Is the proper procedure to torque the axle nut then tighten the pinch bolt or is it the other way around? The reason I ask is that when I follow this procedure the hole used to remove the axle is pulled all the way into the pinch clamp. This is not the way it was when I first removed the axle.

Thank you

[sumran]

Fortunately, all is well. The rivets are tight and the splines are all in great shape. Cleaned and regreased the axle and the splines and put the wheel back on. Thank you for the tip.

Is the proper procedure to torque the axle nut then tighten the pinch bolt or is it the other way around? The reason I ask is that when I follow this procedure the hole used to remove the axle is pulled all the way into the pinch clamp. This is not the way it was when I first removed the axle.

Thank you

The axel nut should be tightened first. The axle should not be pulled in that far. Any chance a washer or spacer was left out of the assembly? What torque value are you using?

[richardak]

The axel nut should be tightened first. The axle should not be pulled in that far. Any chance a washer or spacer was left out of the assembly? What torque value are you using?

Torque on the axle nut - 32 ft-lbs (I think. Whatever was listed in Clymers). No parts were left over and no spacers or washers shown in the diagram. My concern is whether something is bent since it looks like force was used to get it to line up...

[20774]

Is the proper procedure to torque the axle nut then tighten the pinch bolt or is it the other way around? The reason I ask is that when I follow this procedure the hole used to remove the axle is pulled all the way into the pinch clamp. This is not the way it was when I first removed the axle.

As I recall, the tommy bar that is put into the hole in the axle is used to rotate and push the axle completely home, and the hole in question should be within the curved portion of the pinch bolt on the end of the fork leg...this is from memory. If it is not this far in, then the axle is not seated. It might torque up fine, but I expect that the shoulder on the axle is hanging up on the bearing stack inside the wheel. Be sure the axle is completely home. Tighten the big axle nut first, then the pinch bolt.

[richardak]

Thank you all for the replies. The hole in the axle is actually partially inside the pinch clamp. Installed the helicoil this evening without pulling the head and I can actually torque the nut down now! But the valve cover still leaks. I used a new gasket and thoroughly cleaned the mating surfaces. Frustrating... I guess something is warped.

[lostboy]

It is very common on late model/big valve heads for the valve cover surface on the head to warp. The ideal solution is to remove the head and machine it flat, but you can also put a bead of silcone sealant under the gasket to fill the gap. Remove your valve cover and gasket and install the cover; you'll be able to see the gap. Reinstall the cover wth silicone in the right places and let it cure before starting the motor.

[brickrider]

How much play should there be in the driveline? While turning the engine to TDC, I had the trans in 5th and kind of rocked the rear wheel back and forth. The play seemed excessive to me at about 15-20 degrees of rotational play at the rear wheel. Is this about right? If this is excessive, where should I start looking? Replaced the final drive and tranny oil and it looked very clean (as in recently replaced) so no clues there.
I rode an 83 R100RT for 16 years and 117,000 miles. At 60,000 miles, the rear wheel drive hub (the one riveted to the wheel) required replacement - the mating teeth were no longer square. You do not mention how many miles on your bike, but 15-20 degrees of rotational tire movement sound exactly like what my bike had. I suspect that you looked at the driving splines on the final drive and saw that they were in good shape. These are really tough. But the driven splines inside the hub on the wheel are not so tough. Suggest taking another, closer look inside that wheel hub, and I'll bet you will find that the mating cuts for the final drive splines have badly lost squareness on the side to which the force is applied. This is a fairly common problem on that model bike, particularly with more agressive riders.

The rear wheel hub replacement will put a $$$ dent in your wallet, but there is no alternative.

Ride Safely,
Brickrider