Over torqued. Did I do damage?

[Armando]

Finally, almost 2 weeks after the NE Tech Daze, I just finished doing the valve adjustment on my bike Next is the TBS.

 

However, I am now worried about possible damage I may have done by over torquing the T45 bolts holding the lower rocker arm. I misread the table and instead of setting my torque wrench to 15NM, I set it at 40! It did not feel quite right so I never got to 40. Not sure the bolts could make it to 40. In any case, I backed them out and then set them at 15NM. Chances are the bolts were probably starting to strip and my question is, what is the possible damage? should I replace the bolts or just let it be for now?

[Tony_K]

That was a bad read on the torque!

 

Good thing you didn't try to strong arm it to what you thought was correct.

I say let it be but go back and re check them after a few good rides and heat cycles.

 

If they sit nice at the proper torque your more than likely good !

[David]

I would guess that they aren't "starting to strip" or they'd already be stripped. Instead, you probably got to 40 very evenly and just stretched them. Lucky you indeed.

 

Just replace the bolts, but I'd probably do it sooner rather than later.

[ElevenFifty]

I think you're fine - in this case sounds like an 'educated hand' saved you some trouble. If they torqued to 15 then I wouldn't worry about it

[LeaninLouie]

Torquing a bolt or nut is the process of tightening the fastener to the below the point of yield. This varies by the metalurgy of the fastener material and the loads anticipated by engineering. Overtorquing a fastener generally stretches it and the potential is set for the fastener to fail. You know all those broken bolts you see on the road! The most common place of failure is at the point where the shank starts the threads, as a stress point is created there.

Safety and security dictate replacing the fasteners. In regards to stripping the threads, that may have started to happen but if you did torque them to the proper torque you are probably good for now. When you next remove those fasteners if the threads are partially stripped you should notice that the fasteners will not unscrew easily, there will be a considerable drag by the threads.

 

Good luck.

[Wooster]

Overtorquing a fastener generally stretches it and the potential is set for the fastener to fail. You know all those broken bolts you see on the road! The most common place of failure is at the point where the shank starts the threads, as a stress point is created there.

 

Good luck.

 

LeaninLouie (great name, btw),

 

All well and good yet a bit off the mark here. Given the different characteristics of steel (what bolt is made of) vs aluminum (what cylinder/female threads consist of), the easily replaced bolt will be just fine (when overtorqued): unfortunately, when we bikers strip threads, we invariably mess-up the more costly, larger part's (Armando's cylinder head) female threads.

My suggestion to Armando is that if you've got the specified torque reading, i.e., 15 Nm, I'd leave it be. Replacing the harder steel bolts will not improve any damage done to the softer aluminum female threads.

 

Wooster who's stripped a few

[Stan Walker]

I am now worried about possible damage I may have done by over torquing the T45 bolts holding the lower rocker arm. I misread the table and instead of setting my torque wrench to 15NM, I set it at 40!

 

Your profile indicates that you have an '02 RT, is that the bike we are talking about? Your bike must be different from my '02 RT. I don't have any torque value of 15 Nm associated with the rocker arms support. I also don't have any T45 bolts in that area. What am I missing here? I'm so confused.

[Armando]

This is what I am affraid of. I know the head is made of aluminun but do not know what the bold it made of, steel?. I don't even want to think about what I will need to do if the threads are stripped. I am hoping that they are not in bad shape I as I was able torque at 15nm.

 

I will buy some bolts to replace the existing ones the next time I take the valves cover off. So, assuming that the bolts stretched or the threads started to strip, what would potentially happen if a complete failure of either occurred while riding?

 

 

LeaninLouie (great name, btw),

 

All well and good yet a bit off the mark here. Given the different characteristics of steel (what bolt is made of) vs aluminum (what cylinder/female threads consist of), the easily replaced bolt will be just fine (when overtorqued): unfortunately, when we bikers strip threads, we invariably mess-up the more costly, larger part's ( My suggestion to Armando is that if you've got the specified torque reading, i.e., 15 Nm, I'd leave it be. Replacing the harder steel bolts will not improve any damage done to the softer aluminum female threads.

 

Wooster who's stripped a few

[Armando]

Yes, this is my 02RT. See the attached for the location of these bolts. Part of the reason for making the mistake is that I was looking for info in 3 different sources. I got confused when reading the Clymer manual. I should had taken a break but I wanted to get it done because it was getting late and the bike has been sitting in the garage for almost 2 weeks now. When it comes to torquing, I should have taken the measure twice and cut once approach.

 

 

a

 

 

I am now worried about possible damage I may have done by over torquing the T45 bolts holding the lower rocker arm. I misread the table and instead of setting my torque wrench to 15NM, I set it at 40!

 

Your profile indicates that you have an '02 RT, is that the bike we are talking about? Your bike must be different from my '02 RT. I don't have any torque value of 15 Nm associated with the rocker arms support. I also don't have any T45 bolts in that area. What am I missing here? I'm so confused.

[Stan Walker]

See the attached for the location of these bolts.

 

According to my copy of the BMW shop manual those are M6 x 30 screws and the correct torque is 40 Nm.

 

Frankly, I don't trust Clymer. I have one of thier shop manuals for the 1100 RT and I almost never look in it.

 

BMW has been changing away from hex head screws so the T45 doesn't surprise me. A change in torque value for that part does. If it were me, I would double check with a dealer before putting on too many more miles.

 

Stan

[Stan Walker]

Oh, one more question.

 

I assume you were adjusting the end play. If so you must also have retorqued the one cylinder head nut. What did you torque it to? (trick question). I seem to recall that Clymer had this wrong in some of their manuals too.

 

Stan

[Armando]

Yes, that is what I was trying to do. The head nuts were torqued in criss-cross sequence to 20nm and then an additional 90 Degrees.

 

I guess I will have to double check on that torque. The other two docs I was referencing where the Anton method --> Anton Method and the Internet BMW riders doc on the same topic. Both have the torque specified at 15nm. Anyone else know for sure what the proper torque should be? I have to say when I first loosen the bolts, the torque seemed higher than the 15nm. I stopped trying to torque at 40nm because it felt as if something was giving in.

 

a

 

Oh, one more question.

 

I assume you were adjusting the end play. If so you must also have retorqued the one cylinder head nut. What did you torque it to? (trick question). I seem to recall that Clymer had this wrong in some of their manuals too.

 

Stan

[bmwmick]

Yes, that is what I was trying to do. The head nuts were torqued in criss-cross sequence to 20nm and then an additional 90 Degrees.

 

I guess I will have to double check on that torque. The other two docs I was referencing where the Anton method --> Anton Method and the Internet BMW riders doc on the same topic. Both have the torque specified at 15nm. Anyone else know for sure what the proper torque should be? I have to say when I first loosen the bolts, the torque seemed higher than the 15nm. I stopped trying to torque at 40nm because it felt as if something was giving in.

 

a

 

 

Now I'm as confused as Stan

 

The M6X30 carrier screws should be torqued to 9Nm. The M10X 70 is torqued to 40Nm. The Head nuts (lightly oiled) get 20Nm plus 180 degrees. I think you are mixing a lot of different specs. The camshaft caps are the only screws specified at 15Nm and you haven't touched them.

 

Mick

Tucson

[Stan Walker]

From the IBMWR doc

 

Retorque the T45 torx screws to 15 ft.lbs. Retorque the head bolt to 17 ft.lbs. and then turn the bolt an additional 180-degrees (torque it and then move the wrench through another half circle).

 

NOTE: Their spec's are NOT in Nn, but in Ft-Lbs!!!!!!!!!!!!!!!!!!!

 

Also note 180 degrees!!!!!!!!!!

 

So sorry, but Clymer sucks big time!!!!!!!!! Burn it, shoot it, use it for TP, but DON'T use it for fixing BMW's!!!!!!!!

 

Stan

[groundeffect]

I bought a Chlymer manual a couple of years ago...inserted as loose leaf was a sheet of ammended torque values!!!

I don't have it in front of me, but some were very different than the original manual values.

[Spyder]

 

Now I'm as confused as Stan

 

The M6X30 carrier screws should be torqued to 9Nm. The M10X 70 is torqued to 40Nm. The Head nuts (lightly oiled) get 20Nm plus 180 degrees. I think you are mixing a lot of different specs. The camshaft caps are the only screws specified at 15Nm and you haven't touched them.

 

Mick

Tucson

 

That is what my factory manual says as well Armando.

[Armando]

So, the T45 referenced in the Clymer and links posted above, is now the M6 or M10? I really need to take a look at a BMW service manual.

[T__]

So, the T45 referenced in the Clymer and links posted above, is now the M6 or M10? I really need to take a look at a BMW service manual.

 

 

Twisty

[T__]

 

Twisty

[MarcS]

You said it felt as if something was giving in -- if the bolt lost torque/became easier to turn suddenly, you probably DID strip threads. This is bad but not unfixable.

 

Cheapest/easiest solution is to clean the remaining threads out of the hole (say, very carefully with a drill), re-tap it, and throw a TimeSert or HeliCoil in. You will want to be very careful to keep metal shavings from getting inside the engine, and you'll have to remove parts to get at the bare, level hole.

[Armando]

Twisty,

 

Thanks for scanning the diagrams.

 

All,

 

I stopped by Spyder's house to look at his manual and it shows the same thing that Twisty scanned. Here is what makes things confusing. Both M6 and M10 show 4 of each. There are only 3 T45's. I looked over the Clymer and some of the data I got from the net and there are torque values for each. As you can see from the diagram above, it does not show the T45 bolts. So I went back to the Clymer. Chapter 3 is the general maintenance. Chapter 4 is the detail of the top end. I probably got things mixed up because chapter 3 make reference to the t45's and their torque setting on table 4 within that chapter. Problem is that the torque for the T45's is not listed anywhere in chapter 3!!! Now, if you go to chapter 4, you will find the proper torque of 15 NM for the T45. I did not look at chapter 4 last night and assumed that the torque setting was the 40nm for the m10 bolt.

 

So, I took Spyder's advice. I took the valve cover off again and backed out each bolt, 1 at the time. I pulled and pushed to determine if there was any play on the threads. There was some moving sideways but none pushing in or pulling out. This started to get my confidence back up. Then I pulled the bolt all the way out looking for shavings from the head or damaged threads. None found I retorqued the T45 at 15nm. I also retorqued the head nuts to 20nm plus 180 degrees. I put it all back together and I am going to forget about it until I put a few miles on it. I will then check the torque again to see if it is holding.

 

As ElevenFifty mentioned, I think having stripped a few bolts in the past saved my skin this time!!!

 

One question remains and that is, where on the BMW manual can we find the T45 bolts? I will be looking at the BMW manual and chapter 4 of the clymer to see if I can find a better schematic depicting the m10, m6 and t45's.

 

Thank you very much to everyone who took the time to pitch in.

 

 

Armando

[Boffin]

Just to be sure, T45 is a size designation for a Torx drive head. M6 and M10 are standard size designation for threaded fasteners. M6 is 6mm diameter threads amd M10 10mm diameter - either of these could have any head type, Torx, Hex, Socket, slot etc.

 

Andy

[Armando]

I think I figured it out. page 11.25 of the bmw manual has the diagram for the valve gear carrier. there are 3 bolts attaching the rocker bearing cap to the valve gear carrier. these 3 bolts are m8's and should be torqued to 18 nm. these are the bolts which have the torx t45 head on them.

 

Now, if you flip the valve gear assembly you could also remove the camshaft bearing cap which is also held by m8 bolts. the torque for the bolts holding this cap is 15nm.

 

Last night I torqued the m8 in question to 18nm based on one other doc I had from the net. I don't have it me now but will post it when I get home tonight. this doc was updated in 04 and had the torque for m8's at 18nm.

 

I think I am set for a few hundred miles. I will definitely have to check the torque again to make sure I did not do damage.

 

armando

 

thanks again to all.

[RSL]

Per advice from various experienced machinists, mechanics, etc.: If you do need to restore stripped threads in the stud or bolt mounting holes, use Time-Sert or similar high quality inserts. Helicoil are considered by many (but not all) of these sources as an inferior application, more prone to failure. Time-Sert costs a bit more, but is generally considered a more reliable and durable device. A Time-Sert of correct size for the stud mounting holes in the aluminum engine case should retail for $4 to $5 each.

[Armando]

Hopefully I will not have to go that route but if I do, this is good to konw. Thanks.

 

 

Per advice from various experienced machinists, mechanics, etc.: If you do need to restore stripped threads in the stud or bolt mounting holes, use Time-Sert or similar high quality inserts. Helicoil are considered by many (but not all) of these sources as an inferior application, more prone to failure. Time-Sert costs a bit more, but is generally considered a more reliable and durable device. A Time-Sert of correct size for the stud mounting holes in the aluminum engine case should retail for $4 to $5 each.

[RSL]

Google for the Time-Sert website and view their short video clip on installation. Same size tap as Helicoil, but much better and more durable product, for $2 or $3 extra per hole.

 

If I had this to do over, I'd do it myself with the Time-Sert kit, which includes drill bit, tap, counter-sink, and a few inserts. Or, local machinists offered to lend their tools, in which case I'd have just needed one ~$5 M10X1.5X 25mm insert. Every single one of these machinists recommended Time-Sert over Helicoil. Check into it.

[Chugger]

Google for the Time-Sert website and view their short video clip on installation. Same size tap as Helicoil, but much better and more durable product, for $2 or $3 extra per hole.

 

If I had this to do over, I'd do it myself with the Time-Sert kit, which includes drill bit, tap, counter-sink, and a few inserts. Or, local machinists offered to lend their tools, in which case I'd have just needed one ~$5 M10X1.5X 25mm insert. Every single one of these machinists recommended Time-Sert over Helicoil. Check into it.

 

Great information

[Anton Largiader]

...there are 3 bolts attaching the rocker bearing cap to the valve gear carrier. these 3 bolts are m8's and should be torqued to 18 nm. these are the bolts which have the torx t45 head on them.

 

Now, if you flip the valve gear assembly you could also remove the camshaft bearing cap which is also held by m8 bolts. the torque for the bolts holding this cap is 15nm.

The R1100 manual shows 15 Nm for both, whereas the R1150 manual shows 18 for the rocker shaft bearing cap. I don't think you're going to go too wrong with either number.

[Armando]

I figured the difference in torque values is not enough to really matter.

 

I am surprised to see that you just joined the board. Your method for doing the valve adjustment had been discussed around here quite a bit.

 

a

 

...there are 3 bolts attaching the rocker bearing cap to the valve gear carrier. these 3 bolts are m8's and should be torqued to 18 nm. these are the bolts which have the torx t45 head on them.

 

Now, if you flip the valve gear assembly you could also remove the camshaft bearing cap which is also held by m8 bolts. the torque for the bolts holding this cap is 15nm.

The R1100 manual shows 15 Nm for both, whereas the R1150 manual shows 18 for the rocker shaft bearing cap. I don't think you're going to go too wrong with either number.