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Torquing Bolts Problem - Subframe


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7 replies to this topic
  • Snow Drift

    TT Member

81 posts
Location: United Kingdom

Posted September 24, 2016 - 06:16 AM


Although this is a bit of a general question, because it is on my 2007 WR450 I thought it would still be better to ask it here. I have just put my sub frame back on the bike and looked at the manual to see the torque specifications for the bolts.

 

It appears the top bolt is 38 NM and the two lower ones are 32NM. I tightened the one on  the left fine but the right side by the exhaust just seems to keep going and I get to the point where I am extremely concerned the bolt/hole is going to shear.

 

I have occasionally come across this issue and I don't know why it happens. The torque wrench isn't that old, it isn't premium brand but I don't think it is way off, also considering the other side tightens fine with it. I wondered if it is the fit of the subrame to the main frame, maybe at a slight angle which means the two faces aren't flat and it flexes as it tightens.

 

In the end I have now just tightened without a torque wrench as I will probably be removing it again soon anyway to get to the carb. However, what is the general advice going forward on this issue. I would be really upset if I sheared a hole on the frame.

 

thanks



  • Snow Drift

    TT Member

81 posts
Location: United Kingdom

Posted September 24, 2016 - 06:32 AM


The only other thing I would add is that I put a bit of copper slip grease on bolts to aid removal next time and so that they don't shear when I try and take them out again. Is this wrong?



  • Krannie McKranface
36,174 posts
Location: California
Garage View Garage

Posted September 24, 2016 - 07:00 AM


I never use a torque wrench for anything but motor fasteners (into castings) or motor mounts, and triple clamp bolts (very critical to prevent binding of the tubes).

Everything else is done by feel.

Many will dissagree with me...

 

The specs are only for new bolts, un-lubed, removed only once....so you have to take all of that into consideration.....

If you tighten a typical grade 3 bolt to 35ftlbs a couple times, it will have stretched, and now bind when tightening...giving you a false torque reading.

 

If  wrench you are using for this does not have a primary adjustment that deliniates down to 5lbs or less, then you are using the wrong kind of wrench for anything under 35 lbs of torque...(or equiv)

 

A low range torque wrench is in order....

 

https://www.amazon.c..._cs_sce_3p_dp_1



  • GuyGraham

    TT Platinum Member

1,673 posts
Location: England

Posted September 24, 2016 - 09:02 AM


The thread in frame might be knackered and about to strip.
It can be recovered with a helicoil or timesert thread repair if it is
Try a different bolt to see if it will torque up. The slightly twisted faces arent the issue

The copper grease is good practice for aluminium threads

Edited by GuyGraham, September 24, 2016 - 09:06 AM.


  • Snow Drift

    TT Member

81 posts
Location: United Kingdom

Posted September 24, 2016 - 09:18 AM


Thanks for the replies it is just nice to get some feedback as a lot of the time I feel in the dark on things like this. It is good to know that I'm doing the right thing with the copper slip grease.

 

I have a good torque wrench that I like made by Britool which is for 5-35NM and I sent it away to be calibrated in 2014 by a specialist calibration company. The other wrench is a cheaper one for 32NM upwards. I was using this cheaper bigger one because the smaller one is on the limit at 32NM and wouldn't do the 38NM bolt anyway.  

 

I guess I just get upset and frustrated when your trying to learn yourself how to strip and rebuild, you put so much effort into things and follow the manual etc and then things like this happen. I loosened and tightened the bolt a few times trying to get it to torque and then finally did it by feel without the wrench, it doesn't feel stripped but I don't know if it is about to be. I hope not. It is now relatively tight and it did torque at lower settings.

 

I think from now on I am going to do what you say Krannie. I am only going to use a torque wrench when it is a critical engine component etc because I just can't stand damaging my bike in an area that can't be easily replaced. The only reason I like to use a torque wrench is so that I don't have to think if something is going to vibrate loose. I lost one of the seat bolts as it came loose when riding and it made me worry about others on the bike.


Edited by Snow Drift, September 24, 2016 - 09:20 AM.


  • GuyGraham

    TT Platinum Member

1,673 posts
Location: England

Posted September 24, 2016 - 10:01 AM


If i remember correctly the oe subframe bolts are a bit short and i put longer ones in to get more thread engagment
I also seem to remember that there is enough room to use an even longer bolt and put a nut on it if the thread does strip

  • Pinepig

    TT Member

73 posts
Location: California

Posted September 24, 2016 - 04:26 PM


The only reason I like to use a torque wrench is so that I don't have to think if something is going to vibrate loose. I lost one of the seat bolts as it came loose when riding and it made me worry about others on the bike.

 

 

I put blue Loctite on damn near everything.,   I hate stuff vibrating loose.



  • falconjet

    TT Bronze Member

336 posts
Location: California

Posted September 27, 2016 - 07:00 AM


I never use a torque wrench for anything but motor fasteners (into castings) or motor mounts, and triple clamp bolts (very critical to prevent binding of the tubes).

Everything else is done by feel.

Many will dissagree with me...

 

The specs are only for new bolts, un-lubed, removed only once....so you have to take all of that into consideration.....

If you tighten a typical grade 3 bolt to 35ftlbs a couple times, it will have stretched, and now bind when tightening...giving you a false torque reading.

 

If  wrench you are using for this does not have a primary adjustment that deliniates down to 5lbs or less, then you are using the wrong kind of wrench for anything under 35 lbs of torque...(or equiv)

 

A low range torque wrench is in order....

 

https://www.amazon.c..._cs_sce_3p_dp_1

This is good info from a long time rider and wrencher.

 

I too rarely use an actual torque wrench. I mostly rely on the torque wrench in my elbow.

 

Friendly FYI to low time wrenchers. Better to err on the loose side than the tight side. Especially on the smaller bolts and even more so if they are threading into aluminum.






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