Cr250 02 Rear linkage bolt info

[Agent_CR250]

Hello
I just regreased the rear linkage on my CR250 02. Seems I have stripped the bolts/rods on all three. Not sure how this happened. Can anyone out there help explain what my have happened. I was torquing down the bolts to 60 ftpnds when this happend. I did not grease the bolts but some form the greasing did get on the bolts and rods. When the bolts stripped I was only showing 55 ftpnds on the torgue wrench.


Any sugestions for not doing this again? Where can I get the parts to fix this? Thanks Agent_cr250

 

[James]

Clean your threads with brake cleaner THOROUGHLY before torquing those bolts. No grease should be on those or they will strip every time. The newer spec is 45 ftlbs on the 04 CRF450s !!I THINK!! (check the manual) and that may be the better torque to use...that is what I am using from now on.

 

[Rcannon]

I think sometimes these bolts get really corroded. Taking them apart for the first time, it tears up the threads. When you put them together again, they get ruined.

I had two bolts on the head stay on my YZ do the same thing. They were ruined before I was anywhere near the required torque level.

 

[Agent_CR250]

Humm, yeap this was the first time I had done my rear linkage. I have heard and read different things about putting grease on the bolt threads now. Should I grease the link rod and just not the the threads?

 

[James]

I don't put grease anywhere but on the bearings themselves. I am not saying this is the only way or THE correct way to do it, but it works best for me.

 

[Agent_CR250]

It strange how this kind of stuff always seems to happen at the end of gettting things back togther!! I did the front head set with no issues SO far!!

 

[James]

I was getting ready to ride Sunday and was doing my last minute checks and found that my linkage-frame bolt (the one with the lower chain roller on it) was stripped. Threads were clean and I was careful (or so I thought) when torquing it. So I rode street bikes instead.

It happens :thumb:

 

[bedell99]

I always grease the bolts but clean the threads when reassembling. I don't torque the bolts down with a torque wrench, but 60 lbs seems like a lot.

 

[James]

59 is the spec but I don't think that much is necessary. The only one I have ever had a problem with is the frame to dogbone bolt on the 02 (ruined two of those). The rest of the 02 linkage nuts and all of them on the 00/01 torque to 59 no problem.

The ones that really kill me are the 93 ftlb rear axle and the 100 ftlb steering head nut. I have backed off on those a bit.

 

[Rcannon]

James, I dont thing it is reasonable to blame the grease. The fasteners need to be lubricated to give a decent reading.

Have you ever tried to torque the rusty bolts on a car or trucks steering linkage? It is a joke. Many times the wrench will "click" and a person can see that the bolt is nowhere near where it needs to be.

I think most of the factories use very lousy hardware. The hardware is so soft it will stretch.

I will try and explain how most of my ruined hardware happened.

I broke a bolt on the frame to head mount on my YZ 250. I went to the shop and bought two new bolts, grade 10.9, to replace my broken ones. I was only going to replace one, but the guy at the shop gave me two.

To my surprise, the second bolt was shaped like an hourglass. It had been overtorqued, obviously. BUT, it was still strong enough to make my wrench "click" at 20 lb/ft. When I increased the torque to 25, it finally stretched so much it broke.

I wonder if sometimes we overtighten bolts and end up making them very weak?

 

[James]

Just to be clear, I am not talking about tightening rusty bolts.

Unfortunately, the torque wrench is measuring rotational friction not clamping force. On many of these fasteners, the flange on the bolt or the nut making contact with the surface has as much or more to do with the proper torque than the threads. Unless otherwise specified, the specs in the Honda manual are for a clean/dry bolt.
59 ftlbs is a lot of torque to put on those bolts as is, and then to try and tighten them to 59 with grease will snap them every time. I think you end up applying nearing double the clamping force on that bolt if you torque it greased.

I wonder if sometimes we overtighten bolts and end up making them very weak?

I agree with that completely. By adding grease, we are guaranteeing that we will over tighten them...unless you adjust the torque spec accordingly for the lubricant.

 

[Rcannon]

I wonder if they are going to consider using two different torque values. Lubed vs unlubed?

 

[Rcannon]

I found this article. I have no idea who wrote it, but the information sounds reasonable...

http://www.engineeredracingproducts.com/art/art1.htm

 

[Agent_CR250]

Man this is alot of info. I do belive that the grease was most of the problem along with the fact that the bolts were just overstressed from never being changed in the year and a half that I have had the bike. Anyone know a place that has the peices in stock. i cant seem to find them!! Agent_CR250

 

[James]

I wonder if they are going to consider using two different torque values. Lubed vs unlubed?

There are some very detailed "conversion" charts available that give a factor for adjusting the torque value for different lubricants. One weird thing to make note of is that thread locking compounds (locktite) can act as a lubricant during that initial torquing of the nut. Obviously it changes again once it is dry. I can't remember the adjustment factor for locktite as I have quit using that too.

I am pretty sure Honda specifies which to lube/locktite/replace and probably won't give you a lubed spec because they don't recommend it (that is my take on it...not gospel).

I pulled this out of the article you provided Rcannon; that was a good read:

In most cases, following the manufacturer’s torque guidelines with a high-quality torque wrench will be sufficient. Just be aware that changing the fastener coating or lubrication may drastically change the ideal torque value.

 

[James]

Anyone know a place that has the peices in stock. i cant seem to find them!! Agent_CR250

I will be ordering mine from ServiceHonda.com. They are one of the DRN sponsors.

I do belive that the grease was most of the problem along with the fact that the bolts were just overstressed from never being changed in the year and a half that I have had the bike.

I would bet it was only the grease. I have tightened and untightened the linkage bolts in my 2000 a hundred times or more on top of riding the bike solid for the last 2.5 years. That on top of my 240lb carcass should stress anything that is likely to be stressed. If you don't overtighten them, they should last a long time.

 

[Agent_CR250]

They dont have them in stock I tried them today!!

 

[James]

Since you don't know where you are at, I don't either :think: ....but I doubt you find these "in stock" anywhere. Service Honda sends it to my door about as quick as the dealer gets it, but then I still have to drive over to pick it up at the dealer.

You'll have to call every dealer in your area to find out for sure.

 

[Agent_CR250]

Luckily I founf them in stock at a dearleer here in CO. I was quite surprised!! Altough the Nuts were $5.30 and the bolts were $7.00. I installed the bad boys tonight and my girl is runnin good again!! Thansk for all your help!
Agent_CR250

 

[silveco]

Make sure the bolts are fully cleaned.
Inspect for burred/galled threads.
Repair damaged threads with a die nut or replace.
ALWAYS use lubricant on the threads. Preferrably a Nickel Anti-Seize compond such as Loctite 771, at least use a good Moly grease. Nickel anti-seize is preferred due to its anti-corrosive properties. Make sure to apply a thin smear to the mating surface of the nut. This will ensure correct torque is applied. If you are concerned about any bolts/nuts shaking loose, I recommend using Loctite 222. It can be easily undone with regular hand tools, offers thread lubrication on assembly and stops your bike from falling to bits. It will also help preserve those delicate threads in aluminium.

 

[James]

ALWAYS use lubricant on the threads. It will also help preserve those delicate threads in aluminium.

Didn't you read the rest of the thread where it says NOT to lube those bolts? What aluminum are you talking about? Are you adjusting the torque spec because there is no way you are tightening those bolts to 59lbs with moly grease on the mating surface of the nut.

 

[silveco]

The aluminium I was referring to was just in case people reading this might take my advice on using Loctite 222 on other areas of their bike. eg. Engine components, Triple clamp pinch bolts, perch bolts etc.
Also, years in the engineering game has taught me that the greatest cause of stripped/galled or seized threads is due to lack of lubrication on assembly.
Of course you are correct, I do not torque to original specifications when using a lubricant. I didn't feel it was necessary to repeat your point about the torque values varying due to thread lubrication. Point well made.
The torque wrench is one of the handiest tools to have in your toolbox. Unfortunately, this method is not very accurate, because as much as 85% of the applied torque is used to overcome friction. This friction is a function of lubricant, surface finish, plating type and a host of other variables, and is not consistent.
Lubrication of the fastener will reduce the frictioal loads and make the torqing process far more consistent by removing/reducing one of the variables.
The big question is, with 30-85% of radial torque preload being inefficiently used to overcome friction of the thread/mating surface, what is the actual axial preload? How do we know for sure with such a variance in friction?
This is why manufacturers give us torque guidelines. They are just that, Guidelines....not law ....not exacting. This is where an training, knowledge and experience come into play.
Honda won't use assembly lube on the assembly line simply because it's a bit messy. A brand new bike sitting on the showroom floor with a little grease weeping out around the fasteners wouldn't be a good selling point.
They won't specify to use lube either(They don't specify not to:) ). Think about it, when you strip/gall the fasteners on your bike you have to hand over more money to Honda for the replacement spares; and when your bike gets old and tired before its time, you have to hand over more money for a new one. It's win win for the manufacturer.

 

[James]

They won't specify to use lube either(They don't specify not to ).

They absolutely do tell you not to use lube on many nuts/bolts and they also tell you which kind of lube to use when it is required, in the service manual. I am not sure on the owners manual but I am guessing it is clarified there as well.

All conspiracy theories aside, they give you the correct torque for a DRY fastener in most cases. Takes all the guess work out of trying to adjust/compensate the torque for whichever lubricant you are using. By adding lube, you are not making it more consistent, you are adding variables. DRY is DRY and as long as the fastener is clean, undamaged, and not rusty, it will be very consistent.

Yes, you are correct, that the applied torque is used to overcome friction, and the recommended specs are based on that friction to give us the proper clamping force. I don't care what the actual axial torque is and I doubt you can tell me what that figure is even with lubed threads. They figure all of that out for us. Keep in mind, that friction is also used to keep the nut in place and that is why many of them have flanges.

The 1st time I stripped one is when I lubed it based on somebody else's incorrect advice and the second time is when I didn't see grease on the mating surface. It is amazing how they never strip when I assemble as instructed. My experience also tells me that you can lube a bolt without it weeping all over the floor and I doubt that has anything to do with why they aren't lubed from the factory. I think the win for the manufacturer is when they can sell spares to replace the ones messed up as a result of bad info.

To each their own.