Top yoke threads help

[MJM_58SR]

I've posted in the wanted section for an A10 top yoke but I also wonderef if I could get a bit of advice.
The one I have had bolts that were partl stripped / ill fitting etc. I've got some new ones from draganfly and have screwed them into the yoke but they are very stiff going and I'm a bit nervous that the piece will break out.
The new bolt comes out clean with no thread damage. I've looked inside and cleaned out what I can of the old metal shavings and it seems clean but does anyone have any ideas
I'm thinking a bottom tap or something to clean the thread but not sure.
Any help appreciated
Thanks

[chaz]

Are these the handlebar clamp bolts ? Not much meat either side to helicoil.

[MJM_58SR]

Hi Chaz
Yes they are. I was thinking of cleaning the threads if I can.
If I can't then I will get a replacement as I want it safe

[Bess]

Hi,
    I would send a tap down to clean the threads. They are usually salvageable as the bolts are rarely removed during the lifetime of the bike, I always find corrosion as previous owners haven't used a smear of grease during assembly.

Best wishes..

[MJM_58SR]

So
I've cleaned out the threads a bit (I don't have a tap to do it yet) and it seems to be looking promising.
The bolts I have are from Draganfly and are polished stainless, the are 1 1/2 inch from under head.
The bolts don't scree in deep enough on the yoke to hold the handlebar clamps. I know there are washers and spacers that need to go on.
I'm pretty sure that the front bolts are shorter than the rear bolts.
Maybe I have all rear bolts and with the clamps, spacers, washers and damper plate they will secure on properly at the rear but I need shorter for the front?
Any ideas? Does anyone have any measurements that I can work to please?
Thanks

[JulianS]

Mine are 1 1/8 inch under head. Any longer and the lower ones would stick out through the yoke.

[DAVE BRADY]

Once you have run a tap down the threads the bolts will probably tighten up.  Buy a good quality tap as you would not want a cheap one to snap off and you will find lots of other threads the same that need cleaning up. 

Dave.

[MJM_58SR]

Hi Dave
The threads on the yoke seem to be ok, I've run a normal bolt through them and they run free. The ones I was sent are stainless so I think that's an issue.
I intend to get a selection of taps so I have them for future.
The things that's done interesting me at the minute is to establish if the bolts are different lengths front and back and if so what length are they.
Julian has given me a measurement but the ones I have are quite a bit longer.
They were sent from Draganfly so I thought they should be ok.
Martyn

[chaz]

Martyn, I have found that a lot of today's fasteners are near or thereabouts!!, hex heads in metric , stainless over chrome plated steel for cost, stainless does not give like mild steel and can be prone to shear forces. I did 3 square 4 rebuilds was supplied with metric hex engine shock absorber nuts, the metric socket would not fit in the cup washer so you are tightening to 60lb/ft on half the length. Also, instead of sticking all the lengths to the nearest 1/16th they are pl
Probably one size fits a couple 4 or 5 mm longer, drags say one of the footrest studs they stock they send the longer one and you have to cut down. As Dave says, decent taps needed, Chinese cheese dodgy, I got mine from work, you need to try classic auto jumbles or machinery sales. Check out a few brand names like Dormer or Armstrong.

[DAVE BRADY]

Morning,

I have just been out to the shed and I have a set of s/s clamp bolts.  They are all 1 1/4" long and never been used.  If I remember correctly I did not use them because of the tight thread so used chrome ones instead.
I believe that they are all the same length as standard and as Julian says 1 1/8".
On the A65 the thread is specified as BSC is the A10 the same?

Dave.

Just had a thought!  Rather than make the thread in the yolk fit the bolt, get a die and run it down the thread on the bolts thus modifying the replaceable part. 

[MJM_58SR]

Hi Dave
I think we are about there now!
After a bit of cleaning out I tried a normal bolt in the holes and they go in nice and smooth, the stainless ones don't.
So
I think I get some chrome ones.
Julian sent me the spec of the two sizes of bolts over so between all the answers I've got some good info to go on.
Thanks to all who have contributed.
Martyn

[idie]

I think the yoke bolts are 5/16 cycle 26tpi. Why waste the bolts you have. Buy a die and run down the threads to bring them to size.  You don't need to buy an expensive hss one as the carbon steel ones are good enough for the occasional use we put them to.

[chaz]

as an addition to my previous, Stainless tends to be a drier thread and also a harder material which does cause slightly larger threads that dont give as well as stainless, also with regards to the plating operation, plated bolts are threaded to a "pre-plate" size. the British standards give an idea for pp against up sizes. say 0.0007" a side that is 0.0014" on diameter. An allowance is made for both flanks of the thread has plating on. therefore the thread on a bolt is smaller to allow the plaing build up...over time the plating wears or peels off  thus making the bolt feel loose...
sorry, I was an inspector in a machine shop setting plug and caliper gauges for screwcutting on lathes and cnc mills. BS84 if I remember!

[MJM_58SR]

Hi Chaz
That's explains it nicely! So throw the stainless away then...

[idie]

Throw the stainless in my direction please. I will run a die down them.