Cush drive Bolts?

[trojan]

Eeewwwww.... ok that one back fired :P

I log on and see that this thread is at the top....cool....some more pics maybe? Some video? No, it's the same old jackass's thread jacking the thread with their crap.....

Yeah I know what you mean, I had to resort to browsing your build thread instead

[Fineline]

Would the cush drive help eliminate shearing off every single bolt holding the sprocket to the central drive hub? Im begining to think that the flat head bolts cant take the load. I sheared them all off this past weekend.

Doug you are probably four steps ahead of this all ready but I will try to help from what happened to me
The countersink in the sprocket is a different angle to the flat head bolts
So when they are tight the contact patch is not even one third of the bolt head area no matter how tight you do them up.
Probably why you snapped them off and ours actually come loose coz you make your own exact
Making a bigger hub with bigger and more bolts to bolt the sprocket to I think will be the solution

That being said, I acknowledge the problem Doug is suffering with.  It happened on the first day we took Ray's buggy out.  You know what the solution appears to be? 
Are you sitting down?
They are welding the sprocket to the hub.
I kid you not.

Yep might not be the whiz bang engineering solution that every ones hoping to hear but I assure you that it works
Every barracuda that I know of has had the same problem with the sprocket coming loose
Edge put roll pins through the head of the bolt into the sprocket now to stop it but I have my doubts as to that solving the problem either

[Doug Heim]

Welding... Thas a BS way to fix it. Roll pins? Im aware of this method and how the hell do you get them out. Thats BS too as it still dont fix it, my bolts did not come loose. Fix it the right way! Sounds like a bad design to me. Ill be changing it and already have requests to supply upgrades. That will be soon to come. I also fixed the racks by making complete new ones with a totally different design. Itd a direct REPLACMENT of the XRV Rack. NOT a copy!

[Doug Heim]

OK I just learned somthing. I take back the possibilty of my bolts being loose. It is very possible without even knowing. I still need to tear the cartridge down to inspect it.

What I just learned is that metric flat head hardware is 90* and NOT 82*. This can make a huge difference in the way the bolt heads seat in the countersink. I am ordering a 90* countersink 1" diameter today. To go the extra step I am also going to fixture the bolts in the lathe and re establish that the 90* is a perfect machined finish surface.

Not knowing the difference in the degrees, I countersunk the sprockets at 82*, I think this will fix it.

I also made a few drive hubs withe the orientation offset to get a nut on the backside. Booyah! 

All in all it took over a year to fail and alot of hard riding.

[fabr]

I think you're going to find that the countersunk area is not very concentric with the threads. If it were me I'd redesign if possible and avoid their use. My first drive used the CS bolts and even though they never loosened it was impossible to torque to proper value. I was using 7/16" torx drive CS flat head cap screws.

[Doug Heim]

I think you're going to find that the countersunk area is not very concentric with the threads. If it were me I'd redesign if possible and avoid their use. My first drive used the CS bolts and even though they never loosened it was impossible to torque to proper value. I was using 7/16" torx drive CS flat head cap screws.

The re machining of the backside of the heads will make it concentric with the thread. I do agree maybe redesign it, but Im also trying to help others with the info I have and fix it rather simplified for those without resources. Im going to try it for my own education.

[Rick S.]

OMG, You're just realizing that a metric flathead is 90 degree.
I thought every machinist knew this sort of thing.
How many have you made at 82?

[Wyattboche]

OK I just learned somthing. I take back the possibilty of my bolts being loose. It is very possible without even knowing. I still need to tear the cartridge down to inspect it.

What I just learned is that metric flat head hardware is 90* and NOT 82*. This can make a huge difference in the way the bolt heads seat in the countersink. I am ordering a 90* countersink 1" diameter today. To go the extra step I am also going to fixture the bolts in the lathe and re establish that the 90* is a perfect machined finish surface.

Not knowing the difference in the degrees, I countersunk the sprockets at 82*, I think this will fix it.

I also made a few drive hubs withe the orientation offset to get a nut on the backside. Booyah! 

All in all it took over a year to fail and alot of hard riding.

Thats why your the cuda master, not GOD. lol

[fabr]

The re machining of the backside of the heads will make it concentric with the thread. I do agree maybe redesign it, but Im also trying to help others with the info I have and fix it rather simplified for those without resources. Im going to try it for my own education.

Actually my concern is more that if remachined there MAY? be an issue with the heat treat and the depth being eneven? I don't know other than that a bolt is not just a piece of metal. Grain flow and such . I mean bolts have rolled threads for that reason and I'm a bit concerned with the area where the CS meets the threaded portion. Maybe I'm just a worry wart too tho.

[Boostinjdm]

Since this thread has been sidetracked....suppose somebody could post up a pic of the sprocket/hub set up that is shearing bolts so at least the rest of us know what you are talking about?

[Doug Heim]

OMG, You're just realizing that a metric flathead is 90 degree.
I thought every machinist knew this sort of thing.
How many have you made at 82?

Yes Rick, Not everyone knows everything like you do!

[Doug Heim]

How many have you made at 82?

I have made 5 at 82* 2 for me and 3 for others, The parties (except one but will be) have already been contacted and offered replacment sprockets with shipping covered by me.

[fabr]

There you go.Honest mistake being taken care of properly. Good to hear.

[Doug Heim]

That's how I roll!  Lance W will be getting a new sprocket and so will Troy and John (you guys know who you are)

Master on your concerns I do believe that with the tooling at my disposal I am fortunate enough to be able to cut these properly. I actually do this to flat heads for my fastener supplier as a side job. They send me 1000s of SS Flat head bolts to have the taper machined down. Not for the eccentric reason, but instead to sharpen the diameter edge for one of there food company hardware customers. I'm actually doing that job now so Ill take some pics on how I do it.

If you want to move this due to being off topic feel free. Ill post a video of my failed cartridge. The real issue to keep in mind here is this... It took over a year for it to fail, It was an easy fix at the dunes (having the extra parts), only parts to be scrapped are the bolts, and now it is being addressed. Most of all I can admit when I don't know something or when I'm wrong and like to share the info to educate others. As a machinist I work off of prints more than anything. All prints have always called out the countersink type (degree), depth, size, etc.  The Plans do not call out the degrees so not knowing that metric was different, I did what I knew to be common in my industry. Just like Jet pointed out that I needed to use grade 12.8 or whatever. In Imperial the 12.8 is Grade 8's equivalent. Have you ever seen how thick a machinist hand book is. The machinist hand books still do not contain everything either as we just needed to purchase some other info on DIN undercuts for relieving corners on shafts in the paper industry. No one can possibly have an entire machinist hand book memorised.

[trojan]

Have you ever seen how thick a machinist hand book is. The machinist hand books still do not contain everything either as we just needed to purchase some other info on DIN undercuts for relieving corners on shafts in the paper industry. No one can possibly have an entire machinist hand book memorised.

maybe that the difference between a good one and one that just insists he's good?