Texas Two Step Taco

Texasstar

Can't is a four letter dirty word
There's very little side thrust on the bearing - the clutch is designed so that all of the spring force is self-contained within the hub, unlike the chain drive Bul clutch and most others. So it really won't take much to retain the bearing at all, a thrust washer behind the basket as Teazer suggested or a sheetmetal retainer ring over the top of the bearing would do it. If you really wanted to get quick-and-dirty (my favorite kind) you could just put a thin ring over the outer race and tack weld it down in 3 or 4 places. You'd have to grind the tacks off to change the bearing - not a big deal - but they last forever anyway.

Incidentally, and as someone who has battled primary drive issues for many years with big Buls, these sorts of problems commonly surface when the rotating mass is reduced and the rpm range raised, they're rarely a problem at all with the stock heavy flywheels. It's not the torque that causes the problems, it's the hammering from the intermittent impulses. So while a lighter rotating assembly certainly has its advantages it does make life difficult for everything downstream of the crank, even with the spring-and-cam drive pinion. Things get hammered and rattle loose.
Now your are talkin’ down under QUICK and dirty cheap! Since we have a couple of primary drives around here why don’t we give that the old Texas try!


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Texasstar

Can't is a four letter dirty word
That's dowright filthy ;) I think I'd prefer a separate ring tacked in four places. It'd be more dependable.
Agreed this will get us to the dyno for the time being. The ring will require a greater relief/recess in the back of the clutch plate housing.

On another note I think you will be surprised on how little throttle it takes to get it 8k.


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Texasstar

Can't is a four letter dirty word
We need a thrust washer 45-50mm od 30mm id and 2.55 mm thick
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John Murray

Member
Not sure that I'd want any thrust against that thin aluminum face. I'd be more comfortable holding the bearing from the other side. Should be a simple machining job.
 

Texasstar

Can't is a four letter dirty word
Not sure that I'd want any thrust against that thin aluminum face. I'd be more comfortable holding the bearing from the other side. Should be a simple machining job.
Maybe we do both. Redundancy. If we can keep the basket off the shifter selector gear we can finish the race. BTW I think you are right about the pulse and the harmonic resonance moving the basket.

Ralf said that a steel washer was ok, but a steel washer and a brass washer would be better, and then what Teazer suggested an axial needle bearing (if there is room) would be the best. Then there is Texas down and dirty.


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John Murray

Member
Maybe we do both. Redundancy. If we can keep the basket off the shifter selector gear we can finish the race. BTW I think you are right about the pulse and the harmonic resonance moving the basket.

Ralf said that a steel washer was ok, but a steel washer and a brass washer would be better, and then what Teazer suggested an axial needle bearing (if there is room) would be the best. Then there is Texas down and dirty.


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John Murray

Member
I don't agree with that. The thrust washers aren't the problem, it's the thin cast Spanish alloy that they might be working against, and those cases are pretty rare. If it was me I'd be machining the clutch to take a retaining plate and not sticking anything behind it. This is something you'll just have to spend a little time on.
 

Texasstar

Can't is a four letter dirty word
I don't agree with that. The thrust washers aren't the problem, it's the thin cast Spanish alloy that they might be working against, and those cases are pretty rare. If it was me I'd be machining the clutch to take a retaining plate and not sticking anything behind it. This is something you'll just have to spend a little time on.
I am betting you have had an experience with that case


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Texasstar

Can't is a four letter dirty word
This is 26 lbs with the dirt tire. My buddy Juan Verde gave me the wheel and tire off of his HONDa xr650l’s. That was my first motorcycle BTW. That is light!
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Texasstar

Can't is a four letter dirty word
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Got the Sava MC7 mounted and it weighs 24 lbs and the current slick and bultaco hub weighs 33 lbs.


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Texasstar

Can't is a four letter dirty word
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Have this coming tomorrow.

We can Split the collar in half add washer in between them turn them down .5mm ea for the 1 mm washer and then
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use this thrust bearing. The needle bearing is 2mm and each washer is 1mm. Overall thickness is 4mm. There are two in the kit so we have plenty to play with. Everything would be on the shaft.


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Texasstar

Can't is a four letter dirty word
Ok we now have 9 lbs off the rear rotational mass. Had to add a brake stay mount to the swing arm coped to the cross support.
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Still haven’t decided where I want my pegs I don’t like them in their current location.


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teazer

Well-Known Member
DTT BOTM WINNER
9 pounds is a lot to get rid of in one go. And that arrangement for the thrust washer looks good.
 

John Murray

Member
The thrust washer is a bad idea. What's going to happen is the forces on the gear are going to make the basket creep back very slightly on the main bearing, just enough to load up the thrust bearing. This position is where the basket will stay, and both the main bearing and the thrust bearing will remain permanently loaded. If you're lucky the Torrington will survive and won't scatter a hundred hard little rollers throughout the primary drive.

Putting a retainer over the original bearing adds no more moving parts and doesn't add a permanent axial preload to a bearing that isn't meant to take one. You're overcomplicating things and adding complexity where it isn't required.
 

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