piranha-bro2
Hero member
- Location
- Melbourne
Corrected above!! Getting xed between tyres and chains!!
Building my Jota
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motoddrob
Hero member
- Location
- S/W Australia
I'm referencing clearance on a 530 chain. Doesn't matter whether it's a 17" or 18", the c/l of the rim to the chain remains the same.
I have a new set of sprockets waiting in the shadows, hoping I can find someone to grind 1/8th" off the inside of the primary sprocket.
The rear is ally so I can deal with that on my mates lathe.
I have a new set of sprockets waiting in the shadows, hoping I can find someone to grind 1/8th" off the inside of the primary sprocket.
The rear is ally so I can deal with that on my mates lathe.
piranha-bro2
Hero member
- Location
- Melbourne
I'm going to do my own Rob, using my angle grinder attached to the tool post trick.
motoddrob
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- Location
- S/W Australia
I guess it could be softened, turned down and then rehardened.
chrisk
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- Location
- Brisbane, Australia
Is what Piet suggested in another thread on the same topic.
Dellortoman
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- Location
- Tasmania, Australia
If you go with the cross-over type of design like in PB2's photo, you might be able to crib an extra couple of mm by using flat bar rather than round. You may have to get inventive with the rose-jointed ends on flat bar though.
I had a parallel linkage like Hooksey's on the Kawasaki Z1 that I use to race back in the day. I hated it. The rear wheel would chatter and hop all over the track under brakes. My preference would be an anchor point on the swing arm. It's easier because you don't have to make the caliper plate floating.
I had a parallel linkage like Hooksey's on the Kawasaki Z1 that I use to race back in the day. I hated it. The rear wheel would chatter and hop all over the track under brakes. My preference would be an anchor point on the swing arm. It's easier because you don't have to make the caliper plate floating.
hooksey
Hero member
- Location
- Vic , Australia
Chain clearance is the issue.....
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motoddrob
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- Location
- S/W Australia
Told ya so CK
Hey Hooksey, what are the dark fixings at the spoked areas on your Astralite?
Hey Hooksey, what are the dark fixings at the spoked areas on your Astralite?
hooksey
Hero member
- Location
- Vic , Australia
Yep, just a mock up shot Q. Ended up going inside the mega and onto swinger..... a la stock 750 rear drum torque arm location.
hooksey
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- Location
- Vic , Australia
M8 Bolts..... on rear only.Told ya so CK
Hey Hooksey, what are the dark fixings at the spoked areas on your Astralite?
motoddrob
Hero member
- Location
- S/W Australia
Did the rivets let go?? which happened on the Motodd rear. I fixed it by having some female bolts especially made from 316 stainless that I still had to modify on a lathe to reduce the outside dia. The other side I made some ally washers of a similar size to simulate the f/m bolt heads and used a m6 cap screw and locktite them together. Lasted for years without problems and also peace of mind. Since upgraded to gixxa rims on the total rebuild.
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motoddrob
Hero member
- Location
- S/W Australia
I would seriously think about replacing all the rivets considering their age. I know of a couple of these rims that have popped the rivets.
hooksey
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- Location
- Vic , Australia
Certainly a nice solution there Rob
These wheels came from UK with bolts installed..........fair chance they have seen some salty roads..............!
motoddrob
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- Location
- S/W Australia
Once I sourced a supplier that could make the bolts it was an easy fix. I'd consider doing the same just for peace of mind.
If any rivets popped it would deflate instantly. After bolting back together I resealed the joint with silicone along the inside join
If any rivets popped it would deflate instantly. After bolting back together I resealed the joint with silicone along the inside join
chrisk
Hero member
- Location
- Brisbane, Australia
Told ya so CK
Oops, I forgot that my wheelwright offset my hubCanny do that with Astralites
Dellortoman
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- Location
- Tasmania, Australia
Astralite wheels are interesting. They weren't a bad wheel when they started making them back in the late 70's. They were arguably lighter and stronger than the cast wheels that were available at that time. The following is a bit of "off the cuff" engineering advice if you have Astralites.
They made the wheels that way so they could press the shapes out of plate rather than cast the wheel (solid aluminium plate was stronger than cast aluminium), but relying on rivets to hold the two halves together was something of a compromise.
Those Astralite wheels are now getting pretty old. The manufacturer probably never expected them to still be in use 40+ years later. Rivet failure is starting to become an issue (there's a lot of discussion on the Hesketh forum as they were original fitment to those bikes). The most common failure mode is fatigue cracking. The rivets simply break without warning and ping off into the distance. Or if you're lucky, they'll fall on your garage floor where you can see them before you get on the bike.
The rivets are under a lot of tensile load because of the tyre pressure. So use heaps of soap or rubber lube when fitting tyres because you don't wanna be over-inflating them to high pressures to seat the bead. If you do have trouble getting a bead to pop onto its seat and want to use anything north of about 40psi, use an air hose fitting that will stay on the tyre valve without you needing to hold it there with your hand, lay the wheel flat on the ground and stand well away from it - preferable behind a large tree! There's a massive amount of stored energy in an inflated tyre. People have been killed by exploding rims.
The original rivets were aluminium, 7.5mm dia. If you're going to replace them with bolts, you'll need to drill the holes out to 8mm. A grade 4.6 M8 steel bolt will have roughly the same tensile strength as the original 7.5mm aluminium rivet (because the thread only has a root diameter of about 6.5mm). But you may as well choose Grade 8.8 as the cost difference is bugger all and they're about twice the strength of 4.6. You can also do them up tighter so you'll end up with a stronger wheel.
As for what nuts to choose, you need to consider how to stop them coming loose. Nylocs might be OK, but they're not infallible so you'd wanna keep an eye on them. I'd go for normal hex nuts, cut the bolts off close to the nut then peen the bolt end over to stop the nut unscrewing. It'll look neater than nyloc and will be a more bullet-proof locking method. It's not as if you'll ever have to undo them again. Even if you do need to disassemble the wheel again (say for powder coating) just grind the threads back so you can undo the nuts, and replace with new bolts and nuts when you reassemble.
By "female bolt" I assume Rob is referring to barrel nuts. His were custom made, but they're available "off the shelf".
The problem with barrel nuts from an engineering standpoint is that they're generally used where a neat appearance rather than strength is the main requirement, so they're normally un-graded 304 stainless steel, so probably similar to a Grade 4.6 - 4.8 bolt, but you can never be sure there are some variables in the manufacturing and hardening processes that can affect the ultimate strength. I guess the choice you need to make is: Do I want a neat looking wheel or a strong one?
If appearance is important to you, I reckon you'd be OK with M8 barrel nuts, but an M8 barrel nut has a body diameter of about 9.5mm, so you'll need a bigger hole. The head diameter is 16mm.
An M6 barrel nut will fit an 8mm hole and has a head diameter of 14mm, so will probably look closer to the original appearance of the wheel, but the smaller M6 thread means a weaker fastening. I'd be reluctant to give an engineering opinion on the suitability of M6 barrel nuts for this purpose. My guess is that they may not be as strong as the original rivets.
Another thing to think about with barrel nuts is that you're pretty much restricted to thread locking compound to prevent them coming loose. You may need to go around with a pair of allen keys occasionally to make sure they're still all tight.
A final thing to think about when replacing Astralite rivets is the potential for corrosion. Unless you actually replace with new aluminium rivets, you'll have dissimilar metals. The aluminium will be sacrificial, so you could get some corrosion of the aluminium around the bolt holes. The best way to protect the wheels is to make sure you have a good paint or powder coat layer on the wheels before you bolt them up, and use a marine anti-corrosive compound on the bolts (eg. Duralac, available from boat chandlery stores).
Casting techniques must have improved since Astralites hit the market. Modern bikes have spindly little cast spokes that look about as substantial as a spider's web, but they evidently do the job.
They made the wheels that way so they could press the shapes out of plate rather than cast the wheel (solid aluminium plate was stronger than cast aluminium), but relying on rivets to hold the two halves together was something of a compromise.
Those Astralite wheels are now getting pretty old. The manufacturer probably never expected them to still be in use 40+ years later. Rivet failure is starting to become an issue (there's a lot of discussion on the Hesketh forum as they were original fitment to those bikes). The most common failure mode is fatigue cracking. The rivets simply break without warning and ping off into the distance. Or if you're lucky, they'll fall on your garage floor where you can see them before you get on the bike.
The rivets are under a lot of tensile load because of the tyre pressure. So use heaps of soap or rubber lube when fitting tyres because you don't wanna be over-inflating them to high pressures to seat the bead. If you do have trouble getting a bead to pop onto its seat and want to use anything north of about 40psi, use an air hose fitting that will stay on the tyre valve without you needing to hold it there with your hand, lay the wheel flat on the ground and stand well away from it - preferable behind a large tree! There's a massive amount of stored energy in an inflated tyre. People have been killed by exploding rims.
The original rivets were aluminium, 7.5mm dia. If you're going to replace them with bolts, you'll need to drill the holes out to 8mm. A grade 4.6 M8 steel bolt will have roughly the same tensile strength as the original 7.5mm aluminium rivet (because the thread only has a root diameter of about 6.5mm). But you may as well choose Grade 8.8 as the cost difference is bugger all and they're about twice the strength of 4.6. You can also do them up tighter so you'll end up with a stronger wheel.
As for what nuts to choose, you need to consider how to stop them coming loose. Nylocs might be OK, but they're not infallible so you'd wanna keep an eye on them. I'd go for normal hex nuts, cut the bolts off close to the nut then peen the bolt end over to stop the nut unscrewing. It'll look neater than nyloc and will be a more bullet-proof locking method. It's not as if you'll ever have to undo them again. Even if you do need to disassemble the wheel again (say for powder coating) just grind the threads back so you can undo the nuts, and replace with new bolts and nuts when you reassemble.
By "female bolt" I assume Rob is referring to barrel nuts. His were custom made, but they're available "off the shelf".
20X 304 Stainless Steel Allen Flat Nut Hex Nuts Bolt Round Head Sleeve Furniture | eBay
Material: 304 Stainless Steel. One set included 1 piece Nut and 1 piece Bolt.
www.ebay.com.au
The problem with barrel nuts from an engineering standpoint is that they're generally used where a neat appearance rather than strength is the main requirement, so they're normally un-graded 304 stainless steel, so probably similar to a Grade 4.6 - 4.8 bolt, but you can never be sure there are some variables in the manufacturing and hardening processes that can affect the ultimate strength. I guess the choice you need to make is: Do I want a neat looking wheel or a strong one?
If appearance is important to you, I reckon you'd be OK with M8 barrel nuts, but an M8 barrel nut has a body diameter of about 9.5mm, so you'll need a bigger hole. The head diameter is 16mm.
An M6 barrel nut will fit an 8mm hole and has a head diameter of 14mm, so will probably look closer to the original appearance of the wheel, but the smaller M6 thread means a weaker fastening. I'd be reluctant to give an engineering opinion on the suitability of M6 barrel nuts for this purpose. My guess is that they may not be as strong as the original rivets.
Another thing to think about with barrel nuts is that you're pretty much restricted to thread locking compound to prevent them coming loose. You may need to go around with a pair of allen keys occasionally to make sure they're still all tight.
A final thing to think about when replacing Astralite rivets is the potential for corrosion. Unless you actually replace with new aluminium rivets, you'll have dissimilar metals. The aluminium will be sacrificial, so you could get some corrosion of the aluminium around the bolt holes. The best way to protect the wheels is to make sure you have a good paint or powder coat layer on the wheels before you bolt them up, and use a marine anti-corrosive compound on the bolts (eg. Duralac, available from boat chandlery stores).
Casting techniques must have improved since Astralites hit the market. Modern bikes have spindly little cast spokes that look about as substantial as a spider's web, but they evidently do the job.
hooksey
Hero member
- Location
- Vic , Australia
Appreciate the insight Cam..... but if it’s off the cuff, then it’s Water off a ducks back for me we might as well wrap ourselves in cotton wool and remain inside!
Now where’s the fun in that......?
Well unless the Mrs is wrapped up with ya
we might as well wrap ourselves in cotton wool and remain inside!Now where’s the fun in that......?
Well unless the Mrs is wrapped up with ya
Tippie
Hero member
- Location
- Dr?bak, Norway
My floating rear brake had the torque arm underslung and like yours it chattered badly on chopped up road. With the crossed arm it never has, and is brilliant especially on loose surfaces. These days everyone has caliper fixed to the swing arm.
motoddrob
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- Location
- S/W Australia
Good write up there Cam. Always good to have an engineers perspective.
I made a mistake with my write up and should have said I used a M6 cap screws into the as you call it Barrel bolt.
I drilled the holes out to 10mm for the barrel bolt. In hindsight I would have made the barrel longer protruding into the opposing washer to get more depth for the M6
For the first couple of months I checked them regularly and none had come loose and thats the way they stayed till it was retired for the gixxer rims.
Travelled about 45000 kays and around 8 years.
What would the tensile strength of 316 stainless be?
I made a mistake with my write up and should have said I used a M6 cap screws into the as you call it Barrel bolt.
I drilled the holes out to 10mm for the barrel bolt. In hindsight I would have made the barrel longer protruding into the opposing washer to get more depth for the M6
For the first couple of months I checked them regularly and none had come loose and thats the way they stayed till it was retired for the gixxer rims.
Travelled about 45000 kays and around 8 years.
What would the tensile strength of 316 stainless be?
sideshow
Hero member
I’ve been playing with the exhaust a bit. I’ve chopped about 200mm out of it. With it like this the torque arm still won’t run where I want it unless I go more extreme twisting the muffler more parallel to the foot peg
