caster size????

[Williamclark77]

I've ordered from The Big Bearing Store also. I live in Mississippi. Stuff arrives quick from them out of Tennessee.

If the bearings are stainless, about as magnetic as carbon steel, and affordable then they're either 440c, or occasionally, 416. There's nothing wrong with either. They're typically rated at about 75% load/RPM of a typical 52100 carbon steel bearing (DO NOT QUOTE ME ON THOSE EXACT NUMBERS).

If they're stainless and have roughly the same load/RPM rating as carbon steel bearing, then they're probably S30v. Easily noted by the premium price tag. That stuff is fantastic for knives. As soon as I can build a proper heat treat setup I will be investing in some.

If they're stainless and non magnetic they'll be Haynes 25 (I THINK that's the correct name, can't remember off the top of my head),food grade 304 or 316. They're all much softer than 440c, 416, or 52100 and will be rated at a much lower load/RPM. Perfectly fine for our chairs though and aren't usually a whole lot more expensive than 440c. They are a bit more "stainless".

[ex-Gooserider]

Thanks for the info Will....

No response from Big Bearing Store, just made the time to send off a note to KML, will see what they say (if anything...)

I was happy with the speed of BBS as well, I think it was 1-2 days, which I pretty much expected since it was a standard USPS priority mail box... BBS shipping was about what USPS charges for their boxes, so reasonable.

Price was pretty reasonable, and definitely the best I found for any sort of SS - US$3.99 each... Cheapest I saw a moment ago on Fleabay was about US$12 plus more for shipping... By comparison, their 'matches fewer terms' gave a listing for plain steel of $11 for 10 bearings w/ free shipping... I hope these bearings last at least 4X as long Amazon had a couple listings that were only a little more, but looked like the same KML bearings from the picture... Amazingly, some were over $100 (and didn't mention gold plating...)

So based on what you said, I'd agree probably 440c, as they are about as magnetic as the steel ZZ bearings I pulled out of the wheels...

I've gotten the inside bearing spacers turned, using the (I think) 303 stainless shaft I fished out of our cruft pile - whatever it is, it machined really nicely - even with the cheapo HF carbide insert lathe tool I used... I like that shaft material, glad I have a pretty good stash of it...

Still working on the outer spacers, have the bearing side of the first pair cut, one on each end of the originally 12" long chunk of aluminum round I'm using, need to part them off and make the other set, then figure out the best way to hold them while facing the outside down to the ~3mm final thickness.... I also need to turn a couple mm off each end of the hubs...

ex-Gooserider

I've ordered from The Big Bearing Store also. I live in Mississippi. Stuff arrives quick from them out of Tennessee.

If the bearings are stainless, about as magnetic as carbon steel, and affordable then they're either 440c, or occasionally, 416. There's nothing wrong with either. They're typically rated at about 75% load/RPM of a typical 52100 carbon steel bearing (DO NOT QUOTE ME ON THOSE EXACT NUMBERS).

If they're stainless and have roughly the same load/RPM rating as carbon steel bearing, then they're probably S30v. Easily noted by the premium price tag. That stuff is fantastic for knives. As soon as I can build a proper heat treat setup I will be investing in some.

If they're stainless and non magnetic they'll be Haynes 25 (I THINK that's the correct name, can't remember off the top of my head),food grade 304 or 316. They're all much softer than 440c, 416, or 52100 and will be rated at a much lower load/RPM. Perfectly fine for our chairs though and aren't usually a whole lot more expensive than 440c. They are a bit more "stainless".

[Williamclark77]

303 stainless is good to work with. As long as you don't have to weld the part it is a better choice for stuff like that than 304.

Workholding small or thin stuff like that can be a pain, especially when you need to turn the od. If I can't part it off to length I will sometimes center drill the end of a bolt that fits fairly snug in the center hole then put the head of the bolt in the chuck. Put the part on the bolt and use a nut to keep it from spinning. Stick a live center in the tailstock to support the end of the bolt where it's center drilled.

I made some expanding mandrels for stuff like that. They work surprisingly well and accurate as long as you don't cut too hard.



Drilling in a lathe wears my arms out and slow. I have four parts to make this evening from 1018 cold rolled steel that need fairly precise 1.001" holes 2" deep. (tight slip fits on a 1" 4140 steel shaft). I'm going to see if my little Tormach 1100 has the gonads to push a 7/8" drill through them then finish boring on the lathe. I know it can do 1/2" pretty easy with a small pilot hole.

[ex-Gooserider]

Thanks for the workholding ideas - if I can't just grab the stub end of the outside spacers I will give it a try... The challenge is that I need to face across the entire outside end of the outer spacers to get them down to size (the magenta bit in the drawing I posted a while back in the thread) I made them over length on purpose initially, with the plan of getting the hubs done and then shaving them down to just the right size to fit the forks as the last operation...

The stub that goes into the bearing is only about 0.3" long, but the lathe I'm using has a 6-jaw chuck, so I (hopefully) will be able to clamp on the stub if I'm just facing and keep my cuts light... After all facing will just be pushing the part into the chuck...

On the rest of the project... Looks like I F'd up the center pieces - I did the trim on the hubs, taking about .1" off each end, which still leaves about the same amount sticking out past the bearing...

However when I did a quick eyeball test it looks like the center spacers I'd made are to short by about 1/2" I will need to go back and check to see where I messed up, but I'm expecting I did a math error when calculating the distance between the bearing seats (I don't have anything to measure it directly - to narrow to get in with my calipers, and the width of the seats means I can't get in with a micrometer....)

At least I have plenty of the same shaft, so just need to get better measurements and start over...

ex-Gooserider

[ex-Gooserider]

Progress...

As an exercise, rather than starting over on the center spacers, I decided to make them longer...

I turned one end of each spacer down to 1/2" OD, and about an 0.1" stub - plus shortening the body a bit - I wasn't real fussy about this, just getting a clean end... I ended up with spacers that had a body length of about 1.6-1.68", a 12mm diameter, 0.125" long stub on one end, and a 1/2" diameter by 0.1" stub on the other... (You'll see why in a moment)

Careful measurement showed I should have made the spacers about 1.86" long, so I was about 0.25" short

I then drilled a scrap length of the shaft for the 7/16" axle, and turned each end to 12mm by about 1/2" long, then cut off a stub with about 0.4" of body, and repeat for 4 short lengths.

I then took each one and chucked it on the 12mm stub, and faced the body down to the exact length that was needed to add with one of my existing spacers and total 1.86" - I then put a 1/2" end mill in the tailstock drill chuck and put a recess about 0.15" into the body end - this was pure eyeball - I just wanted to be deeper than the length of the stub from the first step...

After confirming that the two pieces fitted together with the right length, I chucked the very short length of body at the nose of the chuck and faced the 12mm section down to about 0.125" - again mostly by eyeball, I just wanted to be short enough not to hit the stub on the outer spacers when everything gets put together...

The idea is that the 12mm stubs on the ends of the spacers lock them into the bearings, and the 1/2" stub and recess on the two pieces lock them together....

I took a couple of the metal shield bearings that came in the wheels - the ones I'd messed up the worst when driving them out - to the belt grinder and worked them over to be a slip fit in the hubs - which makes them nice drivers for the new bearings...

I then used the arbor presses to seat the spacers and bearings in the hubs....

Seems to have worked as planned - they fit tightly enough that if I turn the inner race on one end of the hub, there is enough friction on the spacer that it drives the inner race on the other end....

Now my next step is to measure the actual space in the forks, and face down the bodies of the outer spacers to be a TIGHT fit.... The end result will be a solid fit across the fork - spacer-bearing-spacer-bearing-spacer, so there won't be any compression side loading on the bearings...

I have ordered the replacement nuts and bolts, they should be here in a few days at most...

Then comes the final test, can I find a combination of parts that will run true?

ex-Gooserider

[ex-Gooserider]

I did a spreadsheet after measuring all the hubs - came out pretty consistent I think...

I did the measuring by standing the hubs on a surface plate and checking the difference between the end of the hub tube and the bearing outer race to get the amount the hub came past the bearing on each side. I measured the overall length w/ a micrometer, and subtracted to get the center length, which is really the only number that mattered...

I measured the inside width of the forks as 3.00", and the rest is math...

#caster-spcr-china.pdf

spreadsheet as .pdf

(31.37 KiB) Downloaded 109 times

I've faced the outer spacers down to about 0.16" and they are close, but don't fit, as expected... So I need to take a bit more off, but they are getting close to done...

I've also gotten the bolts so I can start building the wheels back up once the hubs are finished...

ex-Gooserider

[ex-Gooserider]

Finally made the time to finish trimming down the outside spacers - I think they came out pretty good - the finished thickness ranged from 0.1380 to 0.1413" - targeting 0.140".....

The worst tolerance combination of thickest spacers and longest hub measurement is a TIGHT fit in the fork with a bit of struggle needed to get it in. The worst combo for shortest total is a snug sliding fit...

Seems like good enough, so next step is figuring out how best to get a wheel setup that will run as true as I can get with the available parts...

ex-Gooserider

[shirley_hkg]

Finally made the time to finish trimming down the outside spacers - I think they came out pretty good - the finished thickness ranged from 0.1380 to 0.1413" - targeting 0.140".....



ex-Gooserider

I filled this cavity with kitchen paper , and soak it with lubricant . Bearings will be kept moisted as wheels spin , and no rust after getting wet .

Lasts 2-3 years and get refill with change of tyres .

Poor me that I couldn't have 4 set of spacers you made .

[Burgerman]

Why would you bother doing all that when you can just use STAINLESS STEEL sealed and greased for life bearings? They are grease packed, have 2 rubber seals to keep dirt out and water out, and cannot rust or corrode. And easily available. They are even used under water in outboard motors. And in food production in steam rooms on conveyer belts etc. Those dont fail even in seawater.

[ex-Gooserider]

The adventure / frustration continues... I started trying to build up wheels from the hubs... It does not look like it will be easy...

My first check, which I only did on one hub so far, was to put it on a 7/16" bolt with nut in order to act as an 'axle' to use when checking runout. Putting an indicator on the hub barrel says it turns to +/- 0.0015", with the variation from zero only in one short spot that might just be the tube seam... So it looks like my spacers are accurate and the hub runs about as true as I can measure...

Things went downhill from there...

I started by measuring the relative height of the wheel halves - I put them with the rim on a surface plate, and used a digital dial indicator on a stand to see how (not) flat the center flanges that bolt to the hubs are.... Answer is not very... They have a slight doming where the area next to the hub is about 0.01" higher than the area by the bolt holes... Given that they appear to have been stamped, it sort of makes sense as you expect some spring-back on stampings. More importantly, when I measured the height in a circle around the halves, they showed about a 0.015" difference so are slightly warped. Interestingly the high and low spots were not opposite each other...

However they do appear to be relatively consistent - all the halves show about the same amounts of error...

So I tried putting a pair of halves together, lining up the high and low spots as best I could, and bolted them onto a hub.... Spinning it gave me serious visual wobble... It is hard to measure as there isn't any flat surface that would make a good reference near the edge, but I ended up tilting the indicator about 30* from vertical and putting the tip on one bead seat so that I would mostly see the lateral runout. About 0.05" side to side wobble...
Took the wheel apart, spun the halves 180* - same thing, but the high and low spots reversed... Repeat, spinning 90* - got about 0.065" wobble, not only worse, but the high and low spots were 90* from the first two attempts... From this it seems the problem can't be just the wheel halves....

So I went back and tried to do relative height measurement of the bolt flange on the three hubs I hadn't done anything with yet... The flange was not flat - but at least it appeared to roughly match the dome of the wheel halves (it is obviously another stamped part) This was a very hard surface to measure as there were several curves from the stamping around the holes in the ears, but on each of the three hubs I measured it looked like three of the ears were within about 0.005" of the same (maybe less?) but the fourth ear was at least .015-.02" off... Given the increased distance from the axle to the bead seat, this WOULD seem to account for most of the wobble...

So now the question is do I try to knock the bad ear back into line w/ a big hammer or other such tool, or chuck the hub in a lathe and try to skim the flange to be uniform... The latter would obviously do bad things to the plating, not to mention slightly shifting the wheel center and weakening the flange by however much meat I took off...

ex-Gooserider

[ex-Gooserider]

Why would you bother doing all that when you can just use STAINLESS STEEL sealed and greased for life bearings? They are grease packed, have 2 rubber seals to keep dirt out and water out, and cannot rust or corrode. And easily available. They are even used under water in outboard motors. And in food production in steam rooms on conveyer belts etc. Those dont fail even in seawater.

I agree stainless is better, but I don't see any harm in the oil soaked towels that Shirley is using either... As you have pointed out, the furballs we pick up do get water into the bearings by damaging the seals, so supplementing the lube probably doesn't hurt... Also worth noting that the hubs themselves are steel, so it isn't going to hurt to do something to keep the rust down on them....

On my Guzzi's the drive-shaft U-joint ran 'dry' under a rubber boot between the output shaft of the tranny and a sealed carrier bearing in the swing-arm. Many owners claimed that the bearing and U-joint lasted better is one poured a few ounces of gear oil into the boot before closing everything up.... I can't say for certain that it helped, but it didn't do any harm... If nothing else, it meant that if the boot failed, you got a puddle that would let you know there was a problem...

ex-Gooserider

[ex-Gooserider]

Caster saga continues.... Finally made the time to go tackle them some more - I measured one set of the rims, and found they definitely had high and low spots, but weren't completely terrible. But then discovered that I had burrs on the edges that were making for irregular contact with the surface plate So my measurements were questionable at best...

Next I started measuring the flanges on the hubs, and found they were also not consistent - some seemed to be warped, others not welded level... They were apparently much worse than the rims. So I started trying to tweak them so that they were closer to level - a mix of clamping them in a vise and pressing the flange with an arbor press and hitting them with a big

Got three of them pretty close, given the challenges of measuring them, I felt I was within my error margin... The 4th one had a partial weld failure - poor penetration of the weld into the flange plate.... I might use that hub in an emergency, but I wouldn't trust it to roll on...

So I have built up the three surviving wheels without tires - worst one has about 0.94mm of lateral runout according to my indicator, the best has 0.36mm... I'm now debating whether to make a fixture so I can try to press them into better, or just see how horrible they are if use them as is...

I may also try finding some better wheels...

ex-Gooserider

[Burgerman]

Wondered how long it would take!

[ex-Gooserider]

Well, the first question, is just how critical is it... I know from BM's build descriptions that he is super OCD about getting it perfect, but if one isn't doing a dragstrip chair, but just a 6mph chair with the seat moved as far back as possible, etc... How much runout is probably 'acceptable' in that it doesn't cause problems?

I have also been doing some research, and it isn't real clear what I need for sizing either...

Per Shirley, the Cheng-Shin 2.50-4 tires that came on the hubs won't fit, so he recommends some Kenda 2.50-4 tires that he says will... I haven't tried either tire inflated and mounted on a wheel, but eyeballing the unmounted tires, they look to be about the same OD but the Kenda is narrower....

Earlier in this thread, Shirley pointed at some nice looking cast hubs - presumably also for 2.50-4 tires (I can't read the Chinese to be sure) which are very low cost, but are they likely to be any better? Knowing there isn't a practical exchange makes me nervous...

I found an ebay listing https://www.ebay.com/itm/2-50-4-aluminum-scooter-split-wheel-rim/323569852175?hash=item4b56441f0f:g:ghYAAOSwi1pbtgnh:rk:3:pf:1&frcectupt=true which are a lot more expensive, but from a high rated US vendor... Casting looks a bit rough in the photo, but not terrible... The dimensions don't seem consistent with the China hubs, but don't look like high precision either... Good side is she says 30-day refund if they aren't good, downside is she didn't understand what I meant when asking about runout. She did say that customers were using them on electric scooters...

BM pointed at some Trampa mountain board wheels which look nice and probably would be about as true as you can get, but hard to say if they would fit - I found some pictures of tires showing a 2.50/2.80-4 on the side wall and others showing a 2.0-5 (either way adds to 9"???) depending on the hubs - but none of the descriptions seem to give a width....

ex-Gooserider

[Burgerman]

Well, the first question, is just how critical is it... I know from BM's build descriptions that he is super OCD about getting it perfect, but if one isn't doing a dragstrip chair, but just a 6mph chair with the seat moved as far back as possible, etc... How much runout is probably 'acceptable' in that it doesn't cause problems?

Almost anything will work at low speed. But I would know! And think about it.

[ex-Gooserider]

Both as an experiment, and to see just what they looked like in the fork (and to see how big I could actually get away with...) I built up the two best wheels with tires - one using the Cheng Shin tire that came on the casters (Which Shirley said wouldn't fit) and one using the Kenda tire he said to use instead... I inflated to ~50psi, the maximum on the sidewall, figuring that would give me 'worst case' dimensions to deal with...

As a reminder, the forks have two sets of bolt holes where the casters can mount... One is higher on the fork and further from the pivot centerline, the other is lower and closer to center. Shirley says the lower hole is to close to the center pivot and won't work for driving. The forks are cast with legs that curve into the center at the top (which limits the tread width on large tires). They are 'suspension' forks, sort of like Frog Legs, and there is a bulge across the top inside for the suspension bushing which limits the diameter of the fork (which limits the diameter of the tire)

The Cheng-Shin tire would barely fit and allow the axle to install in the upper holes... It wouldn't rotate as the outer tread corners were hitting where the fork legs curved in, and it was possibly rubbing on the center bulge. It fit fine in the lower holes, except for a light rub due to run-out...

The Kenda cleared and would fit in the upper holes, again except for runout... However the wheel would also hit the motor (I have the motors in the most forward of three possible positions to get the weight back...) Lower holes fit OK (except runout) and would clear the motors... One of the things I need to do is move the caster mounts out in order to clear the center foot-plate, and that might solve the motor problem but not sure...

The stock tire clears the motor in the upper hole

I then worked on taking measurements of the 3 wheels for comparison... (Stock is the OEM caster w/ tire that doesn't look badly worn)

Code: Select all

Measurement    STOCK        Kenda         C-S
Max diameter    7.4375"        8.3125"       8.5"                  (no load on tires)
Max width          2.25"            2.5"             2.5"                  (sidewall bulge)
Tread width       2.1"              1.75"           1.85"                (outside corners of tread - estimated)
Tread bulge       0.375"          0.25"           0.125"              (est height diff. btw outside corner and center)

The stock tire had nearly straight sidewalls and a ribbed tread that was very rounded profile.  The Kenda tire tread was almost a "V" shape, nearly flat on each side coming to a point in the center.  The C-S tire was nearly flat across, but rounded evenly


What I'm wondering now is where to go from here...

ex-Gooserider

[Burgerman]

The pub. Obviously.

[ex-Gooserider]

I may come back to them, but I have decided to look at other options...

I have ordered a pair of the hubs from e-bay that I mentioned earlier - since it's a US vendor I will get them quickly, and have a promise from her that they can be returned if not OK... She said a lot of the people purchasing them were using them on electric scooters for whatever that is worth...

The bearings in them are a different size, so will need to get more SS bearings if they are a good fit, though I might just use the steel bearings they come with for as long as they last...

I will need to make new wheel spacers as well, but that is no big deal, I still have 10-12" worth of the aluminum bar that I made the last batch from...

ex-Gooserider

[ex-Gooserider]

I've gotten the e-bay casters I ordered in the last message - they aren't perfect but seem a bit better than the China stamped steel parts...

They seem to have about 0.8mm of lateral runout, and about 0.1mm of radial which isn't a LOT better, but somewhat improved. They do look nicer and as the valve stem exits on the seam between the two halves, it appears that they will have less of a concern with the valve hitting the fork.

Mildly interesting, they came with a rubber-seal bearing on one side, and a metal seal bearing on the other - I'm wondering if this was just to give a visual indicator when assembling them as to which side got the three bolts holding them together...

I may also want to take a look at the center spacer to see if that is true - seems to me like it might be causing the bearings to be a bit angled if the spacer isn't true, which might account for the wobble...

ex-Gooserider

[shirley_hkg]

Try it out first .
Leave the spacer afterward .

Spacer is not a MUST . I never have one .

[ex-Gooserider]

Try it out first .
Leave the spacer afterward .

Spacer is not a MUST . I never have one .

IMHO the spacer isn't an absolute must in the sense of won't work without it, but it is important... If you look up the usual design methods for bearing selection, the caged ball bearings that we see in casters are intended for high radial loading, but NOT a lot of axial loading... If you have a caster wheel without center spacers, unless you use a very careful tightening process, the fork legs and outer spacers will bend enough to preload the bearings by pushing the inner races towards the center of the caster. This is VERY bad for the bearings.... But if you don't tighten the axle enough, you will have side to side wobble, and the bearings can spin on the axle - again a bad thing... In theory even if you get it right at one temperature, you can end up with excess or inadequate loading pressure just from the metals expanding and contracting from temperature change...

OTOH, if you DO have a center spacer that is properly sized, tightening the axle just squeezes the fork legs, spacers and inner races together into a single piece, so the inner races are locked in place WITHOUT putting any side preload on the bearings...

(Worth noting that the stock caster wheels on both my power chairs and my manual have spacers... On my Moto Guzzi's the front wheel used a snap ring on ONE side to lock the outer race into the bearing carrier, on the other side the outer race was intentionally NOT secured so that it could move back and forth slightly within the carrier to adjust for temperature changes...)

============

I have pulled the casters apart, and the spacers are pieces of steel tube. They look to be cut square on my initial checks, but could use a better job of deburring the cut ends - both inside and out... They are also a little on the long side as the bearings aren't fully seated by a noticeable amount - however they are close enough that I am not inclined to do any more than deburr them if they are as square as they look....

The castings appear reasonable, I'm guessing die-cast aluminum or 'pot metal', a bit on the grainy side, but reasonable. They are a three angled spoke style, with an M6 bolt in the middle of each spoke holding the halves together. I can't find any manufacturer or country of origin markings anywhere on them. The bearing seats are wide enough to completely cover the outer race - which isn't 'bad' but does mean that one has to push on the inner race only in order to remove the bearings... Other than possibly the bearing seats, I don't see any signs of machining, but it seems the castings are made precisely enough not to need it - at least when I was doing my runout checks, both flanges had their high and low spots at the same place, and were off the same amount, so the flanges are parallel with each other...

These casters are about 10mm / 3/8" narrower than the China casters, which presumably will pull the tire sidewalls in so that the assembled wheels are narrower but taller... Given that I found the China casters had possible clearance problems on both width and diameter, this might be a bit of a mixed bag...

ex-Gooserider

[shirley_hkg]

A little bit of care in tightening axle bolt is easier for me . I need not to do it everyday after all.

[ex-Gooserider]

Deburring complete - there was a tiny bump at the seam on each spacer... Now rolling them through the jaws of a micrometer or my caliper, I get a length all around of 1.014" +/- 0.001" ( 25.75mm)

The bearings are 6002 series, so 32mm / 1.26" OD, 15mm / 0.59" ID, 9mm / 0.354" thick.

So 2 bearings plus the spacer gives 43.75mm / 1.722" for the hub thickness. The fork opening is 3.0" so outer spacers need to be 1.278", divided by two, = 0.639" (16.23mm) each...

ex-Gooserider

[ex-Gooserider]

Much futzing around with bearings and so forth, I was able to get both wheels to about 0.5mm / 0.02" of lateral runout at the flange - at least part of it seemed to be the approximately 0.2mm of variation in the width of the wheel....

One of the interesting things is how small half a millimeter looks on a ruler, but how big it looks when watching the stem go in and out on a dial indicator...

This isn't great, but it may be OK.... Next step will be to put tires on them and see how they look - given that the tires in this size aren't noted for high precision construction it may not be worth trying to get the wheels better...

After that I can start turning spacers...

ex-Gooserider

[ex-Gooserider]

I put tires on the wheels - and did some measuring... If nothing else, I think these wheels are a better fit for the tires ...

As a reminder, this is what I got with the China casters...

Code: Select all

    Measurement    STOCK        Kenda         C-S
    Max diameter    7.4375"        8.3125"       8.5"                  (no load on tires)
    Max width          2.25"            2.5"             2.5"                  (sidewall bulge)
    Tread width       2.1"              1.75"           1.85"                (outside corners of tread - estimated)
    Tread bulge       0.375"          0.25"           0.125"              (est height diff. btw outside corner and center)

    The stock tire had nearly straight sidewalls and a ribbed tread that was very rounded profile.  The Kenda tire tread was almost a "V" shape, nearly flat on each side coming to a point in the center.  The C-S tire was nearly flat across, but rounded evenly

With the new casters I got

Code: Select all

Measurement      KENDA                C-S
Max Diameter      8.5" / 215mm      8.6" / 219mm
Max Width            2.36" / 60mm     2.32" / 59mm 
Runout                 0.05" /1.25mm   0.09" / 2.2mm


As I expected that the new wheels were narrower gave me a narrower inflated width and slightly greater diameter. It is interesting that the narrower wheels made both tires come out with much closer to the same measurements. I didn't try measuring the tread bulge, but the tires were very similar in profile - much less difference than with the wider wheels.

Both wheels the valve stem without the cap barely stuck out past the tire sidewall,

The runout assumes that the center mold rib on the tire is a good reference - I measured it by putting each wheel in the lathe between two centers (no power...) I put a cutter on the tool post and ran it to the rib, spun the tire and used the crossfeed to position the cutter tip at the extreme of the rib's wobble on one side... I then visually spun the tire to the other extreme and measured between the cutter and the rib....

I may end up regretting it, but I think the above results, at least with the Kenda tires are 'good enough', so next step is make the spacers and see how they fit in the forks...

ex-Gooserider

[shirley_hkg]

That little increase in diameter worries me .

[ex-Gooserider]

That little increase in diameter worries me .

Well I can't completely test the fit until I have made the outer spacers (since the bearing ID's are the same, I could use the spacers I made for the China casters to test the vertical fit?) but it won't be a problem if I use the lower holes - the upper holes might be a problem with the top center of the fork...

It is also worth noting that the measurements were taken with the tires blown up to the full 'sidewall maximum' 50psi pressure - I seriously doubt that I'd be running at even half that - IIRC others have ended up between 8 and 20 psi... That may make a lot of the bulge disappear?

ex-Gooserider

[ex-Gooserider]

Just tried a test fit with the outer spacers from the China casters... Just on the upper holes since I am positive the lower holes would be no problem...

At 50psi, I couldn't get the Cheng Shin tire to quite fit, but if I let the air out of it, it fit barely but rubbed on the top of the fork...

I was able to get the axle in on the Kenda tire, but only with force at 50psi, and wasn't able to turn the wheel... After letting the air out, it turned easier than the CS tire did, but was still rubbing on the top of the fork...



Good news is that there was PLENTY of clearance on the side of the fork, including for the valve stem with cap....

So options -
1. Use lower holes - easy, but Shirley says that will give caster shake...

2. Use upper holes, after going at the top inside of the fork with a grinder or other metal removal tool... Tempting, but not sure how much material there is to be removed w/o weakening the fork...

3. Make bearing spacers with axle hole off center - so that wheel would be lower (I have about 0.06" / 1.7mm available) - problem is that if the spacer turned in the fork (seems likely) the wheel would suddenly be much higher and I wouldn't be going anywhere...

4. As someone suggested earlier, drilling a new set of axle holes in the forks to be lower and farther from the pivot axis... The challenge would mostly be in locating the corresponding points on each side of the fork so that they matched (the legs would need to have each side drilled in a separate operation...)

ex-Gooserider

[shirley_hkg]

I deploy 26psi , never reach 30 ever .

Is your chair nose heavy ?

[ex-Gooserider]

I deploy 26psi , never reach 30 ever .

Is your chair nose heavy ?

It better not be... I have the seating system as far back as I can make it go, and the motors in the front most holes...

The little bit of testing I did on it with the crappy lead bricks in it that it came with had it doing wheelies without to much trouble...

It is a brush motor "H-Frame" with the 2GTR tilt / recline seating system, and I have added a power lift center platform off a (I think off a TDX) foot rest...

I replaced the MKIV power box with a Pilot+ box in the same place. The seating system frame is flush with the back of the tiedown loops, and the foot rest is against the control box when its all the way down, so no real easy place to make it any shorter... (I may have to end up adding some ballast in the rear battery box if it is still to nose heavy once I do the Lithium pack...)

ex-Gooserider