Caster Stem Bearings

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Caster Stem Bearings

Postby ophir6 » 25 Sep 2018, 02:31

I replaced the tiny 8"x2" front casters on my new Invacare Storm Torque 3 with the entire fork assemblies from one of my previous chairs (with air-filled 9"x3" tires). However, after a few days of use I started getting these terrible cracking noises from both caster stems every time I turned any direction, and each day it just got louder and louder and seemingly tougher to actually turn.

I chalked it up to bad bearings so I purchased a set of 4 replacements from Amazon (99502H-2RS Double Sealed Ball Bearings 5/8 x 1 3/8 x 7/16 Inch, for those interested), and installed them over the weekend. Vastly improved sound and turning capability initially, but now 48 hours later I am getting the same symptoms with super loud cracking noises and harder turns.

So, I am now assuming I am not assembling this correctly and I am killing the bearings. Does anyone know the correct sequence and number of spacers to install along with the bearings? Bringing the stem up from underneath, I am using 1 bearing all by itself with no spacers on the stem. Then from the top down, I am putting another bearing down first by itself, then I am using a white spacer next, then the nut to ratchet mostly tight. I am not adding any additional grease anywhere either.

Am I doing this anywhere close to correct?
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Re: Caster Stem Bearings

Postby Burgerman » 25 Sep 2018, 07:18

After you tighten things, does the caster fork rotate freely?

If not then you need a spacer between bearings, Or sometimes there is a step on the caster stem so that the nut does not crush the bearings together. Or your bearings are the wrong size or something.
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Re: Caster Stem Bearings

Postby ex-Gooserider » 02 Oct 2018, 04:14

You don't say where you are from, (it helps if you set this in the User Control Panel BTW) but is this one of the US made "H-Frame" chairs?

If so, on my ranger X, there are a couple of circular shim strip spacers that go between the bearings and the actual frame tube. You need those to prevent side to side play. (Parts book P. 137)

My parts book (P. 205) seems to show spacers above and below the bearings.

However if you are doing parts mixing, the parts books are not a lot of help, you need to do your own figuring out how to make stuff fit... :geek:

The important things in mounting any ball bearing

1. Is that there is nothing on the stem rubbing on the seals or outer race as those don't turn with the bearing... Any stem hardware should touch ONLY the inside race (use shimming spacers if needed)

2. Less likely to be an issue, nothing on the frame rubs on the inner race or bearing stem.

3. The fork needs to not be touching the bottom of the bearing tube on the frame...

4. There should not be significant pressure driving the two inner races together - this is a major bearing killer! There should be just enough pressure to eliminate any end play, and possibly a little extra to 'dampen' the caster rotation...

Ideally (and I'm not seeing this in the parts book) there should be some sort of spacer between the inner races so that tightening the nut on the top of the stem doesn't crush the bearings together. In practice what it looks like is often done is to match the length of the stem to the length of the bearing seats so that the nut hits the bottom of the threads at the point where you have just the right amount of preload.... You might not have this if mixing parts unless you play with spacers or how tight you make the nut... If you try to spin the fork with the wheel off the ground it should not have obvious drag....

IMHO, Despite the fact that all the manufacturers seem to use them, I don't think sealed ball bearings are really the right choice for stem bearings, as they aren't really intended to take a lot of side loads, which is what they are primarily getting as stem bearings... I would have preferred tapered rollers or similar as those ARE intended for both radial and side loading...

ex-Gooserider
T-5, ASIA-B
Jazzy 1100
Jazzy Select 6
Quickie Q-7
Invacare Mariner
Want to make / get a better chair, ideally one that stands.
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Re: Caster Stem Bearings

Postby ophir6 » 08 Feb 2019, 04:20

Thank you ex-gooserider, it was the missing circular shim strip spacers that you mentioned. I had no idea about those.

My chair came with these weird angled extensions for the front end which gave it more stability, but it made driving around corners nearly impossible in my tiny house. I believe they were Flared Front Casters for Storm Base by Motion Concepts, or at least that is what is mentioned on the order form. I am guessing the shim strip spacers were not needed to install the flared front end so they were not put in. When I took the flared front part off and simply put my old larger casters directly into the frame with the bearings, there was really too much play side to side.
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Re: Caster Stem Bearings

Postby ex-Gooserider » 12 Feb 2019, 04:38

If you are interested in getting rid of them, I would be VERY interested in obtaining those angled extension pieces - when going to a center mount foot plate and moving the seating back like I am doing on my project chair, the stock castes hit the footplate...

I've been working on making my own version of those extensions, but if I could save the work, it would be nice...

If you'd be willing to part with them, send me a PM and we can talk about pricing and so on...

ex-Gooserider

ophir6 wrote:Thank you ex-gooserider, it was the missing circular shim strip spacers that you mentioned. I had no idea about those.

My chair came with these weird angled extensions for the front end which gave it more stability, but it made driving around corners nearly impossible in my tiny house. I believe they were Flared Front Casters for Storm Base by Motion Concepts, or at least that is what is mentioned on the order form. I am guessing the shim strip spacers were not needed to install the flared front end so they were not put in. When I took the flared front part off and simply put my old larger casters directly into the frame with the bearings, there was really too much play side to side.
T-5, ASIA-B
Jazzy 1100
Jazzy Select 6
Quickie Q-7
Invacare Mariner
Want to make / get a better chair, ideally one that stands.
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Re: Caster Stem Bearings

Postby Furio » 17 Feb 2019, 18:01

Hi all,

Could someone advice what should be the ideal caster trail for 3.00-4 caster wheel?

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Re: Caster Stem Bearings

Postby Burgerman » 17 Feb 2019, 20:20

Ideal to prevent shake = long trail.
Ideal to prevent it swinging wide and hitting footplate or walls etc = short.
Correct length is then a compromise that works for both... Its a case of trial and error.

things that change this shake behavior is te HEIGHT if the chairs CG, the mass sat over the tyre, weight of fork/wheel/tyre (heavier fork is worse usually), pressures, tyre profile, tyre type, tyre damping, and 101 oher things. So the correct answer is whatever works!
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