Invacare Aviva Storm RX20

[Flagmax]

DME did use some grey grease.

This is what it looked like when I pulled it out before I cleaned it and added the red grease.

[Flagmax]

This is me adding Luca's Red N Tacky grease.
https://www.lucasoil.com/pdf/04_Greases ... y_PDS2.pdf

[Burgerman]

That stuff should be OK I think. I use the same grease for many things.

[Flagmax]

Uploaded a video about the fix
https://www.youtube.com/watch?v=9IXHNECikxI

[Burgerman]

Good vid. Very clear. Your editing skils too!

My take?
I suspect the better place for the wave washer is under the nut and washer at the top.
The purpose of that wave washer is so to take up any free play and stop it rattling up/down as it rolles over uneven stuff. The correct tension or top nut tightness is when the caster rotates freely and theres a tiny amount of free play that is taken up "just" by the washer. So it turns freely and no rattle/play. If that washer is at the bottom, the caster fork will move up/down a little as you roll and make a noise. Or feel like a clunk as you roll over uneven stuff. The idea is to pull the bearing up tight with the chairs mass on it and keep it there when it is not.

I still think a grease nipple would be a good addition too since the grease will dry out over time. Half way up that caster barrel. Those are cheap and easy to fit. A single threaded hole. Because I think that half if this fix is actually due to the grease between the plastic sleeve and the casters plain steel stem. That takes a heavy sideways londitudinal "twisting" load since the tyre contacts the ground a couple of inches off centre. So it tries to lean back as you are rolling forwards. And so it isntjust the thrust bearing that takes a load as you turn, and that plastic/steel interface causes friction.

Also those thrust bearing should be stainless steel. Because if they are steel they will get wet, corrode and sieze. They probably are? I dont know what you ordered. Stainless ones are cheap on eBay. But you never mentioned that which is quite important if this is to be a long term fix. Road salt will soon destroy normal bearings, high carbon steel.

[Flagmax]

I suspect the better place for the wave washer is under the nut and washer at the top.

I thought about that but the wave washer ID is to big to seat around the threads and likely would go off center with shaft rotations.

Also those thrust bearing should be stainless steel. Because if they are steel they will get wet, corrode and sieze. They probably are? I dont know what you ordered. Stainless ones are cheap on eBay. But you never mentioned that which is quite important if this is to be a long term fix. Road salt will soon destroy normal bearings, high carbon steel.

So I wasn't sure if this fix would work and how well, so I got the cheapest ones I could get to size. They are not stainless. I live in California where it never snows and hardly rains. https://www.amazon.com/dp/B09CG2TFJM

The Thrust Needle Roller Bearings are 0.75 Inch Bore 1.25 Inch OD in size.

I did find stainless steel from a reputable company, a complete set is $40 per chair
https://www.bocabearings.com/products/s ... 0-i0003042 x4
https://www.bocabearings.com/products/s ... 0-i0003057 x2

I am not so sure about ebay.

[Burgerman]

If it doesent rain it cant rust!

I thought about that but the wave washer ID is to big to seat around the threads and likely would go off center with shaft rotations.

Yes but those come in all sizes. I have a draw of oddball washers and special washers and shims. Comes in very useful for these sorts of jobs.

[Marcelo]

Another picture from underside. Nothing is rotating inside the headtube. The bronze washer does the job of the bearing. To make the problem worse, the fork stem is able to move in the headtube, so the washer has to also flex under load.

It's a lot of disqualification from the manufacturer And a lot of disrespect for wheelchair users, right? It's very sad.

[Arima]

Wow this is super helpful!! I have the same chair and the same issues.

Are you thinking about trying thrust bearings or ball bearings?

Invacare chose to go with the "plain bearing" vs "ball bearing" design on the Aviva RX20 available in North America vs Europe.

I don't know what I am going to do yet. Mostly because my attitude sucks from having the flu most of February. Still trying to shake it. Needle bearing sounds the most promising fix for the casters. Curious to see what my DME says about it all but I do not have the energy to talk to those people right now. Pretty sure I would say something that I'd later regret.

[Flagmax]

I don't know what I am going to do yet. Mostly because my attitude sucks from having the flu most of February. Still trying to shake it. Needle bearing sounds the most promising fix for the casters. Curious to see what my DME says about it all but I do not have the energy to talk to those people right now. Pretty sure I would say something that I'd later regret.

I wish you a quick full recovery.

The needle bearing fix is the easiest to install and no modification or special tools required. After experiencing first hand the improvement the thrust bearings give, I would never go back to the terrible bronze spacer washer design. I think they undersized the bronze spacer coupled with pour machining, resulted Aviva winning the worst chair to turn of all times. With the fix, its acceptable. But the two ball bearings fix would still be the best and I hope Invacare will give such an option.

[Burgerman]

If it didnt have the seat and user sat over the front end to load it up too much it would work properly without all this messing about. And would work much better if the CG was corrected no matter if it ghad ball bearings, or whatever. Whats we are talking about here really, is trying to repair or fix a symptom of the stupid CG position.

[Flagmax]

If it didnt have the seat and user sat over the front end to load it up too much it would work properly without all this messing about. And would work much better if the CG was corrected no matter if it ghad ball bearings, or whatever. Whats we are talking about here really, is trying to repair or fix a symptom of the stupid CG position.

I thought about drilling few holes in the seat mount brackets to move the seat back but then stopped for the following reason. The front casters on the Aviva flare out and are stretched forward compared to the previous generation. Moving the seat back will make them even more noticeable and become an issue for some. If you need to pull up to a bed flush, casters might be in the way. Pulling up to a sink might be an issue with casters hitting the cabinet baseboard. Also, moving the CG back introduces a risk flipping backwards when fully elevated or reclined without footplates. But the CG would not help at times when you lean forward to pick something off the floor and need to turn the chair a little with most of your body weight on the casters. Or when you shifted forward to transfer and need to turn a little. I used to get off the floor by standing on my knee's on the footplates laying on the seat and drive to some chair, then use tilt to get unto that chair, then transfer from there in to the wheelchair.

So the caster must swivel easily at all conditions and various weight. You will never get that with plain bearings. More weight equals harder to turn. Or worst, the drive wheels spin tearing up your floor sliding sideways.

[Burgerman]

Everyone has different needs etc. But on my chairs the total weight on the rear drive wheels is 75% approx of the total.

Give or take a small amout depending on what was is possible on each design. (Q700R? run away!)

If its any further forward based they drive like oil tankers, with the rear which does all of the control trying to swing a heavy long front end around sat on small casters. With no traction. That makes the chairs feel unweildy, long, they do not like turning and they feel heavy and hard work indoors. Programming cant fix that.

This is only possible if the casters are wide enough apart, and a centre footplate is used. So that your heels go between the rotating caster fork/wheels as you manoever around. Allowing a or drill etc to let you shift the seating back.

Downsides, the chair is much more tippy. Well you soon learn this and then reverse up anything steep! If traveling forwards you can easily lift the front as you approach a small curb or whatever so as to climb it easily. Lift the front and allow momentum to crash the rear up. Like a sport manual chair. This takes some skills and needs good throttle control and balance and a proerly programmed chair. Wheelying superbikes up and down the runway and down motorways all day long was useful after all!

Tipping out the rear? Yes I have done that a good few times. I dont like it, but so far its never done any real damage other than embarassement! Hold head forwards...
But thats how you learn how far is too far! Goes right over the anti tips. And what is possible. Its worth it for the shorter chair, ease of steering and indoor lightness of control. Because you use and feel that 100% of the day.

Of course everything is a compromise. So whatever works best for you.

As far as tipping back when lifted high. That CAN be an issue. You dont want to fall out while lifted. But it can be mitigated some my making the lift mechanism move you forwards as it lifts you up.
How? Tilt the whole lift on its mounting so it is 4 or 5 degrees forwards and drill new holes, or use existing options for seat dump angle etc on the base or whatever it takes to do that. Mind over metal right? Then add spacers under the front edge (the forwards bolts) that locate the seat on top of the lift mechanism. Set that angle to whatever your prefered dump angle is.

So now the seat is back to the best place for you when sat normally low. With correct dump angle when tilt is at the low position. In my case 5 to 6 degrees of dump so you dont ride on the tilt mechanism. Thats bad!
As the seat elevator now lifts you up, it moves you forwards an inch or so too. So now its less likely to tip back. But still be CAREFULL!

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Everything is a balance, a compromise. After years of experiment I now know EXACTLY what I want to the mm, and in fact have a list of dimentions for seating and control positions written down. Its very long!
And all of this is taken care of on any new chair during the initial proper configuration. That may require a week, a little creative thinking, to achieve.
But it must all happen. A new chair is the STARTING POINT of the chair that you will end up with once set up properly. You must KNOW what you want. And dont stop till you get that. Its just metal. It can be changed and adjusted. Take bull by the horns and it into shape.
Or the chair will be forever crap! This and 101 other settings and positions needs to be done!

That would (in my case) include a stainless thrust bearing and grease nipple on those casters or replace with proper bearings, as well as stainless caster wheel bearings and correct assembly with adequate grease etc on shafts, bolts, on your chair. Same attention to detail on the rest of that full chair. Replace steel bolts, any place where water goes with stainless allen bolts and grease all of them too. Dielectric grease and so on on wiring/batts and heavy connectors, de-oxit on signal/bus connectors, rebuild swing aways to get rid of play/movement and position correctly, better chargers, and programming. seating and controller positioning, cable routing etc. Ready for use!

You cant make an omelette without breaking a few eggs.
Every stock new chair is assembled badly, configured incorrectly in 100 ways, and needs fully configuring and sorting out. To fit your needs. Then finally programming properly (not 10 mins fumbling by a dealer) before first service use. It can take half a dozen goes to fine tune all that stuff. Delivery quick kick then, or a "fitting" session is not that!

Of course this never happens to 99.9% of chairs, sadly and so they are always mess or at best a compromise that dont work properly. But if you have a few slkills and some patience you can get there!