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 Wheel chair hold down track corrosion
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sambrutay
Advanced Member

United States
271 Posts

Posted - 06/24/2014 :  04:48:37 AM  Show Profile  Reply with Quote
How many of you out there are having an issue with floor tracks for wheel chair hold downs. We are having quite the problem with corrosion as seen in these pictures. This bus is only 2 years old.



slippert
Top Member

USA
630 Posts

Posted - 06/24/2014 :  07:38:15 AM  Show Profile  Click to see slippert's MSN Messenger address  Reply with Quote
Is a common problem here..Aluminum mositure and salt, calcium cloride don't mix along with steel fasteners and aluminum together. state of Michigan we have to use alot of corrosives to keep roads clear in winter and same is used in summer to keep dust down on gravel roads in my county! I normally can get 4-5 years on my track, did have some 02 IC's that went bad in 2, dealer told me wrong plywood was used in manufacturing bus and chemicals were eating up track... I always use mylar tape on new track and try to somewhat seal out moisture don't let my drivers use alot of water inside bus(they use to pressure wash inside alot before I came here).... once that plywood in mine gets wet never seems to dries out anyway... of course water and corrosives get tracked in by riders, chair and driver too...

Usually I can get a couple more years on replacment track after I replace it at approx 5 years by doing some extra sealing...

Also my newer IC's are suppose to have anodized track in them, not painted seems to be holding up a little better so far some of them are coming up to the 5 year marker and still look good no corrosion around fasteners yet....finger crossed... but found in pulling alot of track last 11 years track usually gets nasty against plywood regardless... so basically I have a 5 year replacment program here...

Wonder if your busses have marine plywood in floor....assume it is a Thomas bus? looking at rubber cover.... maybe chemicals in plywood used are causing your issues?

Edited by - slippert on 06/24/2014 08:50:38 AM
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JRob
Advanced Member

207 Posts

Posted - 06/24/2014 :  09:56:28 AM  Show Profile  Visit JRob's Homepage  Reply with Quote
I don't buy the chemical in plywood explanation. Marine Grade and Exterior Grade, Treated plywood both use 100% waterproof sealer in the bonding. The main difference making Marine Grade "premium" is the allowable exterior imperfections in the plywood sheet (i.e. knots & footballs). Marine Grade must have an exterior layer Graded at B or better (A grade means no knots or imperfections). I would believe dissimilar metal corrosion between steel floor or fasteners and aluminum track where there is insufficient isolation. Tracked in salt and chemicals don't help either.
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slippert
Top Member

USA
630 Posts

Posted - 06/24/2014 :  11:17:07 AM  Show Profile  Click to see slippert's MSN Messenger address  Reply with Quote
I didn't buy the plywood explanation at the time I got it either... coming from trucking transport industry, before working at school ...saw a lot of issues with dissimalar metals causing corrosion problems.. i.e. older aluminum bulk transport trailers with steel suspensions and frames for instance... but certain vin's of those year busses did get new plywood installed in them, I was told...of course my weren't in the range...lol so put less stock in plywood explanation too..

I have some pics of track removed somewhere....can't find them right now...top looks alot like above pic's but bottom looked much worse.... don't think you would ever get away from this issue with track in busses...due to environment it is used in....but only 2 years old with corrosion happening is not good!! my 02 ic's were so bad after 2 years from new you had to literally beat straps into place to knock corrosion out of way...then beat them out if left in same spot very long... which is not a practical or safe thing to have to do IMO...so I had no choice at that time but to replace it...

I find one brand of track does it worse than the other...although I think both might be owned by same manufacture now?... not sure again just what I had heard... the pic's above look like the brand of track I had more issue with here myself... also there is a couple different versions of that A track you can buy some for less money(cheaper) but won't last as long(seems to corrode faster) than more expensive version does....I assumme different structure, properties, alloys, refining.. involved to make it cost less... I will just say I spec new busses and replace with all Q- straint track with anodized coating since about 2008 and seems to be holding up better...

Edited by - slippert on 06/24/2014 11:44:16 AM
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JRob
Advanced Member

207 Posts

Posted - 06/24/2014 :  3:08:45 PM  Show Profile  Visit JRob's Homepage  Reply with Quote
In my experience, track can be sourced from the Wheelchair tie-down supplier or it can be sourced elsewhere. There are also various grades of aluminum button track. I could definitely see where you would have different wear characteristics on different units based on the sourcing variable.

This is just my personal opinion but I don't think the manufacturers do enough lifecycle testing on this type of thing. They will take the word of a supplier. Lifecycle testing is done, just not enough.
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