swing-arm autopsy...

[ST1100Y]

So if anyone thinks he can mend such by simply welding a patch onto the cross-member, scratch that...

The one shown came off my '94 ST1100, PO seems to have abused it quite a bit with winter-riding, brine on the roads and such...

Upon inspection it showed two soft spots on the underside:





So to be sure I had it blasted and cut open:










Quite badly rotted inside out, even the longitudinal arms are already perforated, structural integrity compromised, scrap...

 

[SMSW]

Good thing you did not try to patch it....

 

[ChriSTian_64]

Thanks for the autopsy. Very interesting.

 

[ToddC]

Because of wonderful people like you...this site rocks..!!!

 

[ST1100Y]

I think that adding two drain bores plus applying some decent, long term cavity protection could extend the lifetime of any swing-arm still in proper condition:



Yellow indicates the gaps where the water spray enters and then collect in the "belly" of the cross-member, which is the lowest point.

Care is advised though, as any excessive cavity protection wax or oil will drip out those new bores, right in front of the rear tire...

 

[Upt' North]

I think that adding two drain bores plus applying some decent, long term cavity protection could extend the lifetime of any swing-arm still in proper condition:



Yellow indicates the gaps where the water spray enters and then collect in the "belly" of the cross-member, which is the lowest point.

Care is advised though, as any excessive cavity protection wax or oil will drip out those new bores, right in front of the rear tire...

That unwelded flap on the driveshaft side is complete madness. Not shown on that picture. It just fills with crap and merrily rusts away. Then as it pushes out with rust build up it'll eventually rub on your tyre and kill you. Not a good day at Honda HQ.
Upt'North.

 

[ST1100Y]

That unwelded flap on the driveshaft side is complete madness. Not shown on that picture. It just fills with crap and merrily rusts away.

Well, it doesn't seem a general problem per se, since it basically roots in intensive winter use (road salt and that...)
Hence it appears in UK and the Netherlands with their mild winters permitting bike use, and with a few hard-corers who ride year round through any condition...
Also neglect seems contributing, as frequent washing would dissolve the salt crusts, slowing the destructive corrosion...

I doubt that any Californian or Florida resident nor the "summertime only" riders will be facing this issue anytime soon...

The seams on the swing-arm of my '00 ST don't show signs of corrosion yet, but I treat it with ACF-50 on regular bases which seems to keep the problem at bay so far...

Just found a low mileage swing-arm for decent money (€ 180,-... incl P&P! ) to restock my shed and will mull over lasting solutions with a friend of mine who is in car bodywork and does a lot on old-timers once it arrives and is fully cleaned...

 

[Upt' North]

I imported one from the states last year and it's now sitting in painted and waxoil glory as a just in case. The swingarm was peanuts, the postage and duty not so. But I think it was about £200.00 painted and put away which I guess I could recover if I never need it on the bike.
I did post pictures on here but it's a while back.
My own started to touch the tyre but it was just the flap which appeared affected and was soon remedied but your inside pick shows you don't know what's going on inside, but how do you with a replacement?
Upt'North.

 

[ST1100Y]

One can glance at the welding seams to determine corrosion being present or not...
An eBay search unveils quite a few which must have been sitting on the bottom of the ocean for some time...
I just wouldn't dare to put such up for sale... (but the same goes for stuff like rotors worn down beyond recognition offered there...)
The one I had in the shelf was obtained years ago, wrapped in plastic and stored "just in case"...

 

[ST1100Y]

Had a shipment arriving today, being a happy camper again...



Donor bike had 33K-km/20Kmiles on, hence the thing looking like new...

I'll add some drain bores (which I'll fit rubber plugs in) and flood the cavities with ACF-50...

 

[ReSTored]

I'll add some drain bores (which I'll fit rubber plugs in) and flood the cavities with ACF-50...

Not an issue where I live as virtually no one rides during the winter months when salt and brine are used heavily. Adding drain holes and spraying some kind of preservative into the cavity seems like good ideas.

I'm not thrilled with the mickey mouse construction of the exhaust 4 into 2 collector box and when the rear wheel is off I give it a good scrub with a wire brush and spray it with WD40 to slow down rust. The whole design and execution of this seems poor and not in line with the rest of the bike. just like leaving an open water collecting cavity on the swingarm.

 

[jrp]

To help protect the swing-arm from crap thrown up by rear tire, some ST1100 owners have extended the part of the rear fender that sits directly behind the center of the swing-arm:

 

[DeanR]

To help protect the swingarm from crap thrown up by rear tire, some ST1100 owners have extended the part of the rear fender that sits directly behind the center of the swingarm

Is there a template floating around for that homemade extension?

 

[Sheriff41]

Have you considered something like this? https://www.eastwood.com/eastwood-internal-frame-coating-14oz-aerosol.html

Works good in my old VW's heater channels.

 

[ST1100Y]

To help protect the swingarm from crap thrown up by rear tire, some ST1100 owners have extended the part of the rear fender that sits directly behind the center of the swingarm:

Yes, but while the flap might keep wheel spray and pebble blast away from the cross-member, is it rubbing paint, primer as well the galvanized layer off other areas of the arms, hence possible just relocated the issue...
And the parts wrapping around the arms (creating the gaps left & right) are still oncovered...

 

[ST1100Y]

I'm not thrilled with the mickey mouse construction of the exhaust 4 into 2 collector box and when the rear wheel is off I give it a good scrub with a wire brush and spray it with WD40 to slow down rust.

I'm keeping that at bay by applying copper slip as well as copper spray on those areas at any occasion the wheel comes out...
So far no rust on the clamps, bolts or the collector...

 

[ST1100Y]

Have you considered something like this? https://www.eastwood.com/eastwood-internal-frame-coating-14oz-aerosol.html

I've been mulling over such (like WaxOil), but ACF-50 seeps deeper into micro gaps, and I'm not sure about the issues of possible wax leaks/dripping in the area of the rear tire...

 

[aSTerix]

I've been mulling over such (like WaxOil), but ACF-50 seeps deeper into micro gaps, and I'm not sure about the issues of possible wax leaks/dripping in the area of the rear tire...

I'm loving the ACF-50 , drenched my newly stripped and repainted swing arm with it then wrapped it in cling film, by the time I get to use the swing arm , the ACF-50 will have migrated into all the nooks and crannies. I recall it lasts for about 15 months and then needs re-applying .

As an aside , I had a chunk of paint fall off my bike trailer (the trailer that I put the bike onto ) exposing rust, just sprayed ACF-50 onto the rust and within a day the ACF-50 had done its job, at some point I will prime and paint the patch but not in any hurry

 

[SMSW]

I am highly skeptical of rust preventers' claims having tried a number of them and seen them fail. However, Locktite Extend Rust Neutralizer is pretty impressive. I painted it on a steel step bumper on my box truck that was rusting through and it bonded with the rust, turned it black, and seemed to prevent additional rust on the top surface where I had applied it. The bottom of the bumper, which was not very accessible continued to rust and flake away until I had to replace the entire thing. I don't know if this stuff can be used to coat internal cavities, but it is a product worth researching. BTW, if you try it, follow the directions. The stuff hardens when exposed to moisture and if you contaminate the bottle of Extend (by dipping your brush into it and then painting with it) and store it for any length of time, you will find it has become a solid mass. Better to pour a little into a disposable container and use that. Don't pour the excess back in the original bottle.

 

[mello dude]

I am highly skeptical of rust preventers' claims having tried a number of them and seen them fail. However, Locktite Extend Rust Neutralizer is pretty impressive. I painted it on a steel step bumper on my box truck that was rusting through and it bonded with the rust, turned it black, and seemed to prevent additional rust on the top surface where I had applied it. The bottom of the bumper, which was not very accessible continued to rust and flake away until I had to replace the entire thing. I don't know if this stuff can be used to coat internal cavities, but it is a product worth researching. BTW, if you try it, follow the directions. The stuff hardens when exposed to moisture and if you contaminate the bottle of Extend (by dipping your brush into it and then painting with it) and store it for any length of time, you will find it has become a solid mass. Better to pour a little into a disposable container and use that. Don't pour the excess back in the original bottle.

I'm a fan of the Extend Neutralizer as well. I use it any where a rust spot may be developing. And as a buyer of older used cars , I have even used it to patch from the inside of a rusty panel by painting some of it onto a fiberglass mat and sticking it over the the rust. It turns hard and is solid for years. I also like to paint the nooks and crannies of a car where water seeps in. I 'm cheap and I keep cars a long time.

I wouldn't hesitate to flood the inside of a swing arm with it...