Seizing horseshoes

[Athame57]

Much is said of CB400F cam tensioner arms (horseshoes) seizing up, but I don't recall anything being said about repairing them. I'm soon to find out if my own is truly seized up but will this mean I need to buy a new one, or can I get it fixed?

[Nurse Julie]

High probability you'll be able to free it off and, fettle it and refit George.

[Bryanj]

Siezing is probably not wholly acurate, what happens is a loose camchain batters the metal of the pivot point and burrs it around the pivot, most of the time,but not all, you can fettle the pivot with heat a carefull filing but it can take a couple of hours to get right

[McCabe-Thiele (Ted)]

Bryan describes how mine was - it repaired easily enough the burr I filed away then a combination of heat & sovents to free the pivot that was gummed up with carbon deposits.

I did consider the alloy upgrade but in the end stayed with my original as it was so nice & free.

[Oddjob]

Keep the camchain properly tensioned and replace the chain when it needs it and it shouldn't happen again. The problem was owners not wanting to spend money on the bike and running the engine into the ground, saying that the design left a little to be desired IMO, far better to copy the 500/550 system but Honda decided not to for some reason. Maybe they just didn't foresee the problems the system would have, lets face it Honda are not well known for camchain tensioning design, CX500 anyone?

If nothing else I'd consider replacing or modifying the pivot pin, IIRC they look like dogs teeth when you remove them.

[Laverda Dave]

This is the horseshoe taken from the rat bike. The tensioner adjustment rod was still in its fully compressed position.
Luckily I was able to fix the horseshoe with the aid of a large dustbin and a wad of your best English pounds 

[Deano400]

Check the condition of the tensioner push rod. This is one I've just had to replace.

[ Guests cannot view attachments ]

[Mikep328]

"Luckily I was able to fix the horseshoe with the aid of a large dustbin and a wad of your best English pounds "

  LOL!  Often the best fix for a variety of issues!!

[Matt_Harrington]

I've repaired the horsehoes by judicial filing to free it all up.....

[McCabe-Thiele (Ted)]

To remove the carbon deposits in the pivot I soaked mine in oven cleaning gell for a couple of days, refreshing the gell after the first 24 hours when it had turned black.

[K2-K6]

To remove the carbon deposits in the pivot I soaked mine in oven cleaning gell for a couple of days, refreshing the gell after the first 24 hours when it had turned black.

It is exactly this that "seizes" them, oil going over critical temperature and baking into a harder sticky residue to stop movement.

Many engine from that period had been affected by such, with reformulation more obvious in products of early 1980s that show less susceptibility.  One of the most useful aspect of synthetics too, their vulnerability to high heat break down being moved substantially out of component latent heat operating range.

The chains are affected too, needing just pure oil flow through the pin/pivot sites to prevent captured oil there from passing critical temperature, the hi-vo primary an absolute copybook example of this working characteristic.

[McCabe-Thiele (Ted)]

I remember the days of  black sludge deposits all too well.

[K2-K6]

Yes Ted, I've experienced it literally inches deep in chocolate fudge cake like consistency within early 70s car engine, particularly aluminium cylinder head that look to have a higher heat transfer to the oil near and around the combustion chamber "skull cap" areas.