FT: Frame (Twin) RFM wear through the FT66 bore

[Dreamer]

What's the 'normal' repair for any wear in the RFM where the FT66 (cross shaft) passes through. I'm more concerned that greasing that cavity will just result in grease exiting by the clearance rather than getting to the taper bearings. Perhaps I should also ask 'what's OK wear?'.

Hi Steve, Did you eventually find a solution to your cross over shaft problem? Did you remove it from the RFM and how did you do that. The cross over shaft in my Comet doesn't rotate freely, it's very tight, and I'm considering removing it and see what's the problem.

 

[Martyn Goodwin]

Hi Steve, Did you eventually find a solution to your cross over shaft problem? Did you remove it from the RFM and how did you do that. The cross over shaft in my Comet doesn't rotate freely, it's very tight, and I'm considering removing it and see what's the problem.

I recently replaced the bearings in my RFM (see OVR #70 - it's in the OVR Archives) and at that time like you, I found the brake cross shaft FT66/1 was very stiff in the frame.

My fix was a complete bearing service of the RFM. Once I had it stripped down I used a 5/8" parallel reamer to clean up the corrosion in the cross shaft bore. Having removed the grease niples I used a suitable sized drill bit to clean up the grease passages. I also used a flex drive tool with suitable wire brushes to clean out as much of the accumulated corrosion as possible from the inside of the RFM main casting. Before reassembly I applied a liberal (possibly excessive) quantity of a rust preventer to the interior of the casting in an endeavour to prevent recurrence of corrosion in there.

Within the RFM , behind each pivot bearing, there is the pivot bearing dust washer F42/1 that also acts as a grease retainer. With that retainer in place and the grease passageways clear, when you apply a grease gun to the nipples on the RFM assembly, grease is forced into the main pivot roller bearings AND into the plain bearing areas around the cross over shaft.

With all the accumulated corrosion (crap) removed from the inside if the RFM casting, the cross shaft bearing surfaces cleaned up and the grease ways unblocked, following reassembly all is now working smoothly in my RFM. To keep it working that way all that's now needed is the occasional squirt of grease via the nipples on the RFM casting.

 

[Dreamer]

Thanks Martyn for your response. Did you pressed out the cross over shaft after heating up the exterior of the cross over bore? I've read your article on swing are bearings in OVR 70 and I'm following the processed outlined and I'm planning to replace everything and also fit the Nilos seals.

I bought a packet of tobacco pipe cleaners (50 for $3) which I'll dip in kerosene to clean out the grease pathways.

 

[Martyn Goodwin]

Thanks Martyn for your response. Did you pressed out the cross over shaft after heating up the exterior of the cross over bore? I've read your article on swing are bearings in OVR 70 and I'm following the processed outlined and I'm planning to replace everything and also fit the Nilos seals.

I bought a packet of tobacco pipe cleaners (50 for $3) which I'll dip in kerosene to clean out the grease pathways.

The cross over shaft is 'meant' to be a slide fit. I applied liberal amounts of WD40 and then used a suitable sized drift and a 4 lb. hammer to tap it free. To protect the thread fit a nut to the end you tap on - once you break the corrosion seal you can remove the nut - then the shaft should be able to be drifted out with just a little encouragement . Remember Tap - dont bash.

With my rebuild I ended up NOT using Nilos seals but rather the standard F42 pivot bearing dust seals as I realised that there is simply insufficient movement at the rfm pivot for the Nilos to work properly. The seal for a Nilos Ring is obtained when the leading edge of the seal, rotating under slight pressure, laps the surface of the inner or outer bearing ring. This lapping process creates the sealing surface which keeps grease in and contaminants out of the bearing. I don't think there is sufficient movement to perform the 'lapping'

Reminder - the factory drawings for both the inner and outer dust/grease seals F42 and F42/1 bears the cryptic notation “To be dressed on assembly”, in other words, the OD is intended to be linished or filed down till they are a snug but easy fit.


M

 

[Dreamer]

Thanks Martyn for your suggestions.

 

[vibrac]

I have often considered but never taken further the replacement of the tapered bearings with a low friction plastic inserts I am sure the radial movement of the RRM is small I know wear has been reported when lots of trailer use has-been encountered

 

[Martyn Goodwin]

I have often considered but never taken further the replacement of the tapered bearings with a low friction plastic inserts I am sure the radial movement of the RRM is small I know wear has been reported when lots of trailer use has-been encountered

I have never considered towing a trailer with my Comet. Still it's an interesting line of thought

 

[bmetcalf]

A trailer doesn’t seem like a larger burden than a chair, depending on the load, of course.

 

[oexing]

Taper roller bearings are quite OK in the swing arm but I will try a spherical bearing like in my link. One side is hard chromed, the mating partner a teflon type maintenance free cup. Some friction in there is no factor here but what´s great, no grease and water is not a problem, dirt is.

Vic
spherical bearing

 

[vibrac]

Trailer as in Trailer queens taken to rallies and exhibitions constant hammering of a single roller on one point of the race