37 replies to this topic

[stoneface]

Hi Spider, I have been following this thread with interest.

 

I have a few sets of forks I’d considered resurfacing but so far not had the time, need or inclination to progress with it.

 

If we assume they are aluminium bronze, then they could be resurfaced with aluminium bronze brazing/welding rod by the tig process with pure argon gas and pre-heating of the part.

 

You could also mig braze/weld with aluminium bronze wire which would probably be easier, relatively. Never tried it.

 

Another option is spray metal transfer with an oxy-acetylene spray torch and powder such as Eutectic. I have a set in the workshop somewhere but not used it in 20+ years.

 

I’ve no idea what grade the forks are and I’m not sure it matters that much.

 

What probably matters more is the grade of rods, wire, or powder you use as most will stick, weld, bond, or whatever you wish to call it to a variety of base metals.  

 

Another method could be selective bronze plating, but I don’t know much about this and if it would work or what thickness could be built up.

 

Fancy welding materials and processes are not cheap. And then you have to re-machine them or get them machined.

 

I would be interested if someone has a go at it and how it works out, but it’s not near the top of my very long to do list.

 

If you are worried about the materal grade, just thinking outside the box, and without really looking deeply at the part. Maybe the forks could be cut down the centre, squashed together slightly and the cut then brazed/welded back up.

 

 

[gaspen]

 

 Maybe the forks could be cut down the centre, squashed together slightly and the cut then brazed/welded back up.

 

That is what I wrote to my friend some days ago    

 

I sent the question for the local companies, now I have one response where they take a look at the forks. 

 

I think there will some process after the holidays

Edited by gaspen, 18 December 2023 - 09:44 PM.

[Gaz66]

I would hazard a guess that all these suggestions of renovation will be more costly than buying a new set of forks!

[gaspen]

I would hazard a guess that all these suggestions of renovation will be more costly than buying a new set of forks!

 

This is the question which for we need an answer  

Edited by gaspen, 18 December 2023 - 10:05 PM.

[stoneface]

If you can do it yourself then cost is not as big of an issue.

 

And even new forks are often on the limit of acceptability.

[Spider]

Many thanks Stony for your thoughts.

 

Locally in Australia a single Rod Shift Fork retails around $300 AUD.

 

I have to say though, my interest in doing them is not so much the cost, but I feel the original Rod Shift Fork for 1st / 2nd is a less than ideal design. It has 4 small 'pads' for pushing the Hub Track over. With a vehicle that's driven around town a lot, I have observed over the years that this fork has a poor life span due to this.

 

My idea (and like yourself, I haven't had time to follow through) is to build up some worn forks Nd maybe even some new ones too), adding material not just to the original pads but also fill in in between them. Then re-machine them back to size.

And that now reminds me of the other reason I was looking at this. The factory give a wear limit clearance of 0.015" for these forks. I would say around 60% of the new ones I've had over the last 15 or so years have been out of spec, right out of the bag. So, reclaiming them is also a means to correct this quality issue.

 

For me, the only cost would be the Rods and any Flux I might need, the rest is just a few hours of my time.

 

 

I'm not sure that slitting a work fork down the middle and then 'sticking' the 2 halves back together would be a good idea. My reason for that is the fork will end up out of alignment to the lower fork that the bell cranks engage in to, so in particular, when in Neutral, the Hubs will end up biased towards 2nd and 4th gears, possibly prematurely wearing the Baulk Rings for those gears.

[nicklouse]

The factory give a wear limit clearance of 0.015" for these forks.

Chris how is this measured?

[Ethel]

I think the adding metal bit could be a mates rates job, if you can find somewhere that works with the stuff. Like I said, they made boat props  out of ally bronze & there's bound to be a repair market for spinny things bobbing about above rocks etc. 

 

The machining could be pretty complex. I guess they were originally done with a purpose made cutter of the right diameter & thickness. Possibly clamping against the machined slot to bore the hole for the rod in the correct alignment.

 

Maybe something could be rigged up on a lathe with a fly cutter in the chuck & the fork mounted on a rod in the tool post - not very solid so you'd have to take some fine cuts. 

[Spider]

 

The factory give a wear limit clearance of 0.015" for these forks.

 

Chris how is this measured?

 

I check them using a feeler gauge between the fork and the Ring on the Outer Synchro Hub Track, though you could set up a DTI to check them too.

 

 

While I know you're on top of it Nick, for the uninitiated, when the Selector Fork (Change Speed Fork in factory lingo) becomes excessive, when a gear is selected, it won't go all the way in, with the Syncho Hub Detents not engaging. This results in it jumping back out of gear, usually on the application of power. After it does that about 6 - 10 times, it rounds off the Dogs on the Gear and to a lesser extent, on the Synchro Hub, then it will never hold gear, even if the Selector Fork is later replaced. It makes an expensive repair even more, much more, expensive.

 

 

The machining could be pretty complex. I guess they were originally done with a purpose made cutter of the right diameter & thickness. Possibly clamping against the machined slot to bore the hole for the rod in the correct alignment.

 

Maybe something could be rigged up on a lathe with a fly cutter in the chuck & the fork mounted on a rod in the tool post - not very solid so you'd have to take some fine cuts. 

 

I've thought about this on and off many times. I'd make a fixture for sure, it would just make the job so much easier and repeatable. While they could be machined in a lathe, I'd most likely do them using the Fixture in the Rotary Table on the Mill. I'd say the factory most likely had a cutter that would have done both faces of the fork in a single operation, though, to maintain precision and finish, I'd only at one side at a time.
 

[gaspen]

Earlier this month I bought a pair of forks from Spain, he said the are NOS's. I've asked him to measure the forks before payment, but this request was lost on the web. So I believed they will be fine. (115EUR for the pair with shipping seemed a fair price)

 

This is what I got : 3/4 is spot on, but 1/2 is scrap

 

https://photos.app.g...fccnNBDavroAsS7

 

About the machining : maybe we can use the fork's own shaft to fit to the lathe/milling machine's table and machine it with little feed(?)

 

But I am not an expert just try to use my brain 

[GraemeC]

Out of the box thinking (and that's maybe where it should stay) - how about adding material to the synchro? Possibly a shim, but this may not be too successful on a rotating part.

[gaspen]

Out of the box thinking (and that's maybe where it should stay) - how about adding material to the synchro? Possibly a shim, but this may not be too successful on a rotating part.

 

I guess it is a hardened surface and it should be heat treated after the welding but I'm not sure.

 

Shims will wear out, possibly into little pieces....

 

Question : what if I sacrifice one fork - I mean its material - to repair anothers ? 

[Spider]

Yeah, that NOS fork is good for nothing as it is !

Graeme, not a bad idea, but I'm not sure how to do that. In a scratch built sketch I play around with, I have bearings on the Hubs but I'm not sure it's practical.

Another idea I have had was to fit replaceable faces in the forks.

[Ethel]

I've thought about this on and off many times. I'd make a fixture for sure, it would just make the job so much easier and repeatable. While they could be machined in a lathe, I'd most likely do them using the Fixture in the Rotary Table on the Mill. I'd say the factory most likely had a cutter that would have done both faces of the fork in a single operation, though, to maintain precision and finish, I'd only at one side at a time.

 

 

 

Sure, I'm just trying to brainstorm (fart) a least cost 'n most amateurish way to do it. Agree, the best solution  would be for some kindly expert machinist to gather up all the dead ones and do a batch of 'em 

 

If you were try a replaceable face approach, might it be easier to fab up some sort of carrier, a bit like a brake caliper & pad arrangement?

The forces involved can't be too bad, even with a foot & half of gearstick. I'm imagining a kind of sandwich of CNC cut plates & possibly a scrap gearbox to serve as a welding jig.

[nicklouse]

 

I've thought about this on and off many times. I'd make a fixture for sure, it would just make the job so much easier and repeatable. While they could be machined in a lathe, I'd most likely do them using the Fixture in the Rotary Table on the Mill. I'd say the factory most likely had a cutter that would have done both faces of the fork in a single operation, though, to maintain precision and finish, I'd only at one side at a time.

 

 

 

Sure, I'm just trying to brainstorm (fart) a least cost 'n most amateurish way to do it. Agree, the best solution  would be for some kindly expert machinist to gather up all the dead ones and do a batch of 'em 

 

If you were try a replaceable face approach, might it be easier to fab up some sort of carrier, a bit like a brake caliper & pad arrangement?

The forces involved can't be too bad, even with a foot & half of gearstick. I'm imagining a kind of sandwich of CNC cut plates & possibly a scrap gearbox to serve as a welding jig.

 

I know Mr Guess is planning to get them recast.