Keep Bending Heater Cable - Need Routing

[djwarner]

There was a technical service bulletin covering this issue. TS71-25 dated May 11, 1971. I believe we should have a book of TSB in the documents file on this site. If not, I can donate a copy.

[Namerow]

39 minutes ago, djwarner said:

There was a technical service bulletin covering this issue. TS71-25 dated May 11, 1971. I believe we should have a book of TSB in the documents file on this site. If not, I can donate a copy.

I just read that bulletin.  It does zero in on bent cables associated with the 'heater-vent control flap', saying that the flap may stick because of 'excess adhesive' (the two big control control flaps have skinned-foam padding bonded to both sides to help them seal better and also to help prevent unseemly 'clanging' noises when the flap snaps shut).

The TSB recommends that the technician fab their own replacement cable using 0.049" music wire (1.25mm).  They offer this interesting recommendation for forming a modified 'device-end' bend...

It seems that it's only intended to keep an overloaded cable from slipping through the engagement hole in the control lever arm, rather than a way of offering some compliance.

Personally, I wouldn't get too excited over the need to buy 'factory original' cables.  It's only wire.  Buy some and bend it to shape.  I pre-tested the 'oversize' 1,3mm wire in the Series 1 plastic sheathing and it works just fine.  Not even a whiff of binding.  So now I'm running the 'big' 1.3mm cable, complete with my DIY, custom-bent Series 1-style bent (no loops) ends while preserving the original Series 1 cable sheathing.  Although the system hasn't been put back in the car yet for final testing, I'm confident it's going to work just fine.  Everything's been clean and lubed, all the flap pivots ditto, and the 1.3mm cables are 70% bigger in cross-sectional area than the original 1.0mm cables, so they're going to be a lot stronger.  The loop-and-pin design of the later system is definitely a better mechanical design, but I prefer the 'flawed design integrity' of the older system.

[sweatybetty]

6 hours ago, Hardway said:

 mine has a screw and threaded barrel with a hole in it to accommodate the end of the cable to be inserted and tightened with the screw.  (Just like in the picture Namerow posted)  I am assuming/hoping this means the loop will go around the outside of the barrel and I can put a small washer on the screw to prevent the cable loop from slipping off.

no. just insert the end of the cable through the  barrel, tighten the screw and you are done

[djwarner]

For those interested in functionality rather than restoration, hobby shops specializing in radio controlled aircraft sell low resistance, flexible plastic pushrods with clevis ends. These rods work well with the loads involved and have the advantages of being adjustable, local and cheap.

Edited November 2, 2016 by djwarner

[Hardway]

17 hours ago, Namerow said:

So now I'm running the 'big' 1.3mm cable, complete with my DIY, custom-bent Series 1-style bent (no loops) ends while preserving the original Series 1 cable sheathing.  Although the system hasn't been put back in the car yet for final testing, I'm confident it's going to work just fine.  Everything's been clean and lubed, all the flap pivots ditto, and the 1.3mm cables are 70% bigger in cross-sectional area than the original 1.0mm cables, so they're going to be a lot stronger.  The loop-and-pin design of the later system is definitely a better mechanical design, but I prefer the 'flawed design integrity' of the older system.

I like this idea your quote of the flawed design integrity of the original system.  Where did you find your 1.3mm music/piano wire?  I see that 16 wire is 1.3mm - 1.5mm thick.  Looks like they carry this as picture hanging wire.  Would this work or does it need to be hardened to keep it from bending?

Edited November 2, 2016 by Hardway

[Captain Obvious]

I'm not sure if picture hanging wire you would find at a hardware store is going to be good enough for this. You definitely need something pretty high quality for this. You definitely need something heat treated. Probably tempered back from full hard, but certainly not something annealed and malleable.

Couple ideas:

Last time I needed a cable for something similar, I went to a junkyard and harvested a cable from another vehicle. Didn't matter what it came from as long as it was longer than what I needed. I then trimmed the jacket and snipped the wire to fit and bent the necessary features on the ends of the wire.

Other idea would be to support absolutely as much of the wire as possible. In other words... Extend the jacketing beyond the clamp(s) as far as you can before they start to interfere with the movement of the actuating arm. I don't know anything about the 240 control head as all my experience is with later designs, but it looks like you might be able to extend the jacket a half inch or more to help support the cable before it gets to the arm?

[Zed Head]

Piano wire is a type of heat-treated steel wire.  It's a "thing".  The good hardware stores carry it, it's actually pretty common.  The one I got was better than the factory wire, I thought,  Very stiff. https://en.wikipedia.org/wiki/Piano_wire

Getting a used part from a wrecking is a good idea.  You have to look a little harder to find a long enough wire though.  Most newer cars are more compact and don't have their valves far from the actuator.  I went through this search when i was modifying my heater water ****.  I think CO did too.

[Namerow]

17 hours ago, Hardway said:

Where did you find your 1.3mm music/piano wire?

I bought my wire over the counter from the local outlet of Canada's equivalent of McMaster-Carr (Acklands-Grainger).  They stock several different gauges...

https://www.acklandsgrainger.com/en/product/WIRE-MUSIC-22-049-1LB-COIL/_/R-CMG66MW049

Important to note that the Series 1 system uses not only different-size wire but also different-size cable sheathing in comparison with the later, revised system.  I'll fill you in on that later.  Out of time right now.

[sweatybetty]

i bought wire from grainger, and the outer sheathing at a local bicycle shop. maybe $20 for everything

[Namerow]

More on the OE cable sheathing...

Early-type sheathing has an OD of 0.18" and fits a 0.039" (1.0mm) wire.

Later-type sheathing has an OD of 0.19" and fits a 0.051" (1.3mm) wire.

BTW, the Z's carb choke cable wire measures as 0.055" (1.4mm).

[Hardway]

So I am looking to order some music wire from Grainger and running in to an issue that even their people can't fully explain.  On their website, 1.295mm wire is shown as .051 inches and a gauge of 23.  Their website actually shows it as 10.295mm but that is obviously wrong.  On Inspire with Wire's website and others they show 1.3mm to be 16 gauge.  22 gauge on their site (they don't have 23) shows to be .64mm.  According to dewitt tools conversion chart, 1.3mm is .05118 inches so it leads me to believe the gauge of 23 that Grainger is showing is incorrect.  I only want to order wire one time as Grainger only sells it by the pound which provides well over 100ft of cable.  What do I order?

[Zed Head]

You live in Texas, surrounded by industry, and can't find a hardware store with piano wire?  I live in the Portland metro area and found it at a True Value store.  It came in three foot length's, if I recall.  Sometimes the internet makes things so easy they actually get more difficult.