Window Cable Tensioner

The windows in my 1975 308GT4 had become problematical. I cleaned and rebuilt the drive mechanisms (the old grease had the consistency of beeswax), cleaned and lubed the pulleys, sprayed the channels with silicone/teflon dry lube, etc. Still didn’t work well. I replaced the fusebox with one I fabricated using ATO-type fuses. Cleaned up all the connectors, including the ones on the relays. Still not good.

When I restrung the cable the static tensioner was at the limit of its adjustment and the cable seemed loose in some areas, tight in others. Overall it seemed too loose to me. I researched later 308 models (with Pininfarina bodies), and noticed that they retained the cable mechanism for the windows, but at some point they had added a dynamic, spring-loaded tensioner element. The 348 or Mondial (can’t remember) had an even more elaborate dynamic spring tensioner

So I cooked up a simple, easy to fabricate and install dynamic spring tensioner. I looked into sourcing a couple of pulleys (sheaves) and only found one place that had a plastic replacement for $47 each. Off to McMaster-Carr, where I found a slightly smaller nylon pulley with an integral bearing for $11 each.

https://www.mcmaster.com/catalog/126/1613 Item B, 3/32 cable, 1.5” OD. P/N 3434T15

The mechanism was fabricated out of ¾” x 1/8” aluminum bar stock from the local hardware store and the springs are available here:

https://www.amazon.com/gp/product/B008RFPA8C/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Here’s an image of the pieces. Note that they are assembled as mirror images, and the orientation of the pulleys is critical for alignment.


View attachment 3176427

 

No, but it stabilizes the cable so it can't slip off of any of the pulleys. I'm waiting for the relay modules I ordered to tackle the electrical issues.