(305) Finally, no more failed clutch cables!!!

[nametooshort]

So, as im sure you all know, I really like my 305. I got it originally because somebody told me it would be like a oldschool passat (big, ugly and practical) only better, and since then I havn't regretted it.

But there are two things I don't like about it that major bug me.

The minor one is the brakes. The front brakes are not great.

The major one is the clutch cable. No matter what I did, it kept eating through clutch cables, and so they all do it seems. One cable lasts less than 1k miles, and worst, fails without warning.

It seems that there are basically three failure modes, both involving the plastic end-flange that clips to the firewall.

The cable, which is molded into the flange, can just break the molding and pull through.

One of the flange's ears (which keep it located in the hole in the firewall) can break off, which allows the cable to grind against the metal edge of the firewall which cuts the cable very quickly.

Or, finally, the flange does not break, but deforms/bends, which allows the cable to eat it's way though the side of the flange until it gets to the metal firewall, when it again gets cut very quickly.

It seems that the problem is that all modern cables are made by the same company (and sold by various under various brands), but they are all the same product. The plastic that's used in them is just too soft. I think the original cables from back in the day were made of a different material, but nowadays the company that makes the cheap pattern copies that everyone sells obviously just copied it with the cheapest plastic their manufacturer could get, or whatever.

I don't know the whole story but what I do know is that every 305 that I know suffers from the problem, and mine specially. I have been through so many cables, and I only owned it for like, what, a couple of years?

Well, whatever, enough is enough, I decided that I need to fix this, as randomly losing the clutch in traffic is awkward.

So, at first I looked into 3 options:

1) Using a oldschool trick developed by various people, which is to use a battery terminal (the kind that clamps onto the cable) and clamp it around the cable. This fixes the pulling-through issue, but doesn't fix the breaking-off-ears issue.

2) Using the method that came from European cabbies from the 90s (I believe?) which is to remove the plastic flange and get a machine shop to make a two-part clamp-on flange out of aluminum or steel, so you can clamp it onto a stock clutch cable.

3) Just lost the whole transmission all together and fit a auto transmission. Problem solved.

But then I remembered a dumb idea that I had a while back. The 305 xud transmission was shared with a whole bunch of vehicles, including the Talbot Horizon. The Horizon was the only one which had that tranny and a hydraulic clutch.

Sure enough, my 305 had the lugs machined into the transmission casing to take the slave cylinder. I tried this before but it didn't work, but now I realized what I was missing before, and tried it again and it actually worked.

So, anyways, long story short, after a custom-made pedal cluster firewall insert plate thing whatever it's called, a Talbot Horizon slave cylinder bolted to the location where it would have been if it was a Talbot Horizon, and a generic master cylinder (the kind they use in drift cars and such), and some custom made linkages and plumbing, I now have a fully working hydraulic clutch system in my 305!

So far it seems to work great. The drag racing cylinder is 19.05mm and the Horizon slave cylinder is 22.something mm. Cable clutches waste a lot of pedal movement space, because they have to account for cable stretch and also for adjustment position, so more leverage is possible with a hydraulic clutch for the same given pedal stroke. In practice the 19mm/22mm master/slave ratio, combined with the leverage of the pedal being moved slightly further from the stock pivot distance, means the pedal to clutch leverage ratio is a bit higher, but because the clutch slave position is self-adjusting it can be higher. It gives the same stroke as stock at the clutch end, but utilizes the entire stroke of the pedal end to achieve that, which results in a very light and comfortable clutch.

The clutch master cylinder sticks out of the firewall just under the brake master cylinder/servo.

All the pushrods and mechanism geometry have been designed to have plenty of free slack in all conditions, whether with a brand new or a almost dead clutch, to make sure the clutch not releasing properly issues that the Horizon was known for is not possible with this setup.

So, there we go. Problem finally solved, at least for me. Sure it was heavy on the custom work and probably cost more than the car is worth, but, it IS my favorite car.

And now at least I won't have to change no clutch cables every month ever again!

[spider]

Excellent.

[nametooshort]

So, this is a diagram of what the whole mess looks like in the end after some more tweaking.

So far seems to work surprisingly well!



The custom pressure hose is a teflon/stainless steel braid hose and came from a company that makes hoses for racing stuff and such, as did the generic master cylinder (as found in adjustable-bias brake systems etc). The teflon/stainless hose is probably way over-kill, and just a nylon hose would be fine, however I couldn't find any companies that make nylon clutch lines like old cars used to have, so just used a typical modern style teflon/stainless hose instead.

In the original prototype, just to see if it would work, the clutch line from the master to the slave was made of various sections of copper brake pipe (both 4.76 and 6mm) connected with various assortments of fittings (including a flexi hose from something really random like the stick version of a Blazer or something) to make it all fit together, however once I made sure the setup worked properly, I just ordered a custom pipe instead to replace all that.

The feed hose is actually a Honda HRV (or CRV?) front brake hose. In the prototype stage it was a piece of copped pipe with a brake-line style flare and pipe end, connected to a piece of brake-fluid-proof silicone hose, connected to the Volkswagen fluid bottle, however this caused some clearance problems, and since the Volkswagen fluid bottle has a really small outlet, which a cut brake hose fits on nicely, and the Honda brake hose already has a banjo fitting, we decided to just drill the banjo for 7/16 inch (which is almost exactly M11) and then just cut the hose to length and connect it directly to the fluid bottle with a ear-style crush-clip just in case.

So, there, I finally achieved it, yay!