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clutch cable keeps breaking - other alternatives


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Hi all,

Yet another clutch cable failure on the Elite after only 1500 miles ;  this time with a new genuine Lotus cable and replacing the nylon pulley wheel with an alloy one. What seems to be happening is that Inner cable wears because it is not entering the outer cable at the pedal box squarely. There's no way to adjust the pulley height to compensate unless I feel like bending the mounting brackets holding the pulley which will probably end in disaster.

Are there any successful alternatives ?

I had a chat with Mike Taylor about using an Excel pedal box but it involves an awful lot of cutting and re fibreglassing so have eliminated this option

I've also considered fitting push type a master cylinder inside the car but the pedal travel would be too little.  Still thinking about this option.

Finally , I also saw on the forum that someone had replaced the pulley with a sprocket and run a small chain from the pedal to the inner cable.

Any ideas would be appreciated and hopefully I can get some use out of the car this year instead of leaving it as a street ornament! 

Regards,

Simon

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Simon, sorry to hear your woes - I've yet to get to the front end of my car but have been giving this issue a bit of thought. Like you I don't really want the hassle of the excel conversion. I am wondering about looking at motorbike assemblies to see if there are any useful pointers from them, given that pretty much all clutches on MBs are cable operated. I imagine the force required by lotus box would be bigger.

It occurs to me that 1 option may be a single 'cable' pulley system to open the clutch and a big spring to return the lower arm - removing the business of a small cable running inside an outer and pulling against each other.

There has to be a better way than standard design. If a push type master cylinder was somehow attached to the bottom of the pedal (maybe with an extended plunger rod) would there not be enough travel? Not sure how the slave cylinder attaches at the bell housing even if you do an Excel conversion?

I will keep thinking - let me know if you make any progress.

As an aside, where in Surbiton are you? I lived in Maple road for a couple of years in the late 90s. Nice area.

Cheers

Ant

http://www.handhsurplus.co.uk/product/land-rover-series-23-2-25-petrol-throttle-accelerator-linkage/

Suddenly thought about this and wonder if it can be adapted. S2-3 Landrover throttle linkage....maybe something along these lines. I like the idea of rods rather than cables....

Also wonder if silicone liquid (I have a small bottle with squirtable spout) poured into the cable would help keep it moving freely?

Is the price for that bit in Yen or £?

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Hi Simon

Another possible option is a Hydraulic slave cylinder like this one  http://www.wilwood.com/MasterCylinders/MasterCylinderList.aspx?group=Slave Cylinder

Not something I have done, but would have thought it would be possible to fit this sort of system.

http://projectzerog.com/wilwood_slave.shtml

Roland

 

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After three cables and 2 breakdowns still under warranty, the last one just half a year later, one of the PO, a former RAF engineer, has drawn his own solution on paper with comprehensive calcution of it. I should have the drawing, the manufacturing company and even the bill of it. Will have a look for it tomorrow for you guys. :)

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Hi Simon,

Because this cable has so much pressure on it requiring a heavy pedal is why it is a weak link with the Elite so I have decided to go the hydraulic method as well and I think this is the way to go even if I haven't had one of the original cables break yet.

Even though I now have a modified Buick 215 V8 aluminum engine in place of the 907 in my '74 Elite with a stiffer clutch to accept the more powerful engine, there is simply way too much pressure required to depress the clutch and no one today uses anything but hydraulics, as far as I know, so they are very reliable and isn't that what we want in this very enjoyable car.

Plus, the cable traveling through the engine bay is ugly and the location can't be modified even a little. I know some don't care about what it looks like in their engine bay but for me neatness counts in my car.

This is a modification I have been thinking about for a long time in my 35 years of owning and modifying my Elite for a more enjoyable ride and improved reliability.

 

atb,

Richard

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sorry for the delay guys, but... the invoices were quick at hand, but the drawings ... for that I have had to turn the office from the ceiling to the ground :stuart: twice...

Never the less, attached you will find the two invoices for the cable and the chain next to the drawing. The parts are now in for 20years. btw the clutch is not heavy to use... It is like in a normal average car from today.

IMG_3507.jpg

IMG_3509.jpg

IMG_3511.JPG

IMG_3508.JPG

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  • 3 weeks later...

Hi Simon

This is really funny timing, me reading this post, I have on my work bench 8 sets of specially designed clutch pulley and chain replacement parts. I had the same problem with the clutch cable breaking on my éclat and I've designed and made a kit to replace the pulley and short length of cable. I've had one in use for the past year or more now and no problems as yet. I've got a small amount of machining to do on the parts and the idea was to put up a post on here and maybe a an eBay listing. If I get to the workshop today I'll post some pictures.

Re. Why the cable breaks so often. From my experience, It's a compound problem. An issue is, as you've pointed out, the sharp U bend on the cable to the pedal. The other issue to address is the clutch bearing wearing away the tube/sleeve that it slides on to form a step/stop at the end of the bearing travel. What you may find is that when the engine is hot the clutch pedal becomes very hard to push down and extra stress is put on the cable. This is because, when hot, the clutch bell housing expands and moves the bearing away from the clutch and the bearing then needs to travel further to contact the clutch, except the bearing then has to get past the step in the sleeve that it has formed, which it may not be able to. Hence, broken cables.

The problem was caused by some clutch bearings having a very sharp corner on the internal diameter. This sharp corner wore the sleeve away. I think modern bearings have a plastic internal sleeve, which should negate the problem.

The chain and sprocket conversion won't solve a bearing problem but it makes the pedal much easier to push down and you can use a plastic covered cable for the majority of the cable length, which also reduces friction.

More soon. 

Max

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Here's a picture of an early model. I've included in the picture the old nylon pulley for size comparison and an updated end piece.

The kit will include

The chain and connecting parts (1 piece)

Sprocket and sleeve axle

Small amount of silicone grease for the sleeve axle

Instructions for mounting, including dimensions to cut clutch inner cable to.  ( you'll need some very good wire cutters for this)

More soon

Max

 

 

Version 2.png

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Hi Max, I am really keen to buy one of these kits from you.  I've got the Essex Elite S2.2, and the weakest point of the car is the clutch pulley assembly.  I carry a spare clutch cable with me (two snaps in 30,000 miles despite lubrication), and I would love to have a permanent solution, which your kit should provide.  In fact I am already planning to swap the entire pedal box this spring, as my existing pedal box has a deformed pulley mounting bracket where the forces have pulled the pulley's axle towards the pedal, if you see what I mean.  So I bought a replacement pedal box, have strengthened the pulley mounting area, made a bushed axle for the pulley and was intending to fit the pedal box some time soon. But now I'll wait a bit longer and use your brilliant solution.

Are you in the south of England? I'm near Oxford and would happily bring the pedal box over to you if that helped you finish the arrangement to make the kits available.

Leigh

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  • 5 weeks later...
On Tuesday, March 21, 2017 at 10:27, xam69 said:

Here's a picture of an early model. I've included in the picture the old nylon pulley for size comparison and an updated end piece.

The kit will include

The chain and connecting parts (1 piece)

Sprocket and sleeve axle

Small amount of silicone grease for the sleeve axle

Instructions for mounting, including dimensions to cut clutch inner cable to.  ( you'll need some very good wire cutters for this)

More soon

Max

 

 

Version 2.png

Did you managw to put these kits together and If so where can we get them and how much?

 

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Sorry about the delays in getting back. Been tied up with work jobs and things. I have some kits ready but need to check on legalities and liabilities of selling the items. I think It's out of the scope of my usual business insurance.

Some legal advice would be much welcome. Maybe someone knows about product liability.

Max

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Hi Max,

I can see where you are coming from regarding your “concerns”, but, playing devils advocate wouldn’t the worst that could happen be a broken clutch cable mechanism. (can't see this happening though)

 Would this not be the same as the cable straining with the original “flawed” design and it snapping anyway?

The way I see it is. You have tested the mechanism over a number of months, you are obviously happy with it enough to share it with others as solution to a flawed design/problem.

Isn’t this what we Brits do, Men in sheds righting wrongs for our fellow Man or Woman  For which we would all be eternally grateful

Just my two pence worth.

Roland

P.S. We could all be your test pilots, make a "donation" for the device, to see if you are an engineering genius....or not :lol:

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