Firewall speedo cable entry
Discussion
Just out of idle curiosity, has anyone else noticed how the speedo cable and bonnet release pass through the firewall adjacent to the pedal box?
As long as I've had my car I've been meaning to address the poor sealing - essentially an ill-fitting and perished rubber grommet, designed for sheet-steel thickness and not 8mm of GRP - on my car.
The hole in the firewall is 34mm diameter, while the knurled nut on the speedo cable is about 17mm and the bonnet release captive nuts are 7/16" (about 11mm) so I figured I could get them both through a 20mm hole. You can buy compression glands that go quite large (to fill the 34mm) but where's the fun in that? Why the hell they went so large is a mystery, unless the speedo cable was attached to the speedo first and then they realised how large the gearbox end fitting was...
Having rummaged around and found nothing that looked like it would be any more robust, I decided to make something.
I turned up some 50mm black acetal into a male and female threaded pair, stamped some rubber washers to fit around the 34mm thread and grovelled under the dash for some time until eventually it was all screwed together. My attempt at a neoprene stuffing insert didn't work, alas, so I had to resort to filling the remaining space around the cables with some silicone sealant
- but at least now no fumes or rainwater can sneak in that way.
Only took me 24 years to get around to it...
As long as I've had my car I've been meaning to address the poor sealing - essentially an ill-fitting and perished rubber grommet, designed for sheet-steel thickness and not 8mm of GRP - on my car.
The hole in the firewall is 34mm diameter, while the knurled nut on the speedo cable is about 17mm and the bonnet release captive nuts are 7/16" (about 11mm) so I figured I could get them both through a 20mm hole. You can buy compression glands that go quite large (to fill the 34mm) but where's the fun in that? Why the hell they went so large is a mystery, unless the speedo cable was attached to the speedo first and then they realised how large the gearbox end fitting was...
Having rummaged around and found nothing that looked like it would be any more robust, I decided to make something.
I turned up some 50mm black acetal into a male and female threaded pair, stamped some rubber washers to fit around the 34mm thread and grovelled under the dash for some time until eventually it was all screwed together. My attempt at a neoprene stuffing insert didn't work, alas, so I had to resort to filling the remaining space around the cables with some silicone sealant
- but at least now no fumes or rainwater can sneak in that way.Only took me 24 years to get around to it...
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