Printable Version of Topic
Click here to view this topic in its original format
914World.com _ 914World Garage _ I need to know the pressure to depress the clutch pedal.
Posted by: bdstone914 Jul 30 2017, 07:56 PM
Why you ask ?
I have an idea to use a ball bearing in the clutch arm shaft of a pedal set to prevent the wear that occurs with the bushing bearings. Half of the ones I see have worn through the bearing and into the arm. Have to weld the hole and file round again. The other problem is the shafts get rusted internally making the bearings sloppy. New ones are about $65 from Porsche and are NLA for 74-89 911's. 1 I figured it will be easier to make a whole new shaft by laser cutting the lever, welding it to a 14mm shaft and drill a hole for the roll pin. I found a 6mm ID, 6mm width and 19mm OD bearing. I can have the lever made to accept the bearing.
The bearing has a 525 dynamic lb axial load limit. My calculations on a 914 pedal set are that is is a 6:1 lever ratio. So if if take 40 lb to depress the clutch the bearing will see 240 lb of axial load. Later 911's have a longer lever and clutch pedal.
So can anyone with fish scale tie a rope around the clutch pedal and to the fish scale and see how much pressure it takes?
Would be nice to see if 6 conversions with bigger engines and higher pressure plates take more pressure. Also 72 and later 911's with the 915 trans.
Going to need some one to test the first prototype too.
Posted by: rgalla9146 Jul 30 2017, 09:23 PM
Why you ask ?
I have an idea to use a ball bearing in the clutch arm shaft of a pedal set to prevent the wear that occurs with the bushing bearings. Half of the ones I see have worn through the bearing and into the arm. Have to weld the hole and file round again. The other problem is the shafts get rusted internally making the bearings sloppy. New ones are about $65 from Porsche and are NLA for 74-89 911's. 1 I figured it will be easier to make a whole new shaft by laser cutting the lever, welding it to a 14mm shaft and drill a hole for the roll pin. I found a 6mm ID, 6mm width and 19mm OD bearing. I can have the lever made to accept the bearing.
The bearing has a 525 dynamic lb axial load limit. My calculations on a 914 pedal set are that is is a 6:1 lever ratio. So if if take 40 lb to depress the clutch the bearing will see 240 lb of axial load. Later 911's have a longer lever and clutch pedal.
So can anyone with fish scale tie a rope around the clutch pedal and to the fish scale and see how much pressure it takes?
Would be nice to see if 6 conversions with bigger engines and higher pressure plates take more pressure. Also 72 and later 911's with the 915 trans.
Going to need some one to test the first prototype too.
Hey Bruce
I think you are looking for a deep sea fisherman.
I have 6 fish scales and none read more than 64 oz. I'm not an avid angler, my scales
are antiques and purely decorative.
There must be a device that can be put on the pedal that can provide a pressure value.
I'm curious how you see the rigging with a fish scale. Perhaps a simple diagram ?
Your premise is certainly interesting.
Rory
Posted by: Chris914n6 Jul 30 2017, 09:55 PM
1. A bushing is a bushing, a bearing is a bearing. There is no such thing as a bushing bearing.
A bathroom scale and a 2x4 to space it away from the other pedals.
You might be better off with a roller bearing instead of a ball bearing.
Posted by: 76-914 Jul 31 2017, 10:44 AM
1. A bushing is a bushing, a bearing is a bearing. There is no such thing as a bushing bearing.
A bathroom scale and a 2x4 to space it away from the other pedals.
You might be better off with a roller bearing instead of a ball bearing.
Not even an oilite (spelling) bushing?
Posted by: bdstone914 Jul 31 2017, 11:02 PM
1. A bushing is a bushing, a bearing is a bearing. There is no such thing as a bushing bearing.
A bathroom scale and a 2x4 to space it away from the other pedals.
You might be better off with a roller bearing instead of a ball bearing.
Not even an oilite (spelling) bushing?
Actually many bushings are bearings. To say bushing bearing may be redundant but not incorrect.
Definition of bearing. "a part of a machine that supports another part that turns around"
Posted by: Elliot Cannon Aug 1 2017, 08:21 PM
Get one of these. (A cheap one) Place the hook into the end of a short length of tubing. Elect. conduit etc. Put the end of the conduit etc. against the peddle and push. Read the scale as the peddle is pushed. 
Attached image(s)
Posted by: bdstone914 Aug 1 2017, 09:03 PM
Get one of these. (A cheap one) Place the hook into the end of a short length of tubing. Elect. conduit etc. Put the end of the conduit etc. against the peddle and push. Read the scale as the peddle is pushed.
I bought a digital one on Amazon for $9 shipped that reads to 88lb. I think I can hook it up with a bungie cord to the clutch pedal.
Also decided to make the shafts from stainless steel are half of the ones I see are badly rusted. Material expense it not much more and eliminates the need for zinc plating. Found a grade of SS that can also be heat treated.
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)