Chris Duncan
Supporter
As promised in the electric water pump thread this is a post about hose clamps.
All hose clamps are not created equal.
This research was brought on by a custom 240Z Scarab (Chev V8). It had an oversize radiator and custom hoses and tubing from engine to radiator. Hose clamps were just your typical off the shelf piece from the local budget auto parts store. While cruising through the mall the lower radiator hose blew off and dumped all the coolant on the ground. Luckily it didn't happen in a high speed turn on the freeway because it slimed the rear tires. More embarrassing than anything, and the fix was to put double clamps on all the large hoses, which worked in that situation.
The GT40 is a little more crowded especially where the main coolant pipes come out of the tunnel by the front crank pulley. There's no room for double clamps. Hence a search for a better clamp.
These are all 5/16" nut size stainless steel clamps, and all are similar quality of construction.(except E which is 7/16")
Clamp A is an off the shelf typical auto parts clamp. Actually it's their higher line clamp. It's 1/2 wide and the screw holder is one piece and is crimped around the clamp/screw. It's torque rating is about 30 in/lbs.
Clamp B is also 1/2" wide but the screw holder is two piece fastened with bent over tabs. Torque 40 in/lbs
Clamp C is 9/16" wide with a similar 2 piece bent tab construction. Torque 50 in/lbs. This clamp also has a longer length band on the ID that keeps the slots from digging into the hose.
Clamp D is 5/8" wide with a 2 piece swaged tab construction. Also note the longer length bolt for more thread engagement. Torque 80 in/lbs.
Clamp E is 3/4" wide with a bolt and nyloc nut. While it's also 80 in/lbs it probably is more re-usable and vibration proof.
There is another stronger bolt/nut clamp offered at 110 in/lbs. At this torque you may be approaching collapse of thin wall tubing.
Clamp D was used on the GT40, it's plenty strong and has more clearance than the bolt/nut variety. It's called a vibration resistant (high torque) hose clamp. All clamps were torqued with a 1/4" drive in/lbs. torque wrench.
Clamps B, C, D, and E are from www.mcmaster.com (although probably available elsewhere) They are a wealth of information with many specs on most stuff they sell including metal alloys and complete fastener and fastener material specs and applications.
So we've gone from the 30 in/lbs. to the 80 in/lbs. clamp. This may be particularly relevant with some of the kits having large coolant pipe connections inside the cabin. A blown off hose in that position could be disastrous.
All hose clamps are not created equal.
This research was brought on by a custom 240Z Scarab (Chev V8). It had an oversize radiator and custom hoses and tubing from engine to radiator. Hose clamps were just your typical off the shelf piece from the local budget auto parts store. While cruising through the mall the lower radiator hose blew off and dumped all the coolant on the ground. Luckily it didn't happen in a high speed turn on the freeway because it slimed the rear tires. More embarrassing than anything, and the fix was to put double clamps on all the large hoses, which worked in that situation.
The GT40 is a little more crowded especially where the main coolant pipes come out of the tunnel by the front crank pulley. There's no room for double clamps. Hence a search for a better clamp.
These are all 5/16" nut size stainless steel clamps, and all are similar quality of construction.(except E which is 7/16")
Clamp A is an off the shelf typical auto parts clamp. Actually it's their higher line clamp. It's 1/2 wide and the screw holder is one piece and is crimped around the clamp/screw. It's torque rating is about 30 in/lbs.
Clamp B is also 1/2" wide but the screw holder is two piece fastened with bent over tabs. Torque 40 in/lbs
Clamp C is 9/16" wide with a similar 2 piece bent tab construction. Torque 50 in/lbs. This clamp also has a longer length band on the ID that keeps the slots from digging into the hose.
Clamp D is 5/8" wide with a 2 piece swaged tab construction. Also note the longer length bolt for more thread engagement. Torque 80 in/lbs.
Clamp E is 3/4" wide with a bolt and nyloc nut. While it's also 80 in/lbs it probably is more re-usable and vibration proof.
There is another stronger bolt/nut clamp offered at 110 in/lbs. At this torque you may be approaching collapse of thin wall tubing.
Clamp D was used on the GT40, it's plenty strong and has more clearance than the bolt/nut variety. It's called a vibration resistant (high torque) hose clamp. All clamps were torqued with a 1/4" drive in/lbs. torque wrench.
Clamps B, C, D, and E are from www.mcmaster.com (although probably available elsewhere) They are a wealth of information with many specs on most stuff they sell including metal alloys and complete fastener and fastener material specs and applications.
So we've gone from the 30 in/lbs. to the 80 in/lbs. clamp. This may be particularly relevant with some of the kits having large coolant pipe connections inside the cabin. A blown off hose in that position could be disastrous.
