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Author
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Topic: Hydraulic throwout bearing for drag racing
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XR7
Gearhead Posts: 129
From: north Idaho
Registered: Mar 2003
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posted 01-27-2004 02:27 AM
  
I know some guys run these with a shuttle valve on stick shift drag cars. What are the advantages and disadvantages over mechanical clutch linkage? I've never been happy with my clutch linkage. The engagement is very short and I can't change the ratio of the linkage. Can you change the ratio of the pressure plate levers? It's a RAM single cintered iron adjustable clutch with 900# base pressure.
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TomP
Gearhead Posts: 5761
From: Delta BC Canada
Registered: Dec 99
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posted 01-27-2004 03:29 AM
The hydraulic isn't as good when it comes time to shift gears. You can change the linkage ratio, to slow the clutch action down shorten the lower lever, use a longer throwout fork or lengthen the upper lever. Change the pedal ratio by moving pivots. A bit here and there adds up.
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Rory McNeil
Gearhead Posts: 1542
From: Surrey, B.C. Canada
Registered: Nov 2000
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posted 01-27-2004 11:21 PM
I know 2 guys that used the McLeod hydraulic TO bearing set up, one likes it, the other didn`t. One was in a 429 powered Cobra kit car. He didn`t think it released quickly enough for clean powershifts, plus it always seemed to "sweat" a bit of brake fluid. The other guy runs in our stickshift class in a mid 8 second tube chassis 70 Nova. However, he runs a Lenco, so he doesn`t use the clutch for gear changes.He does like the unit in his car.Personally, I prefer mechanical clutch linkage. When I switched my 428 Fairmont from a automatic to a Jerico 4 speed, I considered trying either a cable or hydraulic setup, but I ended up building a mechanical setup, modeled after my 74 F350`s linkage. I`m very pleased with it.Also, with a sintered iron disc (I run a complete McLeod "Soft Lok")you don`t have much clutch pedal travel anyhow, as there is no marcel in the disc.I have my pedal sitting only about 2" off the floor when it`s released.------------------
78 Fairmont 428 4 speed 10.20@130mph
80 Fairmont 302 5 speed 12.8@105mph
85 Mustang NHRA Stocker 302 5speed. 13.04@101mph
59 Meteor (Canadian Ford) 2 dr sedan 332, auto
74 F350 ramp truck 390 4spd
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XR7
Gearhead Posts: 129
From: north Idaho
Registered: Mar 2003
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posted 01-29-2004 07:01 PM
Well that wasn't what I wanted to hear  I will look into modifying my Z-bar, thanks for the tip Tom. Rory do you know if the Cobra kit car had a shuttle valve or not? It is supposed to dump the fluid back into the resevoir much faster. A tech guy at McLeod did say it wasn't as fast shifting especially with a softloc type clutch because of the lower base pressure. I asked how much slower and he said "milliseconds"!
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Rory McNeil
Gearhead Posts: 1542
From: Surrey, B.C. Canada
Registered: Nov 2000
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posted 01-30-2004 01:03 AM
I don`t believe the Cobra had anything like a shuttle valve. It just had 1 line running from the clutch master cylinder into the TO bearing.------------------
78 Fairmont 428 4 speed 10.20@130mph
80 Fairmont 302 5 speed 12.8@105mph
85 Mustang NHRA Stocker 302 5speed. 13.04@101mph
59 Meteor (Canadian Ford) 2 dr sedan 332, auto
74 F350 ramp truck 390 4spd
IP: Logged |
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