glorydime Posted July 12, 2016 Report Share Posted July 12, 2016 While I was replacing the master cylinder on a friends truck I noticed this Is this correct? Why would the switch be connected to the clutch? 1 Quote Link to comment
Lockleaf Posted July 12, 2016 Report Share Posted July 12, 2016 The one on the clutch is a neutral safety switch, to keep the vehicle from starting without the clutch pushed in. There should be a separate one for the brakes on the brake pedal 1 Quote Link to comment
glorydime Posted July 13, 2016 Author Report Share Posted July 13, 2016 So odd my 72 521 doesn't have that neutral switch but has a brake pedal switch. This 70 521 has only a brake junction switch in the engine bay. Is this normal or do I need to instal another switch to the pedal or will the junction switch suffice for the brakes? 1 Quote Link to comment
datzenmike Posted July 13, 2016 Report Share Posted July 13, 2016 Never liked this idea. My Canadian '71 didn't have this and I would have disconnected it anyway. In a pinch you can shove in gear and use the starter to move your inoperative vehicle to the side of the road. 1 Quote Link to comment
Doctor510 Posted July 13, 2016 Report Share Posted July 13, 2016 Probably not a neutral switch on the early trucks and cars, it's a 3rd gear retard activator, I could be wrong... As stated, early trucks and roadsters had a brake light switch that is hydraulic on the brake line junction block on the engine side of the firewall. 1 Quote Link to comment
glorydime Posted July 13, 2016 Author Report Share Posted July 13, 2016 We're lucky the trucks at home in the garage, we've been slowly repairing stuff to get it back on the road. But this brake switch at the junction will work with out a pedal switch? I only ask cause if I need to instal a pedal switch might as well do it now before I put the new master cylinder in. 2 Quote Link to comment
datzenmike Posted July 13, 2016 Report Share Posted July 13, 2016 Probably not a neutral switch on the early trucks and cars, it's a 3rd gear retard activator, I could be wrong... As stated, early trucks and roadsters had a brake light switch that is hydraulic on the brae line junction block on the engine side of the firewall. I don't think so. The transmission would have that switch. A clutch switch could only interrupt this and there's no reason to use the clutch while in 3rd gear other than to up or down shift in which case the trans switch would do. 1 Quote Link to comment
MikeRL411 Posted July 13, 2016 Report Share Posted July 13, 2016 The in engine compartment hydraulic brake switch has a unique advantage over the brake pedal mounted switch. The brake pedal switch tells the following vehicle "Well, at least I tried to brake, so good luck if you are following too closely!" The hydraulic switch says "I am braking stupid! Back off! Because I WILL be stopping all too soon for you to realize that something has happened while you were texting." If you don't have enough brake fluid to actually stop, the brake light switch will not close and you have to pray that the follower is not texting or sexting. 2 Quote Link to comment
dat521gatherer Posted July 13, 2016 Report Share Posted July 13, 2016 Clutch switch on the bottom of the diagram. Click on the photo. Press the plus symbol on my photobucket for a larger photo. Save as needed. 1 Quote Link to comment
glorydime Posted July 13, 2016 Author Report Share Posted July 13, 2016 Thank you! Master cylinder installed and brake lights working great! 1 Quote Link to comment
DanielC Posted July 13, 2016 Report Share Posted July 13, 2016 The switch on the clutch pedal is used in the retard the timing when in third gear, one of the conditions that has to be met for the timing retard to happen is the clutch must be fully out. If your 521 has a Weber carb, or a five speed transmission, or a matchbox distributor, you have already disabled the timing retard system, so the clutch pedal switch does nothing. I have only 1970 to 1971 521 trucks. No 1972 521 trucks. All my 521 trucks do not have a neutral safety switch. That might have changed for 1972, I do not know 1 Quote Link to comment
datzenmike Posted July 13, 2016 Report Share Posted July 13, 2016 If you are in 3rd gear the clutch will always be fully up as likely, you are driving along. Under what conditions would it be down if in 3rd?????? Shifting into or out of 3rd, or maybe stopped at the lights with the transmission in 3rd???. So what does this do exactly? 1 Quote Link to comment
DanielC Posted July 13, 2016 Report Share Posted July 13, 2016 I am not the Nissan engineer that designed the system. I do not know why. I figured this out a long time ago, while driving through city traffic in third, just touching the clutch pedal, caused the engine to speed up slightly, because the timing got advanced. I am probably one of the few people who even know of the existence of this manual, and have one. 1 Quote Link to comment
glorydime Posted July 13, 2016 Author Report Share Posted July 13, 2016 Hey DamielC, We are going to put a weber on this 1970. To disable can we just snip it out or do we need to do anything else to disable the switch on the clutch? 1 Quote Link to comment
datzenmike Posted July 13, 2016 Report Share Posted July 13, 2016 I am not the Nissan engineer that designed the system. I do not know why. I figured this out a long time ago, while driving through city traffic in third, just touching the clutch pedal, caused the engine to speed up slightly, because the timing got advanced. I am probably one of the few people who even know of the existence of this manual, and have one. Very, odd. 1 Quote Link to comment
banzai510(hainz) Posted July 13, 2016 Report Share Posted July 13, 2016 I have a 72 model year and don't have that switch on the clutch. that pedal in the photo looks down far. Most masters ordered now you have to cut the threaded shaft to get the pedal in the general area otherwise when you mount to the fire wall the pedal will push in as the rod is too long. 1 Quote Link to comment
glorydime Posted July 13, 2016 Author Report Share Posted July 13, 2016 The truck in the photo is a 70 and yeah on my 72 I had to cut the thread on the master to make sure the pedal didn't push. Last night to my surprise once I figured out about the brake switch we didn't have to shorten the master thread at all. Bleed and adjusted great. Lucked out. But yes on my 72 I don't have that clutch switch. By the way this truck will turn over without the clutch depressed. i think DanielC is correct. I don understand it but he must be right!!! 1 Quote Link to comment
DanielC Posted July 13, 2016 Report Share Posted July 13, 2016 There is also a throttle position switch on the stock carb. The third gear timing retard is deactivated about 2/3 to wide open throttle by this switch. There are some other switches used in a series arrangement, that all have to be turned on to trigger the retard points relay. Replacing the carb with an after market carb breaks the circuit for third gear activation, so after that, eliminating the clutch pedal switch is just extra work. Yes, you can crank, and start a 521 in gear, with the clutch not pressed. Learn to shift your 521 without using the clutch, and you can still get home if you have a clutch master or slave cylinder go bad 1 Quote Link to comment
banzai510(hainz) Posted July 13, 2016 Report Share Posted July 13, 2016 done that many times with my 4 speed 510/521. drive home w/o clutch start in first let off gas just right slides right on. 1 Quote Link to comment
Lockleaf Posted July 13, 2016 Report Share Posted July 13, 2016 Interesting system. 1 Quote Link to comment
Charlie69 Posted July 14, 2016 Report Share Posted July 14, 2016 Install a matchbox and a Weber. Quote Link to comment
glorydime Posted July 14, 2016 Author Report Share Posted July 14, 2016 We will in do time, I'm going to make sure this friends truck runs with as much stick parts as possible. Only reason he went with a weber was because the stock hitachi was thrashed. But yeah sooner or later we will set him away from the original distributor and put in a matchbox. Quote Link to comment
banzai510(hainz) Posted July 14, 2016 Report Share Posted July 14, 2016 just disconnect the 2nd set of points. find a single point distributor and put a Petronix or find a matchbox or 1st Gen electric distributor with a GM module Quote Link to comment
datzenmike Posted July 14, 2016 Report Share Posted July 14, 2016 Matchbox EI distributors are stock on later L series engines. Put one in and no one will even notice the change. Quote Link to comment
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