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seattlejester

seattlejester's 1971 240Z

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Goodness I love this forum, you really can find everything.

 

Quote from this thread:

DO NOT, DO NOT, DO NOT preload the brakes. EVER!!!

 

The master cylinder needs to fully release in order to open up the little ports that let the brake fluid back into the reservoir. If they can't release ALL THE WAY then they can't release the pressure.

 

This makes no difference at first, because you let off the brake and there is no pressure, then you step on them and there is, let off and there isn't. As the brakes gets hotter from you applying the brakes, say, in traffic, the heat generated transfers into the fluid, which expands. If the pressure can't release back into the master cylinder reservoir then this results in a light drag on the brakes. As the drag continues, more heat is generated, more fluid expansion, more pressure, more heat, more expansion, more pressure, etc.

 

I had this happen with my clutch once and I learned to have free play in the system. On the brakes you want a little free play in the master to booster connection, and you want a little in the pedal to the booster connection. 1/8" of free play in both won't make a noticeable difference in the pedal throw, but not having that free play will be a BIG problem.

 

Pretty sure that is what happened. 

 

I measured what I did and found that I was sticking 13mm past the flange of the aluminum spacer at first, that caused the pre-load on the master and the exact symptom of the brakes coming on and staying on. Then on the side of the freeway I moved it down to 6mm past the flange and the car drove back with no problems. I have it currently set to 9mm which is in spec, but I will be checking for preload and complete release to make sure I don't run into problems again. 

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Work has been interesting and been keeping me busy, but continuing on.

 

Twinning done correctly:

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With the brakes somewhat adjusted (after that experience I decided to leave myself a 1mm buffer from the correct measurement). I tested it to find the brakes fully disengaged and the dead pedal throw was reduced by a good margin.

 

I added some rubber isolators to the tank strap bolts as well as loctite, sealed up the hole the new much smaller filler neck revealed, and fixed the fuel filler hose.

I even adjusted my hatch which has been loose for years causing a little rattle at speed if a microfiber towel wasn't put on the gasket to help put tension on the aerocatch latch.

 

The reason for all this was a drive a friend had setup. The last time we went, my car was in the middle of the full rear end overhaul. Right after finishing if memory serves I killed the battery and popped a fuse which until was found caused a lot of things not to work. Decided I was going to definitely make it this year.

 

It was supposed to be crummy weather, but as with this time of year it really is unpredictable. The morning started out overcast and cold, but glorious weather waited.

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The car made it 140 miles with no real issues.

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As the car ticked cool with the hood ajar, my copilot and I sat around waiting for the remainder of our group to arrive.

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As much as I enjoy Z cars, it seems like all the locals *cough cough* are down or in progress at the moment. I swear it is some type of curse, only one running Z at a time allowed. However I really enjoy the mishmash of cars the last few drives I have done there were no two cars the same.

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Had a nice beverage or two (don't worry I was the passenger), and we took off the long way back home through Packwood.

 

Turns out they had an autocross earlier in the day, may have to try and squeeze one of those in soon.

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By the time we rejoined a major highway it was golden hour. 

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And golden hour means great lighting especially for rollers.

 

So what does this road trip have to do with anything? Well it was the first time I filled up my gas tank to the full mark. With the filler neck hose from a Jeep I bought I was able to make it so that there was no noticeable kink allowing the fuel filler to fill at full speed. The full tank of gas also helped add weight on the rear helping damp balance some of the weight and giving the shocks more weight to play with. To top it off even at our brisk pace combined with some traffic the 3L turbocharged engine managed 360 miles with the 16 gallons. 22.5mpg. That was with some pretty extensive brisk driving. I imagine sticking strictly to cruise we would see something closer to 30 or so. 

 

Definitely some faults did rear their ugly head. The car is loud even with the cat and ultra quiet resonator, the first stint we did without earplugs, only when we stopped to stretch our legs did we realize how loud it had been. Some rattles definitely need to be chased. Under extensive driving the seats do get warm, I imagine time for some heat mat under the seats, maybe some insulation and carpeting. Driving position still sucks not sure what can be done short of cutting out the floor or finding some way to make the seat reclining mechanism narrower or jack the front of the seats up a couple inches. There also was some smoke coming up from the shifter, we didn't find anything more than a bit of oil dampness not even dripping, so perhaps it was the adhesive used for the tunnel shield slowly cooking off.

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Thanks!

 

We really didn't get a chance to do much comparative driving, the route was long and our breaks were long and we had things to do in the evening to find emptier roads. I would like to imagine in a straight line and maybe even in the twisties I would give all of them a good thrashing :D, I've played with the BMW before and he had a hard time keeping up even with my wonky fuel pump. I think other than the porsche we were the only car to make it on one tank of gas as well. 

 

I think I have a soft spot for the facelift E46, but I do enjoy the E30. His especially, I've never been taken around a corner as hard or quietly. His old setup was running a double muffler so the only thing you would hear would be turbo spool.

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