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TR's 260z L28 Build Thread


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I played with the check valve last night. It seemed stuck at first, but it didn't seem like it took much to free it. I went ahead and cleaned it up with brake cleaner, and it appears to work. It feels like I have power brakes again, and the engine doesn't rev when I tap the brakes.

 

I just don't understand how a one-way valve would cause the engine to rev if it was blocked... wouldn't it just cap off the vaccum? One thing I didn't mention is that it felt like the brake pedal was "bubbling" when the power brakes were going out. Engine would rev about 400rpm, pedal felt bubbly. Weird.

 

I haven't driven it yet, so we'll see.

 

Whoa, slow down. What else was going on?? You only said "I lost power brakes," nothing about engine hiccupping.. :wink:

 

think about it.. the brake booster is a vacuum load on the engine. When you rapidly tap the brake pedal on any car, its going to show up in RPMs at least. A car thats barely running can easily be stalled by pressing and fully releasing the brakes a couple times in a row.

 

When the check valve was sticking, it was bleeding vacuum off in an irregular way.. I can't give you a firm explanation of why anything may have happened, but its a load on the engine and when something gets schmutzed, its bound to manifest in other, subtle ways. If you have problems you think are real, we can examine them... but what I am saying is a little oddness in motor run condition can be expected when experiencing a simple check valve failure like this. If it goes away, don't sweat it :2thumbs:

 

Good luck, hth

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Thanks for the tips. I cleaned up the check valve and it's made no difference. I found a re-man booster at O'reilly for $110 (8.5 in?), so I think i'll just go ahead and replace it.

 

Additional good news! My roomate bought an Autozone 0-100psi oil pressure gauge, and he let me borrow it to check out the Z. It must be my pressure gauge that's bad (I replaced the sender).

Extended periods of idle barely drops below the 12.5psi mark, and after blipping the throttle it sits right above it. Reving it got the pressure up past 50psi. That makes me feel much better about driving it.

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  • 2 weeks later...

Alright, got the Z back from the bodyshop.

 

Verdict is that it had been hit from the front, left side went down, right side went up, all of it shifted to the left some.

 

They got it all straightened back out, and the body panels line up pretty well now. They'll look even better after some shimming and tweaking. This does show me how bad of shape the hood is in though. It was pretty bad to start with, before it fell over in the gravel, so no big loss b/c of that accident. Good thing I have a spare... no vents for it though, yay.

 

It still lists a little bit to the left, but they said it's the springs, which I could definitely believe. Coilovers should fix that problem. Hopefully this weekend I'll get most of the bushings installed and take it to be aligned.

 

 

So that's $500 knocked out of the budget. This is turning into quite the cluster$@#^ of surprises. Now I just need to swap out the crapped tranny (around $300 :() and replace the dead brake booster and it'll be DD comfy. From there I'll install the bushings, get coilovers, do the bodywork and paint, and then I'll be in my happy place with it for awhile till I can afford megasquirt.

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Alright, some progress tonight...

 

Got both LCA's redone in poly, the forward TC bushing is poly and the rear is stock shitty rubber till I can get a new OEM rubber replacement.

 

Hit some major snags doing the front sway bar. First off, I unknowingly grabbed the rear sway bar instead of the front, and ordered front bushings based off that size (1"). If the front (which is 1.5 hours away in Oklahoma) isn't 1", I'll have to order more bushings and wait for them. Sucks.

 

So, I decided to re-install the stock bar with the new endlinks for now. No dice. There is no way that bolt is long enough to get the nut on. I'll have to hit up the hardware store tomorrow and see if they have two longer ones.

 

 

 

I'm going to wait to do the rear end bushings until I have a spindle puller. Might as well do it all at once. I'm planning to replace the tie rod ends and ball joints when I upgrade to coilovers. I'll replace the various steering bushings when I pull the motor to drop in the L28ET.

 

Tomorrow I'll try to finish up the endlinks, install my new brake booster, and flush and fill the diff fluid. If Nissan is open, I'll take it for my friend to align as well, if not then Monday.

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Well at least I now have my endlinks installed. I went by Autozone to get some brake fluid, and Dan found me some bolts that ended up working. I think they were only about a 1/2" longer. The nut did bottom out on the threads, as you can see, so I hope it's tight enough.

 

Also ran out to Gentry and got my 240sx transmission. Came with a 240mm flywheel and clutch, so that'll be a slight upgrade from my 225mm.

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Welp, got her all put back together and went for a test drive, and I'm quite pleased.

 

It might be my imagination, since we didn't get above about 40mph, but it seems like it drives much smoother and there isn't as much shimmy in the front end. I'll see about getting an alignment sometime next week, if it still needs it (likely).

 

The brakes just make me smile. It feels perfect, like a modern car. Love it.

 

 

Didn't get around to swapping diff fluid since I slept in a bit today, but maybe I'll get around to it tomorrow.

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Nice progress! I had the same issue with the swaybar end links but I figured out if I put the bolt with the threads toward the ground I could wedge a board under the body and lever down on top of the bolt head, which compresses the bushings enough to get the nut started. Not as "clean" underneath with the threads sticking down but no big deal.

 

You have a way to machine that bellhousing? I've been eyeing the 240sx tranny swap mainly because turning 3100 rpm on the highway sucks! Also, if I go turbo 2.8 I'll have the beef I need already. There's one at the Upullit here in LR that I'm tempted to pull. I parked the Z a couple weeks ago because I had the windows down and I could hear a bearing spinning... in the middle of swapping rear wheels bearings right now so I hope to end my Z withdraw tomorrow!

 

Keep trucking... good luck :icon30:

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I've been eyeing the 240sx tranny swap mainly because turning 3100 rpm on the highway sucks!

 

Four-speed, I presume?

 

I am not 110% on my gearing, since my car had an unidentified 5 speed swapped into it when I bought it.. (a later one, definitely not the original 240 5speed) BUT I know that in fifth gear at 3100 RPMs I would be going about 75-80 MPH. The same RPM in fourth (also in the 4-speed that got swapped in by me b/c I suspected a possible bent shift fork) gave me about 60+ mph.. I think i've got a 3.545 rear in it, which should be common enough.. so if you have a four speed, a simple five speed swap will give you the overdrive gear you need to get highway RPMs down, and it is a bolt-in.

 

Just letting you know, in case you weren't already aware :)

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Yeah I've checked out all the various gear ratios and stuff.

 

I've got the 3.36 diff, which is nice for cruising. My trans should be the "A" style '76 5spd. Problem is that it's dying (bad syncros I think), and 5th pops out (unusable). Even if 5th did work, it's the highest gearing of all the styles, so NOT good for cruising.

 

I've already bought the 240sx tranny, just gotta do the swap work. Should be a little stronger for the turbo stuff too, so win-win.

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Yeah, it's the original 4-speed that came behind the L26. Speedo jumps all over the place but I'd say 3100 rpm is about 65 mph. I am keeping my eyes peeled for a 81-83 NA 280zx 5 speed since it bolts in and is good for 25% overdrive. Big Phil has a NA tranny holding 400 rwhp so it should hold my 120 rwhp just fine :P It's just a matter of finding one nearby. I see lots of z31 cars in the yards here but few s130 cars but I'm sure something will eventually come up... hopefully before gas hits $5 / gal!

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I got the tranny dropped, and both transmissions taken apart. Hopefully by the end of tomorrow I'll have the bearings swapped, shift rod hole drilled, tranny mounted, and be working on the tranny mount.

 

Tomorrow I'll rent a bearing puller, and just swap to the L bearing for now. Once I swap for the turbo motor I'll go ahead and mill the housing for the sx bearing.

 

Pics of the old tranny insides, one of the work area, the new tranny's magnetic drain plug, then pics of the new tranny's insides...

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Thanks to a friend of mine with a drill press, I got my shift rod hole drilled out. When I got it home I measured, and it's just BARELY over 16mm (like it's supposed to be). I just hope it's in the right spot, and the rod lines up.

 

While I was over there, I noticed that his dad also has a hydraulic press. That means when I do my rear suspension bushings I don't have to take off work to go to find a 4x4 shop and pay to have the spindle pins removed. Excellent!

 

 

 

Nobody around here has either the KA or L countershaft bearing, so I may just wait till Monday and see if I can get the bellhousing machined to fit the stock KA bearing while I'm out to get the driveshaft shortened.

 

That's a bit of a setback. I can't mock up and modify the crossmember till I can get the box back together. Looks like that won't be till Monday or Tuesday now. :icon51:

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Well, it's together. For better or worse, my Frankenstein 240zsx transmission is together...

 

Took my driveshaft to the shop today to be shortened 1.5", and the machining at the physics dept. was flawless, a perfect fit.

 

The drill-pressed shift rod hole was horrible. Somehow it wasn't straight, or big enough. Between milling down bosses and fixing the shift hole, we probably put in 3 hours of dremel work and about 6 test-fits.

 

But it's together, spins freely, and shouldn't leak (hopefully). Tomorrow I should get my driveshaft back, and hopefully have time to stab it and weld up the tranny mount.

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You might want to make some friends in the mech. engr. dept as well, they have a full on machine shop and a few guys who really know how to use the machines.

 

Looking good. Hope you're not working in the sun in 101 degree heat like I was... glad I'm done! Now to get the a/c working :icon30:

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Got my driveshaft back today, and tonight we mounted the tranny back in the car.

 

Unfortunately, I'm an idiot and didn't have the driveshaft shortened enough. It ended up 1/2" too long. Luckily I was able to dremel the collar off and now it clears and is all bolted up.

 

 

Tomorrow I'll get the crossmember welded up and take it for a drive!

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