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Everything posted by JMortensen
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37:10 = 3.70 gear ratio. It is the Z31T LSD. Congratulations! That's a huge score.
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The cover is from a Z31 Turbo. Doesn't necessarily mean that it's LSD. Pull the cover off and take some pictures of the carrier. An open carrier has round cross pin shafts. The LSD will have a square pins, or diamond shaped if it's the more rare NISMO version. There are pics of both in my big diff post in the drivetrain FAQ section. If it is LSD it's worth lots of money. Seen the finned cover alone up for $400, not sure if they sold it at that price. Seen the whole diff with CVs go for $1200+.
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2) Strut doesn't need to be vertical with this design as you mention in point 4. It can tilt and the freed up toe link allows the strut to compress without side loading. You can move the wheel back for aesthetics if you want, just not so far that the toe link or the rear link bottoms out as the suspension goes through its travel (I think you'd have to go really far for this to happen, but never tried it). 3) I did the math 15 years or more ago, but if you use the 1.5x the thread diameter I think that means you can move the heims joint out 5/16" before you run into the limit. There are a lot of people who run them further out than that, including me - my front LCAs were out probably 1/2" for a long time, might still be - but anyone doing this is ignoring the rule of thumb in that case. How big a deal that is is up to you.
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The 39 spline option doesn't neck down to the splines, so the splined section is stronger, but it still necks down to the nut, so that part wouldn't be any stronger. The best solution is to get rid of the stub axles and go to a more modern CV where the splined end of the CV plugs through the stub and the axle nut is on the outside of the flange. There are a couple options that are available. The unfortunate thing about those is they generally have extremely heavy uprights and require all new brakes, struts, etc. so you might gain strength in the driveline but at the cost of well, cost since you're replacing a lot of parts, and weight. I wouldn't even consider this kind of change without ditching the R200 and going to something with more ratios and LSD options like the F8.8. YMMV.
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I paid out for my Miller 135 mig, and at the time 15 years ago, that was the common wisdom; you get what you pay for. Nowadays I'm not so sure. Lots of cheaper migs, including HF brands, with good ratings. 15 years ago the main concern was getting infinite wire speed adjustment, and I paid $200 more for Miller than Hobart because Hobart had 4 or 5 clicks for wire speed. Now, you can get the adjustability in a bunch of different brands.
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More bots? FWIW I went down to HF and picked up the $400 tig I had mentioned 5 years ago. It was on sale, paid $319 before tax. Got it home and had a case of buyer's remorse about it not doing AL, and returned it and bought a $600 unit off of Amazon that had good reviews. By the time I added an Argon bottle and a few accessories I was up at $900, but that's still dirt cheap for a tig. My electrician neighbor is going to finish up wiring 220V outlet and I need to heal up from surgery, but in about a month I too should be laying some crappy beads down.
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IMSA GTU vintage racer build
JMortensen replied to clarkspeed's topic in S30 Series - 240z, 260z, 280z
Man, what a great place to start from! Can't wait to see it finished. -
There is very little money to be made in making performance parts for a 50 yo Japanese sports car, both because the market is so small and because for many people the attraction to these cars is that they're cheap. Maybe that last part will change, but certainly when I bought mine price was the primary concern. Seems to me that Apex does more engineering than most, since he actually shows his FEA results, etc, and looking at some of the other kludged together shit that has been sold his looks relatively good. That said, there have been problems, like the failure to produce the track kit, the flexibility of the rear uprights, etc. I'm past the point of just bitching about it when a vendor makes mistakes, because I've seen them from every vendor I can think of. What is more important to me, YMMV, is that they try to fix the inevitable problems that do arise. Every part I buy is purchased with the knowledge that bolt ons don't, and that I WILL have to figure out how to make it work. As a guy who tried and failed to sell Z parts, I'm glad that people are willing to continue to do so, given the low return on their investment in time and effort.
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ANOTHER Datsun Z/LS3/T56 Swap Thread
JMortensen replied to Ironhead's topic in S30 Series - 240z, 260z, 280z
The wrong one. Hawk Black. John Coffey recommended them 15 years ago and I bought based on the idea that they have a decently wide temp range. There are better options these days. Main issue I have is insane amounts of dust. -
Plates around bell-housing - racing application
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
I think you'll find that all those warnings you heard about not having any bottom end are way overblown. It will be fine, you're going to love it. -
Plates around bell-housing - racing application
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
I had a .490/280 cam and wanted to step up to something like you have but ended up LS swapping instead. I love almost everything about the way lightened flywheels work. Revs drop faster so it will shift faster as a result, much easier to heel/toe, engine braking is better, acceleration is better. 2 complaints you'll hear about them is that they make it hard to hold a consistent speed on the freeway, and the trans will probably sound like it has marbles in it at idle in neutral. I never had a problem with the freeway thing at all, and the marbles thing is irritating, but worth it. I've read that it's the gears in the trans rocking back and forth because the flywheel's smoothing of the power strokes is diminished. I had a friend that was really bothered by the noise, and she had the HKS 10 lb flywheel. Seemed a lot more noticeable in her Z than mine, not sure if that was because of engine or trans mounts or different interiors or what. -
Plates around bell-housing - racing application
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
The lightest you can get, I'd go steel if possible, and with the least mass around the edge of the wheel. You see some with holes around the perimeter. That is the way to go, as removing mass from the edge is more important than in the middle. When you go light you do have to be good about not putting too much heat into the flywheel, so if you have bad habits, you'll want to get rid of them before you ruin your new part. FWIW the AZC one was 12 lbs, I drove with a heavy pressure plate and cammed L28 with 44s in traffic, was easy to drive. I think the crankshaft itself is so long and heavy that the flywheel weight isn't as important. Had a friend with an AL flywheel on his cammed L18 with 44s and Datsun Comp pressure plate (VERY heavy), and that thing was hard to get moving. He got used to it, but I stalled it a lot whenever I drove it. -
Plates around bell-housing - racing application
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
Takes 5 lbs off, OK. Turns a 25 lb flywheel down to 5? I don't think so, but I certainly wouldn't run it if they did. If you really want lightweight, get a button clutch that has a smaller diameter multiplate clutch on an automatic flexplate. Here's the dual 7.25" clutch I've got on my LS. IIRC the flexplate and clutch and everything was right around 20lbs. -
Plates around bell-housing - racing application
JMortensen replied to AydinZ71's topic in S30 Series - 240z, 260z, 280z
I did something similar with 1/4" steel after 3 different machinists looked at my old AZC flywheel. All three picked it up, looked at it for about 5 seconds, then looked at me and said: "That's cool. Do you have a scattershield?" I think the stuff he was selling after the 90s was better designed. Mine had sharp corner cuts right through the pressure plate bolt holes and nothing was radiused. -
ANOTHER Datsun Z/LS3/T56 Swap Thread
JMortensen replied to Ironhead's topic in S30 Series - 240z, 260z, 280z
Mine's a trailered autox car so not many miles on it. It definitely has some stone chips in the flares, but the biggest damage so far has come from hitting a cone with the rear flare. Spider cracked the gel coat. Still haven't decided what to do about it, but I don't want to put a lot of work into making it pretty because it's a Rustoleum painted race car. -
ANOTHER Datsun Z/LS3/T56 Swap Thread
JMortensen replied to Ironhead's topic in S30 Series - 240z, 260z, 280z
I dig it. Reminds me of the 80's 930 Turbo with the black guards on the rear flares. Was considering doing something similar on mine. -
Having the cell in the pass side was done back in the day. It offsets driver weight and makes a lot of room for a big ass diffuser, which isn't legal but could be made to be easily removed. Search youtube for AJ Hartmann, he makes CF parts and shows how to install onto the car, IIRC shows how his gigantic splitter and diffuser are removed so he can get the car on the trailer.
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Moving front wheels outboard
JMortensen replied to fusion's topic in Brakes, Wheels, Suspension and Chassis
The JTR manual says up 3/4, out 1/4 inch. IME from stock on a 240, you need to raise the pivot about 7/16" to minimize bumpsteer, without moving it outwards at all. Making either end wider will increase grip at that end, so if you have an understeering Z (which is their natural tendency) then making the front wider would help. Almost nobody does it though. Some racers will run wheel spacers for that reason, that's about it. -
I'm betting those wheel speed sensors could be used for traction control. That would be really cool. Is that part of your plan?
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What is up with the SCCA shutting down the season? Is that just a covid thing? Just saw something hit my inbox yesterday about it being shut down. I'll probably be out of commission this year due to an upcoming surgery anyway. Can't tell if your pic is ABS or fire suppression. LOL
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The springs on a Z are soft and aren't compressed that much. I've taken plenty of them off by just aiming the strut away from me and zipping the nut off with an impact. The top hat will only fly a couple feet. It's not a big deal on a Z. On most newer cars, MUCH different story and very dangerous. IIRC though the 240 front spring rate is under 100 lbs rear is just over, and is compressed an inch or two. Not that much force. 280 has slightly stiffer springs and similar compression distance. If you removed the springs and then couldn't get the gland nut loose then I would think that using a sawzall or a cutoff wheel and cutting through the strut tube without cutting the insert itself would be pretty easy to do and should work fine. The problems I can see arising are: 1) if you have OG Nissan struts with the oil in the tube, when you cut through the strut tube it will leak everywhere and 2) if you have inserts and cut into them then you'll squirt pressurized oil everywhere. Also, if you didn't remove the spring first, it's going to go flying when the strut tube is cut, so whichever way you do it, get the spring pressure alleviated before you cut the tube. You're going to need to clean the thing up before welding the new tubes on, so I don't know how much time this is really going to save.
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Welcome back Tom! I agree about social media, useless for tech. Great for posting pics and getting likes.
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ANOTHER Datsun Z/LS3/T56 Swap Thread
JMortensen replied to Ironhead's topic in S30 Series - 240z, 260z, 280z
Just tell Tilton what you're doing. They'll give you advice. Take it. Worst case scenario you need to swap a master or both. They're not that expensive. Or make your own thread and state what you have for brakes and people can give their thoughts. -
ANOTHER Datsun Z/LS3/T56 Swap Thread
JMortensen replied to Ironhead's topic in S30 Series - 240z, 260z, 280z
On the flip side of the pedal ratio vs master diameter/effort thing, if you don't have a booster then the pedal won't travel as far. If I let you drive my car you'd never come back with a comment about the brakes, either travel or effort. Just feels normal. As to your first drive comments, when I drove mine for the first time it was just around the block and I found that I could just step on the gas and roast the tires for basically as long as I held the pedal down. It was intimidating, and immediately brought up that Mark Donohue quote. Anyway once I got it out on the track I realized that it is in fact drivable, and doesn't do anything stupid. Pretty easy to drive for what it is. Hope yours turns out the same, I expect that will be the case. Congrats!