Ironhead

Welded in the T3 adjustable camber plates. This was a more fiddly and time consuming job than I expected...I was obsessed with getting them at exactly the right angle, alignment, spacing, etc....and it is not easy to come up with precise, easily accessible, accurate measuring points. I think I got it pretty much dead on though. They are perpendicular to the centerline of the car...within .30 degrees of the same angle....and within 1/16" equally spaced fore and aft. Probably far straighter than my chassis is anyway. I also tidied up my welds with a grinder...which I don't usually do...I just embrace their ugliness. But in this case the beads were above the flat surface of the camber plates and would have caused problems with my plans down the road....so I went to town with the grinder. At least now I know none of the welds had any porosity.

Drove up to T3 today and picked up most of what I need to start mocking up the rear end. I tell ya, if this T3 stuff works as good as it looks, I will be damn happy. Appearance wise, it is pure porn. Almost too nice to let it get dirty. A few parts seem like they might be needlessly heavy. The hub carriers are made from something like 1" thick steel....seriously beefy. I suppose they know what they are doing, and I imagine potential liability plays a part in the design as well.

Thanks guys!

Finished the fuel cell mount. Once welded in place I am going to skin the outside with 18 gauge sheet metal. I realize it might be a tad over-engineered, but in addition to the safety aspects, I am going to weld a rear jacking point to the bottom of it, and probably mount a diff cooler pump, possibly a diff cooler, and probably rear exhaust hangers as well. Thanks for looking.

I had to postpone finishing the roll cage...without more critical parts on hand to mock things up too much chance of welding in a tube where it will end up interfering with something. So I started working on a structure to support the fuel cell. The cell is a 15 gallon, with an integral surge tank and in-tank fuel pump. I am going to wind up making it a bit beefier than necessary to support the tank and fuel, just because it seems like it would be a good idea to include some crush protection in the event the car gets hit from behind (or crashed backwards). I am using .095" wall tubing, so it is pretty sturdy (also, sadly, fairly heavy). This is where I am so far. Just need to include some more bracing and a bolt on "lid" then I can work on welding it into the car. Nice doing some welding on a work bench for a change, rather than contorted inside or under the car.

Thanks much! I have a JD Squared notching tool....very useful but it will only notch to about 45 degrees...so a lot of the time you have to mostly do it by hand.

More roll cage nonsense.... The diagonal roof bar is just wedged in place and is coming out for a redo. I can tuck it a bit tighter to the roof if I change some of the angles. I don't think I have ever gotten one of these bars right on the first try. Kind of frustrating being an idiot...lots of wasted steel...although a lot of it can be cut up for smaller pieces....and/or used for welding practice since I am a noob welder. Thanks for looking.

Yeah...the dash that came with the car is trashed...and I am not really bound to maintaining any sense of originality anyway. All I need is a place to mount a digital dash. I was taking stock today....other than the doors and body shell...there is really almost nothing OEM Datsun that I will be reusing.

Got the driver side door hoop bent, fabbed up the bases, and tacked them in place. I also mounted my seat to see how everything fit. It looks like the setup will meet the SCCA requirement that the main hoop be at least two inches above the top of my helmet....but barely. I have the main hoop 1/8" from the roof metal, and the bottom of the seat is scraping the floor....so there is not much else I can do other than choose a bigger car for my fun. I don't intend to do any door to door racing in the car, but am following the SCCA rules to the letter just to avoid safety/design errors. I have enough clearance that in a side impact my bare head would go below the upper door bars, but I with a helmet on I would probably hit them. Overall everything is really tight. I am sure I am not the first to face these issues due to my height (6-3). When the car is actually ready to roll I think I will invest in a halo seat, and obviously a lot of FIA padding will have to be used on the relevant bars.

Thanks for the kind words Vanilla. I spent most of the day today getting the passenger side door hoop bent. It really fought me. To make it fit decently, bends in multiple planes are necessary, and each subsequent bend affects the angles of prior bends. It had me pulling my hair out, but on my fifth try I was finally satisfied with the fit. And of course, all the FAILS:

Had to redo my main hoop base plates. They were within about 1/8" of interfering with the seat I was using for mock-up....and since I am not even sure what seat I am going to use in the future, and that the original base plates were bigger and clunkier than they needed to be, I figured I would slightly redesign them lest they cause problems and bug me down the road. Same basic design, just streamlined a bit. Also got the main hoop bent and tacked in place. The tape at the top of the hoop was built up 1/8" inch thick to give me very tight clearance....I wanted the bar as high and tight to the ceiling as I could possibly get it. Thanks for looking.

Finished the main hoop bases. They are only tacked into the car, so I can remove them down the road to drop the cage and weld the hard-to-reach areas up top.

Definitely interesting to see how others have done it. I positioned mine slightly higher, because I want the top of the hoop as tight as possible to the roof of the car (I am 6'3"), and if I tack the cage in place on the "higher" base, it should give me a bit more room to drop it off the bases for 360 degree welding. At least that is my thinking... I also wanted to preserve the stock seat belt anchor to use for my harness...as it seems to be in a good location for that....I figured why re-invent the wheel?

Finished the stitch welding....nice to have that chore done....and moving forward at my normal glacial pace. Started building the supports for the main hoop of the roll cage. I included close-ups of this because I couldn't find much in detail about how people built these up on prior projects, hopefully some day someone might find the pictures useful. I pondered a bit wondering the best way to do it. I am using 12-gauge (.100") steel....which meets the SCCA requirements that cage bases be at least .080" thick. Thanks for looking.

My goal is to make the photos in each update look identical to prior photos. I think I am succeeding:

Thanks....I just use one of these https://www.mcmaster.com/#compasses/=1akhiyh set at 1" and a Sharpie to mark where the welds are going. Obviously it is just about aesthetics and precision is not needed. It only adds a few minutes to the process. As I said....it is removing the primer and seam sealer prior to welding that is driving me nuts. And of course, after I make a string of welds having to go back and grind down/redo all the contaminated ones that look like a donkey dick....

I think I am going to keep it and eventually build a second diff. I have so many parts lying around I might as well.

Finally got my diff more of less sorted... As I mentioned previously, I am using an R200V from an N/A 300zx, which comes with a 4.08 ratio. After doing the math and pondering it a bit, I decided the 4.636 ring and pinion (I bought on Ebay) would meet my needs better. As best I can determine, these come out of the front of assorted Nissan 4WD vehicles like Pathfinders. It is a 51/11 gearset. On first trial assembly, I was a bit confused because the input flange would bottom out before the pinion bearings had even tightened up.... It soon became apparent that the 4.636 pinion gear is significantly shorter than the 4.08 pinion: This fact somewhat complicates setting up the diff with the new gears, as the prior spacing pretty much has to be thrown out the window...there is no using the original diff shims and hoping it will leave you in the ballpark... You kind of have to start from scratch, and without having the specialized diff setup tools (who has those?) the only recourse is a lot of trial and error via assembly and disassembly. If it helps anyone, I wound up needing 5.75mm spacing between the inner pinion bearing and the pinion gear. Checking the Nissan shim charts, the minimum thickness available (if you can find them) was around 3mm, and the max I believe was 3.66mm. So none by themselves are thick enough, and two of even the smallest would be too thick. To get around this, I would up using these 2.5" ID shims https://www.onlinemetals.com/merchant.cfm?id=1217&step=2&top_cat=1175. They are not an exact duplicate of the OEM shims, not being metric and all, for example they are slightly looser around the shaft....but they are close enough to work fine. Like I said it took a lot of experimentation...assembling and disassembling until things were close enough to leave a recognizable pattern in the gear engagement dye: In this picture you can see the pinion was too close to the ring gear.... After a lot of experimentation I wound up with the pattern below, which I think is about "right". If nothing else this process will make you an expert at tearing down and assembling a differential.... Once the contact pattern appeared correct, the backlash seemed to take care of itself and measured out within spec at .004". Once that was done, tear everything down AGAIN, paint it (yes, freakin orange!) start final assembly, new seals, and stub axles. The six bolt stub axles are for a Skyline GTR, which I used so I could use the beefy Q45 axles (which are also good because I have a set). The OSG LSD is also the model intended for the Skyline GTR so things like spline counts and lengths would all be compatible. Mike Hanson at Whitehead Performance helped me with the Nissan diff parts interchangeability questions, which had me completely confused (be forwarned, a lot of the info circulating in the 'net about Nissan diff parts compatibility is just plain wrong) but Mike seemed to have this stuff down, fortunately. The only other aftermarket parts required were the Nismo M12/M13 ring gear bolts...because the 4.636 ring gear has M12 threads but the OSG LSD has 13mm holes. Someone will probably weigh in now with a much simpler way I could have done all this....but such is life.

Looking very tidy, good work! Where did you get the radiator/fan shroud? Looks like a nice unit.

Just more stitch welding.... I would be inclined to beg someone to kill me....but I think I am over half done now. Must press on....

Finished welding in the Bad Dog frame rails today. Doing this actually killed two birds with one stone. My floor pans were kind of wavy and bowed inward from decades of improper jacking and other abuse, and I was not having much luck straightening them with mallets and 2" X 4"s. I just drilled through the Bad Dog rails and through the floor pans and used longish M5 bolts to draw them tightly together. This not only positioned the rails properly for welding, but the rails were rigid enough that the bolts forced the floor pans straight. Not sure why that did not occur to me sooner.... I experimented a bit with what sort of stitch weld to use on the rails so as not to grossly distort the floor pans. I initially was going to use 1" weld beads spaced 1" apart, but quickly found the heat from the longer bead was pulling/distorting the floor pans. So I resorted to 1" spaced plug welds in the flanges, and larger 1" spaced spot welds between those. Seems like this should be more than strong enough and kept the distortion to a minimum. I only used long weld beads where the rails mated with the thicker steel of the car's OEM frame. I know others have enthused about them for many years, but I wanted to add again that the Bad Dog rails seem to be a great mod for a tired beat up car (which all "Zs" are to different degrees). They were also far easier to install than I expected. Great product. Beyond that I have been working primarily on stitch welding all the OEM joints. Really a grind of a job, had I fully known what would have been involved I might have skipped it entirely, but now that I have gone this far I have to go all the way right? The welding is the easy part, what is driving me crazy is trying to get all the metal clean enough of primer and seam sealer so I can wind up with decently solid welds, rather than gonad-looking porous monstrosities. Probably 10X as much time is spent working assorted wire brushes and dental picks than actually welding. Thanks for looking.

Thanks, The worst part....I was just starting to set up the new diff housing today....and it is going to require completely different shims than the prior one. Starting completely over, but I guess that should not be a surprise.

I got pretty lucky for sure on the lack of rust. I gave the car a very thorough inspection prior to buying, after looking at several cars in which the floorboards consisted of hardware store galvanized sheet metal held in with rivets or duct tape. But I bought the car in Palm Springs, and I think it spent its entire life there. I would imagine most Southern California cars have little or no rust. As far as the diff, I am planning to use the TTT rear end conversion kit, which is designed around Nissan components, so I was not really thinking Ford. Also, the short nose came with a 4.08 on the 300ZX....all the other R200 diffs had ratios in the 3.XX range. Turns out I am using a 4.6 gearset from the front of a Pathfinder, which if I understand Nissan diff interchangeability at all would not work in a longnose R200. I just hope the diff is beefy enough for a 525 HP LS3...as it did not come on any Nissans with anywhere near that output. But all the advice I got from people who claim to know this stuff said that it should be fine. Besides my only stronger Nissan option was the R230....which comes with something like 3.5 gearing....not good for my purposes. And AFAIK there are no other R230 gearsets available.

You ever have the feeling with these car projects, that you are working your ass off but getting nowhere....or even going backwards? I got tired of stitch welding the body shell(mind numbing PITA of a job, far worse than I expected), and I got the rest of my diff parts from Japan, so I was hoping to finish setting up all the diff parameters and buttoning it up...you know....so something was "done". As anyone who has done this knows, it involves a ton of assembly and disassembly checking bearing tension, backlash, and gear contact pattern. Well, the last time I was taking it apart, one of the carrier bearing cap bolts decided to gall/seize in the threads in the casting. Not sure why...I had the bolts lubed...but it did. I managed to get the bolt out, but it took massive force and took all the female threads in the diff case out with it. I figured, minor setback. Timeserts have saved my ass many times in the past, and they are nearly idiot proof....so I plunked down almost $100 on a M12/1.50 Timesert thread repair kit. Timesert went in like always, I was feeling good about myself, and all that. But when I went to thread in the bearing cap bolt, it became apparent that somehow I managed to drill out/tap the damaged diff threads crooked. So, of course, the Timersert went in crooked. You can't tell from the pictures, but the Timesert is roughly 5-10 degrees "off" from perpendicular to the rear diff cover sealing surface. So far off, that the bolt contacts the casting and will not thread in. So basically, my carefully prepped and painted diff case was toast. As I said, Timeserts are pretty much idiot proof, and I managed to f*** it up. It was a proud moment. Fortunately, I managed to find another 300ZX diff online for a decent price (sort of), got it dismantled today.....and ready to begin round two. I sure have an embarrassing pile of smelly/nasty diff internals lying around the shop. Can't get rid of them yet....don't know what else I might manage to f*** up. This time...I'm not going to bother painting it until I have everything set up and ready for final assembly.

Good to hear....I am not clear how the 4.6 ring and pinion was used in its OEM application, because it needs more shimming than would be met by any of the Nissan shims I can find part numbers for...if that makes sense. I think most of these 4.636, 51/11 R/Ps came from the front of Nissan Pathfinders....but the parts diagrams don't list any particularly thick shims, so I assume the front diff case was just different in terms of spacing. By my calculations....I am going to use 5.32mm ...total...shims as a starting point. Thanks for the input....good to know we came to the same conclusion.