mjrstar

The catch can is all good, it's this ghost I'd be deleting.

My personal preference would be to mig it with .6 wire and co2 for the gas as i reckon you can get better penetration at a lower amperage (just my opinion on gas selectionhete). Run a longer post flow for extra cooling if it's adjustable on your machine, if not a second click of the trigger will give you another dose of gas I think the access sucks enough for tig to be annoying, even though I hardly ever use my mig these days..And agree with others around tack wait method. If you want some extra insurance you could get someone with a purge cup to backpurge the HAZ with argon as that will cool the back side of the weld very quickly. This is a bit unconventional with mig and maybe overkill but hey. Cover up the inside of the outer skin to stop any splatter finding it's way into the seam. TL:DR I reckon inert gas is the best cooling method.

You should be able to fit an evo spec 17x8 at 38p with a 215 45 17 I dunno about an 18 you'll probably need very minimal tyre profile at that diameter. Probably also depends on how much slam-dog-millionaire you are aiming for.

I have another driveshaft which is too long to fit, but it has no dust shield so I could potentially fit this and get a closer measurement for actual radial play, and see if it varies from the current one. And maybe i can get closer with veriners instead of the dti. Right up at the output it will be less than 1mm. I didn't measure engagement but I'd say it's probably something like 70mm maybe a bit more. There shouldn't be much in the way of axial travel as the diff is solid mounted and the gearbox is very close to solid mounted. I probably should shorten the spare driveshaft, but it's a bit of a process being carbon fibre.

Yeah depending on wheel width offset etc a bit of slotting at the knuckle connection could very quickly eat up tyre to strut clearance. Best to figure this out during a mock-up. I'd be looking for something preetty foolproof for a locking mechanism as it's not quite loaded like a standard suspension bush eccentric bolt. Something similar to these serrated washers and tabs to be confident it can't shift. Then do your fine tuning back at the top off the strut. https://jp3motorsports.com/products/mazda-rx7-fd3s-eccentric-lower-control-arm-lock-washers The simplest cheapest (free)option would be to weld up the portion of the strut hole that's nolonger used.

I'm assuming they are all IRS, perhaps there was a different variant for a ute that was live axle. You might be right about the box not having a replacement bush. The parts breakdown I found was pretty comprehensive and didn't show one.

Shaft is tricky to get good purchase on, but appears snug. It's a 32 spline nissan cd009 gearbox from a 370z. It's pointing to an outer bush but the parts breakdown I found looks like that's not really a thing it has. Some garbage google results suggest these gearboxes are OK with radial play up to 1mm.

So the internet suggests that too much air gap can lead to poor signal performance..... so I reduced the gap and took it for another road test. That resulted in it losing its shit at even less speed.. it turned to haywire at around 50kph. So there is something in that.. next up I tinkered around with more air gap on the hoist to get the smoothest slow speed signal then sent it in 5th gear on the hoist. ( no need for 6th gear on this test) its cleaner but not perfect , maybe this is because its basically not producing any torque I'll need to put it down the road to confirm.. i also need to look deeper into this slip yoke bushing..

There's no sign of backlash, and the oil seal isn't leaking and looks OK. But the 1mm radial sure feels bad by hand. And is significantly more that the cv cups play out of the diff. That measurement is probably exaggerated a little as I can't get my dti right up to the gearbox output. I've been trying to track down the correct replacement part to see if I can get some dimensions to calculate oem clearance.

Before you carve out the holes you could mock up with just the lower bolt installed and then pack out the strut to knuckle with something of appropriate thickness to see what sort of result is possible. I'd also be looking at something such as an oval washer or space to make sure the bolt can't shift in the slotted hole as it'll be under a fair bit of load at the track.

The slip joint od looks mint and measures up at 44mm. There is about 15mm of additional plunge remaining which seems reasonable? I can't get a good look at the outer bush but it looks like it has some spiral slots that I assume are for allowing a bit of oil to splash into. Maybe once the oil is in there doing it's thing that movement would reduce.

Back to speed sensor woes, it's a hodge podge (of course it is) it needs to work better. Clint's suggestion had me thinking is the issue torque related with twist in the drive train messing with the air gap. Because it seemed to lose it's shit at higher speed. This snip is an accelerate to 6th gear (legally of course) and then maintain speed with a bit of full throttle run holding the speed on the brakes. So if it was working properly the top white line would be a tabletop but really the oy bits that are representing correctly are the ramp up in speed and then the deceleration at the end. It's also interesting that off throttle at higher speed it comes right (kind of anyway) Maybe I need a proper mount, an actual tone wheel and an automotive sensor rather than my industrial one?

That's a good point thanks Clint. The setup was a total bodge to prove the concept. Ie: is this free sensor going to work, can I pick up off the universal joint, can the ecu even handle this, how do I calibrate it etc.. I was mostly expecting it to be a total failure whereas what I have us only partial failure. But now I'm down of the side quest, is my gearbox output bushing /bearing a bit chooched or just normal?

Gearbox slip yoke radial play. How much is too much and what is normal. The internet is giving me mixed results I've got ~.9 to 1mm which seens / feels like a lot.. I'm chasing an erratic speed signal on my bodge pickup arrangement but there is also a fair bit of drive train noise which I had been putting down to solid mount diff and poly bushes for the gearbox mount.

Yeah have done turbo wheel swaps and not balanced afterwards without an explosion. Does it maybe shorten bearing life, I guess it would eventually..

I don't know if this is viable or not but I'll chuck it out there just in case.. If you were able to bring the font cross member forward say 40-50mm to fit the rack back in its original home this could give some advantages from a car setup perspective. -Longer wheelbase so more stable. -Added castor -Improved front/rear weight distribution. Yes you'd have to shorten the front swaybar arms, and modify the engine mounts, and probably make up a couple of new brake lines.. but you wouldn't need to buy much additional hardware.

Wife's one had some fault like that and was a dirty windscreen.

Time for a roof scoop, they are amazing for ventilation, and pressuring the cabin.

That shifter bracket is quite the design! With the engine and box combo did you consider uprighting the engine to to sit level which would maybe give more room for headers, or do you think the headache of getting the tilted over gearbox to work nicely isn't worth the headache? My mate with the Datsun is keen on an upright k with the s2000 box and to me it looks like clocking the gearbox will result in the window for the starter being a no-go as well as some clashing of bolt holes.

You'd think if you had it working just the outside wheel with some toe and the inside wheel off the gound it'd want to rotate a bit. I reckon it would be a tricky combo to build something that excels at nz style hillclimbs as well as smooth circut work. I'm confident my car would do pretty poorly at a circuit. I've put a video in the video thread of an event that has a set of bumps and a few crests to deal with.

To reduce understeer just get the rear to toe out under compression. You have to lean on the rear tyre a bit on entry by being slight less smooth but it seems to work.

Maybe I'm garbage at explaining my predicament, yeah the shock extends of course but depending on the dampener settings it takes a bit of time to get to fully drooped. Ie if you fully compress your shock and let it go ot doesn't instantly hoon to max extension due to the flow restriction. This is with no preload on the main spring. Potentially this is a me problem as I'd already gone as soft as I can on the shock and reduced rear spring rate from 8kg to 6kg before putting the helper on. With ~ 1.3 ratio and a 6kg spring it seemed like there wasn't enough mass acting on the spring during a violent application for it to soak up the bump and extend the droop. (~ 130kg corner weight in the rear). A 2kg spring compressing 50mm will take 100kg, which seems reasonable?

Potentially, I know MCA often run a paper thin tender springs that you can comfortably compress by hand. Sure this stops your spring jingle jangling about, but would it overcome the dampener. I'm suggesting you need "enough " spring to get the shock working so the compression works progressively. I found with the fwd if you happen to have the power on when it's on 3 wheels then no dramas. But if you get the 4th wheel making significant touchdown from standstill it would upset my car. Probably negligible on a circuit car. ( I only started noticing it at hillclimbs) I'm suggesting a decent rate keeper that is fully compressed when static but has some assistance to extend the shock were otherwise maybe full droop wouldn't occur for a little while. (With dampener set relatively slow and relying on un-sprung weight to extend) ~2kg/mm would be pretty sweet, ypu could compress the keeper spring then let the jack go to see if it extended as expected. Still trying to get my head around an 800lb rear spring on a 1:1 ratio. But hey if it works then Allgood.

Let's say your rear corner weight is 140kg each side, the assumption that the car weight(static) would compress the 800lb spring ~10mm ( probably less given some of your corner weight is un-sprung) So when you unload the main spring does it lift a wheel on the dampener or does it droop under its own weight plus spring pressure (plus swaybar tension)?

Thanks to @gibbon for testing and cleaning my mix and match injectors I now have the best four in the car, a couple of spares and a cou6of do-not use. I moved on to tweaking the idle stability, i don't have anything in the way of iacv,so was limited to some ignition trickery, so I out in a target table to improve stability. then I thought hey I could add a sectable second table for idle instability because who doesnt like being able to turn on choppy cam noises.. With those dialled in I worked through a bit of cold compensation as an assist on first start. So now I've got it happy enough to idle from cold without the hot idle being crazy high.. It seems to like a bit more base timing than i was expecting but I don't really have an explanation for that yet. Video is garbage sound on my phone due to lack of bass, but makes correct noises via headphones. https://youtube.com/shorts/E9g4cweMnm0?si=lab_Xx-eGIflzYQP