Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt

[gibbon]

continuing to try and remove boxes from our offices, what the heck is this thing? two fibre cables, but also a big power cord thing? 

[tortron]

Power over Ethernet injector

 

Probably has a camera at one end?

[gibbon]

yeah looks like it might be part of the cctv setup. Weird because in the next room is a big cabinet devoted to it. Dunno why this little guy lives in a different room by himself 

[Rookie]

Has anyone tried swapping a billet wheel from the likes of Mambatek onto a turbo in the home shop before? Im aware of the balancing issues, but I have a turbo that got the wheel pulled off it at 3am one night on streetweek and reassembled that has been doing the duty for the last 5000km so it is looking like the likely recipient. Just curious if it was even remotely a success?

[mjrstar]

On 23/03/2026 at 10:34, Rookie said:

Has anyone tried swapping a billet wheel from the likes of Mambatek onto a turbo in the home shop before? Im aware of the balancing issues, but I have a turbo that got the wheel pulled off it at 3am one night on streetweek and reassembled that has been doing the duty for the last 5000km so it is looking like the likely recipient. Just curious if it was even remotely a success?

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

[mjrstar]

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.

[cletus]

you may need to mount the sensor to the gearbox? there might be too much movement between the body and the box for that to work?

[mjrstar]

47 minutes ago, cletus said:

you may need to mount the sensor to the gearbox? there might be too much movement between the body and the box for that to work?

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?

[tortron]

You could probably check the machineries handbook. It will certainly have acceptable fitments for slip yokes id imagine

[mjrstar]

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. 

[NickJ]

Yeah 1mm radial sounds pretty excessive for a splined joint, I would also imagine it has horrific backlash too?

If no blacklash then likely the bearing so i'd be looking to replace that, must be giving the oil seal a good working?

[mjrstar]

9 hours ago, NickJ said:

Yeah 1mm radial sounds pretty excessive for a splined joint, I would also imagine it has horrific backlash too?

If no blacklash then likely the bearing so i'd be looking to replace that, must be giving the oil seal a good working?

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.

[NickJ]

Is there any play in the gearbox output shaft?

No backlash suggests its not the splined joint, unless really old square splines?

[mjrstar]

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.

[RUNAMUCK]

On smaller nissan boxes, I've encountered  issues with the bush in the tail.housing getting worn. (These were not replaceable on my gearboxes, although @fletch did find  source for the 71C boxes) i had issues with the oil seal leaking due to eliptical orbiting of the output shaft. 

was there an OEM application for this box with a solid rear axle? Most of the cars that I can think of that used them were irs? 

 

[RUNAMUCK]

Has anyone ever repurposed an Air fryer as a bearing heater?

[gibbon]

5 hours ago, RUNAMUCK said:

Has anyone ever repurposed an Air fryer as a bearing heater?

i do sintered bearings in a toaster oven

[mjrstar]

5 hours ago, RUNAMUCK said:

On smaller nissan boxes, I've encountered  issues with the bush in the tail.housing getting worn. (These were not replaceable on my gearboxes, although @fletch did find  source for the 71C boxes) i had issues with the oil seal leaking due to eliptical orbiting of the output shaft. 

was there an OEM application for this box with a solid rear axle? Most of the cars that I can think of that used them were irs? 

 

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.

[RUNAMUCK]

Iirc, the ones I've seen were actually a two item.

One housing I had rebushed, and then machined to size after it was pressed in. 

(On everything else, I replaced the factory shield incorporating the rear oil seal for two 7mm wide oil seals. 

It fixed my leaking issue.

[ThePog]

All this sexy spline talk has reminded me I need to get a custom rear driveshaft made for the truck. It currently has a SWB safari one that I had the joints replaced, balanced etc.

But the thing was secondhand and the splines are not all that, which was noted by the boy at the time.

It works ok with no vibrations even though it sits at a significant angle, but it often makes creaky clunky sounds at low speed, particularly if I have neglected greasing it.

So can anyone recommend an outfit to sort something? I want to go with CV joints rather than UJ or double cardan, and obviously would want a new spline setup and for it all to be chunky as all fuck so I never have to worry about it..

TIA