Im kinda blind. Do these look like matching thread to you?

Posted by Obvious-Dinner-1082@reddit | projectcar | View on Reddit | 40 comments

New is a Russell 639530 5/16” x 24 Speed Bleeder.

Old is a stock bleeder for the 1979/1980 Camaro drum brake wheel cylinder.

It doesn’t hand thread in like butter, (the old one does) but it doesn’t “look” like it’s going to cross thread. So I’m second guessing if the resistance is just the thread sealer.

Looking for a sanity check before I fuck myself I guess.

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realsalmineo@reddit

Mesh the threads together. If they fit, they are the same. If they don’t, then they are different. No tools required.

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fartsmcgee63@reddit

This only confirms the pitch is the same, not the major diameter or pitch diameter.

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Hedgesmog@reddit

Any examples of those where they would be so close you wouldn't be able to tell? But different enough to cause a problem?

The only times I've every checked diameter is when it's been very obviously wrong.

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10-32 and M5x.8 are basically identical, to the point that you may actually be able to interchange them depending on manufacturing tolerance. 5/16-24 and M8x1.0 are very close but are both relatively uncommon sizes. 1/4-28 and M6x1.0 are sort of close but the 1/4" is big enough that it wouldn't fit into an M6 hole. There are probably others but those are the first that come to mind.

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The 5/16-24 and M8x1.0 mismatch is such a frequent issue with 80-20 spare parts at every place I've worked. Always a bin full of bolts, and while everything will fit the matching sections, the fasteners get hung up in the little T-nuts. It's really annoying.

Thanks for the insight!

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TechnicianGlobal4312@reddit

Just hold them parallel against each other to see if the threads mesh

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Obvious-Dinner-1082@reddit (OP)

https://imgur.com/a/BDHKugC

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LiterallyCameron@reddit

Go up as high as you can on the threads, get as many threads to mesh as possible, some threads between metric and standard can be very close until you get a few threads deep

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Square-Job5632@reddit

M10 x 1.0 and 3/8 x 24 is a prime example. Literally a few thousandths difference

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FesteringNeonDistrac@reddit

Oh man, yeah that's going to be 25.4 tpi for a metric 1.0. Thats visually indistinguishable from 24 tpi for the most part. 3/8 is 9.5mm.

I work with my kids robotics team and they strip soooooo many M4 cap head screws that use a 3mm driver with a 7/64 hex key, which is 2.78mm. It works great, until it suddenly doesn't.

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GoodLunchHaveFries@reddit

I work in construction and custom fab. These two are the bane of my existence.

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Duhbro_@reddit

Sae should burn in hell

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chris_rage_is_back@reddit

Yeah I was just dealing with that shit yesterday, I've got some metric shit from India that I'm working on that's so close to 10-24 the nuts will mostly thread on until the last thread or two

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Obvious-Dinner-1082@reddit (OP)

I went for it. All the way, pulled it out. Looks fine. Thanks for the look!

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CiforDayZServer@reddit

Make them 69! See if they mate.

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NoAdhesiveness4091@reddit

If you squint, it's mint

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fartsmcgee63@reddit

Thread sealer? Why are you using thread sealer on a bleeder? The conical end on the bleeder acts as the seal surface, not the threads. The only threads that require sealant are tapered pipe threads like NPT and BSPT.

For what it's worth, they look the same to me, but impossible to say without proper measuring tools. Your old bleeder could just have a pitch diameter on the small end of the tolerance window for that thread class, and the new one could be at the large end of the window - manufacturing variance creating different thread fit.

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AltoTheDutchie@reddit

doesn't look it to me, right threads seem to be a bit smaller, but if you wana check, press the threads together, if they fit together perfectly, they're identical

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doubled240@reddit

All you have to do is see if the threafs mesh.

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TheBuzzyFool@reddit

I just bought a lanyard of sae and metric thread testers so I don’t have to ask questions like this. It’s like $30 on Amazon, I expect to use the shit out of it

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Vengeful-Wraith@reddit

I double that. Wonderful tool to add to the shop.

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Klo187@reddit

Just by eye, the one on the left is an imperial thread and the one on the right is metric.

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Roadkill215@reddit

No. Take 6 threads each. Left starts above and ends below.

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DakarCarGunGuy@reddit

Someone probably said this but if you "spoon the threads together if the mesh and NO light comes through your good. If light shines between them it's not a match.

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Pistonenvy2@reddit

i would say they are the same, you should be able to tell while youre installing it, some threads just arent formed all that great anymore and wont be a perfect fit but they are still the right spec.

the old threads look cupped and the wheel cylinder threads could be a little wallered out which would explain the fit while the new one is a little tighter.

if they are the wrong threads they will get tight and stop well before the bleeder is seated. i personally have a feel for it after cross threading about 1000 different things but its certainly not subtle if youre doing it by hand.

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Obvious-Dinner-1082@reddit (OP)

It seemed okay, I couldn’t do it by hand, but very light with the socket, it didn’t feel like anything binded. Pulled them out, they looked okay. I just double checked here at work, all the reman wheel cylinders are 3/8”-24.

I did fuck up the front. Fortunately a new caliper was only $25. lol

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legojoe7874@reddit

One seems way dirtier than the other

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Whizzleteets@reddit

Invert one and touch them thread to thread.

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MilkyWaySamurai@reddit

They look like they match. The old one is just worn.

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Mundane-Bumblebee-83@reddit

Get a gauge to be sure or an calipper if you know how to use one

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Maxzillian@reddit

Yup, a cheap thread pitch gauge is a great tool to have.

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robomassacre@reddit

This is what i would do

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pironiero@reddit

No.

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No-Government-6798@reddit

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fasurf@reddit

Looks like a tighter thread on the right

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Witcher_Of_Cainhurst@reddit

Wouldn’t you be able to take both to a hardware store that that has those little thin metal slab things with threads to let people thread in their bolts to see what thickness and thread pitch they need? You could see if these both fit into the same hole on one of those things.

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