620owner Posted October 26, 2015 Report Share Posted October 26, 2015 OK I know I'm opening myself to a lot of chatter on the topic..... but I am replacing wheel cylinders on my 620 and the new wheel cylinders do not come with a NUT. The original Datsun nut is not the same thread as the new one (Dorman) W37381 Can't find the bolt size or thread type anywhere. It's machine thread not sure if it's metric or standard thread and I think it's 1/2" bolt. I looked through my buckets of old bolt & nuts couldn't find one to fit. 1 Quote Link to comment
HRH Posted October 26, 2015 Report Share Posted October 26, 2015 I got some nuts for ya!!! :D But seriously, go to the hardware store and find a bolt that threads into it, then you'll have your size. Or get out your thread pitch gauge and find it that way. I have one, most don't. 1 Quote Link to comment
Rjawm Posted October 26, 2015 Report Share Posted October 26, 2015 And agreed with HRH, best bet is to go to a hardware store, or maybe a a place like Fastenal or Tacoma Screw, and match it up. 1 Quote Link to comment
620owner Posted October 26, 2015 Author Report Share Posted October 26, 2015 I've got a couple die and thread sets and none of the dies would thread. I checked with the pitch gauge and I think it's metric 12-28 Taking your suggestion and heading for the Zieglers Nut & Bolt Store. Want a good hardened steel nut not the cheap box store rust to pieces in a year stuff. I ruined one new wheel cylinder not realizing the nut was a different thread. Dorman had to save a penny not including a nut on the cylinders but they really F***ed with us by changing the thread on top of no nut. 2 Quote Link to comment
banzai510(hainz) Posted October 26, 2015 Report Share Posted October 26, 2015 antiseize compound and CRC in a can. I hate they dont come complete on brakes 2 Quote Link to comment
HRH Posted October 26, 2015 Report Share Posted October 26, 2015 12-28 isn't metric. That's machine thread. 1 Quote Link to comment
KoHeartsGPA Posted October 27, 2015 Report Share Posted October 27, 2015 Ask Busta! 1 Quote Link to comment
kelowg Posted October 27, 2015 Report Share Posted October 27, 2015 Sounds like u got 521 wheel cyls, those sae not metric 1 Quote Link to comment
ericsb210 Posted October 27, 2015 Report Share Posted October 27, 2015 I try to only buy wheel cylinders marked with original Japanese origins. Always have a better performing brakes system that way and they last way longer. 1 Quote Link to comment
Loryde520 Posted October 28, 2015 Report Share Posted October 28, 2015 K,....Well I've had the same problem. I read somewhere on here, not really sure 'cause I'm gettin old and can't remember squat! Someone stated these trucks are sae not metric. So I went to my local parts store and he called B.S.. I bought some fine thread standard bolts, and they barely fit the threads. Now I am really confused. Did Nissan have their own thread pitch like VW's ?? I just removed my front wheel cylinders from the backing plates and lo and behold,.. a 3/4" socket fit the best! along with the bleeder stem nut,...7/16" nut. So am I nuts or the guy at the parts store??? 1 Quote Link to comment
Laecaon Posted October 28, 2015 Report Share Posted October 28, 2015 fyi 3/4 is practically the same as 19mm. 520/521 should be SAE everywhere except the motor itself (and well any other parts that are shared with the cars). Threads are just standard thread pitches. Get used to identifying by sight, makes life easier. Your lug studs/nuts are SAE... 1 Quote Link to comment
Rjawm Posted October 28, 2015 Report Share Posted October 28, 2015 Just for conversational sake, 19mm = .748" (.75 is exact 3/4) 11mm = .4331" (.4375 is exact 7/16) Add the rust and road grime to a 19mm or 11mm and the SAE probably would fit better lol. Everything I've ever heard aligns with the SAE on 521's but then Metric for all newer. Worst vehicle I ever had for this kind of problem was my 1987 El Camino, body built in Canada so mostly metric, drivetrain and suspension built in US so mostly SAE. 1 Quote Link to comment
DanielC Posted October 28, 2015 Report Share Posted October 28, 2015 520, and 521 trucks are SAE standard. I believe the 620 truck switched to a metric standard. When they left the factory. Several metric sized wrenches will fit inch sized bolts and nuts. 5/16, and 8 MM interchange. 7/16 and 11 MM are close. 1/2 inch, and 13 MM are close, and so are 9/16 and 14 MM, 5/8 and 16 MM. 19 MM is .748 of an inch, 3/4 is .750 of an inch. Many 521 brake parts will fit on a 620. So will many 620 brake parts fit a 521. Lets take a rear wheel cylinder. A 521 rear wheel cylinder is held to the backing plate with 5/16-24 thread, and has a 3/8-24 flare nut. A 620 wheel cylinder is held to the backing plate with a M8-1.25 thread, and has a M10-1.0 flare nut. There is a reasonable chance that a 521 has some 620 metric parts that fit, and there is also a chance a 620 has some 521 SAE parts. 2 Quote Link to comment
620owner Posted October 29, 2015 Author Report Share Posted October 29, 2015 I took the cylinder to the bolt & nut shop. They say Metric 8-1.25 thread too.... the nut they gave me is a 19mm 1.25 thread. I still say it threads on sloppy. I can wiggle it and there is play but it does tighten up. I put it in the vice and torqued it to 35 against some washers. It seems it will work but I'm not satisfied it's the right nut for the bolt. My cousin who is a machinist said it's OK to use and that it's just not machined to a high quality. He said something about different quality standards of threads. I see in the previous post to use a M10-1.0 flare nut. OK where can I get one. What's the difference between a flare nut and a standard nut ? 1 Quote Link to comment
DanielC Posted October 29, 2015 Report Share Posted October 29, 2015 The flare nut is on the brake line. It holds the brake line on the wheel cylinder. It is probably there already. 1 Quote Link to comment
HRH Posted October 29, 2015 Report Share Posted October 29, 2015 If you have 8x1.25 and some jerky tries to thread a 5/16 bolt into it, that will make them feel sloppy, 5/16 is just a smidge smaller than 8 mm. Or it's just the wrong bolt. Most of the 521 stuff I've dealt with is half and half, just like mid 2000 Chevy. A lot of the items though are standard, not metric. 2 Quote Link to comment
620owner Posted October 30, 2015 Author Report Share Posted October 30, 2015 OK here's what you shouldn't do. Didn't check thread before using original nut and striped the threads. And this is what it should look like with right nut. 1 Quote Link to comment
620owner Posted October 30, 2015 Author Report Share Posted October 30, 2015 Does anyone know if the ruined stud can be backed out of the wheel cylinder and replaced ? The ruined stud doesn't appear to have threads all the way to the wheel cylinder casting like the replacement. Quote Link to comment
KoHeartsGPA Posted October 30, 2015 Report Share Posted October 30, 2015 Does anyone know if the ruined stud and be backed out of the wheel cylinder and replaced ? The ruined stud doesn't appear to have threads all the way to the wheel cylinder casting like the replacement. You can fix that thread. 1 Quote Link to comment
620owner Posted October 30, 2015 Author Report Share Posted October 30, 2015 I was thinking about just taking the same size Die/thread cutter and trying to re-cut the threads in the bolt but I didn't think there was enough metal left to make a strong enough thread. My second thought was to maybe try a different thread, not sure how that would go either. Besides I didn't think there was enough room to re-cut. So I bought another one. I'd like to fix this one if possible, hate to toss it. I also thought about cutting the bolt off, drilling out the remaining and taping out the casting and putting in a new stud bolt.... a little more work. Nice to have a spare. 1 Quote Link to comment
Andres131313 Posted October 30, 2015 Report Share Posted October 30, 2015 I was thinking about just taking the same size Die/thread cutter and trying to re-cut the threads in the bolt but I didn't think there was enough metal left to make a strong enough thread. My second thought was to maybe try a different thread, not sure how that would go either. Besides I didn't think there was enough room to recut. So I bought another one. I'd like to fix this one if possible, hate to toss it. Nice to have a spare. it looks like there is. just be very light on the pressure you put on it. by the way if you want the nut size ask flatcats mom. 1 Quote Link to comment
ericsb210 Posted October 31, 2015 Report Share Posted October 31, 2015 Maybe just me, but I would never use any brake component that had to be "repaired". We are talking about the only thing standing between a safe stop on the road or a sudden stop at the bottom of a canyon. Besides these are what $15-20? Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.