Diff Breathers

[silvtr1000]

Th eanswer to this will probably turn out to be obvious, but I have to ask... What do you mean by "taper thread"? How does it differ from "normal" thread?

Mark

[Guest]

Th eanswer to this will probably turn out to be obvious, but I have to ask... What do you mean by "taper thread"? How does it differ from "normal" thread?

Mark

Mark.

On a normal thread the screw shaft is parallel all the way along therefore the diameter of the threads are the same for the whole length. On a taper thread the diameter gets larger the further up the shaft you go. Basically it's supposed to provide a tighter seal. The threaded hole that it goes in has parallel sides so the screw gets tighter to the sides the more you screw it in.

Cheers

[silvtr1000]

That's what I thought. As I did find that my unions did get tighter as I turned them in, I'm guessing that I will find they're well sealed when I do my blow test when the neighbours aren't looking. I've asked my Toyota mechanic uncle if he can get me the union in JimL's post above. If he can and they're cheap, I'll replace when I can.

Mark

[UKWolf]

That's what I thought. As I did find that my unions did get tighter as I turned them in, I'm guessing that I will find they're well sealed when I do my blow test when the neighbours aren't looking. I've asked my Toyota mechanic uncle if he can get me the union in JimL's post above. If he can and they're cheap, I'll replace when I can.

Mark

Mark,

If you have screwed two threads of different pitch together then it will get tighter as the interference between the two threads increases the more you screw it in.

I think having done that it would be better to leave them in if the the "blow test" is successfull as you have probably damaged the threads and you may not get the new Toyota parts to seal.

Ali

[silvtr1000]

I've been thinking about this. The threads were out by about half a thread over about 5 threads. Before I decided to buy the unions, I asked the shop guy to try a matching nut (out of the box where he got my unions) on my standard breather threads - he did and it spun on quite easily.

It's my feeling that, as the new unions only went in about 5 full turns (front and back) before I felt things were getting just tight enough without stripping threads, the thread on the unions may have been close enough in pitch to those in the diff casing to allow me to give them the 5 or so turns before that stripping feeling.

Either that, or the unions are actually taper thread - I felt after the 5-ish turns that that was enough - any more and I might be in trouble (I presume the diff casing is softer than the unions - those threads would probably strip before the union's?).

I have stripped threads and snapped fasteners in the past - I'd like to think enough to recognise that feeling when it's just about to go wrong.

It would niggle at me to know that things are still ok in diff-casing-thread-land, but I probably agree that if they're sealed as is, leave well enough alone.

I will probably put a longer hose on the back this weekend. Am I safe to assume that as the front doesn't have as much potential travel, it's ok as is?


Thanks a million, all. Aren't these forums great!

Mark

[UKWolf]

I have stripped threads and snapped fasteners in the past - I'd like to think enough to recognise that feeling when it's just about to go wrong.

It would niggle at me to know that things are still ok in diff-casing-thread-land, but I probably agree that if they're sealed as is, leave well enough alone.

The feeling that you get from fitting two slightly diferent thread pitches together is not quite the same as when you strip a thread, its more of just a tightening with a grunching feeling.

You could go back to where you bought them and see if they are tapered threads and in which case you have probably thightened them correctly.

If they are not taper and they are that close in pitch you probably haven't done any serious damage anyway.

Thanks a million, all. Aren't these forums great!

Mark

Yep! theres one hell of a lot of information and experience here.

Ali