904 trans: threads for nss damage

[360duster]

Hi guys, need your help. The neutral safety switch threads in the case of my 904 are pretty damaged. Is there a way to save the case besides welding, like a thread repair? I'd like to save it.....thanks in advance!

Michael

 

[Demonracer]

I believe the threads are NPT (national pipe thread). See if you can find someone, like a machinist that has the proper tap. NPT taps of that size are not cheap for a one time use. If all else fails, a good machinist can probably come up with a good solution.

 

[66fs]

I think they are straight thread. Take your NSS in to a good hardware store and find out what size and how many threads per inch. Then you can look for helicoils and taps.

 

[JBurch]

A couple of possibilities come to mind:

1. Here in the states, Loc-tite makes an epoxy type thread repair kit, net strength is 80% of original. You may have something similar there in Germany.

2. Locate a machine shop that will make you a bushing that you can screw or press into the case, if you gave them a deposit they may loan you the tap to thread the case. Just remember, depth of engagement is important.....too far in and maybe break something, not far enough and the switch doesn't work.

3. Maybe you could locate a helicoil thread repair kit that you could use to repair the threads.

Good luck!

 

[cannucky]

all of the above but I would add that too far in and the reverse lights won't work if it's a 3 wire . In fact the after market units from standard now go too far in and need a washer or gasket to space them back enough for the reverse lights to function .

 

[KickDown]

Michel, The thread size for the NSS is 3/4-16 UNF. For a thread repair you can tap the case for a Heliciol or a Baercoil insert but you will have to use great care as there are only 5 threads in the case. You might have to do some measuring/calculating on how far the NSS protrudes into the case. As was stated in previous posts this is critical to achieve the correct function of the Back-up lights (if 3 pin) & the neutral safety function. Baercoil are in 68542 Heddesheim in Germany
Cheers. Gaz

 

[360duster]

Hi Guys,

thanks for your feedback! did some racing the last days, could not answer earlier.

I put it in with some threadlocker, seems to work. If it´s not leaking, i´ll remove the trans in winter and put in this thread repair kit.

Michael