s15 6mt gearbox, circlip mod?

[motoren]

Hiya all

Im new to this site and new to driving nissan, but only 3 weeks after i bought my nissan s14 my gearbox broke down.
I opened it and saw what went wrong, circlip failure at 4th gear, I started to search the net to see if other people have had the same problem and there were alot .

I have read through many posts, many people talk about a "circlip mod", i havent been able to locate any picture or manuals of what the mod is all about. So choose the change to either rb25, z32 or z33 gearboxes.

If i havent already bought a 2nd hand s15 6mt gearbox, i problably would have gone the way of fitting another gearbox.

The problem with the circlip:
I dont think its the circlip that fails, because there is no presure on the circlip itself other than the outer ring that holds the two c-clips together and there is alittle room between the circlips and outer ring. I think its the outer ring that gets bigger and bigger because the c-clips can move in and out. Please prove me wrong

I took a picure of the shaft with the two c-clips and the outer ring so you can see the room between them and what i want to do to prevent it from failing.

Best Regards
Kent Sorensen
Denmark

 

[motoren]

What about welding it? Flange of the hub to the c-clip.
I have seen pictures of others doing it, but won't it just break apart due to it being hardened steel?

Best regards
Kent Sorensen
Denmark

 

[STF515]

Here is a picture of the circlip weld mod - the mod was done correctly, they used a second hand failed shaft which caused my box to fail.

I hope that helps

Steph

 

[Nemesis Guy]

I can't beleive the shaft was actually able to be welded! I would of thought welding it would of made the material more brittle and weaker.

This is what I had done.

This was the original.

This was the new machined C-Clips and Heavy Duty Snap Ring. It was made out of the hardest material the engineer could find. With out having to be sent off and case hardened. It was a lot of effort for one of these. A new shim also had to be produced so the gear set would be in tolerance to the specified range on the S15 workshop service manual that you can see below. So far nothing has let me down and is all working smoothly. I haven't really given the box any death since the rebuild. I also got the gear set cryo treated at the same time to possible add extra strenth.

INSPECTION BEFORE DISASSEMBLY NMMT0054 1. Measure the end play of each gear. Replace the snap ring ifthe measurement is out of the specified range. Unit: mm (in)Gear End play3rd counter gear4th counter gear​

0.10 - 0.35 (0.0039 - 0.0138)

 

[motoren]

Hello again

One of my friend came with another way of making the circlip hold.

We are gonna mill the 4th gearcup 2-3mm down and them make a huge ring that goes all the way out the outer limit of the 4th gearcup and them up the c-clip and over it and in towards the reverse gear. then use a 3mm steel pin to hold it all together. We will then weld the steel pin so it wont move and maybe lock it with a safety wire.

Hope it makes sense

Best regards
Kent Sorensen
Denmark

 

[S15_SAM]

I think anything is worth a go!!