S15 6 Speed Gearbox Rebuild, Strengthen and Circlip Issue Thread.

[Nemesis Guy]

Well the time had come where the clutch started slipping and needed replacing. So I thought I would replace it with an up rated clutch setup and look into getting the gearbox stripped down, checked out, send the gear set off to be Cryogenically treated to strengthen it and fix the circlip problem and finally get it rebuilt.

Like most S15 Owners I don't want to change from the 6 speed box and thought this would be the best solution for running more power through it as I'm aiming for a responsive as possible 400BHP in the future. Hopefully it will last until I can afford a PAR gear set when it fails.lol

With regards to the circlip issues and how to get it fixed? From searching I haven't yet come across a thread from of how to resolve and fix the problem as it seems to be a bit complex how to do it?????

So the story goes I had managed to source a second hand ORC 409 single plate clutch and flywheel. I now wish I bought a new one for the peace of mind and I think 100 miles use on it description was a bit of a lie from now looking at it. I also had to source the special bearing and carrier required. Oh well we all learn at some point........

Knowing that the gear box was going to be out for some time I spoke to some garages I knew to see what they would quote and the cheapest quote I got was £300. I suppose it’s not too bad, but thought I would rather spend that money on tools and do it my self so bought a quick lift ally jack and another pair of axel stands.

So once the gear box was removed I took it to Bara Motorsport as there pretty much the best in the business dealing with £25K+ Rally gear boxes day in day out.

Through stripping the gear set they found that everything seemed to be ok apart from the fourth counter gear (part 32270M Picture 1) had started pitting. This is where the hardened steel has started to wear away. So thought it would be best to replace it as the 4th counter ran on mainshaft on picture two. If the counter gear was to fail and chew up the main shaft I wouldn't like to know how much that would cost to replace and would most likely be bye bye box! I also had problems engaging into reverse and they found wear on the taper in the reverse baulk ring not allowing it to slow the gear down when engaging. So ordered one of those too! One last thing was that they said 6th gear looked to have been getting hot? They said this maybe because it sits at the top of the box possibly suffering from oil starvation? Something worth noting as I go up into 6th as much as I can for better economy when driving distances but said it would be good too change down into 5th for a bit to give it a break and circulate oil when changing.

I emailed a few companies in Japan and Perfect run came out on top supplying me with Nissan Fast Part Number Images to confirm the correct part. The parts have now been ordered and just waiting on stock to come in on the fourth gear that’s expected on the 1st March and will then be shipped.



Picture 1

Picture 2

So once the gear arrives from Japan I will send the gear set off to be cryogenically treated. The company I have been talking to is http://www.195below.co.uk/ and have quoted me £8 + VAT Per KG so I figure it should cost around £60 to £80? I haven't actually had the chance to weight it yet. They said that it is put in the deep freeze Friday night left in over the weekend and taken out on the Monday morning giving it plenty of time to do its process.

So on to the circlip issue I have been trying to get my head round??? From what I have read the problem lies with part 32204 (Picture 1 front of second line of parts down.) This then holds the thrust washers together (Parts 32414R) that then allows the 4th gear bushing (Part 32253N) to remain in its place on the counter shaft. Once this circlip fails all will become loose and will feed its self into reverse gear blowing the box! Here are some pictures I also took to help get an idea....

So with this where I am a bit confused? Should the counter shaft be machined deeper for the thrust washers and the circlip to hold it more snug or should the thrust washers be machined to hold the circlip deeper within them? As I have no idea how these can be mounted to be machined?

If any one would have any idea how to do this it would be much appreciated and hope my post so far is becoming useful to fellow S15 owners?

 

[S15_SAM]

As a soon to be owner and mechanic it's very helpful! But I see your problem, bar welding the c-clip in place I don't see many options! Once you've rebuilt it is it possible to just tac the clip in areas which will not affect the rotation? I know it seems like a bodge approach but when needs much and all that! Because I see little in any other way of solving it!
Do the gearbox specialists not have a solution!?

 

[craig8585]

Looks like you've been a busy man! Out of interest, how much did the new parts set you back from perfectrun? And which parts are you geting frozen?

Very interesting and helpful read. I intend to do something similar in the future so look forward to reading the next updates.

 

[ichigo-300]

Very Interesting.. And thanks for the cryogenic site link, when my box is out I think i'll be following suit.

I'd also like to know if the gearbox specialists had any words of wisdom regarding what to do about the circlip issue (weld, re-machine etc), let us know thanks.

Keep the updates coming, this is probably the one issue that S15 owners don't have a definative answer for regarding the stock 6sp box.

 

[_Wing_]

I posted up some details on it in a thread not too long ago, hope it helps
http://forum.s15oc.com/showthread.p...tmas-thanks-Santa.-Sound-like-circlip-failure

 

[Nemesis Guy]

Looks like you've been a busy man! Out of interest, how much did the new parts set you back from perfectrun? And which parts are you geting frozen?

Very interesting and helpful read. I intend to do something similar in the future so look forward to reading the next updates.

Well the parts are now on there way. For what I ordered, Perfectrun sent me a PayPal request for £26.37 by EMS for shipping that couldn't argue with. As for the parts the 4th counter gear cost around £91 and the Baulkring cost around £39 along with some other parts I ordered.

I will be just getting the gear set and shafts done might throw a few other lightweight parts in like the baulk rings etc that are more prone to wear than required for strenght. Many people seem to get everything done including chucking in the gear box cases too. But don't really see the point in that??

 

[Nemesis Guy]

Well back on to the circlip issue. I have discussed the possibility of machining the shaft, machining thrust washers or welding the circlip and they are all no no's!

It is a very professional company I am working with and they know their stuff so not going to argue with them. Basically machining the shaft slightly won't make any difference and will weaken the shaft too removing the case hardening. It is then impossible to machine the thrust washers and welding the circlip would make no difference and would be impossible to get the correct fusion between the property materials and would become be very brittle as snap straight away!

The only solution we have come up with is to have a new bulkier thrust washer machined to take a stronger and larger snap ring. The only problem is, is that its not going to be a cheap fix! Because to do this properly and professionally I have an engineer next to the company that would draw up the specifications required, machine the ring as a whole unit then split. It will then need to be sent away to be stress relieved and then be case hardened. The stress relieving process would stop the washer from warping during the hardening process.

So as a process this is a lot of work for such a small single item and would be a lot cheaper if I done a batch of 5 or more say.

So I would like to gauge interest if I was to offer this as a professional manufactured kit to no longer worry and cure the problem of the circlip failure! How many of you would be interested in it? Depending on the numbers it could cost between £70 and possibly go all the way down to £40 depending on how many people would be interested? Please let me know your thoughts. I think this would be a relatively cheap modification for the cost it would save you if the circlip was to fail and blow your box!

 

[eiden88]

I'm having problems with my drivetrain too.
not sure if it's just the cluch disc whose finished or a deeper (hope not) problem.
Also, my car is turning 84k kms now so I'm getting a bit worried after reading all this.

I'll change the clutch for now and i'll let you know. but if we reach a good number and we can get this sorted out, then I think I might have it anyways and keep it as a spare for the future.

cheers

 

[haz's S15R]

Hi, just blown gearbox number two tonight (in 4th this time rather than 3rd :no. Needless to say i'm really interested in the concept of a stronger circlip :nod: - as that's what has gone both times!!!

Maybe time to get some names together...
1. haz's S15R

 

[-8ball-]

Had my 15 two days and the gearbox has got a nasty whine witch is doing my head in (hoping only input shaft bearing) so will be coming out soon so I can fix that.
After reading deeper in to the gearbox and it's problems I would be very intrested in this fix depending on price.
Keep up the good work I know I appreciate it so far.

 

[mitto]

afaik garage-d in watford are onto something... i'll update when i find out any more on it.

 

[Benne]

Maybe time to get some names together...
1. haz's S15R

2. Benne

 

[ichigo-300]

3. Ichigo-300

 

[J0R04N]

4. Jordan

Just my reverse that is poo at the minute. But I know it's just a ticking time bomb. Seriously considering a complete engine swap to the rb25/26.

 

[Nemesis Guy]

I do suppose an update is due on this from me to complete my findings as the gearbox is all sorted now. I will try to get all my information together tonight as to what I have done and the costs involved to pass on to you guys.

As I found out a group buy to have a quantity of larger thrust washers and circlips can't really be done reliably as the tolerances in the gearboxes need to be exact as each gearbox could be different so you wouldn't just be able to know what size is needed until the gear box has been stripped.

 

[Silverstreak]

I do suppose an update is due on this from me to complete my findings as the gearbox is all sorted now. I will try to get all my information together tonight as to what I have done and the costs involved to pass on to you guys.

As I found out a group buy to have a quantity of larger thrust washers and circlips can't really be done reliably as the tolerances in the gearboxes need to be exact as each gearbox could be different so you wouldn't just be able to know what size is needed until the gear box has been stripped.

Hi, I started a thread about this a couple of years back, can't seem to find it at the mo, as I've had to re create my profile! I have also been looking into this issue, and the long and short of it is that in collaboration with Julian at GarageD and Quaif, we have developed a reliable fix for this issue, which is now available from GarageD! It's taken 3years to develop and test, but is now ready for sale to you guys! The mod has been tested rigorously on a 500+ horsepower drift car and it has held up very well! If you are interested in having your 6mt box modified then get in touch with Julian. I shall try to find out how much he is charging for this mod and will post up shortly!

 

[Silverstreak]

Hi guys, having read a few of these 'need a fix threads' and the fact that I also started one a couple of years back http://forum.s15oc.com/threads/7366-6MT-Gearbox-circlip?highlight=Gearbox
So I thought I'd report back that there is finally a fix for this issue! About 3 years ago I contacted Julian Smith at GarageD and told him about my research and asked him if he would be interested in looking into this problem with me. So after a couple of years of tea search and development, and rigorous testing on a 500bhp + drift car, and a little bit of help from our friends at Quaife, this fix is now available to you guys!


If you want to know more or even get this fix done to your own car, you can contact Julian at GarageD. This mod requires a virgin 6mt gearbox in good running order, which will be modified and then returned to you.