Yes, the kit was made here in Brazil, was developed specifically because too there are no kits "ready" for that gearbox here in Brazil.

No dog engagement, is synchromesh, because I use the car on the street and also for rides.


I paid U$3500, I believe the value is high because the kit has been custom.

Mathew.

So this is an old trait of yours eh Flea?

It doesn't look like strengthening the gearboxes has made any headway since this thread was started in 2009.

Boxes keep failing in the same way, but I guess it's because no one is prepared to spend the necessary funds for a good strengthened gearbox.

Pero,patience.Mine is currently under testing.3 trackdays 1/4 mile day and 2 mapping sessions= some road abuse with no issues.

Can anyone help me with JohnS's post above ?

I'm interested to know how the two 5 speed boxes (Early and Late versions) can be identified ?

Apart from the Quaife, have you done anything else?

My box lasted a whole couple of hundred miles.

Erm have you seen what lenths Sparco has gone to with his gearbox

Yes and i think the poor chaps still having issues.

What we all want here is a cheap fix thats reliable and with little modifications.
So unless your willing to spend circa £1500 like me then theres no point in continuing to advise on this.
There is no cheap fix other than throwing boxes in the cars at £50 a time.

Yes John, I think you are correct. In my opinion i think that after 450hp the gearbox options are limited.
450 hp and more investment into brakeing and handleing is in my opinion going to achieve a well balanced track coupe.

I do realise that there will be faster coupes on track easily.
But for an all round every day reliable fast track coupe that can be used year in year out is a 450 hp coupe.
I do realise i am not the best informed but it is just my opinion.

Thanks Joe,
can we clarify here how many people have blown there boxes up around a track?
I have got through 9 and i am on my 10th.Not one has gone on the track (Thank god)
So the undulations in the road play a contributing factor to the issues that have arisen.
1/4 miles dont count

I only killed mine with a full-throttle launch at Santa Pod - broke the planet gears in the diff, which then broke the diff and pushed it through the casing

I agree with magooagain - 450bhp is enough - I won't be going for any more (other than mild tweaks via a remap when I get bigger injectors). It's ultra-reliable, and I can use a Helix Organic clutch (which means I can drive it in traffic).

Yes, I'd love 500+, but I will not accept the compromises that come with it (lag, driveability, traction and of course, broken gearboxes).

Yes, I know a 2.4 would reverse some of the downsides, but I'm not in a position (yet) to splash the cash.

What did Sparco end up doing in the end? I know he spent a huge amount on his gearbox

i cant remember what he did but i know it was a complete custom billet box?

i think thats what he used any way...

I hope he doesn't mind me saying, but it wasn't enough. The casing still gave way.

Ross

Maybe we've found the reliable upper limit of Coupe tuning. TBH, it's testament to the basic engineering that the stock gearbox can happily take double the stock power

Nearly triple on mine soon i hope

That said i have known a few coupes blow boxes on stock power.

Has nobody offered up different gearboxes?

Mounting plates can be made up very easily if one was a close enough fit.

£8.5k and counting guys but that's a full billet steel dog kit i the standard housing which i get the feeling is going to be looked at and possible a new stronger end casing manufactured. This tuning lark is fun isn't it!!!!!!!!!

Just on the gearbox?!!!

Yes and that's me supplying the casings so far too!!!!

Yes £5800 for the full custom dog kit.

First failure after 50 laps was a selector fork which when it broke tried to allow the gearbox to select2nd and 3rd at the same time. The re-made the selector frok from Billet along with a few shafts etc and the repair bill was £2800

Box lasted 4 laps this time and as it stands i'm awaiting analysis on what went wrong. It does look like i will be looking to strengthen the casing in some form though regardless as when the dog kit is working it works very well indeed.

Oh and that's with my own gripper plate diff in it too not and Elite one.

Having this sort of stuff ain't cheap but pioneering stuff for the coupe never is as youwell know and people like Barbz, John S and Taz.

When my car can go toe to toe with a 400bhp factory Porsche GT3 cup car then it's very rewarding and all the hassles and hiccups seem a lot more worth the effort.

Bearing in mind i'm only running 450bhp and not huge BHP like some road coupes.

What is killing your gearbox then? I'm running the same power and I'm not breaking them (although I tend not to jump over saw-tooth kerbs at full throttle on my daily commute...)

Are you being particularly brutal with it?

Nigel, have you ever seen Marco in action

Brutal is on his warm up

You could buy a lot of £50 gearboxes for £8.5k!

Surely its shock-load that's breaking the 'boxes - once rolling, they appear to be capable of holding huge power.

I have to admit that I've heard a couple of worrying thuds and clunks from my 'box, usually when one wheel spins up and grips again (such as over a drain cover in the wet)

I could imagine a 'box in race use would get similar sudden loads as grip drops and returns, although a slippy-diff should lessen the effect.

Dumping the clutch is a bit brutal on a gearbox, but it usually results in loss of grip, especially when delivering 450bhp through the front wheels. Its only if the tyres grip hard that the load is high.

I am still surprised that the box can take 400BHP plus with seemingly no issues...

Not in my case. Third gear stripped on mine after I was well on my way out of a bend.

It looks like it just couldn't handle the torque.

On my first coupe (3rd gear box) I ripped the end casing off in 4th at around 90 dropped the oil over the rear wheel. Was a scarey momment I can tell you.

The failures i have seen down the years have all been to do with the diff or casing.
With 400 BHP on the stock late style box i could pop the diff out every time on a hard right hand bend in 3rd gear .

You see the same rotational marks on the diff casing.
The casing failures are also due to oil starvation and this is noticable on the 5th-6th gear end bearing.

casing failures again are also due to the planet gears fracturing and locking up.
Typical symptoms are locking into gear until the car cools down.
If the planets fail then it will push the diff crown wheel and the secondary shaft apart causing the weakest link which is the casings to shatter.

I am yet to break a box on track which would suggest that the wear to the box plays a big part whan the diff is challenged by undulations in the road surface which you dont get on track.
Also the track offers a much increased transfer of heat into the oil whereas the road doesnt.Thicker oil ie when cold is a contributing factor also.

Biggenz in your case you run the early box which is renouned for having issues with gears under extreme torque or boost.
The grale forum was littered with the same issues at one point.And your box is near identical to the grale boxes.
The later boxes have a much stronger gearset which you can see with the difference in colour between the early and late boxes.
The ''Myth'' that the early type boxes are stronger in my opinion is just that.
The casings are much denser in colour which would suggest that they were made from a different material than the later types.
I havent got 2k or more to spend on boxes so with a spanner and candle light i take the time to address the failures and hopefully it will not find another weak point.

So far i had more probs running 400bhp with boxes than running nearly 600bhp and 500ibsft torque.

So you're saying I gave up my 6 speed box for nothing?

From my understanding, it was to do with the way 3rd gear is created. Something to do with the 2 parts being tack welded together. When they go, the 'grale lot get a coupe 3rd gear as the construction of the gear is different.

No in your case when your running 2.1bar with a 8500 limiter you would kill any box.
High boost hero's.Be wary.

Sadly I'm only running 2bar@8250rpm to keep things a bit safer.