Laur3ns

The word is out - my Quaife 5-speed has died.

I already had the issue of extension housing bolts shearing off and replacing them every session, but now - while looking for a permanent fix for that - we found:"
- seriously overheated bearing
- broken teeth on 1st and 2nd gears
- other gears have serious pitting

So this leaves me at a cross road with mostly dead ends.
- Use 6spd as consumable, $$ and mid-session failures
- Another Quaife, $$$ how long will this last?
- Motorsports gearbox $$$$ is the car worth it?
- V8 conversion $$$$$ expensive in Europe

or

- Find another track car, E46 M3 or something and break that

or

- Detune the 2860 down to .5bar and live a poor life

Suggestions?

soviet

iTrader: (10)

Why not swap a Getrag? Pick a model - 260,265,420.
You're in Europe, plenty of people know these transmissions.

soviet

iTrader: (10)

Or get a faceplated Tremec from good ol' USA - T56, TKO500, TKO600

TNTUBA

iTrader: (1)

The gears from Quaife are replaceable individually. When I got mine from Quaife, the builder (Helios Motorsports), noted that there was pitting and burs on some of the gears. After sending pictures directly to Quaife they were able to overnight individual gears. I would say to call Kevin Hayes at Motivicity (they are the US Quaife wholesaler), tell him what you need and he can get you prices for them.

Who built the transmission for you?
What did you replace when you built it? i.e. Every single part in the gearbox or just the parts that needed to be replaced.
What lubricant were you using? And what was your change interval?

TNTUBA

iTrader: (1)

Opps. Didn't realize you weren't in the US. Might still be worth a call to Kevin....he seemed to be able to get Quaife to make my situation right with no issues at all.

I do know that Quaife does still make these gearsets and will still sell them.

NiklasFalk

iTrader: (1)

I'd be worried about these two to begin with, something is not the way is should be (i.e. why were the bolts shearing?).
If the bearing is overheating for some reason, that reason can be the starting point for all the other problems (except poor quality gears).
Gearbox tolerances are tricky business, more than one have serviced OEM boxes to make them fail very fast.

Buying Motorsport boxes to get away of the teething problems would steer you away from Quaife/Elite and into the arms of Drendt/Sadev etc. €10+k...

Today the 6speed with PAR gears sound attractive, but with the same problem as with your current Quaife box, you have to be QC of the installation yourself. SuperMiata gears for $3+k are not available yet.

Consume 6speeds with a final gear keeping you in 5th a lot of the time (make 6th just long enough for your longest straight)?
My thinking with this is that a shorter gearing will make you spend less seconds in 4th with full torque.
Practice swapping boxes, one hour should be possible.

Laur3ns

Visuals.

Turns out 1-2 are worst. 3-5 look fine still.
Suspect is too much low end torque.

Savington

iTrader: (31)

Where are all of the gears in relation to the bearing that failed?

Laur3ns

Not a failed bearing, but some coloring was visible was said.
The one right next to 1st gear. So the failed gears are close.

See picture.

TNTUBA

iTrader: (1)

From those pictures that looks more like FOD rather than "death by low end torque"

Laur3ns

The O being a stray tooth.

k24madness

iTrader: (6)

What type of trans cooling do you have? What are the fluid temps?

Savington

iTrader: (31)

+1. Hot bearing = gear misalignment = instadeath

schmoo

How the hell are we supposed to be able to guard against less than optimal alignment/install on these multi-thousand $ boxes?

NiklasFalk

iTrader: (1)

Learning by doing (wrong) is one expensive way.

Using a builder who have a track record of making stock boxes survive a rebuild is one tip. Not ignoring the same builders warnings (e.g. about gear quality) is another.

Laur3ns

Well not instadeath. Let's not forget I took the box out to have the bolt issue fixed, only then we found some missing teeth parts and pitting. The box was still drivable in all gears.

The bolts however have definitely contributed to the issue and the root cause for the bolts is most likely drive train slack. So, time for some supermiata motor mounts and checking the diff mounts (energy suspension currently).

The extension housing bolts will be 12.9 grade in the next build.

So, current plans:
- Further post mortem to ID anything that needs replacing
- Replacing gears from Quaife (3rd and main/4th)
- 12.9 bolts in extension housing
- Super Miata motor mounts
- Discuss additional gearbox bracing

The idea of a sequential box is out of the window: sequantials needs a GCU for ign cut and blip and additional hardware if you want the box to stay in one piece, making such an investment >10k.

Laur3ns

I have 100% faith in a guy who gets flown in on Dakar other rally events to look after and repair gearboxes. Quaife never said these gears would do 300lb/ft.

My 2860 on a 99 block and EBC makes from some early boost, something the box doesn't like. So plan is to detune that slightly too.

What kind of oil should I put in?

NiklasFalk

iTrader: (1)

My comment was supposed to be general and aimed at the several reports of failed refurbished junkyard boxes used in e.g. Spec Miata.
If there are some tricks to make the 5sp hold together longer (and don't flex too much?) it will take some iterations to improve it.

Leafy

iTrader: (1)

Whats a GCU? You have an ECU with a spare 0-5v input that can do spark cut based on that input right? Then you only need like $2 worth of parts from the electronics store to make your spark cut setup. Or you could just lift when you shift, that would be easy. Just blip it yourself on downshifts.

emilio700

iTrader: (3)

There is also downshifting too soon. A GCU can also keep the box from shifting down before it's safe for the engine. Shift by wire essentially