Oscar

iTrader: (2)

Because you need a dickload of sets made before they'll cost less than 483047 million a set?

M.Adamovits

Rebuilt six speed checking in. Broke 5-R shift fork.

Used stock parts from Mazda, using their 6 speed tech manual as a guide.

And yes, for whatever reason it broke on a car running NONEOFIT.

bbundy

I may start taking one apart and add up the parts cost to fix it. Mazda comp dosn't seem too bad price wise for parts. but Im guessing once metal bits are flying around the number of parts that should be replaced is a lot more than a shift fork.

Bob

bbundy

Somwhere I found a 6 speed factory service manual on line and printed it out. But I can't find my printed out copy. Andybody got a link to it so I can print it out again?

vehicular

iTrader: (3)

For the record, shift forks break because of abuse, not power.

codrus

Lesher Motorsports Inc. Spec Miata rentals and builds

I dunno what kinds of work he normally does. He was instructing at the MRLS event (I was pitted next to him), and happened to have a few transmissions in his shop when people needed them.

--Ian

concealer404

iTrader: (3)

Don't make it complicated. Just call these guys.

Mazda - NA/NB MX5/Miata Roadster : PAR - Precision Automation Robotics

M.Adamovits

Replaced the fork, 3rd, 4th, and 5th synchros, for iirc ~$200.

Sometimes we get rough..

flying_solo

iTrader: (5)

Confirmed, S1 6spds have shitastick synchros. Last weekend there were 4 S1 RX8s at an SCCA event. 3 of us were nursing a bad 2nd gear synchro. S2s are considered much more reliable, but I don't know if they can be adopted to miata. As for RX7s, it's the 5th gear synchro that explodes so I wouldn't waste money adapting an FD tranny to your miata even though it can handle the power better.

emilio700

iTrader: (3)

Odd. I had been talking to PAR on and off for a few years. Their old website had info for AZ6 (6 speed) straight cut dog and helical syncro conversion, bilet shift forks, etc. Now it's just 5 speed stuff. I'm sure they can still do the AZ6 stuff if you ask. Wasn't cheap though. By the time you did a full gearset with billet forks and got it here, it would be around $6K.

I shipped a pallet full of dead AZ6's to Ron Olsen at BAR in IL about 6 months ago. He's working on a sequential box. Problem is his goal is an EP box so barely able to deal with 180lbs tq. When I told him there was a slightly larger market for turbo Miata guys he was interested.. until I told him it had to survive 400 lbs and 300° for about 30 minutes.

I've heard of guys modifying T5's to hold more torque and adapting them. Those are dirt cheap. Available ratios suck though.

Coolest option is a Quaife QBE60G 6 speed sequential. They even offer a bell housing and input shaft for our B series Mazda engine. Bare bones set up would probably run $9K. Cool guy set up with shifter and electronic controls for anti-overrev, flat shift, etc, would push that to about $13k.

Oh yeah, I have a customer in Australiar that put an RB26 Skyline trans into the Miata. I believe the SR20DETT engines S15 Skyrine used a variant of the AZ6. RB26 was something different.

So yeah, I don't have any answer either.

vehicular

iTrader: (3)

G-Force sells gearsets on the order of $1600/set that are rated to 600hp/500tq in a Mustang sized vehicle. That plus a junkyard T5 case for $50, plus the rest of the rebuild parts you'd need, plus the Quicktime bell housing, plus a clutch disc for a Mustang 26-spline input shaft might be an option. You're still going to have a lot of cheddar in it, though.

k24madness

iTrader: (6)

I have been trading emails with Ron about the project. He was quoting me 240tq limit. Great for us Rotrex guys. Sadly the price will be about the same as the Quaife so not sure if that will happen for me.

Vilko

Dont the series 4/5 rx7 have the strongest gearbox of all the rx7s?
Edit: I don't know many people who own rx7s, that's just what I've been told.

Vilko

Are you sure it wasnt an RB25 transmission? RB26 only came with 4wd transmissions. The gearbox from the r33/r34 skyline and turbo VG from the z32 300zx gear boxes can take quite a bit of abuse and are the go to for RWD nissans putting out high power. Normally wanted for power above 250kw and are known to last quite well even when copping abuse from cars putting out over 300kw. Torque figures would be a whole lot more useful but they aren't thrown around much. Dont know the kw to hp conversion off the top of my head, but you can work it out. Anyway the demand inflates their price so they probably aren't the most suitable option, esspecially not in America.

The 6 speed nissan gearbox from the s15 silvia has a reputation for being quite weak. Far weaker than the earlier 5 speed. People can't agree if its torque or abuse that kills the 6 speed.
Sorry for taking it off topic, just being ----.

Reverant

iTrader: (10)

My experience tells me exactly the opposite. I have customers' car that have gone over 30k on a FD gearbox with no problems, and these are all 400whp+ cars doing drag racing and street racing.

Above 500whp, the first thing that snaps is the input shaft.

FCs have way shittier feel and engagement than FDs. On one particular car, I couldn't tell the difference from a stock Miata 5sp.

soviet

iTrader: (10)

quicktime bellhousing + TKO 600?
http://www.summitracing.com/parts/aw...make/chevrolet

you still need a clutch and PPF solution :/

TurboTim

iTrader: (9)

But the "ratios suck" according to Emilio and Sav (TKO ratios similar to T5z). Sav explained why in a different thread discussing the T5...I disagree but I drive my car on the street.

I :heart: my T5. Well...the shifter isn't as nice as the OEM miata, and the .64 5th feels odd but is nice for my 100mile round trip highway commute. I found ~5 different available .73-.90 5th gear options though. I even found a NOS BW .80 set on ebay for dirt cheap <$100 but missed out on it. I snooze I loose.

Astro .73 $192
Astro .78 9310 $279
Medatronics/5speeds.com .81 8620 $250
Gforce .78 (supplied by Astro), .75, .90 $345

Stan at http://www.pro-forceperformance.com/ is very helpful, dealer & price matches the above.

NiklasFalk

iTrader: (1)

Looking at Quaife you also have Elite to consider, slightly cheaper boxes.

One of my paddock buddies is running an Elite IL300 6S EVO 2 ($8k) behind a 380bhp Rover 8 and when it has failed it has been vibrations, bolts etc and the service form Elite have been great.

Elite lists a number of Gear kits, so they might be one of many companies to contact for a quote for a set or single pairs of gears.

Would new tougher gears for 3rd and 4th be enough to make the 6sp tough "enough", or would a full set be better to do it right at once (labor etc cost the same regardless of how many gears you change)?
Making 3rd-6th gapped for track, 2nd for standing starts and 1st for loading would be nice. Aiming at 4.1:1 diff to have easily accessible rear end options
Personally I'd be pleased with a 6sp mated to my 4.875. I never see speeds where the 6th would run out on our tracks (at my power level...).

I never got anyone to bite on the flawed option of changing final drive to reduce the torque in the box and move some of the driving breaking 4th into 5th. Would it just make the thing break anyway or would it change the time spent on sensitive gears (breaking less boxes per time bu spending more time in 5th).

thenuge26

iTrader: (2)

Is there a problem with the regular Quaife gearsets for the 5 speed? Savington ran one at ~350whp on track for a while right? It aint cheap, but nothing in this thread is.

NiklasFalk

iTrader: (1)

That gearset is cheap in this thread.
How many Quaife actually have and with what gearing rings a bell, but others have actual info.