Another 6 speed bites the dust.
#1
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Another 6 speed bites the dust.
Ok after doing a replacement of my 6 speed earlier this year in the paddock at Laguna Seca putting in a Mazdaspeed version. I stripped out 4th gear again. This time on the back straight of Portland International, full throttle at peak torque in forth and bang strip. I wasn’t even running the motor at full tilt. I have it tuned to do 20psi but I’m running 14-15 psi making 324 HP and I think it was 280 ft-lbs to fit into NASA TT2. I have recently set overall Miata lap records with it on 3 northwest tracks winning NASA and SCCA time trials and also won a couple national events in Solo as well as the Canadian Solo National championship so it has been driven hard.
Trying to decide what to do next. 6 speeds are expensive when you go through 2 a year!
Trying to decide what to do next. 6 speeds are expensive when you go through 2 a year!
#2
Any gearbox alternative would cost at least four 6speeds (including the quife gears ready to go), but if it would work for at least two years it would be worth it (less lost days etc).
How many general US race boxes have been modded into Miatas (non-PPF of course)?
Anyone used these (with a useful road race box etc etc)?
http://www.jegs.com/i/Quick-Time-Bel...-4097/10002/-1
Sorry, I have missed this one (no answers but a lot of the usual speculations)
https://www.miataturbo.net/suspensio...9-motor-74899/
How many general US race boxes have been modded into Miatas (non-PPF of course)?
Anyone used these (with a useful road race box etc etc)?
http://www.jegs.com/i/Quick-Time-Bel...-4097/10002/-1
Sorry, I have missed this one (no answers but a lot of the usual speculations)
https://www.miataturbo.net/suspensio...9-motor-74899/
Last edited by NiklasFalk; 10-14-2013 at 02:18 PM.
#3
To continue to verify my ability to spit out nonsense:
Would a lower final gear help anything, putting the long high torque loads into fifth (i.e. no gears to strip if I have understood gearboxes at all)?
This would of course make 1st a loading gear and 6th maybe a bit short (thinking 4.44 or so).
Cheaper test than a custom gearbox, if there is any possibility that it could work.
Would a lower final gear help anything, putting the long high torque loads into fifth (i.e. no gears to strip if I have understood gearboxes at all)?
This would of course make 1st a loading gear and 6th maybe a bit short (thinking 4.44 or so).
Cheaper test than a custom gearbox, if there is any possibility that it could work.
#5
Why not RX-7 5-speed?
An RX7 gearbox seems to be the next logical step, before going full out crazy on a Jerico box or on a Quaife gear-set.
Luckily, the rx7 gearboxes are pretty cheap. Heck, the bellhousing adapter plate is 2-3x the cost of the gearbox itself. You only have to buy the adapter plate once, and you can probably pick up 3 rx7 gearboxes for the price of one six speed...
An RX7 gearbox seems to be the next logical step, before going full out crazy on a Jerico box or on a Quaife gear-set.
Luckily, the rx7 gearboxes are pretty cheap. Heck, the bellhousing adapter plate is 2-3x the cost of the gearbox itself. You only have to buy the adapter plate once, and you can probably pick up 3 rx7 gearboxes for the price of one six speed...
#6
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Sorry, I have missed this one (no answers but a lot of the usual speculations)
https://www.miataturbo.net/suspensio...9-motor-74899/
https://www.miataturbo.net/suspensio...9-motor-74899/
1. buy that quicktime bellhousing
2. use factory flywheel with a clutch disk that matches a Jerico input shaft
-or-
2. use fancy flywheel/clutch like twindisk jobbies that already have splines that match a jerico
*Jerico has many different length and spline count input shafts. They will work with you on figuring out what you need.
3. Make a trans cross member, pretty simple.
4. Custom driveshaft, pretty simple. Jerico can supply you the front yolk if you want something baller.
5. Custom diff mount/ppf solution, can be simple or not depending on your preference.
possibly 6. Rig up some sort of clutch mechanism depending on how "OE Mazda Miata" that Quicktime bellhousing is in reality.
OH, edit: 7. Shifter. That may require some tinkering.
Most difficult part for most people would be earning the money to do the above.
#8
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G-Force 101 4-speed
Here is a Tex Racing (Jerico competitor) road racing trans for sale.
Doug Nash Super T10 - $1000
Jerico Road Race 5-Speed
Super T-10 Trans - $900
Here is a Tex Racing (Jerico competitor) road racing trans for sale.
Doug Nash Super T10 - $1000
Jerico Road Race 5-Speed
Super T-10 Trans - $900
#12
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Join Date: Jul 2005
Location: Anacortes, WA
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I am suspecting bearing issues start the problem allowing shafts to spread apart a bit and tip load the teeth. Evedence of repeated failures by me and other High hp Torque users sugest 4th is the weak point in the 6 speed.
#13
In five speeds I have broken twice on third gear and once on fifth on track. There has been one time where the gearbox broke on second gear at autocross. Every time the secondary shaft has been used.
Leaves 1 st and fourth, 1st sees torque so short time that it will not break and fourth is straight gear.
Based on tooth angle on quaife set, I suspect also secondary shaft axial loading on stock box has something to do with breaking gearboxes.
Leaves 1 st and fourth, 1st sees torque so short time that it will not break and fourth is straight gear.
Based on tooth angle on quaife set, I suspect also secondary shaft axial loading on stock box has something to do with breaking gearboxes.
#14
Bob contact Ron at Barrington Performance
He seems to be on top of custom work for Miata gear boxes. I bet he has a reasonably priced solution to your problem.
He seems to be on top of custom work for Miata gear boxes. I bet he has a reasonably priced solution to your problem.
#17
Bob contact Ron at Barrington Performance
He seems to be on top of custom work for Miata gear boxes. I bet he has a reasonably priced solution to your problem.
He seems to be on top of custom work for Miata gear boxes. I bet he has a reasonably priced solution to your problem.