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-   -   Who has broken a 6 speed? (https://www.miataturbo.net/suspension-brakes-drivetrain-49/who-has-broken-6-speed-46575/)

miatauser884 11-02-2010 04:19 PM

How much would an adapter plate cost that used the front bellhousing of the 6 speed and mate to an RX7 FD?

I'm sure the aluminum plate could be had for a reasonable price from McMaster-Carr. Flowjet/CNC could be expensive.

If you could get an adapter plate for sub $300, seems like it might be worth it.

customfab87 11-11-2010 11:24 PM

Is a high pitched whine when accelerating 2-4k rpm in 1st gear normal? I just picked up a 01 LS w/ 6-spd and plan on adding forced induction soon but want to make sure the trans is healthy!

Savington 11-12-2010 03:07 PM


Originally Posted by Fireindc (Post 649746)
Will you make a TSE conversion kit of some sort? Which gearbox do you have in mind?

Something T5 based, if it becomes necessary.

I had a brief conversation regarding tranny health with TDH at Streets this weekend. He put a temp sender in his 6-speed after the first one blew and he says tranny temps at Buttonwillow hit 340*F and were still climbing when he pulled in.

Reverant 11-12-2010 03:36 PM

That sure sounds high, I have one on mine and I have never seen anything higher than 270*F.

NickC 05-22-2011 04:15 AM

I'm actually interested in improving the 5-speed but it seems like there are a lot of knowledgeable people in this thread and the following could be mutually beneficial.

Apparently, the MSM 6-speed gears are "shot-peen-hardened", but what else is done or can be done to our gears? Are regular gears just induction hardened or is any carburized case hardening done? I think shot peening and cryo treating could help, I feel like I've heard some very reasonable pricing for it too.

Also, making a set of straight cuts from available spur gear stock could be an option? Even if maybe the original gear hub/center had to be used? (I know that's kinda out there, but you'd be surprised at what you can do with "creative" machining, some GTAW, and an Australian mindset) $1799 isn't awful for the quaife set either if you've made the 6-speed a consumable...

Anyone tried a transmission cooler yet?


Originally Posted by djp0623 (Post 651768)
How much would an adapter plate cost that used the front bellhousing of the 6 speed and mate to an RX7 FD?

I'm sure the aluminum plate could be had for a reasonable price from McMaster-Carr. Flowjet/CNC could be expensive.

If you could get an adapter plate for sub $300, seems like it might be worth it.

McMaster-Carr's nice, convenient, very fast, and well suited to all your INDUSTRIAL needs, but OnlineMetals.com or METALsupermarkets.com are more specialized and have much better pricing, especially for small quantities.

GeneSplicer 05-22-2011 08:15 AM

^^ Thread Necromancer

BUT - since it's alive -


Originally Posted by Savington (Post 656446)
Something T5 based, if it becomes necessary.

If you built - I'd buy. You might see who expresses intrest in getting something going.
I can't justify $3000 for Quaife internals in a 5spd case when you can get a 6spd for $600 or cheaper... but how long with either those handle 400+rwhp - or less as your case Sav?

kakarot 05-22-2011 10:32 AM

You can get mini power steering bump from junk yard, add 12V @2-5Amp motor to that. Use a relay and thermal switch to trigger the contraption. It will have plenty of pressure so you could also add oil filter if you like. The regular tranny cooler that you can get is usable, and can add a cooling fan to it as well. Add a second thermal switch and have a light installed in the cabin, if system cannot cool the tranny, then light should come on and tell you that temp is too high and its going to blow soon.

I am building said oil pump, but for jet engine application. Most pumps you can buy are on a budget are diaphragm based and cannot handle above 120F fluid usually.

I got one from junk yard for 6 bucks, and electric motor for like 30 like this one http://www.robotmarketplace.com/prod...-217-2000.html

If you de-powered steering, then you can use the unused power steering pump for that using engine power.

If there is interest, I can document the electric pump build. Otherwise, I probably wont.

NickC 05-23-2011 09:25 AM


Originally Posted by kakarot (Post 730035)
You can get mini power steering bump from junk yard, add 12V @2-5Amp motor to that. Use a relay and thermal switch to trigger the contraption. It will have plenty of pressure so you could also add oil filter if you like. The regular tranny cooler that you can get is usable, and can add a cooling fan to it as well. Add a second thermal switch and have a light installed in the cabin, if system cannot cool the tranny, then light should come on and tell you that temp is too high and its going to blow soon.

I am building said oil pump, but for jet engine application. Most pumps you can buy are on a budget are diaphragm based and cannot handle above 120F fluid usually.

I got one from junk yard for 6 bucks, and electric motor for like 30 like this one http://www.robotmarketplace.com/prod...-217-2000.html

If you de-powered steering, then you can use the unused power steering pump for that using engine power.

If there is interest, I can document the electric pump build. Otherwise, I probably wont.

Transmission cooler would be pretty light duty. The power steering pump is really awesome since the only "superior" option of maybe an idealized custom aluminum scroll or gear pump would be only marginally better, but a CIM?! That is one heavy chunk of inefficiency... The only reason I'd ever use one would be if weight and power consumption weren't a concern and it was left over from a FIRST robotics competition build.... The chinese and their cost-superior manufacturing (which has really made some increases in quality, for most** things "made in USA" might as well mean over-priced) make brushless motors and their controllers very affordable. (www.hobbyking.com and/or ebay for motor, controller and a servo tester to set your speed) Direct-drive brushless outrunner would be a much better choice for a DIY performance automotive application.

Geez, GeneSplicer you could've at least read my necromancing post :D The quaife internals go for $1799 now, which is still pricey and "while they last", but considering they have significantly less of a helical cut (= less thrust + more cool racecar gearbox noise) the 5spd case rigidity doesn't really matter as much, if anything the 5spd and its buttery smooth shifts would be the preferred transmission for our top end lacking flow choked motors.

I think* the EFR turbo line is going to do a little bit of "game changing" too. Not only will the highly responsive 6258 start to push the BP past 6spd power handling capabilities, after talking to one of the techs over at full-race I believe the T3 7064 could be a midrange friendly turbo with the correct intake manifold and light headwork.

kakarot 05-23-2011 05:24 PM


Originally Posted by NickC (Post 730289)
Transmission cooler would be pretty light duty. The power steering pump is really awesome since the only "superior" option of maybe an idealized custom aluminum scroll or gear pump would be only marginally better, but a CIM?! That is one heavy chunk of inefficiency... The only reason I'd ever use one would be if weight and power consumption weren't a concern and it was left over from a FIRST robotics competition build.... The chinese and their cost-superior manufacturing (which has really made some increases in quality, for most** things "made in USA" might as well mean over-priced) make brushless motors and their controllers very affordable. (www.hobbyking.com and/or ebay for motor, controller and a servo tester to set your speed) Direct-drive brushless outrunner would be a much better choice for a DIY performance automotive application.

Geez, GeneSplicer you could've at least read my necromancing post :D The quaife internals go for $1799 now, which is still pricey and "while they last", but considering they have significantly less of a helical cut (= less thrust + more cool racecar gearbox noise) the 5spd case rigidity doesn't really matter as much, if anything the 5spd and its buttery smooth shifts would be the preferred transmission for our top end lacking flow choked motors.

I think* the EFR turbo line is going to do a little bit of "game changing" too. Not only will the highly responsive 6258 start to push the BP past 6spd power handling capabilities, after talking to one of the techs over at full-race I believe the T3 7064 could be a midrange friendly turbo with the correct intake manifold and light headwork.

Brushless motors came to mind, but they require controller. CIM was an example. I have couple of those motors. I was thinking more of low parts count, simple and cheap. I did not do motor calculations yet for my application. But for low pressure and low volume, not that much power is required.

GeneSplicer 05-23-2011 07:41 PM


Originally Posted by NickC (Post 730289)
The quaife internals go for $1799 now, which is still pricey and "while they last",

Where you lookin?

NickC 05-24-2011 08:57 AM


Originally Posted by GeneSplicer (Post 730551)
Where you lookin?

earlier in this thread :noob: http://www.autotech.com/quaife/news.htm

I assume you'd have to contact quaife though.



Originally Posted by kakarot (Post 730495)
Brushless motors came to mind, but they require controller. CIM was an example. I have couple of those motors. I was thinking more of low parts count, simple and cheap. I did not do motor calculations yet for my application. But for low pressure and low volume, not that much power is required.

I was being a little "excessive" ha in my criticism, because I have a passionate hatred for the CIM even though it's an okay motor for e-bikes/scooters/robots. I don't like the stall currents of the big brushed chunks when they "kick on" (http://www2.usfirst.org/2004comp/Specs/Chiaphua.jpg look at the performance curve and specs) you could always have a starting cap like a home a/c I guess but you'd end up adding 10-15lbs with the mounted cim powered ps pump assembly. Which reminds the power steering pump is a little on the heavy side + the cooler and added fluid + optional filter.... maybe a heat exchanger a little centrifugal pump if anything... actually... helical gears are lame to death and are the cause of all this friction heat and nasty thrust loads.

Conclusion: Straight cuts or GTFO haha. Unless someone happens to know the exact center spacing of the input and output shafts, I'm going to see if there isn't some affordable spur gear stock with the appropriate pitch diameters as soon as I open my transmission and check the spacing. I know a few places where I could get some time on a proper lathe; it'd be a long shot, but I think if I chucked the transmission shaft (with the gear(s) being turned secured onto it) in a 4-jaw with a live center, used a good dial indicator to zero the runout, turned the gears off, put 1-2° taper on the turned outer diameter with the cross-slide, then turned the inner diameter of the spur gear .001"-.002" undersize with a matched taper for a well aligned press-fit, then weld and case-harden the gears a pretty badass gearset could be had for a low material cost and utilizing tooling that's more or less just collecting dust...

kakarot 05-24-2011 05:50 PM

Little known fact, helical gears are superior to spur gears at given width and pitch. Since the contact patch of helical gear is much larger per tooth. They also have higher tolerance to shock loading since more that one tooth is engaged at any time. A good old example were in tank transmissions. Panzer tank had straight cut gears, and suffered from stripped gears too often.

Then again, crazy people do crazy things. So if you got money to burn, go for it.

NickC 05-24-2011 06:33 PM


Originally Posted by kakarot (Post 730899)
Little known fact, helical gears are superior to spur gears at given width and pitch. Since the contact patch of helical gear is much larger per tooth. They also have higher tolerance to shock loading since more that one tooth is engaged at any time. A good old example were in tank transmissions. Panzer tank had straight cut gears, and suffered from stripped gears too often.

Then again, crazy people do crazy things. So if you got money to burn, go for it.

at given pitch* I'm not as well versed with involute gear tooth profiles as I would like to be, but I want to say there's some reason you have to use a higher pitch with helical gears? Regardless, assuming I can find them, I will be using a lower pitch for strength and avoiding helical cuts for cost and mechanical efficiency.

kakarot 05-24-2011 07:09 PM


Originally Posted by NickC (Post 730912)
at given pitch* I'm not as well versed with involute gear tooth profiles as I would like to be, but I want to say there's some reason you have to use a higher pitch with helical gears? Regardless, assuming I can find them, I will be using a lower pitch for strength and avoiding helical cuts for cost and mechanical efficiency.

If you want to find out the distance between shafts in the transmission. You can calculate it from knowing what # tooth is there. Basically only 2 different combination of gears can only have single pitch. Given that gears have exact same pitch. So if you know the gear ratios for each gear or better the tooth count, then you can calculate the pitch and then the distance between shafts. It should be metric too.

chpmnsws6 05-24-2011 07:36 PM


Originally Posted by kakarot (Post 730899)
Little known fact, helical gears are superior to spur gears at given width and pitch. Since the contact patch of helical gear is much larger per tooth. They also have higher tolerance to shock loading since more that one tooth is engaged at any time. A good old example were in tank transmissions. Panzer tank had straight cut gears, and suffered from stripped gears too often.

Then again, crazy people do crazy things. So if you got money to burn, go for it.

We found this to be the case in the T5/TKO world also. Everyone bragged about the straight cut gears, but they barely lasted a pass, let alone an entire weekend.

kaisersoze 05-25-2011 12:27 AM

I have thought about this some and recently bought another 6 speed to try out my ideas on. Roughly it is to strengthen the gears and reduce friction then reduce temps.
I plan to cryo then shot peen the gears. Haven't decided about REM on the gears yet but will WPC treat them as the final step.
I hope to use a transmission cooler and will probably use a mocal or rbracing gear based pump vs a diaphram based pump especially with temps over 350 degrees. I don't know if the smaller in line mocal pump flows enough or not.
Haven't decided where to mount the cooler.

curly 05-25-2011 12:40 AM


Originally Posted by NickC (Post 730912)
at given pitch* I'm not as well versed with involute gear tooth profiles as I would like to be, but I want to say there's some reason you have to use a higher pitch with helical gears? Regardless, assuming I can find them, I will be using a lower pitch for strength and avoiding helical cuts for cost and mechanical efficiency.

No reason at all really, beyond manufacturing. For whatever reason CNC gear cutters are more common in smaller sizes, and vise versa for the manual machines, it's easier to find bigger machines. CNC isn't required for helical, but makes it much easier for multiple (rough and finish) passes. I believe the largest helical I've cut is 5 d.p.. Could be off, +/- a pitch.


Originally Posted by kakarot (Post 730899)
Little known fact, helical gears are superior to spur gears at given width and pitch. Since the contact patch of helical gear is much larger per tooth. They also have higher tolerance to shock loading since more that one tooth is engaged at any time. A good old example were in tank transmissions. Panzer tank had straight cut gears, and suffered from stripped gears too often.

Then again, crazy people do crazy things. So if you got money to burn, go for it.

I believe people's choice between straight and helical gears has more to do with the shaft strength. If you're putting a lot of power through a helical system that can take the side ways forces, straight is better. But if the shafts aren't strong enough, they'll push apart and shatter.

r808 05-25-2011 01:37 AM


Originally Posted by NickC (Post 729998)
I'm actually interested in improving the 5-speed but it seems like there are a lot of knowledgeable people in this thread and the following could be mutually beneficial. . .

. . . Apparently, the MSM 6-speed gears are "shot-peen-hardened", but what else is done or can be done to our gears?

Nothing. Nobody has done anything other than Quaife gearset. There are a ton of things that could be done to strengthen it. (Steel case, aluminum tail shaft comes to mind first). None would be cheap.

There is no money in it, so nobody has done shit. Easier to swap another tranny if you make that much power.

chpmnsws6 05-25-2011 11:39 AM


Originally Posted by kaisersoze (Post 730973)
I have thought about this some and recently bought another 6 speed to try out my ideas on. Roughly it is to strengthen the gears and reduce friction then reduce temps.
I plan to cryo then shot peen the gears. Haven't decided about REM on the gears yet but will WPC treat them as the final step.
I hope to use a transmission cooler and will probably use a mocal or rbracing gear based pump vs a diaphram based pump especially with temps over 350 degrees. I don't know if the smaller in line mocal pump flows enough or not.
Haven't decided where to mount the cooler.

In the Corvette world, RPM Transmissions was showing real positive gains for reducing heat from micro-polishing the guts.

If I were a track rat having trans issues, that and Amsoil would be the first place I'd head, then a cooler.

bbundy 05-28-2011 01:39 AM

Well I am the one who started this thread a little more than a year ago because of strange rattling noises at high revs and finally something in the 6 speed decided to derange itself on a short drive this evening. It popped out of third by itself and now makes loud gear whine noises in everything but 5th.. The shift knob goes back and fourth a whole lot if you go on or off torque in 3rd. It is not like stripped out teeth on a gear though, no metallic pop corn sounds just gear grind-whine in every gear including neutral and not as much in 5th.

A few weeks ago I broke a clutch fork pivot ball and when I drained it there was a pretty good chunk of a gear tooth on the magnetic drain plug. And then it developed a tick idling around in 1st gear but seemed fine in all the others.

Seven five speeds have succumbed to my power and track use and now one six speed.

Bob


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