Gearbox options/experiences
#88
I suspect it’s just that they did no analysis or testing to determine how much stronger it was. They used tribal knowladge and the design philosophy “when in doubt make it stout” Then let the customer find out where the limits are with no warrantee expressed or implied. In reality the Qaife internals make the 5 speed hugely stronger than stock at handling high torque. And likely more robust than the 6 speed by a good bit.
Having said that I’m coming around to the 6 speed. The Mazdaspeed box I put in at Laguna after stripping 4th gear in the standard 6 speed shifts much better than any other 6 speed I have had. With a 3.636 rear end it is usable for autocross as long as you set your rev limit over 8000 rpm and the course isn’t too fast. You hit the rev limiter a bit but it is nicely in the power band most of the time on course.
Having said that I’m coming around to the 6 speed. The Mazdaspeed box I put in at Laguna after stripping 4th gear in the standard 6 speed shifts much better than any other 6 speed I have had. With a 3.636 rear end it is usable for autocross as long as you set your rev limit over 8000 rpm and the course isn’t too fast. You hit the rev limiter a bit but it is nicely in the power band most of the time on course.
#90
just thinking - after reading hundreds of linear feet of posts on this subject - it seems to me that, re the 6 speeds:
a) they break sometimes 3rd but 4th or 5th almost always except maybe the guys drag racing and we're not counting them.
b) very seldom (or at least much less frequently) 1st, 2nd or 6th.
c) can we say almost always 4th or 5th - no problem if you want to correct me. Probably cuz most tracks are spent w/ more time in 4th and 5th existing corners than any other gear.
d) the breakage is bending fatigue related, not lube or contact stress related
e) so could the problem be solved for most by a strong set of 4th/5th gears for not near as much money as a quaife or other solution?
a) they break sometimes 3rd but 4th or 5th almost always except maybe the guys drag racing and we're not counting them.
b) very seldom (or at least much less frequently) 1st, 2nd or 6th.
c) can we say almost always 4th or 5th - no problem if you want to correct me. Probably cuz most tracks are spent w/ more time in 4th and 5th existing corners than any other gear.
d) the breakage is bending fatigue related, not lube or contact stress related
e) so could the problem be solved for most by a strong set of 4th/5th gears for not near as much money as a quaife or other solution?
#92
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just thinking - after reading hundreds of linear feet of posts on this subject - it seems to me that, re the 6 speeds:
a) they break sometimes 3rd but 4th or 5th almost always except maybe the guys drag racing and we're not counting them.
b) very seldom (or at least much less frequently) 1st, 2nd or 6th.
c) can we say almost always 4th or 5th - no problem if you want to correct me. Probably cuz most tracks are spent w/ more time in 4th and 5th existing corners than any other gear.
d) the breakage is bending fatigue related, not lube or contact stress related
e) so could the problem be solved for most by a strong set of 4th/5th gears for not near as much money as a quaife or other solution?
a) they break sometimes 3rd but 4th or 5th almost always except maybe the guys drag racing and we're not counting them.
b) very seldom (or at least much less frequently) 1st, 2nd or 6th.
c) can we say almost always 4th or 5th - no problem if you want to correct me. Probably cuz most tracks are spent w/ more time in 4th and 5th existing corners than any other gear.
d) the breakage is bending fatigue related, not lube or contact stress related
e) so could the problem be solved for most by a strong set of 4th/5th gears for not near as much money as a quaife or other solution?
D is an educated guess, but still a guess. Keeping the fluid cooler might go a long way towards 6-speed longevity, but I don't know of anyone running a cooler yet.
E would be penny wise and pound foolish. If you're going through the expense of opening the gearbox, you may as well do the entire set (or at minimum, a 3-4-5-6 set for roadcourse use). If another gear were to fail, you run the risk of damaging the upgraded gears as well, which is just silly.
#93
so am i rite in thinking that there has not been a failure due to excessive torque/power of a 5 speed quaife box that anyone knows of?
does anyone know of a car (preferably a race car) running ~400bhp using a quaife box on a regular basis and has been for some time without any problems?
i have another 6 speed to go in the car on Monday then it is back to the dyno on Tuesday. lets see if this one lasts the day... was starting to wonder if i should limit the power/torque for the time being but then thought stuff it. all or nothing!...
does anyone know of a car (preferably a race car) running ~400bhp using a quaife box on a regular basis and has been for some time without any problems?
i have another 6 speed to go in the car on Monday then it is back to the dyno on Tuesday. lets see if this one lasts the day... was starting to wonder if i should limit the power/torque for the time being but then thought stuff it. all or nothing!...
#95
Rite that's it... Blew yet another 6 speed at the weekend! That has to be like 5 or 6 now. I am not prepared to throw any more at it. so as far as i can se these are my options:
1. I have a guy that will make me a custom 5 speed dog box in a 6 speed casing but it is a little expensive.
2. Buy a quaife gearset and see what happens at 400whp+ but if it doesn't take it i wasted my money.
3. Put a box in from something else like an rx7 or whatever. I can fabricate everything myself so cost should be reasonably low but i suspect the ratios are going to be less than ideal.
I really want to go with 1 but if i do the car is going to be sat for most of the season whilst the box is made and i will have blown most of this years budget. on the plus side though the ratios will be custom and it should easily take anything i can throw at it.
I am still not convinced on the Quaife box and have yet to find anyone putting as much power as i have through 1. on the other hand i have not heard of anyone breaking 1 either.
Putting another box in is going to be cheap but what to use to get the best reliability and ratios? Fair bit of labor but that's free...
The box is what is holding me back now with both power and reliability.
Decisions decisions.... What do you think?
1. I have a guy that will make me a custom 5 speed dog box in a 6 speed casing but it is a little expensive.
2. Buy a quaife gearset and see what happens at 400whp+ but if it doesn't take it i wasted my money.
3. Put a box in from something else like an rx7 or whatever. I can fabricate everything myself so cost should be reasonably low but i suspect the ratios are going to be less than ideal.
I really want to go with 1 but if i do the car is going to be sat for most of the season whilst the box is made and i will have blown most of this years budget. on the plus side though the ratios will be custom and it should easily take anything i can throw at it.
I am still not convinced on the Quaife box and have yet to find anyone putting as much power as i have through 1. on the other hand i have not heard of anyone breaking 1 either.
Putting another box in is going to be cheap but what to use to get the best reliability and ratios? Fair bit of labor but that's free...
The box is what is holding me back now with both power and reliability.
Decisions decisions.... What do you think?
#96
To the guys blowing up $900 AZ6 6 spds left and right. It appears the only solution is a one off adaption or a Quaife. Unfortunately, those conversions all seem to start at about the price of 3-4 AZ6's. There is probably no way around that.
The only potential lower cost option is a readily available OTS OEM trans with the right form factor, ratios, weight and cost that one can make a billet adapter plate/driveshaft/clutch disc for. A <100lb trans for <$1500 that will hold 300lbs tq with the correct ratios is the unicorn.
I know, that's all obvious. Just wanted to condense it down to it's root factors.
I think we should all be hunting for that unicorn trans and just plan on adapter/driveshaft/disc. If such a trans is found, I'll get the kit made and offer it on our site for less than $750. I need the trans myself so that's where it would start.
The only potential lower cost option is a readily available OTS OEM trans with the right form factor, ratios, weight and cost that one can make a billet adapter plate/driveshaft/clutch disc for. A <100lb trans for <$1500 that will hold 300lbs tq with the correct ratios is the unicorn.
I know, that's all obvious. Just wanted to condense it down to it's root factors.
I think we should all be hunting for that unicorn trans and just plan on adapter/driveshaft/disc. If such a trans is found, I'll get the kit made and offer it on our site for less than $750. I need the trans myself so that's where it would start.
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#100
FD box may 1 for the list then. Pull clutch though.... Ratios + info:
Transmission type Type R152, 5-speed manual
Clutch type Single dry plate, diaphragm spring, hydraulically operated with pull-type mechanism
Clutch diameter, outer x inner, in. (mm) 9.3 x 6.3 (236 x 160)
Gearbox type All synchromesh, with double-cone synchronizers on 2nd and 3rd gears (R type)
Gear ratios
1st 3.483:1
2nd 2.015:1
3rd 1.391:1
4th 1.000:1
5th 0.719:1
rev 3.288:1
Final drive type Hypoid
Ratio 4.100:1
Transmission type Type R152, 5-speed manual
Clutch type Single dry plate, diaphragm spring, hydraulically operated with pull-type mechanism
Clutch diameter, outer x inner, in. (mm) 9.3 x 6.3 (236 x 160)
Gearbox type All synchromesh, with double-cone synchronizers on 2nd and 3rd gears (R type)
Gear ratios
1st 3.483:1
2nd 2.015:1
3rd 1.391:1
4th 1.000:1
5th 0.719:1
rev 3.288:1
Final drive type Hypoid
Ratio 4.100:1