Broken 3rd gear x 3

[Mazdaspeed2oo35]

I got ya...

I'm running Nitto NT555 extremes 225/35/18 which may be slightly less grippy dry than the BFG KDW-2s I had before. Both are great in wet.

Nice Didn't know they make 35 profile for 225's..

 

[shane02pro5]

Nitto is the only brand I've seen that size...those will go in the back soon and new 235/40's will go up front eventually

 

[Signature Sound]

I know solid mounts are said to be harsh on the tranny and I understand why, but it seems like its a good trade off for the added stress wheel hop puts on it. Plus you get a smoother shift so its worth having because either way if you're at those power levels you are going to break something.

I am going to be ordering the gears (hopefully) soon and was just wanting to have the info if its not going to be provided. I have the Mazda Tech manual for the engine, but not the Tranny.

 

[Maxx Mazda]

Solid motor and trans mounts increase the longevity of your tranny.

 

[shane02pro5]

Here you go sig

http://www.mazdaspd.com/resources/Transmission_Rebuild.pdf

 

[Canadian-ES-GT]

i heard that engine mounts my cause the 3rd gear to grind... and that might lead to brakin it! But I forget where I heard that.

 

[cali_axela]

Wow, glad I found this thread and am not the only one in this boat. Although I may be the first with a Mazda3 to be having the same issues as all you MSP people (we also have a G-series transmission, and I believe the gearsets are basically the same).

I broke my OEM 3rd gear a few months ago, after running about 250whp for a year and a half with no problems. Foolishly replaced it with another OEM 3rd gear thinking it'd hold for a few more years. It didn't -- both 3rd and 4th are now gone, it pretty much exploded yesterday during an HPDE session at Laguna Seca. I was flat out in 4th at about 100 nearing the top of Rahal and BOOM... no more 4th gear.

So, I'm looking to replace at least 3rd and 4th with some straight cut double synchro PAR setups. I already have a Quaife, which I hope isn't damaged too from driving the car home with so much shattered crap floating around in the trans. If I can find a good price, I would like to do second gear as well, as there's a couple corners I beat on that one pretty good too. Also a slightly taller cryo-treated 5th gear might be nice for quiet and lower RPM freeway cruising. Going to build it right this time...

 

[shane02pro5]

1st and 2nd gear are cut into the input shaft so you would have to do the 1-4 from PAR. Or 3rd and 4th which can be done seperately.

 

[cali_axela]

Yeah, I guess as long as 5th remains helical that's fine if the rest are all straight.

 

[blaineog]

Actually with straight cut gears the axial forces are pretty much eliminated. This is what causes case flex.

When the stock helical gears are under extreme forces they try to push each axially away from each other. I would think the bearing cup reinforcement would possibly be helpfull even with the stock gearset

I had gone through 4 3rd gears, including a gtx 3rd, and 2 4th gears. Frustrated, i ordered the Par straight cut 3rd and the reinforcement cups. I was disapointed in the cup design so we improved upon it an installed it.
4 months 10,000 miles on broken pavement, and 280lbft of torque, its still good.
When i inspected the housing during the build it was worn around the mainbearing support area... Hence premature failure even at 230lbft (last failure occured at 9psi).

 

[mike2225]

I had gone through 4 3rd gears, including a gtx 3rd, and 2 4th gears. Frustrated, i ordered the Par straight cut 3rd and the reinforcement cups. I was disapointed in the cup design so we improved upon it an installed it.
4 months 10,000 miles on broken pavement, and 280lbft of torque, its still good.
When i inspected the housing during the build it was worn around the mainbearing support area... Hence premature failure even at 230lbft (last failure occured at 9psi).

What did u do to improve on the reinforcement cups?

 

[cali_axela]

Since this seems to be the most popular thread for discussing straight-cut gearsets, seems like the best place to ask this related question instead of starting a new thread...

What kind of noises are considered "normal" from straight-cut gearsets? I was expecting the typical whining noise, but there's also a ton of clattering noises... it sounds like a freaking diesel truck. It shifts and feels amazing, I just want to make sure it's normal and not going to fail prematurely when I start adding more power.

 

[shane02pro5]

Lower gears sound a bit more crunchy since the tooth profile is so much larger than oem but I wouldnt exactly say clattering. Were clearances checked for re-shimming?

 

[cali_axela]

Crunchy is definitely a better word for it than clattering, and it's definitely louder at lower RPMs in lower gears. But going through a tunnel for example, cruising in 4th gear at 2500 rpms, the crunching/churning sound is quite pronounced even over my exhaust.

I had the work done at a shop I've been going to for a long time and trust him a lot -- he's built several G series transmissions before, and I gave him all the specifications to use and am sure they're correct, assuming he did it right.

I've driven it about 1000 miles with the new gearset and it doesn't seem to be getting worse or anything, gas mileage is the same and the car is ridiculously quick with the new closer ratio and shorter final drive... just don't want to have to drop the transmission again for a long time since this was the second time in the last 6 months.

I should also note that I think these are the older style PAR gears and they were expected to be really loud.

 

[Focus]

Crunchy is definitely a better word for it than clattering, and it's definitely louder at lower RPMs in lower gears. But going through a tunnel for example, cruising in 4th gear at 2500 rpms, the crunching/churning sound is quite pronounced even over my exhaust.

I had the work done at a shop I've been going to for a long time and trust him a lot -- he's built several G series transmissions before, and I gave him all the specifications to use and am sure they're correct, assuming he did it right.

I've driven it about 1000 miles with the new gearset and it doesn't seem to be getting worse or anything, gas mileage is the same and the car is ridiculously quick with the new closer ratio and shorter final drive... just don't want to have to drop the transmission again for a long time since this was the second time in the last 6 months.

I should also note that I think these are the older style PAR gears and they were expected to be really loud.

Does it stop making the noise when the clutch is in? And does it make the same sounds at idle ?

 

[cali_axela]

Yes it stops with the clutch in, and it does make some noise at idle with the clutch out but not as much as at low RPM in gear.

 

[iracemine]

bad pilot bearing.

 

[Focus]

Yes it stops with the clutch in, and it does make some noise at idle with the clutch out but not as much as at low RPM in gear.

Yeah I get the same thing. AS for the whining, do you get some in 5th gear as well?

 

[cali_axela]

Yeah it's not the pilot bearing, we replaced it as a precaution, this is a much different type of crunchy noise. I just took it to Thunderhill on friday, transmission shifts like a dream at the limit... much more direct, and loving the new gear ratios. And yeah the whine is pretty extreme, even in fifth.. check out the video, you can ever hear it over all the wind noise. But it's definitely worth it

http://www.youtube.com/watch?v=9mmxSZpvv-o

 

[Focus]

Yeah, same type of noise I get, although in that video you don't hear the crunching/slapping noises.