psreynol

from my previous post, the temps are way too high, but Im sure torque plays a roll well. road racers are not launching and my trans was in gear, for at least a second or 2 out of a corner before it popped so it was not a issue power engagement it was a mechanical failure due to heat, and over time the fluid breakdown and added power caused failure. i'm not an expert but Ive seen several diffs and trans fail in this way on power and I think the heat has a lot to do with it.


red line said it does not really break down till around 400f but they clearly state the viscosity between 200f and 300f is about 1/4, so its like a 3x lighter weight oil at 300 versus 200f.

@ 195 viscosity is 19.5 ( est recommended high temp)
@ 300 viscosity is 6.5 ( this is well into the range you should have a trans cooler)
@ 330 viscosity is 5.5

the 300 temp was based on husler temp sticker, which I presume is a brake temp sticker which simply darkens as each temp benchmark is met. his temp and our temps may be higher


I would really like to see some info on someone who tried a external cooler on a 5 speed and decided it did not work. a setup on a trans that was known to be in good shape.

curly

iTrader: (25)

I was throwing up at your sentence, not your idea.


And like I said please try it. It won't be a waste of money, just time. If it doesn't work it'll bolt up with a little modification to the 6spd you eventually buy. A well placed cooler, an electric pump, a well place return and feed line, and voila. Tell us how it goes and how much it costs. Like I said, I'd love to be proven wrong.

nitrodann

In gear for a second or two so its not torque?

How about the increased torque in gear after a second or two as the revs rise and the boost builds?

In the weakest gear in the box, which is allowed the most flex due to being in the middle of an unsupported shaft in a gear where you are getting 100% traction.

Thats got nothing to do with why is failed in 3rd after a second or 2 in the gear?

Dann

matthewdesigns

iTrader: (8)

Granted, most of the transmissions we build go into cars that are launched more than road-raced, but that does not stop 3rd gear from being the most damaged individual gear we see. Even from a roll or a smooth upshift, the teeth on 3rd will shear off given enough power.

I'm definitely interested in seeing results from this, and your plan for pumping the oil as well. Not trying to discourage you, just tossing in my .02 from seeing lots of trans damage. If you come up with something that can save a bunch of money for a lot of guys, in the long run it'll totally be worth the effort.

psreynol

I'm simply saying that I think heat is causing damage to the gear faces which eventually causes failure. if the torque was the issue, it would rip the teeth off almost as soon as you put on a turbo. I'm pretty sure the gear is getting worn out prematurely due to the due to a lack of sufficient lube caused by excessive heat. one the gear faces get worn the lack of a tight fit causes the gears to smack together and fail. this is a fair hypothesis. I'm sure the torque is a factor but I don't think the torque is killing the trans.

my first step is to send the fluid to get checked out and we shall see what they say. I think I can get a pump for nothing so would just need to figure how to lay out some fittings. my the end of the week I will have the trans pulled and I will take some pics.

has anyone done a cooler ?

psreynol

I think cars that get launched for drag may have a different set of issues versus a road race car. that said, if you say 3rd is is most often failed gear then I would perhaps agree my heat argument may not be correct.

codrus

Yeah, I shattered 3rd gear at Laguna, coming out of turn 11. FM hardware, built engine, making 270 at the wheels. It had been whining in 3rd gear for a while, so I knew it was on its way out.

Here's the last few seconds of life in my 5-speed. As you can see, I was in 3rd for the corner, then when I put the throttle down for the straight it went bang. The tire screech is from the red car in front of me


The car has an MSM 6-speed in it now, with a 3.9. I've got a 3.6 R&P sitting on the bench waiting to go on the diff that just came out.

Note that it's $600-1000 for the 6-speed, but you really need to swap the rear end as well. The 4.3 would be useless, the 3.9 is annoying with a turbo, the 3.6 ought to be a lot better.

The other option is the Quaife gearset for the 5-speed, but the gears alone are $2500+ and I've heard (anecdotally) that the increased strength isn't enough and they still break.

--Ian

Savington

iTrader: (31)

1. Amsoil > Redline. Redline fluids run screaming into the corner at the first hint of high temps - the Amsoil MTG that I use now doesn't seem to be phased by it. I've done some UOAs of both and the Amsoil is a far, far superior fluid.

2. They break in AUTOCROSS. A cooler will help on track, sure, but not in an autocross situation.

falcon

iTrader: (13)

My 5speed is still holding on. However I make no torque so that could be the reason. I'm honestly baffled because I drive the car hard, and have missed a few gears before and crunched it multiple times on the track. Yet it still functions. I won't go 6spd until this one blows.

psreynol

if I need a 3.6 R&P, what car does this come out of and where can I find out. I think I recall reading they are expensive and hard to come by. so what will the effect be if I leave the rear end the way it is? I doubt the 6th gear is shorter then the 5 in the 5 speed. if so that sucks big time.

shuiend

iTrader: (24)

The 3.6R&P comes from a mid 80's 626. If you search on mt.net you can find threads with the exact info in them. Realistically you will not be finding a used one in the junkyard. You can buy them new from a few vendors on mt.net. They run around $550 or so new.

Savington

iTrader: (31)

The 6th gear is shorter than the 5th in the 5speed. The 3.636s can occasionally be found in junkyards for cheap, or you can buy them brand new from Mazda for $500+.

matthewdesigns

iTrader: (8)

Hey Phil, if you tear the trans down post some pics of the remaining teeth on your broken gear, or of the other gears which survived, or both. Some good overall shots, and some macro shots that show both sides of the teeth, so that the surfaces are clearly viewable. That will go quite a ways towards figuring out what happened.

k24madness

iTrader: (6)

I would have guessed the 3.9's were a good match for the 6speed. I have 4:10's in my 6speed and everything seems quite happy.

psreynol

I wonder if I can get it from mazda speed discount program for racers, anyone checked this out?

Yeah was going to do it today but I had to work. I will have it out by the end of the week for sure. I was going to go pick up a six speed this week but now I'm not sure I want to deal with taking apart the diff just to achieve the same gear ratio. if anything I would like a slightly taller gear. its possible the po may have done a shorter final drive for drifting.

I'll get some pics for sure, speak up if they are not good enough. perhaps I'll have you build be me one good for 1000 whp!

codrus

It is $500 from Mazdacomp (that's where I got mine from, part # MA02-27-110). IIRC it's more like $700 from other vendors, but I don't recall who they are. Note that if you want your speedometer to be correct you'll also need the correct VSS, which is another $100 from Mazdacomp (M528-17-400A is the part #, I believe).

The 3.3 is the gearset that many people want with the 6-speed, but it's unobtanium and may even be mythical.

--Ian

psreynol

The 3.3 is the gear set that many people want with the 6-speed, but it's unobtanium and may even be mythical.


so what should my 99 be in the rear? according to this article my final drive should be 3.3 but the axle ratio is 3.9, what number should I be looking at. my car has a 5 speed but I believe it was replaced with a 95 trans due to a failure. so it sounds like the 6 speed is stock for a 99? I'm still new and learning the year to year changes so bare with me.

http://www.motortrend.com/roadtests/...a/viewall.html

codrus

The Motor Trend article has a typo in the spec list (they get it right in the text).

Your 99 is a 4.3 unless it's a 10th anniversary edition (10AE), in which case it's a 3.9. The MT article is about the 10AE. The 10AE is the only 99 that came with a 6-speed.

NA 1.6s came with 4.3.
NA 1.8s came with 4.1.
NBs with 5-speeds came with 4.3
NBs with 6-speeds came with 3.9 or 4.1 (varies by year)

This is all in the USA and for manual transmissions. Other countries and automatics may be different.

http://solomiata.com/RingandPinion.html

--Ian

psreynol

I'm going to go pick up a 6 speed because I still have a lot to do on the car and I dont have time to dick around. I strongly considering mounting a spare temp probe in the drain plug just too see what the temps are inside. I have a some vdo gauges from an old project I can use.


should I open the case to inspect the gears before I install?

the leak I was experiencing was coming from the trans, not the engine so I think i'm going to leave the rear main alone for now and just put the new trans in. or should I really order rear main and trans seals?

what do you guys think about adding a heavy oil to the trans. like 75-110 or 75-110? most people run 75-90 right?

psreynol

https://www.miataturbo.net/album.php...pictureid=2406

what do we need to post a picture, Ive tried the baisics but i'm doing it wrong