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5MT case strength


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stumbled upon this thread..

http://www.rs25.com/forums/f8/152715-5mt-reinforcement-plate-hardware-10.html

 

im about to look and see if this guy moore performance is selling these things on Nasioc. Anybody else know of any 5MT case supports for sale anywhere? My tuner tells me a gear set for the 5MT is pointless because of how weak and flexy the case is, could this be the answer to our tranny problems???

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stumbled upon this thread..

http://www.rs25.com/forums/f8/152715-5mt-reinforcement-plate-hardware-10.html

 

im about to look and see if this guy moore performance is selling these things on Nasioc. Anybody else know of any 5MT case supports for sale anywhere? My tuner tells me a gear set for the 5MT is pointless because of how weak and flexy the case is, could this be the answer to our tranny problems???

 

Find someone else to tune the car. Anyone who thinks gear failures are related to "case flex" doesn't understand physics and just drinks kool-aid poured by people who don't know what they are talking about.

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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I know your extremely knowledged and respected on the forum here but really? If the tranny case does flex how could it not have some adverse effect to whats inside of it? binding, grinding, extra friction, things that should not happen several hundred hp ago?
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No. If you blow up a 5MT case, you did something wrong. The 5MT gets a lot of crap, but it really isn't as weak as it's made to be.

 

Exactly. Lots of people are putting massive torque through a 5MT with only a straight-cut gear set in there.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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from all i have read (from extensive searching) about the 5mt it has nothing to do with the case, but about the smallish shaft center diameter limiting the shaft thickness and the gear diameter, it is late, don't we have enough threads about this, will i get banned if i say "use search", is that what they consider trolling these days?
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I know your extremely knowledged and respected on the forum here but really? If the tranny case does flex how could it not have some adverse effect to whats inside of it? binding, grinding, extra friction, things that should not happen several hundred hp ago?

 

The trans case does not flex any significant amount.

 

The "proof" of case flex was from a poorly designed test that, in no way, is representative of the real world. The rest is perpetuated by gross misinformation spread by the uninformed, but well meaning, public and vendors looking to make a name for themselves by shrugging convention.

 

Look in Proven Power on NASIOC. There are TONS of people making hundreds of whp/ft-lbs more than stock with aftermarket gearsets and no problems.

 

Regarding the durability of OE gearsets. I've seen more failures than most. Are they given a bad wrap? Toss them in the category with the RE92. They are great gearsets if you drive them appropriately. Smooth, quiet, good ratios, and they CAN handle good power. Expect Racecar performance from an OE set, however, and expect to have someone rebuild the box in short order.

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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from all i have read (from extensive searching) about the 5mt it has nothing to do with the case, but about the smallish shaft center diameter limiting the shaft thickness and the gear diameter, it is late, don't we have enough threads about this, will i get banned if i say "use search", is that what they consider trolling these days?

 

Not really the reason, but whatever.

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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if thats the case (har no pun intended) then wtf am I doing wanting to go 6mt for a stronger box, like hell do I want to shift more I love my 5mt im just scared about how bad fourth gear is getting and thinking about spending many thousands of dollars on a better gear set and a rebuild. screw having lots of horse powers i need a sport bike already haha
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Save up for a rebuild, then.

 

Not much way around it. If you want a durable gearbox, expect to spend ~$5k or so.

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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  • Mega Users
thinking about spending many thousands of dollars on a better gear set and a rebuild. screw having lots of horse powers i need a sport bike already haha

 

i have a sport bike and an lgt. the lgt always comes first, as its my primary source of transportation.

 

if fourth gear is on its way out, my suggestion to you is to buy a used 5mt and drive a little more conservatively (unless you know how to rip apart gear boxes and fix them).

 

then you can focus on buying your motorcycle gear, and then your motorcycle.

"Remember Danny - Two wrongs don't make a right but three rights make a left."
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Its weird though, fourth gear is temperamental. Sometimes she's fine other times i cant get into the gear without it grinding and that's with double clutching rev matching and even just holding it to the gear with light pressure and waiting for it to engage. Once I'm done with my engine rebuild I'm going to switch from royal purple to extra-s or that concoction that BAC suggests.
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  • 3 weeks later...
Dave is a knowledgable guy, but an engineer he is not.
[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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Dave is a knowledgable guy, but an engineer he is not.

 

yep, i remember some of the other threads that you chimed in on, the rallispec stuff was the only reasoned explanation i ever read, would be interested to hear your take on the situation

i believe it was your input on the "how to make the MPG read correctly with bigger injectors thread" that i realized, always humble, especially in the presence of a forum member with a smoking animal avatar (at one point in that thread, all the people actively posting had smoking animal avatars)

can you direct us to the correct (and complete) explanation of the source of weakness in the 5mt? or is this a case of "the 5mt is not weak, the people breaking them are clutch dropping monkey fist idiots"

(um, this post is sincerely respectful of your knowledge, i add very little to the knowledge base, but i have a pretty ferocious memory, so i can send people in the correct direction)

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  • 2 weeks later...

After going through my first 5MT (lots of racing), I took a crash course on 5MT vs 6MT and was forced to become somewhat of an expert on the subject. The punchline is: if you push it on a regular basis you need either a built 5MT, or 6MT swap. 6MT swap is cheaper and 6th gear is lovely for MPG at higher speeds, but I, personally, don't care for the closer gear ratios as compared to the longer ones on the 5MT. I love having taller gears for less shifting at AutoX, so to be most competitive, my dream tranny would be a built 5MT.

 

With that said, I couldn't afford to unexpectedly drop $5k on gears, so I opted to pay the dealer $1700 to rebuild my 5MT back to stock (I did the R&R), and I've calmed down on my driving. If I did it again, I'd just go find a used 5MT and throw it in.

 

Here's some of the carnage:

 

Slight wear

http://i180.photobucket.com/albums/x312/kagenmateer/Random/photo.jpg

 

Oops

http://i180.photobucket.com/albums/x312/kagenmateer/Random/photo1.jpg

 

After I developed a slight grind in first, I began running "Smurf Blood", but it was only another year before I lost 1st and 2nd completely and had to drive home in 3rd gear.

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On a side note, after lots of research, I now run a mix of Redline 75W90NS and 75W140NS (with emphasis on it being NS). I learned that Shockproof can be a little too viscous such that, while helping gears slide into place, it can adversely affect gears/synchros properly grabbing one another.
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On a side note' date=' after lots of research, I now run a mix of Redline 75W90NS and 75W140NS (with emphasis on it being NS). I learned that Shockproof can be a little too viscous such that, while helping gears slide into place, it can adversely affect gears/synchros properly grabbing one another.[/quote']

 

You didn't do enough research, then, because that is wrong about Shockproof.

 

Redline NS fluid is garbage. If you are going to run straight synthetic, go for something like Motul Gear300 or Amsoil Severe Gear, or Extra-S.

 

And for the record, gears don't "slide" into place. They are all always engaged, except for Reverse, which does physically slide an idler between the input shaft and the 1-2 shift collar.

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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6th gear is lovely for MPG at higher speeds' date=' but I, personally, don't care for the closer gear ratios as compared to the longer ones on the 5MT.[/quote']

 

6th gear has almost exactly the same ratio as 5th in the 5MT. Close enough that you wouldn't even notice the difference.

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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06GRPLGT, BAC5.2 is the resident expert on these things. Most of us have learned the what he say's is the correct thing to do.

 

It's very hard to beat him. We all have learned a lot from him.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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^^^ I'm not being argumentative...just sharing what I've learned. I should have clarified that the synchros are what "slide" into place with the gears, but I'm just going off information from other sources. Reading back, I think I used the term "expert" too liberally.

 

It's news to me that the 6 and 5 are so close. Very interesting. I've clearly made the mistake of always assuming 6 was a little taller than 5. I wonder if the small difference would give a 1mpg bump though.

 

So this brings us back to the argument that the 6MT having closer ratios helps put power down faster, whereas the 5MT would require less shifting. Overall, and because I've driven a couple 6's, I'd still much prefer the taller gears on the 5MT. Especially for AutoX where I rarely leave second gear. I do think the 6 would be nice for hillclimbing or track days. This is without mentioning all the extra shifting a 6 would require in traffic.

 

Thx for the input BAC5.2. Any info on why you say the Redline NS is garbage?

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All's good, with your low post count, I just wanted to give you a heads up.

 

Having both tranny's I can say I like the 5mt for it's longer gears for DD. My Spec B feels faster then it is because of the shorter gears.

 

The Spec runs a little lower rpm at highway speeds. But I have a different rear diff in my wagon than what came in it. I should check the numbers on it the make sure it is the exact same diff. I feel it has shorter gears, because it seems to rev more at the same old speeds I used to drive at.

 

Maybe its just me finally noticing.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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so, it seems to me the best option for the 6mt would be to have a set of 3.55 ( or 3.45 however it works out with subaru ratios ) gears, especially with more torque,

from a modified car, are there any different ratios available for the front differential?

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