R154's DO SUCK!!

[SD2JZA70]

Lets not bash Toyota techs either. It hurts my feelings.:cry: Maybe the gear got dropped into concrete in its life some time. Never trust a parts department......:nono:

I agree. People give toyota techs alot of flak due to a few bad experiences people have. I trust my friend as he is a great mechanic and very meticulous when it comes to this stuff and it doesnt hurt that he is a supra enthusiast who does alot of work for people in the community.

 

[MRSUPRA]

I wonder what part of the transmission broke. I thought the actual gears were very strong. Makes me wonder if theres something we can still do to make the R154 bullitproof.

 

[Slow66]

This mechanic who happens to be a friend of mine has years upon years of experience building high performance toyotas. He has a 800+hp mk4, a twincharged MK1 MR2 ( that he custom built the set up), 11 sec 71 celica etc.

Same guy with the red mkiv that was testing that prototype Carbonetic clutch? He had one of the few mkiv's i liked at the event Super nice guy too.

 

[88-7MGTE]

When you build a 700 hp car you drive it hard. You don't drive it like a grandma!!!

 

[chevyeater]

When you build a 700 hp car you drive it hard. You don't drive it like a grandma!!!

Not driving like grandma doesn't have to include shock loading the driveline. Woon, SW and all of those 6 speed racers would never make it down the track shock loading the driveline...

 

[F&H Performance]

As I've tryed to say time and time again, once you hit the 700-800rwhp mark the trans becomes very weak, it got to the point where I broke my last one (#6) on the dyno in 4th gear.

 

[bigaaron]

You guys are right, I shouldn't go grouping all the Toyota techs in with the ones I met that didn't have much aftermarket experience. I understand the first post was basically venting and I would probably feel the same way in that situation, so I do apologize for being a little inconsiderate with my response.

But back on topic, an auto would obviously be so much better for what you want to do with it. I keep hearing that a built turbo 350 is lighter and shorter and can be built to be as strong as a turbo 400 for not too much money.

 

[SD2JZA70]

Same guy with the red mkiv that was testing that prototype Carbonetic clutch? He had one of the few mkiv's i liked at the event Super nice guy too.

Yep, thats the guy. Definitely a class act and knows his shit. I do the fabrication on our cars and he is the mechanic/ engine builder. He's been building fast toyotas longer than most so I have faith in his work. We will tear down the trans in the next week or two and post up picks of the failure point. It would be nice to hear from others with similar experiances to see if there is a feasable solution to making these boxes stronger.

 

[SD2JZA70]

Not driving like grandma doesn't have to include shock loading the driveline. Woon, SW and all of those 6 speed racers would never make it down the track shock loading the driveline...

I understand where your coming from but this wasnt a drag pass. I would expect it to break if I launched it off the anti lag and just dropped the clutch. This happened rolling on it and rowing through a couple gears. I was shocked that it happened the way it did. I wouldnt have been as suprised or mad had it happened at the track.

 

[jdub]

Even the best quality parts sometimes have a flaw...could easily be a case of just plain unlucky

 

[tekdeus]

Try getting Marlin to actually do the build since he actually replaces the gears...

Are you sure about this? The rebuild kits on their website do not say it includes new gears.

Duane rebuilt his R154 at a local shop here a few years ago, and got several passes on slicks at over 600hp, right? I'm about to have mine rebuilt by the same shop with some Marlin Crawler goodies, but this thread is making me nervous.

 

[Doward]

Just FYI - The TH400 is stronger than the TH350, built vs built - the TH350 doesn't require as much power to move your car, though

 

[figgie]

YAWN!!

TH350, TH400

ARCHAIC!

Jerico or Gforce.

last transmission you will EVER buy. Of course check with your racing sanctioning body to see if they let those fly in your events. Some do. Some don't. Consider them both clutchless manuals For drag racing, best of both world (ie insta-shift, quicker than any auto) and without any of the energy losses of a slush box.

 

[rumptis]

The R154 was never designed to hold 700 HP so anybody that gets pissed because they blew it up should be kicked in the nutz....LOL

 

[Poodles]

Are you sure about this? The rebuild kits on their website do not say it includes new gears.

Duane rebuilt his R154 at a local shop here a few years ago, and got several passes on slicks at over 600hp, right? I'm about to have mine rebuilt by the same shop with some Marlin Crawler goodies, but this thread is making me nervous.

Last I asked them, they said they do replace the gears. Dunno if that has changed though...

I wish I could remember who runs a Marlin Crawler rebuilt R154 on the forums...

 

[figgie]

BTW

notice who does use a Gforce in thier ride

http://www.gforcetransmissions.com/whygforce.asp

TITAN Motorsports!

and for Jerico

http://www.jericoperformance.com/3.html

btw I want you guys to check something out

particularly THIS sentence.

YOU MUST ABORT PASSES WHEN YOUR CLUTCH DOES NOT HAVE ENOUGH SLIPPAGE.

For the gearbox to survive, CLUTCH SLIPPAGE IS A MUST. THE CLUTCH MUST SLIP DURING GEAR CHANGES. WE CANNOT OVEREMPHASIZE THIS POINT.

and this is Jerico stating this (Gforce also mentions this btw).

Also throw in Lenco to the mix

http://www.lencoracing.com/ST1200MasterPage.html

 

[tekdeus]

Last I asked them, they said they do replace the gears. Dunno if that has changed though...I wish I could remember who runs a Marlin Crawler rebuilt R154 on the forums...

I talked to them on the phone just now, and they said their rebuilds do include all new gears, but the rebuild kit they sell does not. I wonder what kind of break-in miles you'd need to put on new gears to seat them well enough to handle massive power? Maybe this hints at the reason for the original poster's 3rd gear failure, as that was the new gear he intsalled?

 

[Poodles]

That's what I was thinking as well... Most gears aren't smooth faced until they wear in (like the diff). If not properly heat cycled they can become brittle, couple to that if they aren't fully worn in, the grooves in the face of the gears would be ideal spots for cracks.

I've never understood why people take into account the play in the diff (backlash), but not the play in a rebuilt transmission. If I remember right it's covered in the TSRM, but it seems like everyone ignores it thinking that changing the syncros and bearings will give them a brand new transmission...

Like I said, I'm not trying to sound like a dick, but there is more going on in this since first gear should have been the one to go, and as third gear was replaced, I think it's more than just a coincidence...

 

[Doward]

That's what I was thinking as well... Most gears aren't smooth faced until they wear in (like the diff). If not properly heat cycled they can become brittle, couple to that if they aren't fully worn in, the grooves in the face of the gears would be ideal spots for cracks.

I've never understood why people take into account the play in the diff (backlash), but not the play in a rebuilt transmission. If I remember right it's covered in the TSRM, but it seems like everyone ignores it thinking that changing the syncros and bearings will give them a brand new transmission...

Like I said, I'm not trying to sound like a dick, but there is more going on in this since first gear should have been the one to go, and as third gear was replaced, I think it's more than just a coincidence...

Have you read through the TSRM on the r154? There is a whole lot more than just the lash to look at - I don't even want to THINK how many snap rings I've bought in various thicknesses as I've blueprinted my own R154.]

 

[IJ.]

Poo: 1st gear has the deepest reduction/least load, in "weak" boxes 5th is the one that lets go under sheer power usually. (early p series Celica boxes behind domestic V8's in the old day is a perfect example of this)

4th ISN"T a Gear as such you just lock the Input to the Output so doesn't usually Grenade unless you damage bearings or have enough power to actually break the Syncrho hub.

Past experience was I'd usually break 2nd but in the Tremec I broke 3rd as well.