Trans Build Up Question

F

Fella

Low Mileage
From what I understand (very little), the stock X trannys are good up to about 120hp. I'm assuming roughly 100 ft lb torque.

Since I have 2 spare motors and 2 spare trannys (5 spd), I need to come up with a plan to build a reliable trans that will see about 175 ft-lb torque and about the same in HP. Can this accomplished? How? I'm not afaid to spend some money, but I won't spend thousands. (I'll do a 4AGE swap first)

Tranny will be matted to a home brew turbo engine (1500cc). Specs have yet to be determined. However I have 175hp in mind. I think this should be pretty attainable and hopefully reliable.
 
HP and Torque

How much horse power and torque the transmission will take depends on how you drive the car and how the motor makes the power. I regularly exploded transmissions in my sub 100 hp/tq DSP car. But my peaky, 125 hp street car is relatively trouble free.

There isn't much you can do to the transmission to make it more robust. The weakest link in the chain is the diff carrier but the transmission's inherent weaknesses will become more obvious as the power goes up. The Porsche type synchros on 3rd-5th being the most obvious.

The best preventative measure is to do a thorough rebuild using quality parts and good practices.
 
I think a transmission teardown and rebuild is within the capabilities of the X owner who is (a) not in a hurry, (b) is not too stingy (one gear can cost over $150 retail and it's $hocking how fast the parts bill adds up), (c) has average mechanical skills, (d) has an above average level of patience, and above all (e) is a stickler for detail.

I just did it so I know. (If I knew last year what this was going to take, I would have ordered one of Steve's units from MaddMatt! :lol:) To get what I needed I have made friends :grouphug: with EVERY ONE of our stable of parts vendors, and then some.

The above, however, gets you a stock transmission. A smooth shifting, reliable for everyday-use, long lasting (as long as you use Redline) stock transmission.

For high performance you're going to want the services and the *experience* of a guy like Steve who knows the tricks, who knows what breaks under pressure, and who knows what to use that won't break as easily and where to get it.
 
I know what you mean Dan

I will be finishing my tranny today. It was a fantastic learning experience. After the cost of the parts and shipping, the Steve H rebuilds at Matts are a real deal.
 
Robert Mose said:
I will be finishing my tranny today. It was a fantastic learning experience. After the cost of the parts and shipping, the Steve H rebuilds at Matts are a real deal.
Click to expand...

HA! Most people just don't understand what a proper rebuild costs until they do one. Its easy to spend SEVERAL hundred dollars on parts.

In my DSP car, I exploded diff carriers. When they go, they take out the entire rear section of the case. The two axles end up hanging in space. Its very ugly. Sounds like a bomb going off behind you. Also, at those power leverls expect third and 4th gear synchronizer explosions. That can result in anything from just a blown sychro, gear and slider, to bent shafts and a blown apart case (if the gearset eats the synchro).

The taller gears can also start shedding teeth at very high power levels. They just aren't big enough.
 
Trans questions

As far as what parts break (or get the most wear), 3rd gear, 3rd gear sleeve, 1st and 2nd gear and synchros, 1-2 sleeve, reverse idler, and shift forks. I just rebuilt mine and got most of the parts from Vicks and Mid-West X 1/9. It brought back many fond memories...

Dave

Transmission.jpg
 
Well, I don't feel like such a wuss...

Since I ordered one from Mad Matt and was happy with the results.
 
Hello Steve,

Out of curiosity, do you (or anyone else here) have any of these grenaded diff carriers? I would like to do an autopsy on one to try and figure out just what cause this. I'm suspecting there might be a stress riser or other similar flaw in this part that is causing the failures.

Thanks,
Bernice

Steve Hoelscher said:
In my DSP car, I exploded diff carriers. .
Click to expand...
 
Failure Points

Hi Bernice,

I had saved a couple of the worst ones just as soveniers but threw them away when I moved a few years ago. There were an array of break points but the most common was in the center of the casting where the two windows are and the hole for the spider gear pinion shaft goes. You can see a seam in the casting in that area.

While it wasn't legal for me to modify the carrier in my DSP car I have modified the one in my street car. I ground down the seam and shot peened the carrier. To do this you have to remove all of the bearings and internals. After shot peening, I sent it to be Cryo treated.

I did have a diff carrier for my DSP car Cryo treated and that one never failed.
 
Hello Steve,

Just looked at a stock diff carrier, indeed there are what looks to be stress risers near a seam of the diff carrier. Just smoothing these out could help reduce the possibility or diff carrier failures.
If I get the incentive and energy, I'll take one of these apart and point out where these are on the diff carrier in some photos.

Has anyone tried cryo treating that problem 3rd Gear and 3/4 slider sleeve to see if it helps them last a bit longer?

Steve Hoelscher said:
Hi Bernice,

I had saved a couple of the worst ones just as soveniers but threw them away when I moved a few years ago. There were an array of break points but the most common was in the center of the casting where the two windows are and the hole for the spider gear pinion shaft goes. You can see a seam in the casting in that area.

While it wasn't legal for me to modify the carrier in my DSP car I have modified the one in my street car. I ground down the seam and shot peened the carrier. To do this you have to remove all of the bearings and internals. After shot peening, I sent it to be Cryo treated.

I did have a diff carrier for my DSP car Cryo treated and that one never failed.
Click to expand...
 
Rupunzell said:
Has anyone tried cryo treating that problem 3rd Gear and 3/4 slider sleeve to see if it helps them last a bit longer?
Click to expand...

Yes.

I did an entire layshaft gearset for my DSP car, including the shift forks. The specifics seemed to last longer (slider, 3rd gear, etc...). Although it wasn't as obvious as othe parts I have done.

Exampe; brake rotors for the TT Supra. The front rotors on that car would be completely spent after a two hour race. Longer races required a rotor/pad change. Cryo treated rotors would last more than two 2 hour races. And only require one rotor change in a 12 hour race.
 
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