Take a newly rebuilt tranny.
what is the weakest link (aside from first gear burnouts)

What breaks?
Is it the bearings that cant handle it? I dont doubt it...its a flimsy looking thing.
What else breaks?

I am talking about large motors, V8 conversions etc...

Looking for real world events...no speculation.

Rich

Actually seen break:

- Mounting ears broken off
- 1st gear snapped off
- Main bearings disintegrated
- Spinning main bearings

ears....wow
1st gear is well known and simple to just not use...block it off.

Main bearing....do you mean the big one with loose balls?
That is the one I always find falling apart...

I am asking because I am willing to hunt down a different style bearing for this...I dont see why a different style bearing would not survive much better in the same location...

I will guineepig a new style....cause I honestly believe that is the real issue....

Rich

I have at least 450 hp in my V8 and I did nothing to my trans. I was concerned based on what everyone said about the trans. I have never done a 1st gear burn out, but I have jummped on it at about 2500 rpm and gone through the gears at that point. I was very apprehensive when I first finished it but I am very comfortable with it now. It has held up nicely. I have had zero problems other than friggen small leaks in the typical places.

For me, and what I use the car for (no racing or crazy-crazy driving) moderate driving, it has been a great trans. If something were to happen to the trans, I would do a full rebuild and consult with the Dr. Evil who every one boasts about.

914-6 race car, with "more than 300 HP" from a full-tilt-boogie 2.8L with slicks. Probably over 300 lb-ft of torque, but unsure on the exact specs.

Shredded the pinion gear after several seasons.

R&P can be damaged from the case and/or side cover flexing, changing how the R&P are engaged. I haven't actually seen that one, but I've heard about it.

CV joints live short and nasty lives under brutal amounts of torque. They can also fail when lesser amounts are put through them. Many of us have seen those failures.

--DD

Rebuilt 901 with HB 5th gear 350+ hp to the rear wheels from a 5.0 Hybrid euro 16 valve. I never dump the clutch in 1st but I will hit the throttle hard in 2nd. Hard enough to extend the front suspension until the tires break loose. I have used the gear box for decel lots. Specially in Monument National Park.

I'm not sure of the sequence but I had the first bearing on the main shaft break. But the big nut that holds it was completely off. This is only possible if the peened washer gets un-peened. I could assume the lock tab was fatigued and broke allowing the nut to back off. Once the nut was loose the bearing was also loose and shattered.

I would assume the broken transaxle ear problem was caused by engine movement on rubber mounts. I have solid mounts. When my engine throttles the entire car torques with the engine. Rubber mounts are for family cars.

Sorry, I call BS...I was in the passenger seat.

Rich

I have an overbored 327 making about 330 hp and there is no need to ever use 1st gear. I only kept it available for starting off on a very steep hill or idling around a parking lot or stop and go traffic.

It has held up to very hard mountain driving and just about anything until dumping the clutch in 2nd for a monster burn out. Broke the ring and pinion.

Horse power is not neccessarliy the problem, it's torque. When I built my SBC, I chose a cam that didn't come on until about 1800-2000, but would spin up to 6500 and the little box seems to do well. Same thing for the CVs.... keep the back end planted in the turn and don't light up the tires and it will do very well.

Side stepping the clutch and donuts will keep you in the shop.

With sticky enough tires, sufficient torque and and a bumpy enough race track, I can strip the teeth off of 4th gear in a 901.

We have driven the car (track only) for the last 24 years. Maybe 10-12 years ago, it started happening. Rebuilt the original trans, it happened again same gear, same turn. Used a different fresh box and it happened a third time. All the bearings still looked good, the shafts all measured good, the pinion and crown wheel all were still good. I rebuilt the original box one last time with a billet intermediate plate and we decided to go the 915 route. Now the rebuilt 901 box with the billet intermediate plate lives in my street car (with a 3.2). No problems in the last 8 years on the street with the 901 mated to the 3.2.

Likewise, the 915 has not stripped any gears. It did manage to begin to destroy the crown wheel, but we found that the ring had not been properly set up. It is now.

I have seen teeth stripped off of gears, I have seen bearing cages come apart (especially the roller cage on the pinion shaft). I have seen needle bearings flattened, and I have seen a shift fork slid on one of the internal shift rods.


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Street application ~ 4k miles, V8 power I have had 300hp and 375lbs of torque on up to probably 450lbs of tq with fuel injection (butt dyno on the 450lbs of tq, based on the 375lbs of tq its currently at).

Big tires in the back, but they are street tires. It wont break the tires loose unless I punch it from a standing start so all of that tq has been going through the trani.

I would say that the trani has held up fine, sycro's are a little shot. Only recently I have been feeling a little more slop in the gears, and this was immediately after my dyno day which I wasnt present (dad was), so I dont know exactly what happened then as its the only time I wasnt driving the car.

I'v had 2 V8 cars. One with a EFI Ford 5.0 and one with a Chevy 283. Both on stock trannies. The Chevy has an H gear. Never used 1st gear and never had any problems with either after thousands of miles. I have broke many CV joints and tranny mounts. I run semi-solid mounts now and 500hp axles. Before I blew the latest engine, it was pushing up to 500hp @ 20psi. I use first gear with the new motor but don't get crazy. 2nd-5th I hammer on. No tranny problems and Dr. Evil said it looked like new at the clinic.

I'm having Dr. Evil build a trans for my 305 Chevy Conversion car. Any idea what RPM and top speed to expect out of a Flipped H 5th gear? Not that I'm really too worried about the top speed part.

3000rpm = 76-80mph with 26" tires

So we're talking about a 6-700rpm drop over the stock 5th gear.

Gas mileage will improve.