Welp, I have (had) the opportunity to use a running 350 for only a scant 100 bux, BUT, now I have access to a VIRGIN 400 ci, which has *very* low miles, could get by without going 30 over, for FREE. Yes, FREE, from a regular at the bar I work at. The crank needs to go one under apparently. But, I have a few apprentice machinist buddies, so...

Anyhow, point being, will this shread my 100,000 mile non WC T-5? It will be VERY stock, I don't care to put too much money into this. It is a mid 70's MonteCarlo block, (if it matters, they're all low perf.) totally stock. The only goodies will be my Performer manifold, Edelbrock TES headers /w a full catback exhaust. Oh and the nasty 3.73 OPEN rear. No I'm not kidding about the rear end, boy will that be sick in the rain with ~325-350ft/lbs at a very low RPM. This is a daily driver. I love torque, if it even scrapes the 13's I will love waking up in the morning that much more. I WILL get a posi rear. =)

Anyhow, I am fairly nice to the car, with the exception of the occasional row through the gears. How many miles is this gonna last? Should I just throw the goodies off of my 305 into the 350 or what? It seems too good to pass up... RB, are you out there???

Lates,
Hype - '83 T/A - 305ci. Lots (wasted) spent.

 

Argh. I forgot to ask: What needs to be done to get this 400 in there? Flywheel adaption of some sort? I've seen lotsa 400+7004R threads, but I (think?) only RB has the T-5 combo out there.

So... what's needed? I'm doing the cost/benefit comparison now.

Oh, and I need a new clutch. Reallllll bad, to go with my new rear 245's.

Muahaha. I hate to see myself behind a 400 once again, in the chev. variety for a change.

 

your trans may last forever, lot depends on how you drive and abuse it. you'll need to use the flywheel for the 400. a 400 is the same as any other SBC externally as far as fitting in your car and the trans bolting up

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ICON Motorsports

1st & 3rd

 

You'll have to get an externally balanced fly wheel or you can buy small counter balance plates and weld them on yourself. I would have it checked to make sure it is within factory "counter balance specs." Better yet, if you are taking the crank out anyway, have the rotating assembly balanced, even with stock parts. It's worth the hundred bucks to have the piece of mind and vibration free engine. The T5 should last if you drive it conservatively. What usually breaks manual transmissions is dropping the clutch with slicks into an unloaded trans. Any gear lash is taken up instantly when you drop the clutch and the gears slam together like a sledge-hammer. Ka-boom. See ya T5. Nice knowing ya. So now how do I get home? Anyway the moral of the story is to take up the slack in the driveline before making hard launches. SLIGHTLY ride the clutch to get everything tight before dropping it. I wouldn't be comfortable power shifting it. I'd go with a Performer RPM manifold since it will increase your performance for about the same money. Put a cam in it too while its not in the car. For a couple hundred bucks, you could have around 300 hp vs. the 195 hp it probably has now. Good Luck.

 

I have a 400 and an absolutely stock 700R4, and I have about 8000 miles on the new tranny. No problems. Now my old 700R4 did break, but it had 123,000 miles on it, so im pretty sure that it was old age, not motor that killed it. The only problems I have now is that the tranny shifts gay, i guess because the computer is trying to control the TC lockup like a 305. Under normal driving, it shifts fine, but on hard acceleration, it will wait forever to shift, like at 4500 rpm, even though the 400 is barely pulling.

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1983 Pontiac Firebird SE
LG4-Based Chevy 400
700R4 Tansmission
Modified 4 Barrel Q-Jet Carb
Accel Super Stock 8mm Wires
Edelbrock Pro-Flo Air Cleaner
3.23 Posi Rear
14X7" Cragar SS/T Wheels
Clarion 45X4 CD/AM/FM Head Unit
100WX2 Amp
2 Pioneer 12" Subs in Custom Box
Third Gen Performance
"A four cylinder is only half an engine"

 

It will last. See my sig. My trans has OVER 150,000 mi, and I DID power shift it at the strip to achieve my times. No slicks though. On the street I drive it "nicely".

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'83 Trans Am: 400 CID oil burning junkyard long block, 224/234 crane cam, Summit aluminum roller rockers, hand ported intake, home bored 2.09" (53mm) throttle bodies, MSD 454 injectors(75 lb/hr), Holley 255LPH fuel pump, custum modded FPR, Edelbrock TES headers, SLP 3" stainless steel cat back, stock ECM & chip. Borg/Warner T-5 World Class, 12" Corvette rotors and clipers, GTA 16" wheels, South Side Machine subframe connectors, 1LE sway bars, 3.45 ring and pinion, Alpine sound.
Best E.T. 13.532
Best MPH 102.24

 

Well... I have been through more T-5s than I can count. I can remember about 4 or 5 cores, and at least 12 rebuilds. Suffice to say that my experience has not been good with this combination.

I had 4-speed cars for several decades prior to this one, so I was not prepared for a maunual trans as fragile as the T-5 is. I have managed to tear up some 4-speeds in unusual ways: my all-time favorite was a Muncie M21 where the the shaft part of the clutch gear twisted in the gear part, and I rebuilt it at least twice trying to get rid of the weird vibration before I noticed the heating effects on the 2 parts where they were joined.

If you don't dump the clutch on it, and don't speed shift it, and keep it full of fluid, it should last fairly well. The thing that destroys these is shock first and running dry second. The front of the case isn't strong enough to keep the clutch gear and countergear the right distance apart, their natural tendency is of course to spread, and the case stretches across the front. Eventually it stretches so far that the front countergear bearing becomes a slip-fit instead of a press-fit. When that happens, it's time for another trans; that one is no longer rebuildable. It will simply wipe out again in a few thousand miles either by misaligning the gears or by leaking all the fluid out.

The 3rd gen bell housing only accomodates a 12¾" 153-tooth flywheel, which was never available on a 400 from the factory. Consequently you have to get one and have it "unbalanced", not a real big deal. Centerforce just came out with one like that but I don't think it's actually available for purchase yet. You might want to check on that. The 400 block also won't have the inner bolt hole for the starter that goes with the small flywheel, so you'll have to get that drilled. The starter that comes with the car is one of the weeniest things I have ever seen: it would barely turn the L69 over, and with the 400, I never knew whether I'd be able to start it or not. I finally got a CVR mini-starter, and it's terrific. I wish I had done that years ago.

All in all I'd say you should go for it, just be aware that your driving technique needs to be gentle to the trans.

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"So many Mustangs, so little time..."
ICON Motorsports