Thread: Manual Swap in '79 T/A

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I have an olds 455 ready to be dropped into a 1979 trans am. However, it needs a transmission...it originally had a TH-350 and a 400 big block. It is an automatic, but i would love to make it a manual. The only thing i am not sure of is what transmission i should be looking at to do this with. Yeah it'll be a lot of work, but it's my project car and i love making it custom. If you have any suggestions it would be much appreciated =]

How many gears do you want, and how much do you want to spend?

I was thinking just four. Keep it simple haha. And i am not sure, nothing ungodly because i am not made of money but its not gonna happen tomorrow so i have some time to save up..

A Super T-10 would be a good choice behind the Olds engine. You'll need a bellhousing, maybe could find and OEM one, or Lakewood still makes scattershields. Then, a flywheel, clutch, pressure plate, pedals and linkage, or a hydraulic clutch slave cylinder and pedal would probably be easier and cheaper in the long run. Oh yeah, and don't forget the pilot bearing for the end of the crankshaft.

I have so much to learn! Thank you, i will look into it.

Good news is that there's a ton of donor Z-28's and Trans Ams in the bone yards and a lot of them came w/super T-10s so linkage, clutch pedal assembly, etc should be fairly easy to find.

Have Fun,
Glenn

Does anybody know of some decent automatic transmissions that would match up well? I am pretty sure Th-400's came in the old Firebirds right?

Well, I just can’t seem to help myself sometimes when a post like this one come along. I tend to keep just about everything I ever read about cars (gotta love computers with big hard drives) and it just so happens, I’ve always liked Z-28 and Trans Am platforms. Of course, “Smokey and the Bandit” is an all-time favorite and who can forget Pontiac's screaming chicken in that movie set to Jerry Reed’s Eastbound and Down?

In 1979, things really changed for the Trans Am. The last of the 400’s were built in the fall of 1978 and they were never to be resurrected. They were rated somewhat conservatively at 220 horsepower @ 4000 and 220 lb/ft of torque at 2800 and darn few of them found their way into the Firebirds. All 8,326 of the 400 engines (RPO W72, VIN Code “Z”) were mated to Super T-10 four speeds at the factory. Hottest TA? – a real 400 with 3.23 rear end (RPO 2PX). During road testing Car & Driver magazine sent the tach past the 5000-rpm redline to reach 132 mph at 5400 rpm. This was one of the last cars whose top speed was gearing limited rather than drag limited.

Also for 1979, one could opt for the WS6 package that was upgraded to include disc brakes at all corners. The rear disc brakes measured 11.1" in diameter and were had the same internal vents as those in the front to keep them cool –pretty cool, eh? Problem was that GM didn’t make enough of the disc brake axles and the WS6 package was soon depleted. A “true” WS6 today is rarer than hen’s teeth.

The most popular engine/transmission package was the 403 with a TH350 automatic - 94,773 units. The 403 (RPO L80, VIN Code “K”) was really an Oldsmobile small block engine and was, well – disappointing. It was rated at 185 horsepower @ 4800 and 320 lb/ft of torque at @ 2200. It’s easily identified by the oil fill filler at the front of the engine (kinda like an early SBC). Most 403's were 2.41, 2.56, or 2.73 rear-end ratios which hampered their launch.

A four barrel 301 V8 was available for the ‘79 Trans Am. Mated with either a 4-speed manual or three speed automatic, the engine (RPO L37, VIN Code "W"). It was rated at 150 horsepower @ 4000 rpm and 240 lb/ft of torque at 2400 rpm, and it was a true dog. The 301 was originally designed for compacts (Sunbirds…) and mid-size cars. It had a lightweight crankshaft with only two counter weights so the reciprocating mass was again “more fuel efficient” but no bananas when you smashed the go pedal. The cylinder heads were new for this application and had Siamese intake ports and tinny valves - 1.72" intake and a 1.50" exhaust.

If your TA is truly a 400, it could have only been a T-10. If it was a TH350, it was either a 301 or more likely, a 403. There was never a TH400 in a 1979 Trans Am from the factory. The last T/A's with TH400's would have been the '74 455SD

Regards,
Glenn

Start watching eBay. Find a donor car with the trans and pedals you need. Scrap it out for more tan you paid for it when you're done pullin parts off it.

Well i looked up the numbers on the motor i pulled out and it said it was a 400, i will go look at the numbers again and post them tomorrow. And i am almost positive that the transmission is a TH-350. I will post pictures of the motor i took out, the 455, and the tranny. Part of the bell housing on the tranny literally busted off when i got on it in first...that is why it needs a new one. But APPARENTLY it had already been cracked and somebody had just welded the crack. Had i known that i wouldn't have been driving like an ass and would have just replaced it haha. But yeah i will post some numbers and pictures tomorrow.

transmission2.jpgoriginalengine2.jpgnewengine.jpgtransmission.jpgnewengine2.jpg

Picture 1: On the left of the transmission you can see that part of it is missing...
Top- C11
Inside- GM30
L155....i think, 6280238

Picture 2: The old engine. Numbers are as follows:
Drivers side- 6X, D306, D N, GM2 (front d.s.) 526974
Passenger side- 6X, E036, D N, GM1, (front p.s,) 0404543, X7, (back p.s.) 500557
Back(top)- 75, either A226 or 4226 (couldn't read it)

Picture 3: The new engine. Numbers are as follows:
Front(top)- 396021F
Back(top)- 180, CFO
Back(left to right)- 11, 68, F
Passenger side(back to front)- C, CFO, 18, 384, 548, 86, GM
Drivers side(front to back)- C, CFO, 18, 384, 548, 87, GM

This is what i have just to clear everything up haha