4 and 5 speed transmissions

[corvette66]

The 5 speed transmissions used in the 80's camaros are they also the doug nash deal? Or is it similar to the 5 speed used in the 70's Vega? I take it none of these tranis fit in the vettes or everyone would be doing it???

Just in search of something for my 1980. TH400 went out a while back.

 

[Hib Halverson]

Search the web for "Classic Chevy Five Speed". I believe they have a five-speed conversion kit for C3s.

 

[Peer81]

A TH400 in a 80? I thought original it would be a TH350...

Groeten Peter

 

[corvette66]

Pretty sure the 1980 is turbo 400. I could be wrong. Actually it would be nice if it was a TH350 since i have a spare one of thoes.

It seems so odd to me that in the 80's the camaros had a true 5 speed and yet even in the 70's they had a true 5 speed for the vega, but the vettes (most expensive Gm vehicle) had a standard 4 speed with a basically garbage OD unit. Gotta wonder why they did that.

I looked on ebay to find an 80's camaro trani just to see what they looked like. Similar, but they are top loaders. Probably no way to make them work in a vette.

 

[Crimson Thunder]

I believe the 5 speed in the Camaros was " non world class" T-5.Yep the same T-5 found in pre 1988 5.0 Mustangs with a wimpy 300ft torque rating.The Vega 5 speed was a big P.O.S.where 1st gear was down where 2nd gear is supposed to be and 2nd gear was up and over where 3rd is on a normal transmission.I had put one in a 75 factory V8 Monza once and it is definitely not a performance transmission.

 

[corvette66]

"I believe the 5 speed in the Camaros was " non world class" T-5.Yep the same T-5 found in pre 1988 5.0 Mustangs with a wimpy 300ft torque rating.The Vega 5 speed was a big P.O.S.where 1st gear was down where 2nd gear is supposed to be and 2nd gear was up and over where 3rd is on a normal transmission.I had put one in a 75 factory V8 Monza once and it is definitely not a performance transmission"

Yeah, i kind of figured it would be a real PILE!

So i have been trying to find out if the 1980 has a 350 or a 400. any idea?

 

[KANE]

...So i have been trying to find out if the 1980 has a 350 or a 400. any idea?

The OE correct transmission for an '80 is a TH350.

However, you might not have the OE TH350. It depends on if the previous was adamant about replacing it with the TH400 you keep talking about!

Seriously, crawl under the car and take a look. If the transmission pan looks more or less like a square box, then you have a TH350.

Below is a random pic from the internet that shows the design of the TH350 pan-

TH400s look like overgrown corn flakes. Below is a $$$ pan, but you'll see what the TH400 looks like. Yep- the pan plainly looks like a corn flake.

 

[corvette66]

Below is a random pic from the internet that shows the design of the TH350 pan-
Awesome!! its a 350 then for sure. thats good news because a freind of mine has a spare TH350. I wasn't sure about using it, I thought maybe the 400 had a longer tailshaft like the 700R. And would then need a new driveline.
thanx guys

 

[floopcom]

Alternatives

It sounds like you probably have a very high ratio differential, like maybe 3.08. If so your problem with a 4 or 5 speed is the first gear ratio. Most ST10 4 speeds have a first gear of 2.64 or 2.42. This would give you an overall gear ratio in first gear of about 8.2. That is right at the edge of drivability and would be hard on clutches. You really need an overall ratio of about 9.0 in first gear.

You really have two solutions if you want to convert to a standard trans without changing the rear end ratio. The more expensive solution is a Richmond Gear 5 speed with a 1st gear of about 3.28. This gets you a 1st gear overall ratio of about 10.1 and lets you run about 1800 RPM at 55 mph in 5th gear.

The other solution is to find an ST10 4 speed with a 3.42 1st gear. These were put in Camaros and Firebirds, mostly, but are essentially identical to the stock Corvette ST10s except for the gear ratios. The 3.42 1st gear gives you an overall 1st gear ratio of 10.5.

For reference, the most popular gearing in a ’75 Corvette was probably a 3.70 diff with a 2.64 1st gear. That gave an overall 1st gear ratio of 9.8. Either of the above options will give you a better take-off ratio than that and still give you great freeway cruising.