I have a 68 cutlass convertible w/ a 350. I love driving it and I drive it a lot. It's time for overdrive on these 70mph + TX highways!

I've read the other forums debating the 700 vs the 200. I'm leaning 700, but I can be talked out of it.

While a quicker 1st gear and OD are my desired result, I REALLY don't want to lose the factory shifter console housing b/c of a swap. Will I?


Also, I was told by an Olds enthusiast that my original 3spd trans isn't a TH. He said they came out with a wonky trans that year, and THAT'S why it takes forever to take off. I'd like to know more about this odd 3 spd trans. If anyone can point me to some reading on that, then I'd greatly appreciate it.

Thanks!

Rhett

 

You can get a 4 speed / OD shifter conversion from shiftworks that will work with either trans and retain your factory console shifter.

http://www.shiftworks.com/cutlas67-72.htm

4 Speed Overdrive Kit
Cutlass Shifter Conversion Kit

Use your factory-installed automatic floor shifter with a newer 4-speed (TH700-R-4, TH200-4R or 4L60) Transmission. The conversion includes a new laser cut and hardened detent for proper stops and gear selection, a new matching transmission shift lever, cable pan bracket, console lens indicator, all necessary hardware, cable, and instructions.

 

I personally like the 200-4R over the 700 because 1) it's almost a plug and play swap, and 2) I don't like that wide 1-2 gear spacing the 700 has. But sounds like that deep 1st gear is what you're after.

You sure the car doesn't have a 2-speed Jetaway and not a TH350? I've never heard of a weird 350 like you're describing (though 68 was 1st year for it and it may have had teething problems), but I'm also wondering if that car has what is referred to as "plains" rear end gearing- as in 2.48 or taller. That would definitely cause sluggish takeoff.

 

I missed the part about the transmission oddity. I thought the TH350 was first used in 1969 and the 1968 cars had the 2-speed Jetaway.

And yeah, the standard no-cost gear ratio was 2.56:1 in those years, so not performance oriented at all. Both my 70 and 71 came with that ratio. Boo.

 

After much deliberation, I'm going to go with the 700-R4. It was really a 50/50 toss-up. The 700 barely won out.

Joe Padvano says my trans isnt a TH350. The Olds enthusiast says is isn't a TH350. My mechanic, a young guy who took over for his now deceased father says it is a TH350, but he's a Chevy guy.

It is a 3spd trans. The gears are P R N D 1. When I go down the hwy it shifts 3x. I don't know. There isn't a lot of info on it and it's a great Trivia question. I'd just like to see the specs on this mystery transmission and find out what it's called.

 

The transmissions are easy to tell apart if you look at the transmission pan, and shiftworks will have a conversion for both Turbo 350 or Powerglide transmission.


http://chevellestuff.net/images/auto_trans_id.jpg

 

If it is a TH, then it's a TH400, which would be an odd setup for a Cutlass S, but I doubt that's what it is.

 

If your car had a 3-spd AT (TH350 or TH400), the shifter would say P-R-N-D-2-1, or P-R-N-D-S-L. And a transmission that shifts 3 times is a 4-speed. I suspect your '68 S, like mine, either has the 2-speed Jetaway (P-R-N-D-L), or someone swapped it earlier. I seriously doubt the factory put a TH400 behind a 350, even if it was a 4-bbl.


I chose the 200-4R since it was the simpler swap and had closer 1-2 ratios. In any case, keep us posted on your swap progress.

 

I'm pretty sure in 68 the tranny would be a 2 speed power glide, however for a few dollars more they could have ordered the TH400.

 

Here's a pic of my console from when I re-wired the car last summer. You can't see very well and they're worn, but there are only 5 labels on it. I'll have to check when I get home.





The int lights work!

 

Yup! P R D N L is what the console says. There's no extra gear after L either, so I guess it is a 2 spd? It shifts 3x though! Oh well, I'm getting overdrive in July

 

As previously mentioned, if it shifts 3 times, it has to be a 4 speed.

Shift
1 to 2 = 1st shift (this is where a 2 speed would be done)
2 to 3 = 2nd shift (this is where a 3 speed turbo 350 or 400 would be done)
3 to 4 = 3rd shift (now you are in overdrive)

 

I have a 700r4 and I love it. I made a cross member myself but I have a 72 cutlass 350 motor. I'm not sure how this will affect your body style. I also drive my car a lot.(highway miles) At 70mph my RPM is around 2200-2300. You will also need a spacer(Speedway.com).