68cutlassdriver

i just bought a project 68 cutlass that runs but it seems like it goes in first for a while then upshifts to 2nd. And then is that it? 2 gears?
or is my trans just jacked up?

64Rocket

Yep, '68 Cutlass only had two forward speeds.
Easy fix is a 69 and newer T-350 trans. Easy swap.
Gene

joe_padavano

Your trans is a Super Turbine 300, also known as a Jetaway. Note that your shift quadrant only shows P-R-N-D-L. First gear is 1.76:1, second gear is 1:1. Unfortunately, in 1968 Olds dropped the switch pitch torque converter on this trans. Contrary to popular belief, it is NOT a Powerglide.

68cutlassdriver

Wow so what kind of rpms is this thing turning at 70mph? It sounds like highway speed is.not healthy for this combo.

Also, to swap to a th350, will I need any additional parts like a different tail / drive shaft or trans crossbrace?

Will any 69 and up th350 work or will it need to come from a pontiac/olds?


Thanks!

joe_padavano

Your top gear ratio of 1:1 is the same as top gear in either the TH350 or the TH400, so highway RPM is only a function of the rear end gears and tire diameter.

You need a short tail TH350 with the BOP bellhousing (basically, anything that isn't a Chevy). If you get the short tail, your stock driveshaft can be used. The only two issues with this swap are the gear selector (your stock two speed shifter can only access Drive and Second, not Low) and the kickdown cable (your stock trans uses an electric kickdown). The TH350 was optional in 1969, so one option is to get the cable and accelerator pedal from a 1969-72 TH350 A-body. On those cars the cable actually goes through the firewall to the accelerator pedal. You'll need to cut a small square hole in the firewall below the accelerator cable. Alternately you can use the cable that goes to the carb as used on later models. You might need to fabricate a bracket and/or carb fitting for it to work.

Wasted

I did this swap in my 64. The th 350 is a direct bolt in. So the crossmber stays where it's at and you use your old driveshaft.

You'll need to find one from a Buick Pontiac or Olds. A Chevy one won't work because of the different bolt pattern.

It's one of the easiest swaps so you shouldn't have to much trobule with it.

68cutlassdriver

Thanks for this info. So what will I need to do about the gear selector?

[B][/B]

joe_padavano

Do you have a column or floor shifter?

68cutlassdriver

Column shifter

joe_padavano

In that case, your options are:

1) Live with it. You just won't be able to manually shift into Low. Everything else will work fine.

2) Get a column from a 68 Cutlass with TH400. 69-up are different and don't work.

3) Convert to a floor shift.

68cutlassdriver

I think I can live with the column shift for now. I plan on doing an ls swap later in the year with a new trans.

Thanks.for the info

joe_padavano

Too bad.

BILL DEMMER

my '67 cutlass had a s.p. jetaway, i put in a '67 s.p. thm400, i can drop it into L(actual low gear in the trans) the needle hangs lower than the L marking, that's all. i have access to all three gears manually, 68cutlassdriver will have the same. i adjusted my indicator to the D position when in drive.


bill

68cutlassdriver

so i will look for a short tail TH350 from an olds/buick and keep the stock column shifter.

so what i need to figure out is which route to go with the kickdown cable......

does anyone sell a conversion for this or do i need to hunt down a 69-72 cable & pedal?


again thanks to everyone for the info. the more i know about this car the better i feel about the work to come. i previously had mustangs and the information/parts was endless. It seems a bit more difficult with this cutlass!!!

matt69olds

Look for a 69 or later pedal, I'm not sure if the cable is available from the aftermarket. You will like the TH350, I did the same swap on my brother 63 Impala with a 283, would would swear the car had an extra 50 hp. The lower first gear makes a huge difference in acceleration.

joe_padavano

You can certainly do that, but the shift gate in the column will not have the notches for all three gears. Bumping the shift lever may cause you to change gears.

BILL DEMMER

[quote=joe_padavano;251228]You can certainly do that, but the shift gate in the column will not have the notches for all three gears. Bumping the shift lever may cause you to change gears.[/quot

i've never had a problem, the gates for d and l(on the column) line-up perfectly. i also increased the tranny's detent spring tension, that may be why i've never had an issue.


bill

68cutlassdriver

what did you do about the kickdown cable?

68cutlassdriver

well i got a donor BOP Th350 and it looks like it has the kickdown cable still connected.

i also purchase a 69' accelerator pedal.

So i assume that i can just swap the trans & torque converter, install the fluid lines, hookup the vaccum line, speedo cable, and kickdown cable....

am i missing anything? anyone have a diagram of the trans setup?

also, what is needed to convert to floor shift? will i need to swap my column?


thanks.

oldsmobuser

I converted mine to a TH350 and I just live with the shift indicator because I have a tilt column and would like to retain it. I bought the P/S pump, carb, starter, alternator, distributor, and cyl. heads from a 77 Olds in the junkyard. I put all of them on my car in 1991. I used the throttle cable bracket off of the '77 so I could use the kick down cable that I bought from the transmission shop. The combo works very well. The kick-down cable goes from the carb to trans along the top of the trans. No need to put any holes in your firewall. I just noticed this is an old post. I'm sure you have it figured out by now. Take care.

JohnnyBs68S

OR........ you could use an adjustable Kugel column shift linkage that allows you to change the ratio between column shifter motion and the trans arm motion and get your shifter gates lined up w/ the new trans detents (specifically the P and N positions are critical since those are what your neutral safety switch needs to start the car). If it works on my 200-4R swap, it will certainly work on a TH350 swap. Sure the indicator will be useless for the lower forward gears, but PRND will still line up just fine and there is nothing in the column that prevents you from shifting all the way down into 1st, even with the 200-4R.

#6021 Shift Arm Kit – Long – Kugel Komponents

Cheap and simple install if you are not ready to jump to a floor shifter.

Koda

I'm sure he's done it by now.

joe_padavano

Don't bet on it. Sadly, I have unfinished projects that date to much earlier than 2011.

Grayghost

If you are doing a drivetrain swap withing a year or so. leave it as it is.

tiogatwister

If you have not found a trans yet I have a BOP 350, was rebuilt with a new torque converter, will let you have it cheap. I am in the metro Detroit area.