The previous owner installed a three speed trans, I guess it's a th350 but I'm not sure. It dosen't shift until around 2800-3000 RPM so it seems he also installed a torque converter. I was wondering how a 3spd would behave with the stock 1650 stall converter or if there is a better converter I could use. Right now the car has very poor drive-ability, he wanted a drag racer but I want a cruiser. I've considered swapping for a 700r4 but the 3 speed works fine and transmission swaps make me nervous.

 

I was wondering if I should swap my rear gears to 273s. I'm not sure of the current gears but I know for sure that the ratio is over 3. What effect would 273s have?

 

TH350's shift at part throttle based on governor speed, detent cable adjustment or vacuum modulator setting. All three operate together to provide the shift points during different operating conditions and demand.

The converter should be matched to the cam grind. Just because the car may have come with a higher stall converter, it may not be matched to the camshaft. If you only want a street cruiser, you're going to have to change things to give it better street manners.

There's nothing wrong with a 3 speed tranny. There were used for many years with no problems. The advantage of the 700R4 is it's gear ratios. With a low first gear, you don't need a deep gear in the diff. With the OD and the crappy diff gears, it's good to keep the engine rpms down while on the highway. For performance however, the 700R4 is a poor choice compared to just about every other transmission option available.

 

If I decide to keep the three speed do you think I should lower my gear ratio? I'm trying to find a balance between performance and street manners. Since I never intend to race, performance isn't my top priority. I do a little bit more town driving than highway but I'd like to be able to do more highway driving. Of course, none of us want to completely sacrifice performance either. So for a cruiser with a bit of pep, what combination of gear ratio and stall speed do you think would best suit a three speed?
I'm not mechanically inclined myself, I have the basic understanding that the lower my gear ratio the lower my highway RPMs but I also lose some of the initial kick.
As for the stall speed, it's really annoying having to get up to 3000RPM every time I have to slow down too much or stop at a light. It's all or nothing, I either have to stomp the pedal and get her up there fast to get that hard kick or drive in a normal fashion and put up with the slow launch.

 

sounds like you may need to adjust the vacuum modulator. Take a look at it and see if it has a red stripe on it. A decent gear for a cruiser would be 3.42-3.73s and it sounds like you would be happiest with a ratio closer to 3.42. Just because the transmission is shifting @3000 doesn't mean there is a higher stall speed converter in the trans, check the brake stall that will give you some indication of what stall you have.

 

I have a full manual valve body in my powerglide so I can't really compare as to when it will shift however I also have a converter that stalls around 6000 rpm. The rpm doesn't increase a whole lot to get me moving and driving around the pits.

 

Thanks for the help guys, it's very possible that the trans isn't configured properly, pretty much everything else the previous owner did was wrong or sloppy too.
As for when I start to move, the car will move right away but wont shift until I reach 3000RPM. I heard somebody say that that even with a 3000 stall converter the car should still drive smoothly if it's properly installed. Do you agree with this? I wasn't there when the car was bought but my brother was and he said he can remember the guy talking about adding something to the tranny. I'm not sure if this is a converter or a B&M shift kit or both, it does have a B&M Megashifter. The previous owner wanted to make a drag racer. The higher gear ratio would be nice but the RPMs on the highway are killer.

 

I just did some reading about the vacuum modulator and governor. Think I'm starting to get a better understanding about whats going on here.
So from what I understand now, even if there is a 3000 stall converter, as long as the governor and vacuum modulator are properly set the car should still drive smoothly and the launch shouldn't be slow and delayed. Am I getting this right?

 

If the previous owner installed a shift kit, it may ignore modulator settings. Since you mainly want it as a street car, you may have to convert the valve body back to stock or a mild shift kit. Most shift kits will allow you to install them in different versions. Stage 1, stage 2, race etc. Because some of the check ***** are removed, it will be difficult to convert it right back to stock without a donor transmission for parts or know of a tranny parts supplier.

Check the modulator setting
Buy a new shift kit and install it as a stage 1

 

I'm going to get the modulator setting checked. If I decide to just get rid of the trans all together do you have any recommendations for a replacement? I was thinking about a 700R4 but you said they're not the best choice and I've heard that the early models were unreliable. Now that there has been a 3 speed in the car would there be any complications in going back to a 4 speed, like my drive shaft not fitting, etc?

 

What did the previous owner do about the torque arm?

Swapping back to a 700R4 is easy providing you can find one from a third gen in the junkyard. It would probably need to be rebuilt. Driveshaft is close enough to the same length providing you have a 9" tailshaft TH350. If you have a 6" tailshaft, you'll need to get the driveshaft out of a 84+ third gen. Torque arm mount attaches to the tailshaft housing which isn't the best location but for a street car, it will be fine. A donor car can also provide the crossmember unless the one you have was for a 700R4 and has been modified for a TH350. The TV cable is different from the TH350's detent cable but I don't know if it's interchangeable in the hookup.

The 700R4 isn't a good choice for dragstrip use or WOT use but it's a great choice for a street car.