Inliners International Forums General Discussion Drive Train 235 w/ TH350 tranny

I contacted Langdons about their adapter plate so could install a TH350 into my '50 chev. I currently have a later model 235, later driveline and rear end. They suggested I stay away from the TH350 tranny and move to something like a 200r4 or 700r4...what is wrong with using a TH350... that's what I want to use and there's so many available in my area. I'm perplexed because I thought this combo was used quite often. Thoughts?

OK, here is the response I received from Tom Langdon..

"Butch, the 235 doesn’t produce enough torque to give satisfactory “in town” acceleration with a highway axle ratio (3.08?) If you use an original axle ratio (4.11) the engine runs too fast on the highway.

The 200 4R has 10% more 1st gear ratio and with the .67 overdrive ratio you can use a 3.73 axle ratio and still have a highway ratio (3.73 x .67) of 2.50 or a (4.10x.67 ) 2.75." - Tom

So now maybe I'll look for a 200-4R as I only want to do this once and I want to be able to take it on the highway with satisfactory results.

Thanks, Butch.

One item to consider is the 700R4 (aka 4L60) has a 3.06 1st gear ratio as apposed to the TH350/TH200R4 which is in the 2.50's range. So if you have a 3.23 to 3.50 rear gear and a 700R4 it make the vehicle feel like it has 4.11 - 4.30 with a TH350 installed.
Locally we can get good used 700R4's for under $200. If you do need to rebuild a tranny the 350 is Much cheaper to do than a 200/700. A good 350 rebuild is around $250 in parts.

Either transmission will do a good job. Just depends what you want to do.

Well I guess I want to be able to cruise over to Eastern Washington occasionally at highway speeds (approx. a 2 hour drive) or out on cruise runs down to Oregon without laggin' behind. I guess I just need the best bang for my buck. I'm not sure what I currently have for a rear end (I know, I know)...as all of this was updated before I received the car. I have just started diving into it. How do I tell what I have back there? Is there a number on the differential that will determine just what I have. I have a feeling my motor, driveline and rear end came from a '55 - '57. I was hoping to keep the 235, but if this turns out to be a major hassle, maybe I should just bite the bullet and get myself a ....... 350 SB. Hope I said that quiet enough to where not too may will hear me.

The method of check the rear end ratio depend on which rear end is installed.

Does it have a cover or is it a pumpkin type.

If it a cover type, pull the cover off and look at the gear set the ratio or tooth count will be stamped on the ring gear - this will also give you the chance to change the gear oil since it'll come out when you pull the cover. You were planing on changing "all" the fluids before heading out for a long haul right?

The beauty of this thing is I've got the engine and tranny out.. the front end is off (fenders, grill, etc... I'm in no hurry to slap this together as I'm planning on working on it over the winter. I like the idea of keeping the 235. Love the look and I just think it looks a whole lot nicer than another 350/350 combo as was stated earlier. My trouble is that I want this car to do everything. I want to cruise town, and be able to hit the highway (at highway speeds). I want reliability...I'm basically putting together a family cruiser. I also want accessory availability! Making it look nice with all the neat little performance parts is half the fun (dual carb intakes, split exhaust manifolds, Chrome valve covers, etc.). With all that said...I'll take a look at the rear end and see what I have. I like the idea of perhaps switching to a 292? What year / models did that engine come in? Will I need new mounts for the motor? Oh so many questions. Really appreciate all your help. I've been restoring Volkswagens for such a long time that it's really refreshing to work on something else for a change.

Dear Butch;

It's been a long time since I ran a tach. on a 235 with 4:11 gears/old Chevy etc. But I recall 2000 RPM was 40 MPH.

So highway speed (55-60)would be 2500-3000 which won't hurt anything for 2 hr.

The OD transmisions from Chevrolet (circa 55+) will work fine in most cases and are cheap.

Are you sure you want to re-design the whole thing for an ocasional 2hr. cruise?

BTW: A 292" has more Hp & torque than the 283,327 & the early 350s.

Good luck, John M., #3370..

One thing you did not mention was what transmission is currently in your 50 and if you are happy with its cruising or acceleration. If you currently have a PG, the cruise will be the same and acceleration better. If a 3-speed, compare the ratios. There are several on-line calculators that will let you play with trans ratios, rear end ratios and tire diameters to help you determine where you want to be. I put a 700R4 behind a 292 because I wanted the overdrive due to a 4.10 rear and 26" tall tires. Just figure out what you want the car to do and plan accordingly.

On the 200 or 700, remember if you use the lock up converter, there will be some wiring and it is all 12 volt.

A thought for the 350 trany application. On this discusion I was told to use a tall rear gear with the 350 trans and use one size smaller standard converter to raise the stall speed at start up. This would give reasonable off the line perfomance and would be within 5% off converter lockup at cruising speed.

Wow...all this info is jellin' my mind. So many factors, so many combo's available.

Does anybody know the number for "Overhaulin"?

Nah, just kidding..I rather use my trunk than have it stuffed full of stereo equipment.

Well I'll give you all an update once I figure it out. Thanks so much for all the info. This truly is a fantastic source of knowledge and experience.

one other tip. the 200-4r and the long case 350 are about the same length and no other drivetrain mods. if you have a short case 350 trans like i do then you will have to shorten the driveshaft when you put in a 200-4r. [so i wuz told]

What about the 700R4?

OK! I've finally made a decision on this! I'm going to go with my original plan and get the 350! Even if it isn't much better than the PG, I can still use a modern starter and install the Lockar shift linkage which is what I wanted to install orginally. I just say a very slick '49 posted on the "rides" area. Very nice and he's got a 235/TH350 combo. 350's are so plentiful that I just feel it's the way to go for me.

So there ya go!