Technical Why not the C4? TH350 vs C4

Some folks probably thought a c4 trans was from a corvette

 

True statement. I've had a few when I was selling some stall speed converters for the c4 I had extra come and think it was for corvettes.

 

For many applications that is the case, but for many others, it's not. In applications with a deep skirted engine block, like early Cadillac, Olds, Hemi, and flathead, the only options seem to be some wonky adapter plate where there is some weird spacer to make up the gap between the flexplate(s) and the converter with a GM trans. With a C4, because of the detachable bell, the bellhousing itself could be the adapter plate to wide variety of engines. As you correctly pointed out, yes, you could saw the bell off of a GM trans. But if the Ford trans is meant for it, and the trans is just as good, why not just use that?

 

I don't know...but I do know I don't have the skill to make a C4 work right, and I don't have any trouble with the TH350

 

I can't speak to that. I remember as a kid I was so confused by the C4. "Wait, that whole front part just comes off?!" I've never had a problem with either, but I've also never ran either with a kick down, just a vacuum modulator. The only transmission that has legitimately given me a fit was a 700R4 and getting the TV cable adjusted properly

 

I feel for you on the 700.....

 

Friend of mine drove his freshly built 700 to the trans shop to get the TV cable set up.
had to get it built again

 

My 3/4 clutch pack didn't make it out of my driveway. That was a tough lesson to learn.

 

We referred the top case as a "corporate case" because it has both the Chevy pattern AND the B O P pattern.

 

The C4 also came with an even smaller bellhousing in the V8 Mustang II, great for those small trans tunnels that someone doesn't want to beat up. However it also used a special oil pan, I don't recall the details of why.
I believe it used a 148 tooth flex plate. These parts are no doubt very hard to find now.

 

I've got a C4 to 429/460 bellhousing I'd let go of if you're interested.

 

It would need to be a SFI approved bell housing for my application or install a trans shield which I haven’t even explored yet.

 

When I worked at the Lincoln/Mercury dealership back in the early 70's, the C4 wasn't my pick for an automatic. The C6 and the FMX were more robust. Of course we were dealing with large, heavy cars at that time. The state of Illinois had a Ford truck they made into a wrecker. It had and extended frame with a large wrecker mechanism. It also had a C4. I think I personally rebuilt that one twice. I don't know how many times the Ford dealer across the street rebuilt it. They really beat the crap out of that truck. In all fairness, the chassis was probably overloaded before they picked up anything.

In the late 70's they made a change to the valve body and incorporated a throttle pressure relief valve that was held in place by the filter. I rebuilt a couple that had a fluid change elsewhere and the valve was missing. It didn't take long to smoke the trans.

 

When I was drag racing almost every weekend with my OT 427 Camaro I wanted to get my TH400 rebuilt, and went to a local guy to talk about it. This was around 1980 and he posed a question to me that I found shocking; "Why not let me build a TH350 for you?"
Without being rude I asked what he was smoking to suggest a TH350 downgrade? He told me with performance parts available for the TH350 he could build me a trans that would hold up as well or better than my TH400, and have less weight, plus less mass being turned by the engine.
After lots of discussion I gave in and let him built me a TH350 with all the changes to make it race ready. I raced and street drove that car for another decade, and after I stopped drag racing it, I drove it on the street until I finally sold it about 5 years ago. That TH350 he built was still in the car, and still working perfectly. Never an issue, and it did give me slightly better times at the drags. I wouldn't hesitate to do another TH350 if I found someone who could build one tough enough as the previous guy did.

 

Indeed why not? After all, the C4 was introduced for the 1964 model year, which makes it (barely) H.A.M.B. friendly. The TH350 was introduced for the 1969 model year which means it is not.

 

I saw a lot of c4's fried before they started making better parts for them. One of which I owned. But we should never discount "monkey see, monkey do" or follow the path of least resistance.

 

The first year (1964) C4s had a narrower intermediate band, so best avoided for performance use unless upgraded to the later wider band.

 

Personally I like a manual trans. But I am planning to fit a t700 behind the y-block in my 57 ford.
I really don't know why anyone would bother with a 3 speed transmission when there are overdrive transmissions available for a street car

 

That was a feature a lot of C4's left the factory with. Most shift kits address this so they start in first.

 

I've had cars with TH350s, TH400s and 700R4s, as well as 727s. I agree with you that the OD is fantastic. It adds a new dimension of utility to the car that wasn't there if the car didn't come equipped with OD. Less noise, runs cooler, less wear on the engine, significantly better fuel economy and higher cruising speeds are all a reality with OD. But from experience, the simplicity and function of the 3 speeds is better than the 700R4/200R4 and AOD. Setting up the TV cable is a straight up pain in the ass on the custom application, and in many heavy duty applications, the OD transmissions just aren't strong enough. Having utilized all of those transmissions, I think my next experiment will be with a 3 speed and a GV unit. Perhaps that will wind up being the best of both worlds; complete simplicity, total durability, and still retain OD without the use of a computer.

 

I’ve argued with myself many times about the 3 spd automatic vs 4 spd auto and have yet to convince myself that the 4 spd version is worth the money and effort. My cars all tend to have tall 7.10-8.20 bias ply tires and my engines all have small to medium cams and pump gas compression ratios. They are quite happy with a 1:1 high gear and a common 3.00-3.50 rear end gear ratio. My stoplight to stoplight acceleration is more limited by the tires than the gear ratio and the engine runs in a healthy, efficient rpm range at common highway speeds. I just don’t feel the need for a large $2000-4000 transmission and specialty 3.70-4.11 rear gears.
Those who know that their cars will spend a lot of their time on the highway going long distances are wise to build their cars with IFS, more creature comforts, big fuel tanks and overdrive transmissions, but my cars see mostly local drives, and I like a simpler, basic hot rod with few frills.

 

That's really a forgotten point that you highlighted. Not everyone uses their cars the same way, and that's fine. But that means we're going to have different goals in mind. I often hear that argument here on the HAMB that you don't need OD. And if the majority of the use of the car is on local roads or county highways, then I'd agree with that. A transmission like a PG, C4, Jetaway, FOM, etc., is perfectly fine to handle that type of use and OD is not necessary. But some folks use their cars differently, and drive many miles a year, with a large portion of them being on long highway hauls. For those folks, there is a substantial benefit to the OD. So there's no right or wrong answer. I can only speak for myself that having the OD has been really nice, and substantially improved the driving experience over the 3 speed. But it's also not uncommon that I'll drive 8+ hours in one direction, and having those tall legs, not to mention a few creature comforts, is nice for those drives, and especially so if I have my family with me.

 

A 4 speed automatic is all I'll use in the future for a street hotrod if using an automatic. It gives me the ability to run lower rear gear ratio, and allow my engine rpm's to stay well below high rpm's on the freeway. The OD automatics are one reason engines live longer after they became common. I love having 3.73 rear gears for a good takeoff, yet cruise down the freeway at 70 mph at only 2200 rpm's!
I have the same engine and gear ratios for both of my hotrods, but my Austin gasser is a TH350, so cruising down the freeway at 70 mph puts my rpm's at 3400 rpm! That bothers me to be cruising for hours at that rpm range, so I just don't take longer runs on that car. It's fun around town, just better in my '39 with the OD 4th gear.
As for all the mystery of adjusting the cable on a 700R4, it only confused me the more I read. There's so damn much disinformation on the internet that I was scared I'd ruin my new 700 within the first few miles I drove the car!
Instead of chancing internet myths, and bad info I decided to call Art Carr Transmissions, and ask an expert. I couldn't believe how simple it was. He told me to set the cable with plenty of slack in the adjustment. Then open the carb linkage wide open, and hold it there while adjusting the cable tension to it's stopping point. Release the throttle and lock the cable adjustment down. Simple as that, and my trans has worked perfectly since the initial adjustment, and no other adjustments needed.

 

Lots of good points being made. Personally, I cannot even guess as to the number of freeway miles I have driven with the 'old' 3-spd TF or other 3spd auto trans. I just don't recall ever being limited by them. My old 68 GTX is a good example; 440 with TF and 3.23 gear. In 1969 it was damn fast in street 'applications' and an easy cruiser at freeway speeds. Several of my old 73 RoadRunners were different, not as pleasant on the road with 4-spd and deeper gear sets, plenty of engine noise.
Like you have said Joe, plenty of variation not just in the cars but in how we use them. These days OD units are pervasive and we are allowed a bit deeper rear gear for 'spirited' street use. A TF with 3.9 or 4.1 out back is lots-o-fun.

 

Here's a fact not many people know or want to admit. The Ford C4 and the GM T350 are cousins. The designs are both conceived by the same person. A man named Simpson. While working at Ford he patented 24 separate parents for the three speed planetary automatic transmission. Ford C3,C4,C5, and C6 are Simpson designs. GM TH125, 200, 250, 325, 350, 375, 400, and 425 are Simpson designs. Chrysler 904, 727, are Simpson designs. Example, Ford C4 and C6 are two different patents, both function exactly the same. However the C4 uses a band to hold the low/reverse drum and a C6 uses a clutch, thus two different patents. I used to teach students automatic transmissions.

 

Howard Simpson is indeed the father of the first really reliable three-speed automatics. In the early 1950s Simpson attempted to sell his patent to major American automakers in Detroit, but was greeted with skepticism, despite his experience and positive reputation. Ford Motor Company licensed his three-speed gearset in 1953, although they did not put it into production at that time. In 1955 Chrysler licensed the same gearset for use in their new three-speed Torqueflite automatic, which went into production in mid-1956. GM was reluctant to adopt this gearset, but eventually relented and licensed it for their Turbo Hydramatics, which entered production in 1964 . Ford similarly introduced reengineered Cruise-O-Matic transmissions (C3, C4, and C6) in 1964 and 1965 using the gearset they had already licensed. Mercedes licensed the gearset as well, although it did not enter production until the early 1970s.

The C4/C6 were first generation. One problem of changing from first to second gear is that two bands must actuate in synchrony: the planet carrier of the second gearset must release at the same time as the sun band is actuated. Sprag clutches mitigate roughness when a shift requires a combination of bands to be released or actuated.

GM's Turbo Hydramatic 350 and 400 transmissions are second generation, utilizing overrunning clutches in both the low and intermediate gears, allowing for fully progressive shifting with no "overlap".

jack vines

 

Question for the C4 guys, is it a mix-match grab bag like other Fords? What I mean is this starter, this flexplate, this converter combo, not this XXX?
I remember having issues getting stuff to match up on friend's cars.

 

Yes.

 

Build it if you have it and works for your intent.

 

*Opinion from a manual transmission guy, aka outside looking in*

I think the main reason people don't think about the c4 is the same reason most people install sbc into their homebuilt hot rods, rather that a sbf.

Price and Availability of Knowledge/Parts

One cursory glance at FB marketplace had pages of th350 trans, from $50 for a rebuilder, to $1k or more for a fully built race unit.

Even when I tried multiple different search terms for 'C4" into marketplace, I was met with only 5 or 6 ads, with only a few rebuilder options, all $100+

So if I was looking to build a budget street rod with an automatic, or even a street bruiser/ track car, I'd look at parts available for cheap, and put the motor/trans that made the most sense.

sadly, (if you're a ford guy) the knowledge and parts to build higher performance ford motor/trans is just higher than building a comparable motor/trans in chevy form.

Another good point that bears repeating, is you can take a motor out of almost any bbc or sbc from 1955-2000 and bolt it to a trans from any of those years. Ford had a nasty habit of changing things almost bi-weekly. *

*I know people who will say "if you're a "real ford guy" that its not hard to figure out", but to someone looking in from outside, it sure looks complicated.

boy I typed more than I thought I would.