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It is time to make the move to a 3 speed. Car will have a 550hp 408", possibly spray'd with a 200 shot. Has very limited street use, towed to the track. Should I stay Ford loyal and get a C4, or go to the dark side with a TH400?

Thanks,
Jacob
 

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thats a tough spot to be in...

a GOOD C4 can handle it and you might just need to go over it once a season. BUT a well built 400 will handle it with out batting an eye
C4 is lighter
TH400 more aftermarket support now with so many race car stepping away from glides for 400s
 

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Even better a PG. Stock PG with a valve body/brake will hold up to the task. Light, doesn't rob a lot of power ( like 400), cheap to build and car will be faster with it.
Can drive on street no problem from time to time. Final gear is 1.00 just like a 400 and C4.
 

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Even better a PG. Stock PG with a valve body/brake will hold up to the task. Light, doesn't rob a lot of power ( like 400), cheap to build and car will be faster with it.
Can drive on street no problem from time to time. Final gear is 1.00 just like a 400 and C4.
a glide is an option if you can turn some RPM. gotta remember a 1.76 first gear to get it moving will need some rear gear.
a 400 with a 2.48 first wont need near the rear gear.
 

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You do not make enough power to run a glide . Imo
It all depends on the converter, car weight, traction, and power. Some low power combos can benefit from a two speed trans, some won't.

A typical converter in stator lock (stall) has at least 2:1 torque multiplication. That multiplication drops as the stator speeds up until it is almost 1:1 ratio.

The starting line rear axle torque with a typical proper converter is engine torque times ~2 times low gear times rear gear.

It is identical to having an extra 2:1 hydraulically driven gear that gradually changes to a 1:1 as the stator runs looser and eventually syncs with the impeller and turbine wheels.

With 1000lb/ft engine torque my starting line "gear" to the axles is 1000*2*1.69*4.10=13858 lb/ft (less drive line friction and inertia loss).

A three speed is better if you can connect extra torque the higher ratio starting gear gives without blowing the tires off. That might be a 200 HP car with poor traction, or a 700 HP car that hooks really well.
 

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A 200 shot will get it moving with the 1.76 and it won't be as violent as it would be with the 2.48.
i know of a lot of cars like this that dropped from a C4 to a glide to go slower. going from a 2.40 to a 1.76 first gear killed the car at the starting line and they had to go with a lot more rear gear to make up for it then they had to turn a lot of RPM out the back
 

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C4...if you have the suspension to tame it down. For us..800hp seems to be the threshold where c4's are iffy & it doesn't matter WHO built it. TH 400 if you plan on going big time later,or have a heavy car.
 

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My car is almost identical to what the OP has and mine went faster with a glide. Don't cheap out on the convertor, it'll have to be dead on for the glide to work. I'll never run a 3spd.
 

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Once again, the "Theorists" are out in full force. A PG is lighter, requires less maintenance, requires less HP to run it, is just as strong as a TH400, way stronger than a similarly built C4. In "theory" the 'glide would need more gear. But in reality it does not, and I have at LEAST 4 or 5 firsthand experiences with this. All 3 of mine, a '68 coupe with a mild 408, a '72 Maverick with a 408, '85 Mustang coupe with a 302" (yeah, with a PG....remember, "it won't work"), '57 Chevy with a 355, etc.

If it needed more gear to get it rolling, you'd think that keeping your current gearing would cause the 60' to suffer. In EVERY case where family, friends, and myself where they chose to switch from TH350, TH400, C4, C6 or TF727 to a powerglide, whether the 'glide be a 1.82, 1.76, or 1.80, the 60' time IMPROVED. BUT on that note, the converter has everything to do with it. You put the wrong converter in front of it, and you'll be rewarded with lackluster performance. A good example is a guy I know as "MG". '88 Mustang, BBF, makes about 600hp and probably close to 600 lb-ft. Was a C4, ran 1.41 60', and 6.40 at 108 in the 1/8 with the C4. He asked me to build a glide so I did. Problem was that he said he already had a converter, 4800 stall from an old project that was a TH350. No problem right. I advised him to send the converter off and have it rebuilt for the 'glide and the car. Unfortunately he did not, and paid the price. After the install it went 1.46 6.45 at high 109mph, might as well say 110. Stall speed is ONLY part of the equation. He got mad at me and kept saying something was wrong with the transmission-and asked me to pull it down and inspect, so I did-twice. The 2nd time I called him & told him he needed to buy a few gaskets and he got mad again, said something was wrong with the transmission, blah blah. I knew it was the converter from day one. I lent him my 8" CCX 5200 converter, he put it together and went 1.36-6.31 at 110. And even then my converter didn't really match his engine, probably a little too aggressive at the hit since mine's a small block making a little less torque.

Your converter will also help on the big end too if it retains the sprag. I had mine built spragless since all I do is bracket racing, and it works for it's intended purpose. It's slightly more consistent than with the sprag. 1/8 mile only. If you're running 1/4 mile, keep the sprag, it'll help on the back half of the track.

So then why do you need more gear? high gear is 1.00:1 on almost all 3 speed transmissions. And it's also 1.00:1 on a powerglide.

Now I bleed Ford blue just like the rest of ya, but the day I went to the track with a powerglide, I won...and was SOLD. Have not looked back. Street car? They're (PG) not all that great on the streets. Streetable-yes-depends on how much you can put up with.

The TH400 has a sprag clutch inside it....not that it's known to fail, but they sometimes do. I've not seen one personally explode, however, I have seen a C4 and a TON of torqueflite 727's explode due to failed sprags, and it's not pretty. The TF727 was THE reason a transmission shield was invented. PG does not have a sprag. The arguement at one time was that "when it burns the band up, you'll wish you'd stuck with a 3 speed"....a PG band doesn't burn up unless it slips. It doesn't slip if the servo is holding like it should, and where some get into trouble is trying to run a stock single ring servo, they leak, and burn up the band and high clutch pack & drum. Put an aftermarket servo in-problem solved.

Every single part can be bought aftermarket to build a PG, including the case and every nut and bolt and spring. This allows you, the racer, to build it however you need it. If you want one to handle 3000 HP, fine-it can be done. Easily.

The 400 is also heavy. And uses up some HP to run it. But it's very strong. I compare them to the big C6, power hungry but hard to hurt them. TH400 properly built is also a little on the expensive side once you figure in the adapter bellhousing, internal parts, valve body, converter, etc. And it's pretty big, similar to a C6. Lot of guys use them, successfully. After running C4's and C6's for 20 some odd years, I made the switch back in the early 2000's to a 'glide and never looked back.

Powerglide is also REALLY easy to build, which if you're handy with a few tools, saves you some money.
 

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I run a glide with a 1.80 first and 3.08 rear gear and a thousand dollar BTE converter. My car weighs 3,400 lbs. It gets off the line with more than enough power to blow the slicks off. I keep tightening the converter too - it's now as tight as a 10" converter with a "C" stator can be.

The comments with needing more power or gear to get off the line aren't accurate in my opinion - the converter's very important (as has been mentioned). Gear is important too, but secondary to the converter. You need to match everything up RPM/performance/driveability wise. Don't expect a 450hp NA motor with a 5,800 rpm shift point and 3.08 gears to do well. It won't. A 450hp motor with a 6,800 rpm shift point and 4.10 gears would work ok, though.

One thing that is on point is that you'll need to turn at least a little rpm to lock up down track - like 6,500 or so would be the minimum I would shoot for.

Here's blowing the tires off at the track:
https://youtu.be/Avx2elU7-I0

And here's driving it on the street when it had 3.73's and was running mid 10's:
https://youtu.be/vQ7Ww6G0mo4

Now it's got 3.08's and is making a lot more power, and it's even more civilized. I just shot a half hour video driving around two days ago. I'll post it when I get a chance. Driving a stalled glide around is a lot like driving a CVT. Actually kind of nice (a lot nicer than my AOD with lockup was).
 

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AC4 will handle it all day long. it won't need to be freshened up every year either. the way I look at it, if you make enough power to hurt a good C4 you probably need a glide anyway. I've had great luck with c4's and see no reason to run a 400. maybe back in the day when there wasn't a whole lot of aftermarket parts available. but now there's all kinds of super strong parts available. Call up dynamic racing trans, they got some pretty bitchin stuff. they build Glides 2 they would probably give you an realistic unbiased opinion.
 
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