Chevy guys didn't do anything. It was the aftermarket who saw a need and filled it. To this point, no company has seen the need to sink a bunch of money into making a 727 case and they won't. Because there is no need. Plus as mentioned many times here, but you just can't seem to accept it, the 400 is a BETTER race trans, because of converter choices and shift overlap.

You say I jumped the fence because I couldn't keep mine together...........damn right I did. When I was still wringing off the BEST shafts you could buy at the time, please enlighten me to what I SHOULD have done to fix that.

What's best for your application is everything. I took a 904 out and put a Glide in for consistency and low gear ratio because the car was light. Before that it was in a 3000# footbrake car and worked great for that. I like Torqueflites too. But they have their limits, bellhousing depth, stock cases and issues with high RPMs and big horsepower. In a street/strip car, class car or typical stock body, 1.30 or even 1.20s 60' deal, it's what I would use.

In a strictly race deal, starting line ratio is a critical tuning choice. Big horsepower requires taking gear out of it. A Glide is fine for that until it starts breaking. Then you look at a 3 or 2 speed 400 with the right gear set. Packaging is another concern. A stock 727 is substantially longer than other options.

It's all about what's the best choice for YOU. Not everyone is trying to accomplish the same thing.

I agree with this. Does every car need a glide or a Turbo, of course not..........But what really pisses me off is when you get chastised for making the switch, by some purist, who has his head so far somewhere they can't see the light. They tell you what you should NOT have done, but offer up no other suggestions.

Wonder if Jim Kinnett had to put up with that crap when he had a 12 bolt under his SS/AA car. What about the loads of Modified and Gas guys who ran Top Loaders because the HEMI boxes eat main clusters. Wonder if they had to hear that crap

I'm not an expert by any means but have done a few 727's, 904's TH350's and a bunch of TH400's and one or two C4's. All the 727's I built were to support 700hp or less. A few TH400 for 1000-1200HP. I would say that a TH400 can easily be built to handle more power but it does still take aftermarket parts. The intermediate sprag is weak and even with a good early 34 element factory one is living on borrowed time at 700HP and above. Any good TH400 build would need the large 36 element Caddy sprag(otherwise known as Pro-mod sprag) and usually going to cost at least $500 on one that's been retrofitted to a factory iron drum and more for 7075 aluminum. Clutch capacity is OK but requires more line pressure than a 727 because of there smaller clutch and piston area. Some prefer the Ginner spragless conversions but basically turn it into a 727 anyway with the shift timing issues and challenges that come with it.
A lot of the TH400 factory case's need a lot of work to make them acceptable for HP use. Most of the ones I see need to have the VB surface stoned because the factory machining was so rough it would never seal an aftermarket valve body without a gasket. Finding a good pump is becoming harder since a lot of them see wear.
For me I prefer a TH400 because of the flexibility of the hydraulic modifications that can be performed over a 727.
AG.

I've heard that once you get to around 1,000 HP you're usually reaching the limits of a reliable 727. I realize there are other factors than just HP, but is this good guideline.

Like my budget would allow such a build ... lol

Billy I did limited time building Diesel transmissions. I have one in my parts truck that handled 416hp at the rear wheels in a 7000 lb 4x4. The stock trans actaully held up pretty well with just a vavlebody and tighter stock type convertor ... welded steel stator and better lockup clutch material ... from Diesel Transmision Tech in Abbotsford BC. When I putthe big turbo on it and let someone take it for a ride is when the shortcomings of the 4 clutch front clutch reared it's ugly head.

The current trans has 6 clutches in a 4 clutch drum and I think 10 clutches in the OD direct and an extra clutch in the OD clutch pack. It has a TCS billet input shaft and hub ... Diesels towing heavy would split the hub and/or twist off the input shaft ... BW hi energy bands and clutches thru out and a Cryo'd output shaft ... I twisted the original output shaft off with my foot on the brake building boost to do a burnout. That trans has about 130k miles of various abuse since being built with about 1000ft lbs going thru it at various times.

I'm surprised that Chrysler didnt make the bell
housing area deeper for a better conv on the diesel
and 518 type.. for the auto trans they had/have big
torque conv issues

So with the Pro Flight / Pro Trans mods that they are doing for smaller motors, how are those company's going about making modifications to accept gm converters? What are they changing to make this happen? Are they using a spacer and changing the input shaft?

Just curious since there are so many being used for in NA SB classes. A different application than most of course

I thought it was bigger? The convertor on the diesel is big and heavy. But I never compared the bell pattern/size to a BB or SB 727 before.

If you make 1000+ hp why would you need the deep gearset of a 3 speed trans?

Jeff

Maybe I'll see what they are.. I have a 727 and a 518
sitting in the shop... I know the 518 has a big conv
but I didnt think it was much deeper... I have the stock
conv for the 518 but all I have are 8" for the 727 and it
thinner

Totally different bell on a diesel. Not even close to a bb or sb bell.
The non lockup diesel trans converter is shorter than the lock up converter. the difference of converter length in the diesel is made up in the engine bell/adapter, which is removable from the block.
I don't know why a spacer couldn't be used on the gas engine trans to get better converters to fit.

A 1" thick midplate allows the gm depth converter. Slightly different pump gear notch and turbo spline hub in converter.

I didnt know they had a spacer but that would give
more space for a better conv
EDIT
Is the bolt pattern on the diesel the same as the
518 SB unit.. all I ever looked for was the gas units

No. totally different. same as v10 though.

I thought the V-10 used the SB pattern.. or use to
(I'm thinking Viper)

Truck v10.
I can't say for sure what the viper v10 has for a bell. I've put clutches in a few, but never really compared the two.
I will say that the viper v10 is a deep skirt block and has a different starter mount, so I would say "no" as far as being the same as sb.

As Leon said, various companies make a spacer to go between block and trans, to allow more flexible core choices. I had this on my car, but it can cause firewall issues on some. We all know this can be an issue, as we see posts here about flexplate bolts hitting converters, rubbing, whatever. The space is just too small to use certain cores.

Again, I am NOT advocating that EVERY Mopar needs a GM style tranny, but when the HP levels get high, it just makes sense. Personally I hate having to run blankets and or shields. Blankets trap heat, are heavy, get oil soaked and hang low, plus are a general pain. Shields can cause floor pan issues and anything other than the full coverage CSI won't do any good anyway if you blow parts out. So for those reasons I want an SFI case in MY race car. And while not cheap by any means, a full tilt glide or 400 can be virtually bulletproof. We have had a 2 speed 400 in our radial car for 3 years, make over 2400hp and have not had the first issue with it. We have it looked at every winter, but has yet to need anything. Before that, we had a glide that was trouble free other than one broken 1.69 gear set in 5 years. New stuff is also always coming out. Right now you can get a 3 speed 400 with a 1.69 low, 1.30 second and other combinations as well. Our 2 speed has a 1.48 low, with first gear totally removed and weighs the same as a glide.

At the time, I had pretty much the best parts you could buy in a 727 and could not keep it from wringing out parts at a little over 1200hp probably. It wasn't a build problem, just a parts problem. There are likely better parts now, but based on experience, I would NEVER go that route from scratch, for a big power car.

The Pro-Flite deal is another animal. Those are mostly behind high winding smallblocks in light cars. They also generally use small converters, so the core choices are not as limited

Just adding that my car is somewhere in the 1050-1100 hp range and has a 727. Good steel planetary setup, billet steel drum, and a bolt in sprag. That's about it. It's held up so far.
8.90s at 150 mph at 3900 lbs.

If/when it breaks, I'll be pricing my options.

I was thinking about this when you see comp cars and heads up N/a cars running them.....

Carry on....