1000hp 727 full manual build
I've been talking with miszny on some parts to achieve some better longevity with his 727, and we'll get there at some point if some parts would show up.
I've learned quite bit over 25 years on what you can get away with and what you cannot in certain 727 combinations. 727 hard parts are fairly strong, but when you add forced induction, nitrous and transbrakes, etc. things can and typically will break.
Last year I was asked by a good customer to build him a new 727. He was going from a stroker 440 to a gen 2 stroker hemi that made about 950hp on the dyno. He wanted a footbrake 727 rated to 1000hp. We ended up building a transmission with billet steel drums, billet steel planetaries and both 300m shafts. We figure it's good to well over 1200hp. I tend to overbuild my transmissions as to not get that phone call, and I historically have a very low failure rate. This transmission with a converter was not cheap.
The goal is to only see these things back every so often for freshen up, and upgrades--if they were not done on the initial build for whatever reason, usually a budget thing. The goal is to not have to fix a heavily damaged transmission--that is the reason for building it right the first time. ($$$)
Well, here's another example and a new rule I had to put in place several decades ago. Got asked to build a small block 727 for a mild 360 with a procharger and a very small amount of boost. Street car mainly. No big deal I thought.. high pressure reverse manual valve body, good servos, clutches and bands and she's down the road Well, it ripped the input shaft out of the hub. Which then required a new rule--If I was to build a transmission for a forced induction application it got a 300m input shaft and billet hub. I've never seen a 727 input shaft actually break, just rip out of the oem hub. I've never seen an oem 727 output shaft break either and we've used them in blower combinations over 1000hp. However, any serious effort blower combination gets a 300m input and 300m output as to not have a failure.
Had a car this last summer have a strange failure. Super gas car, and the customer insisted on using a SB727. Ok, with gear ratios and 1st or 2nd gear launch we can make something work. 430" W9 small block making 750hp or so, heavier older build tube chassis Daytona. Transmission worked very well for several years and went 150mph on the throttle stop.
With about 200-300 runs on it, at the last mile high nationals, out of the burnout box the transmission goofed up. He pulled to the prestage beam, and the transmission was locked up completely. We didn't know what was wrong at the time, and as the transmission builder, I was hoping for a differential failure. It was not the case, unfortunately for me and we got it to my shop to tear down and have a peak. The transmission looked perfect inside, but the forward clutch was locked on. The piston was not popped out of the bore, the clutches weren't even burned. So I look closer and noticed the forward drum was cocked on the input hub. The billet drum had cocked and broke some of the small retaining teeth off at the end of the input hub splines. It was cocked enough to keep the forward clutches on and lock up the transmission. Running a tight fwd clutch clearance and the fwd drum riding up over those retaining teeth on the one side was all it took to lock the clutch on. Pics attached...
So, of course we came up with a new rule. 750hp and above N/A now gets a 300m input and billet steel input hub. Yep, it sucks ($$$), but I don't want THAT phone call again..
I've been talking with miszny on some parts to achieve some better longevity with his 727, and we'll get there at some point if some parts would show up.
I've learned quite bit over 25 years on what you can get away with and what you cannot in certain 727 combinations. 727 hard parts are fairly strong, but when you add forced induction, nitrous and transbrakes, etc. things can and typically will break.
Last year I was asked by a good customer to build him a new 727. He was going from a stroker 440 to a gen 2 stroker hemi that made about 950hp on the dyno. He wanted a footbrake 727 rated to 1000hp. We ended up building a transmission with billet steel drums, billet steel planetaries and both 300m shafts. We figure it's good to well over 1200hp. I tend to overbuild my transmissions as to not get that phone call, and I historically have a very low failure rate. This transmission with a converter was not cheap.
The goal is to only see these things back every so often for freshen up, and upgrades--if they were not done on the initial build for whatever reason, usually a budget thing. The goal is to not have to fix a heavily damaged transmission--that is the reason for building it right the first time. ($$$)
Well, here's another example and a new rule I had to put in place several decades ago. Got asked to build a small block 727 for a mild 360 with a procharger and a very small amount of boost. Street car mainly. No big deal I thought.. high pressure reverse manual valve body, good servos, clutches and bands and she's down the road Well, it ripped the input shaft out of the hub. Which then required a new rule--If I was to build a transmission for a forced induction application it got a 300m input shaft and billet hub. I've never seen a 727 input shaft actually break, just rip out of the oem hub. I've never seen an oem 727 output shaft break either and we've used them in blower combinations over 1000hp. However, any serious effort blower combination gets a 300m input and 300m output as to not have a failure.
Had a car this last summer have a strange failure. Super gas car, and the customer insisted on using a SB727. Ok, with gear ratios and 1st or 2nd gear launch we can make something work. 430" W9 small block making 750hp or so, heavier older build tube chassis Daytona. Transmission worked very well for several years and went 150mph on the throttle stop.
With about 200-300 runs on it, at the last mile high nationals, out of the burnout box the transmission goofed up. He pulled to the prestage beam, and the transmission was locked up completely. We didn't know what was wrong at the time, and as the transmission builder, I was hoping for a differential failure. It was not the case, unfortunately for me and we got it to my shop to tear down and have a peak. The transmission looked perfect inside, but the forward clutch was locked on. The piston was not popped out of the bore, the clutches weren't even burned. So I look closer and noticed the forward drum was cocked on the input hub. The billet drum had cocked and broke some of the small retaining teeth off at the end of the input hub splines. It was cocked enough to keep the forward clutches on and lock up the transmission. Running a tight fwd clutch clearance and the fwd drum riding up over those retaining teeth on the one side was all it took to lock the clutch on. Pics attached...
So, of course we came up with a new rule. 750hp and above N/A now gets a 300m input and billet steel input hub. Yep, it sucks ($$$), but I don't want THAT phone call again..
