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Posted: 5/17/2016 10:52:42 PM EDT
Short story: we took an AOD out of a Crown Vic (drove the car in the shop) Installed it behind a heavily modified SBF that dyno'd 475rwh in its last application; everything seemed fine with the bolt up, heavy duty cooler, lines, etc. the only modification we did to it was add a B&M shifter lever which required dropping the pan, filter and removing the shifting selector (pretty cut & dry)
So it's running along pretty nice, rolled into it with 11 pounds of boost and the next thing you know the drive shaft is in the road....we flat bed it back and the transmission has a spiral fracture running from the bell housing right through the tail shaft. at first we thought it was u-joint failure, now I believe the trans locked up inside and tore the drive shaft out when it came to a sudden stop. I thought the Ford AOD was a solid performer....Did I miss something? could I have fucked something installing that re-clocked shift lever? absolutely was not fluid failure from over heating, loss (until it exploded). 
Any ideas WTF happened? I've seen my fair share of destroyed components, but nothing like this one. 
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Posted: 5/18/2016 2:08:04 PM EDT
[#1]
Quoted:
Short story: we took an AOD out of a Crown Vic (drove the car in the shop) Installed it behind a heavily modified SBF that dyno'd 475rwh in its last application; everything seemed fine with the bolt up, heavy duty cooler, lines, etc. the only modification we did to it was add a B&M shifter lever which required dropping the pan, filter and removing the shifting selector (pretty cut & dry) So it's running along pretty nice, rolled into it with 11 pounds of boost and the next thing you know the drive shaft is in the road....we flat bed it back and the transmission has a spiral fracture running from the bell housing right through the tail shaft. at first we thought it was u-joint failure, now I believe the trans locked up inside and tore the drive shaft out when it came to a sudden stop. I thought the Ford AOD was a solid performer....Did I miss something? could I have fucked something installing that re-clocked shift lever? absolutely was not fluid failure from over heating, loss (until it exploded).
Any ideas WTF happened? I've seen my fair share of destroyed components, but nothing like this one. Over-torqued bell shaft bolt? |
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Posted: 5/18/2016 2:49:54 PM EDT
[#2]
Quote HistoryQuoted:
Over-torqued bell shaft bolt? Quote HistoryQuoted:
Quoted:
Short story: we took an AOD out of a Crown Vic (drove the car in the shop) Installed it behind a heavily modified SBF that dyno'd 475rwh in its last application; everything seemed fine with the bolt up, heavy duty cooler, lines, etc. the only modification we did to it was add a B&M shifter lever which required dropping the pan, filter and removing the shifting selector (pretty cut & dry) So it's running along pretty nice, rolled into it with 11 pounds of boost and the next thing you know the drive shaft is in the road....we flat bed it back and the transmission has a spiral fracture running from the bell housing right through the tail shaft. at first we thought it was u-joint failure, now I believe the trans locked up inside and tore the drive shaft out when it came to a sudden stop. I thought the Ford AOD was a solid performer....Did I miss something? could I have fucked something installing that re-clocked shift lever? absolutely was not fluid failure from over heating, loss (until it exploded).
Any ideas WTF happened? I've seen my fair share of destroyed components, but nothing like this one. Over-torqued bell shaft bolt? No, I don't think so....I will take pictures tonight....really, I'm perplexed. 
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Posted: 5/19/2016 10:02:59 AM EDT
[#3]
I hate to state the obvious.....but you installed a used-up transmission in back of an engine producing well over 500 hp at the crank.
Right? |
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Posted: 5/19/2016 2:50:10 PM EDT
[#4]
Quote HistoryQuoted:
I hate to state the obvious.....but you installed a used-up transmission in back of an engine producing well over 500 hp at the crank. Right? Yea, I know, and yes we did; plan was just to get everything "set up" then rebuild it....clutches, bands, seals, etc I can see, but damn this was like instantaneous FUBAR! I'll post pictures asap. |
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Posted: 5/19/2016 2:59:19 PM EDT
[#5]
Quote HistoryQuoted:
Yea, I know, and yes we did; plan was just to get everything "set up" then rebuild it....clutches, bands, seals, etc I can see, but damn this was like instantaneous FUBAR! I'll post pictures asap. Quote HistoryQuoted:
Quoted:
I hate to state the obvious.....but you installed a used-up transmission in back of an engine producing well over 500 hp at the crank. Right? Yea, I know, and yes we did; plan was just to get everything "set up" then rebuild it....clutches, bands, seals, etc I can see, but damn this was like instantaneous FUBAR! I'll post pictures asap. The AOD would die unexpectedly behind a stock 5.0, you expected too much from it... |
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Posted: 5/19/2016 3:20:08 PM EDT
[#6]
Quote HistoryQuoted:
Yea, I know, and yes we did; plan was just to get everything "set up" then rebuild it....clutches, bands, seals, etc I can see, but damn this was like instantaneous FUBAR! I'll post pictures asap. Quote HistoryQuoted:
Quoted:
I hate to state the obvious.....but you installed a used-up transmission in back of an engine producing well over 500 hp at the crank. Right? Yea, I know, and yes we did; plan was just to get everything "set up" then rebuild it....clutches, bands, seals, etc I can see, but damn this was like instantaneous FUBAR! I'll post pictures asap. I know the feeling! Probably had an issue to begin with. The extra torque from a fresh motor did it in. |
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Posted: 5/19/2016 4:40:46 PM EDT
[#7]
So you put a 500bhp engine in front of a stock AOD and are surprised it broke?
I hate to be a douche, but I think you put 500bhp through a stock transmission, and that broke it. AOD's aren't fantastic trans to begin with. |
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Posted: 5/19/2016 7:20:05 PM EDT
[#8]
Quote HistoryQuoted:
So you put a 500bhp engine in front of a stock AOD and are surprised it broke? I hate to be a douche, but I think you put 500bhp through a stock transmission, and that broke it. AOD's aren't fantastic trans to begin with. Actually I though they were supposed to be a pretty strong transmission....should have stuck with the C6
I will say the bell housing area is very thin, and that's where the fractures are most prevalent.
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Posted: 5/20/2016 1:13:49 AM EDT
[#9]
Quote HistoryQuoted:
Actually I though they were supposed to be a pretty strong transmission....should have stuck with the C6
I will say the bell housing area is very thin, and that's where the fractures are most prevalent. Quote HistoryQuoted:
Quoted:
So you put a 500bhp engine in front of a stock AOD and are surprised it broke? I hate to be a douche, but I think you put 500bhp through a stock transmission, and that broke it. AOD's aren't fantastic trans to begin with. Actually I though they were supposed to be a pretty strong transmission....should have stuck with the C6
I will say the bell housing area is very thin, and that's where the fractures are most prevalent. Use a proper strong transmission, like a 4L80e, out of a quality GM product 
But seriously, good luck with whatever you choose. Ford makes a lot of great trans lately that might work for your application. 500hp shouldn't be too terribly hard to build for. |
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Posted: 5/20/2016 8:57:56 AM EDT
[#10]
Quoted:
I thought the Ford AOD was a solid performer....Did I miss something? could I have fucked something installing that re-clocked shift lever? They ARE solid performers with minimal mods. An otherwise healthy one will not typically fail in the manner you describe regardless of the horsepower you put through them. What year transmission did you use? 1988 and earlier AODs had internal lube issues so we stick with 1989 and newer for performance builds. If you tear it down, my guess is that you will likely find that you installed a failing transmission to begin with and not a healthy one as will be evidenced by bushing/bearing failure. AODs can take well over 1000HP when built. I am pushing over 500HP at the crank through a stock 1991 Mustang AOD with the exception of a Lentech valve body and TCS converter. The Lentech valve body eliminates converter lockup in 3rd gear. The converter locking up in 3rd gear under alot of power can shear the factory lockup shaft. |
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Posted: 5/27/2016 1:37:03 PM EDT
[#11]
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Posted: 5/27/2016 2:06:46 PM EDT
[#12]
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Posted: 5/27/2016 2:16:35 PM EDT
[#13]
We don't know where the starter went: snapped both ears right off and dropped off into the road.
Sorry for issues with the pictures; I went off the road rounding the learning curve.
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Posted: 5/27/2016 7:29:41 PM EDT
[#14]
I am impressed.
Posted Via AR15.Com Mobile |
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Posted: 5/27/2016 7:36:38 PM EDT
[#15]
Quote HistoryQuoted:
I am impressed. Posted Via AR15.Com Mobile Me too. |
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Posted: 5/27/2016 8:41:39 PM EDT
[#16]
I'll bet that made an interesting noise.
Th400 time? |
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Posted: 5/28/2016 12:27:07 PM EDT
[#17]
Um....yea. I don't even know what to say. That is impressive. I think you are right that something locked the trans up and just twisted it apart before the driveshaft decided to hitchhike.
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Posted: 5/28/2016 3:57:52 PM EDT
[#18]
Are you using a solid trans mount or is it dampening?
Have you checked your motor mounts to see if one broke? I am sure that it just locked up but just some other options to look for. |
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Posted: 5/28/2016 4:14:29 PM EDT
[#19]
Quote HistoryQuoted:
Are you using a solid trans mount or is it dampening? factory transmission mount to the original crossmember Have you checked your motor mounts to see if one broke? I looked them over; neither appeared damaged; couldn't do the "torque test" for obvious reasons I am sure that it just locked up but just some other options to look for. As I can clean the bench off a few projects, I'm going to open it up; maybe see what went wrong where.
It's hard to see with all the grime, but those were new straps from NAPA holding the u-joint into the rear yoke....twisted it right out! I used to be really into mud-bogging, sand drags, outlaw truck pulling back in the 80's; broke a LOT of stuff, saw a lot being broken, never one like this. 
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Posted: 5/28/2016 5:06:39 PM EDT
[#20]
Now is a good time to freshen up another AOD and make it a wide ratio with a 4R70W Gear Set. Time for a valve body that eliminates lockup in 3rd also.
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Posted: 5/28/2016 7:10:35 PM EDT
[#21]
After reading about the power output, I'm not surprised. It looks like it just torqued sideways when you stomped it.
Oh well. Build another. |
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Posted: 5/28/2016 7:27:27 PM EDT
[#22]
Quote HistoryQuoted:
Now is a good time to freshen up another AOD and make it a wide ratio with a 4R70W Gear Set. Time for a valve body that eliminates lockup in 3rd also. Thanks! I suppose this post is as much about wtf happened as what/how to build the next one: We've another AOD pulled out of a F150 as a "core" it's an operating unit, but so was the one that kb'd
The Speed vendors (Jegs, Summit, et.al) advertise a lot of high-speed, low-drag replacement parts, but it's might as well be comic book fantasy as I really don't know AOD's and what they need to survive. Monster looked pretty good until you start tacking on all the "options" then it quickly becomes as much as the Trans itself.  There's a strong chance I'll be back down in FL within the next month, Brooksville (where Monster is locacted) isn't very far away.
If you were building one, how would you go about it? |
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Posted: 5/29/2016 8:10:15 AM EDT
[#23]
Buy a complete ready to go Monster trans.
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Posted: 5/29/2016 5:51:15 PM EDT
[#24]
Quote HistoryQuoted:
Buy a complete ready to go Monster trans. Said no one ever. Buy one from a shop that doesn't have absolute shitty reviews. |
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Posted: 5/29/2016 7:26:07 PM EDT
[#25]
Local builder that (machine shop/engine builder, catering to the race track crowd) will go through it for $600. Having sold a lot of "kits" from NAPA back in the day, I know stock parts generally aren't that expensive, question becomes what really needs to be done to keep it from failing.
I'm not sure what stall speed converter to go with.... Trans Brake: yes, no, maybe? Valve body modifications? (preventing 3rd gear converter lockup) Factory Lock-up Shaft? I've been told something to the effect the later AOD's had four pinion planetary gear sets; I think the replacement trans out of the F150 has the updated gearing. I can put 'em in, take 'em out, adjust the linkage, or anything else service wise, but once inside I might as well be playing with Nuclear reactors, 'cuz I don't know shit.
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Posted: 5/29/2016 8:13:21 PM EDT
[#26]
Updated servos and a shift improvement kit from transgo and it should be fine.
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