About 2/3 down the track the car bucked really bad and then wham !!!
As you can see the trans case broke and then I lost rods # 7 & #8.
Besides being an expensive deal I'm really concerned that I can't figure out what really happened. the car gave me an indication something was wrong in that it ran 7 MPH slow on the previous pass but my compition also ran slow so I thought it might be weather etc.. The car didn't sound funny or vibrate or anything else. It left fine and handled normal until 2/3 down the track.
Any and all advice or input as to what may have happened will be appreciated. I'll put it all back together for spring but I'd sure like to prevent it from ever happening again. Amid plate is very difficult to install in a stock bodied car w/ a stock fire wall but that is something I'll research further.

The rear trans mount is a poly mount and doesn't show anything wrong. I run Moroso solid engine mounts which were and are tight. I was trying out my Alf Weibe suspension so I was leaving very soft off the brake 2500 RPM.

Take a look and comment please.Thanks
Tom

Does the converter/pump still spin, or is the transmission locked up? I'm curious if the trans was the cause, or if the motor was the cause

Perhaps the motor siezed up after the rod(s) dropped (failure around the wrist pin)? If so, then maybe the large drop in RPM (~6kRPM to zero) was too much shock for the transmission and the bell housing couldn't handle the shock?

my guess is one rod or both rods went the motor jerked hard that cracked the trans. case. looking at your trans. case is why i took my brand new trans. back to my tranny guy and had one of those ultra-bells put on. i just got it back and i am tellin you this thing looks strong. it's strong enough to be s.f.i. approved and if you have this you do not need a flywheel shield. if your trans. is still good all you have to do is cut the rest of the bellhousing off and bolt the new ultra-bell right to the front pump. very easy to do.....sorry for your loss....steve

I had this happen to a friend of mines low 10 sec 69 Comaro with a glide and 400 small block. On the top end of the track the tranny locked up cracked the bell housing, binded the flex plate against the black of the block. Broke the 7 and 8 rods and end of a good 10 sec motor.
After the incident. We looked over the car at the track and realized that the tranny mount bolt came loose or off in his case. This caused the tailshaft to whip against the solid motor mounts on the engine. Cracked bell housing and you know the rest of the story.....

That sucks.

That sucks.

That sucks BIG time! Sorry for the loss :(

Sounds as tho the DA CHEVYMAN has your answer.That sucks BIG TIME.

Mike , The pump still turns however the converter is stuck to it and I couldn't pry it loose from the pump. Didn't try to long last night, just unbolted it from the flex plate. The snot which goes into the crank is also gouged up.
All the mount bolts were still in place and tight and the rear mount was still tight and not even distorted.
There was no evidence of the flex plate hitting the case or the block. no scratches etc.. and the flex plate looks fine.
yes that is what I'm trying to figure out , if the tranny broke causing the motor to throw #7 & #8 rods or the motor blew causing the tranny to break.

Do they make the ultra bell for a t-400??

Is the crank busted?

They do make the Ultra Bell for a TH 400. And that does suck big time! I would be surprised if the crank isn't broken. Seems like if the crank broke close enough to the rear main that the resulting shock/vibration could also damage the trans. Just guessing.

no the crank isn't broke. I haven't removed the rear main yet. i plan on spinning the crank to see if it is bent.

ya i've got a th-400 with a brake and an ultra-bell on it. i got it from jegs part # is 564-92451 it's $219.99 it's S.F.I. approved and the add says it's 600 times stronger than OE bellhousing!! it's about 3/4'' thick solid one piece aluminum. fits under your stock floor. i would recomend this for anyone with a trans. brake or just alot of hp.

I'm always skeptical when someone says they know exactly the chain of events to a certain failure like what Da chevyman posted. maybe that IS what happened, but how did you determine that was the exxact chain of events?

Tear the engine apart and look closely at everything you take off, noting anything that doesn't look quite right.

I would also guess the motor took a dump, locked up, and then caused the other carnage but it is hard to say.
Converter hub may be broken causing it to be hung in the pump.

the car gave me an indication something was wrong in that it ran 7 MPH slow on the previous pass but my compition also ran slow so I thought it might be weather etc.. Tom


Sorry for that carnage:(
7mph is a lot to lose for weather conditions. Perhaps you were losing a few valve springs on the prior run. ???
Teardown and look for clues. Again,....sorry:(

I've looked @ the heads from the exterior and see no evidence of a problem w/ the srpings push rods etc.. We will be testing the springs when we rebuild.

One more thought, I have... Did you make any changes in the pinion angle on the rear end. Speaking of this because of the drive shaft may of not had enough travel clearance and smacked against the tailshaft housing on the tranny and could of caused the bellhousing to crack, also.
Welded two bellhousings and replaced two th350s after learning this lession a few years back (smile) younger days....

I would hazard a guess that a rod bearing went out first. The heat generated from that bearing caused the adjoining one to also stick and burn out. The tightening of the bearings is where you lost the et. The heat and excessive clearance most likely caused the rod bolts to break knocking the holes in the pan. The shock from everything else cracked the bellhousing. My theory anyway. Let us know what you find.

I would hazard a guess that a rod bearing went out first. The heat generated from that bearing caused the adjoining one to also stick and burn out. The tightening of the bearings is where you lost the et. The heat and excessive clearance most likely caused the rod bolts to break knocking the holes in the pan. The shock from everything else cracked the bellhousing. My theory anyway. Let us know what you find.

Hmm, I had a buddy spin a rod bnearing and it lost some MPH before it died.

i had a perfectly good driveshaft, get out of balance and tore my trans apart just like that... i think from pulling the ds out of the car lots, someone may have let stood it up one day and it fell...

you never know... doesnt really explain the rods damage... just another thing to verify...

ak

That sucks when it happens. It's hard to say what broke first. The trans could have broke and jammed in the case causing it to try to rip the case out of the car. Then the free moving case could have put a hard load on the crank. Or the motor might have spun a bearing or 2 and locked up. The resulting hit to the trans could have then broken the trans after the rear locked up. Then something bound up internally and broke the case.

inspected the engine yesterday. Haven't gotton to really looking @ the trans as closly yet.Have decised to go to an Ultra bell this time around.
Crank is broke @ the 7/8 journal. Rest of barings look really good. rear main looked like it saw some stress but not bad. The pistons hit the head and bent the valves but it doesn't look too bad. Will need to clean up the surfaces etc. It's amazing what happens when one blows. The piston transfered the size stamping to the underside of the head when it hit.
The lower end of the cylinders are scared up pretty bad.
Interesting is that two of my comp rockers were starting to crack right where they neck down. they have about 250 passes on them. glad we caught that !!
So it is decision time;
#1. Sleeve the two bad holes and bore the block to 80 thousandths. This would salvagae the rest of the block which has had 4 bolt caps installed , block filled, align bored, decked etc.. In other words, alot of machine $$ .
#2. Purchase a used block and remachine it and start from there.
#3. purchase a Dart block and start from there.
#4. Purchase a Reher Morrison or comperable short block and use my heads etc.

I don't really want a bigger or more powerful engine. I'm about @ my frustration point in getting the car to hook consistantly w/ the power I have. A high 9 sec. Chevelle suites me fine so building a 540 or something doesn't interest me.
Anyway thanks to all who have taken the time to respond. Any opinions on which way to proceed will be appreciated.

I have seen a number of bellhousings crack on Thxxx trans (5 or 6). of course its hard to tell, but with the number of them ive seen, I would guess the trans went first & then took the motor out.

for quite some time, Ive heard the same rumor about solid rear Trans mounts causing it to break, but I ran one for a long time & never had a problem. Mind you it was a 11.5 car that did not hook very hard.

Bob

Edit - just saw your last post. but I"m too lazy to edit this post. :D

If the pump spins, it wasn't the transmissions fault. Of course there will be some exterior scoring/gouging. After all, the bell housing let go and the converter to pump connection was the only thing holding that transmission up.

I'm liking the bearing failure idea. At least it is easy to prove once you get the oil pan off. Just take out the rear cap and all part associated with what's left of #8.

Did the lock up happen on the 2nd to 3rd gear shift? I haven't a clue what the suspension is going on a sub 9 second car with an Alf suspension, but the driveshaft yoke travel had me thinking outside of the box a little. I always thought the 4-link suspension caused the transmission yoke to come OUT while the 3rd member travels upward - thus rotating the pinion further from the transmission. :confused:

Either way - we all want to see more pictures!

TWC,were the cracked comp rockers roller tip magnums of full rollers?

I ask this because i run comp magnum roller tip rockers & matching pushrods and am wondering if i need to pull the v/covers to check them.

scott

WHat crank were you running? What RPM do you usually spin it too?

BB Mike, I'd like to but the photo's are too large to download and i don't know how to reconfigure them.
My rockers are comp pro magnuim rockers. They are cracked right wh
ere they neck down between the body and the tip arm.
the Crank was a scat 4340 and the rods were also scat h beams. my shift light goes on @ 6800 but the playback on the tack always says 7300 as max. rpm. It goes thru the traps @ about 67 to 6900.

My thoughts: The torque convertor/trans. was going.
You lost mph on the run prior but everywhere else the engine was doing fine. You didn't notice a seizing up anywhere.

Harmonics from the convertor can split the crank just like a fluidxxxx on the front does to a forged crank.

I think if the bearings were going that quick it would have showed bigger signs on the next to last run. A bearing don't start to seize and then run fine again. It wouldn't have made the last burnout much less the last run. (Without tell-tell signs)

TWC, I'd be happy to resize and host the pictures for you so you can put them in here. Just email me 3 or 4.

It sounds like you aren't too "beat up" about the carnage - and that's a good thing. After my motor hydrolocked, I just left it sitting for a while before I tore it down... then I left it sitting even longer when I realized I didn't have time enough to find a 454 block and build a good running 468+cid. :(

TWC, sorry to ehar, but glad you'll be back to fight another day.

Mike, would you plase get a turbo rat done and finally run some 10's you engineer you!

Frickin rocket scientist and he doesnt have a 900 hp turbo digitally controlld rat yet. I mean, what's wrong with this country!?

Mike, would you plase get a turbo rat done and finally run some 10's you engineer you!

Frickin rocket scientist and he doesnt have a 900 hp turbo digitally controlld rat yet. I mean, what's wrong with this country!?

What's wrong is that I just dropped a large amount of cash on a sweet convertible. I"m going to get better at the "looking good" part before I start thinking about the goind fast part. :cool:

Were the cracked rockers on 7 and 8? Wouldn't that mean the rockers were cracked because the piston smashed the valve up into them?

Jim

no they were on # 6 exhaust and # 3 intake i believe. # 7&8 were fine.

Your pictures are up. To save some time/trouble, here they are:

TWC's engine pictures:
http://chevelle-ss.com/temp/

Each picture is the original 1MB. I dind't want to downsize and lose important details.

Thanks Mike.
Now if someone wants to see my nightmere ( sp) they can!!!!

Ouch, those hurt to look at...

Daniel

Never like to see chevy carnage. Did the car wheel stand alot? If so.. broken trans is common in wheelstanders. When the car lands the trans takes all the front end flex. Is the car caged?