Well not exactly Corvette related, but same transmission to say the least...

So I just wanted to enjoy my 92 T/A with the high revving 306 (350 block destroked to 306 by 3.000" crank) for a bit. I have just finished putting together and got the carb calibrated perfectly for the next trip to the strip. It is obvious that this motor has to really spin way up high to get the most out of it, which is also why its so fun. With the manual valve body, I've shifted as high as 8400 rpms to get the best ETs at the drag strip. It was was seemingly bulletproof with perfect shift performance, well, until now.

Here's what happened:
So I downshifted to 2nd and opened it on a straight empty road and suddenly BAAM, revs shoot way up and bounce off the rev limiter; the 2-3 shift at 7800 seemed to have hurt something bad enough for the trans to be in 3rd gear for a split second and suddenly no gear. So I coasted to the side of the road panicking and shaken, revving it up to see if she'll be able to grab anything. Nope. Shut it off, restarted it, the motor is fine and all, but the transmission sounds toast. It has no park, no reverse, no gears, just neutral, no matter what position the shifter is in. And I am also hearing a whining sound from it. As I rev the motor up, the sound gets higher, kind of like a supercharger. Checked the transmission fluid, and to my dismay, it is still bright red and smells fresh, not burnt. Not really sure if the high revs had anything to do with the transmission failure, but I'm open to hear if high rpms could have hurt this fresh 700R4 "supposedly built with full options" for some serious hp. Any useful input is appreciated.

FYI: The kit I used to build up the trans can be seen here: http://700r4l60e.com/store/product.p...9&bestseller=Y

It is supposedly top of the line and was recommended by a fellow shop owner who uses this same kit on his big block powered S10 with NO problems.

 

So why post it here?8400 doesn't exist in corvette territory unless it's a weirdo.Go impress the NASCAR guys.

 

WOW man chill! I really wasn't expecting that kind of response, but if you would like me to rephrase the question, I will.

Now for the simple minded: The question is that can high rpms necessarily hurt a built 700R4?

 

I'm totally chilled and not simple minded and as you say yourself "not corvette related" So why post it on a corvette forum?
If you want to keep the rpm your engine makes under your hat why not just mail PeteK directly and get an answer from an expert? That saves idiots like me responding to your post.

 

that 8400 rpms is extremely high but that doesnt mean that we cant help him just because he's doing something out of the ordinary. While i'm no trans expert it would be my guess that whoever rebuilt the trans didnt replace everything and left something in there that was a weak link and couldnt handle it. Thats just my guess.

I'm sure Pete K will have a definitive answer for you.

 

im sure peteK will jump in here, but at first sound, i will almost bet you have lost as a minimum your input reaction shell, either sheared the teeth off or broken at the input shaft hub, that would explain the no rev. 2nd and OD. You may also have broken the vanes in the pump, a quick pressure test will reveal that.

Hopefully PeteK will jump in here and add to this

 

I think he was hoping among the ranks of waxers he would find someone who could give him advice.

hooblyboobly: I know you've been hanging out at Thirdgen.org now, PeteK is also a moderator there. His handle is "Floorguy". If you post in his transmission section I'm sure he will help you out.

What kinda cam are you running in that? Most of the guys I know with 8k motors run powerglides, in light cars like early vega's, or nova's. Not that your combo won't work.

-- Joe

 

HAHAHAHAHAHAHA

i had a turbo 350 that did something similar when it finally crapped out it made a whining noise.. i was doing a burnout with slicks and it just hooked as i proceeded forward, still in the throttle, and it hurt the tranny really bad and within 2 miles no longer worked..lol. but you might have broke the output shaft since you have no park on top of the other internal damage.

 

Yeah, I go to TGO every now and then and see threads like this. Looks like some of the crowd there is a bit more mature than some of the crowd here, but they still do have their bad apples when it comes to dealing with newbs. That is one of the reasons why I'm not signed up there yet. But I'll be sure to check into it sometime.

As far as the 306 build, it is really a fully custom setup that a customer suddenly abandoned. For more than 6 months, he has made no contact and probably never will, so maybe he got locked up or died or whatever. Well we basically put it together for him and he never paid us for our time. Because he broke the contract he signed, now its legally ours. I know the crank is 3" and the rods are something way up there like 6.25" something like that. The heads are some really high dollar AFRs I'd say like 195 cc as well as "CNC ported" as he claimed. Last time we were talking about the cam it was a 242/248 cam so maybe its either an off shelf or custom grouned. The intake we used is a Weiand single plane and the carb is a 650 Holley DP all taken from a swap meet.

 

RPM will eventually kill an auto, not saying one couldnt be built to hold up. If it were me Id put a stick in it .

Try more of a gearhead site where motors like this are more commonplace, probably wont get the answers you want here.
Fwiw if that cam is a hydraulic and its being spun up that high its only a matter of time before somethign lets loose.

 

A hydraulic cam would be the last thing I would even think about putting in a motor that spins as high as this. This is a solid roller motor with some high dollar parts on it. Me and pops have quite some time and effort invested in this motor since we absolutely know how high destroked motors have to rev. Leaving the T5 in it would have had more problems. On my sister's stock 5.0L Mustang, that thing completely sheered 3rd gear off as soon as she hit it on the highway! I was under the impression that you could build automatics stronger than you can build a manual so that was one of the reasons why I bought into this.

 

I have never seen a combo that put 8500 rpm through a 700r4. They tend to centrifically apply the clutchpacks when pushed above 6500. Transgo has higher tension springs that help prevent that, and should be considered on a future build. If you still have a stock size, and weight converter, it can be deadly to a super high rpm package.
Speculating what you broke is not nescessary. Sounds like you broke it bad, for lack of a more technical reply. Take it apart and inspect the carnage. You likely destroyed the rear planetary assembly, reaction shaft, and reaction shell at a minimum. The internals of the pump may have shattered as well.
If you did suffer hardpart failure, the converter is junk too.

 

How much power is that thing making?

-- Joe

 

The converter was a Yank 10" 3600-4000 rpm stall w/ lock up that I bought new from a dealer who deals a lot at the local swap meet meet here. My dad thinks just gonna end up as a 250 lb paperweight. I'm trying to hope for the best, but now I'm just pessimistic. I'm gonna take it apart tomorrow to see what gave. If all the clutch packs suddenly got applied at once, then damn, this is gonna be quite a waste of a transmission. I guess that's where the saying, "Gotta pay to play" comes from. Sad, but true. I could core for a few bucks at the salvage yard this if 700r4l6e.com doesn't want to cooperate.

 

Since I trapped a best of 97 mph with a higher ET than normal in the 1/8th, I would think that is around 119-120 mph in the quarter so I'd say I was putting about 400 rwhp on 93 octane pump gas with this combo. I remember weighing the car in on my off day and the weight was 3200 lbs with me in it. I tell ya, this is a hell of a screamer. Starts pulling from 3500 all the way to 8500 so there definitely is a nice powerband to work with. I might need to go to a higher ratio as I have 3.73s on the rear so far.

 

My formula used to trap 119-120mph with the T5. shifting at 6k though, not 8500. 4.11's and 28" tires might work out nicely for you, but the bigger the ratio gear the more problems people have with the 10 bolts. Not sure what trans is going to be happy with 8500rpm shifts. Most of the guys that shift up there are running powerglides or th400s.

-- Joe

 

Yeah.. most likely need to move to another forum..

But You basically have a old school 302, high winding SBC.. great for the old days of TransAM Racing. But a bit short on TQ for the streets.. needing really low gears (4.88 - 5.13's) for the 1/4 mile with those shift at "8" and don't be LATE RPM Range blast!.

IMO... Your 700r4 just was not design well enough to handle those High RPM runs. I would rethink your Transmission or get a really build 700R4 with some high ends internals ($$$).. Most Transmission now a days only design and market transmission for the lower RPM under 6800 or so.... You would really need to work with someone to pick out some internal parts to handle the 8k+ runs..

Good luck. I used to love those 302's.. and shifting at 8k+...

 

I would not expect dana to "cooperate". He only sold the parts to you, if I understand the post correctly. Not at all fair to hold him accountable under those circumstances. He simply assisted in selecting them, boxed them and mailed them. He has no control over the quality control of the parts.
The converter could be cut open, repaired/cleaned, and returned to you, but will likely cost $300 with shipping to do so.
Based on your description, I suspect that you will find the rear planetary assembly destroyed. I agree with dad, it is likely a total loss.
Wait until you pull it apart, and post up pics if you can.

 

I might just have to convert over to a TH400 if the 700 isn't gonna cut it for hard street/strip use. I really love the shorter first gear though on the 700. The TH400 has quite a longer 1st gear than the 700 does. 2.48 vs 3.06. So that means it would be harder on the torque converter. I wouldn't know about how to get lock up on it since TH400s never had lock up from the factory.

I finish the 1/8th mile in 2nd gear with 3.73s at about 7800. 1st gear lasts to like 60 mph and 2nd gear would last to 110 if I let run past 8500.

 

The 400's have a reputation for coming apart hard when shifted from 1st to second gear at high rpm. There is a drum that must stop, and spin the oposite way. If 400 is your solution, build it accordingly.
4th gear, and lock up are not possible on an older trans.