Ok so I was driving on a windy country road following a friend, and we were doing like 85-90 the entire way, so of course for our cars I was driving it like I stole it to keep up and we came to a stop sign and we stopped and I proceded to turn right and saw that my friend was taking off so I stepped on it and right when the transmission was about to shift from 1st to 2nd at around 4500rpm and 30mph, it make a very loud thud noise and you could feel it in the seat and through out the car. I immediately let off and it shifted into 2nd perfectly fine and didn't do anything abnormal for the rest of the night, or this morning, even when I stepped on it.

I've noticed before that when I shift into 2nd, its the only gear in the car that will make a thud noise when shifting, and I've heard the 700-R4 in my work places 1991ish Astro but its never done what mine did....

So of course this scared the **** out of me.....

So my question is....what the hell could have happened? Is that the transmission slipping or what?

Its never done that before, its an original 700-R4 with just under 70,000 miles on it....

I noticed later when i drove past the spot it happened that there was an ice slick in around the exact same area, so could that ice spot have had something to do with the transmission jumping the gun?

 

Your transmission mount broke... It's happened to me twice now. But, the good news is that about half an hour and $20 fixes it. However, it's still weak. You can shell out plenty of money for a polygraphite replacement and not worry about it again, also.

To check, all you do is lift the front of the car and use a jack ot pry bar to try to lift the tail of the trans. If the mount separates, well, that speaks for itself...

:edit: Or there was the possibility you lost traction on the ice and then your tire suddenly hit dry pavement, relaunching the car.

 

I have no idea but it scared the **** OUTTA ME, either way its going to Hulsizer Chevrolet here in town to get looked at

I don't want my baby to get hurt....

 

Thank you so much that makes me feel so much better now that I at least have something else to think about why it happened other than my transmission was just plain old F-ED

 

Granted, things like that are hard on the trans (wheel spinning nicely to getting grip is hard on the entire driveline minus the engine due to the torque converter), and it's scary, but I seriously doubt anything too bad happened.

 

Yeah its been completely fine but now that I look up my symptoms and such that it leads me to a bad mount.

"Cracked or broken mounts can be an annoying source of vibration and noise, typically a clunk or shudder when accelerating hard."

Ok so never really cared much that the car would make a little thud going into second and well I've heard other 700-R4's doing the same thing and nothing bad ever happened, so I let that go.

And well when the torque converter locks up at like 40mph(1750rpm) which is about the lowest it will lock up....it will make the car vibrate and make sounds that will go away once I get to about 45mph(2000rpm), but noises are a symptom of worn/broken mounts.

And now yesterday it finally just snapped I guess, oh well. I also don't think that it could have done much damage to the transmission or the car because well it hasn't done anything else like what it did when it "snapped" since then, and well I just had to test it to find out earlier today

Other than that, its been completely fine minus a little more noise and vibration, so yeah I'm going to advance auto tomorrow to get a new mount put in on Monday at Hulsizer Chevrolet.

Thanks a lot Maverick H1L!

 

My last one went while I was heading to work while I was going to school. It's even worse with a T5... The whole shifter jumps with the transmission and you kind of have to try to hold the tail down to minimize the problem (as well as shift and other things, lol).

Anyways, what I plan on doing the next time it goes is to drill a hole down the middle of the mount, put in a nice long and strong bolt, and put it back in... Serves the same purpose that way, to minimize the vibrations sent through the body, and it should hold a little better (until I can afford the polygraphite one).

 

Because of the way the rear suspension is setup with the torque arm from the rear end to the transmission, there's a ton of stress placed on the transmission mount. They break all the time. For the $10 a stock replacement rubber mount costs, you can spend $25 and get a polyurethane replacement that will last forever.

http://www.summitracing.com/parts/ENS-3-1108G/

 

Yeah it was just crazy, and it held up soooo nice when we were racing through the country, I can only imagine what it will be like when I get the 3.73 posi I want......sigh...


Thanks Drew, and I really would, but I don't have a job right now, so $10 is the way that its gonna have to be to get the job done for now.....

I should be happy with the old mount though, its 20 years old haha



I'm just worried though, how long do I have before this will start to be a much bigger problem for my transmission, if anything other than wearing of parts and vibrations and noises?

 

If you don't fix the mount, at the very least you're going to get a bunch of dents in your transmission tunnel from the transmission slamming into it. Eventually it'll probably also break or damage the torque arm mount, and potentially you could break the tail shaft I guess, but I drove my 83 with a broken mount for a couple weeks without any serious damage. It's so easy to change, there's really no reason not to fix it. Donate (sell) some plasma and get er done.

 

Ok I just bought a new mount, how do I put the thing on? lol I'm gonna have to dig out my jacks...

 

Get the front end in the air with jackstands under the front a-arms, get another stand or the jack under the tail of the trans, remove the crossmember bolts and the lower nut with a 15mm socket (this is about the easiest repair on our powertrains because it only requires one socket), remove the crossmember, remove 2 15mm bolts holding mount on, and reinstall everything with the new mount.

 

Since it's such a common problem, someone wrote a tech article on the subject back in the late 90's.

https://www.thirdgen.org/trannymount

The rest of the articles can be seen here... https://www.thirdgen.org/technical-articles

 

Thanks guys, big help.

 

Ok, so I went and talked with my shade tree mechanic tonight since the dealer can't see the car until Friday, and he said that it could be one of three things if the transmission is still functioning near perfectly:

1) Universal Joint
2) Transmission Mount
3) Jumped a band

What do you guys have to say about those possibilities?

And I haven't been under the car to try to get the transmission to move so I don't know for sure if its actually the mount or not.....

 

IF you hit that ice patch you mentioned, I'll bet it's a combination of both lost/regained traction and your transmission mount. When the rear suddenly stopped spinning, as I mentioned before, the whole rear end jerked the torque arm up at the front, taking the tail of the trans with it and ripping the mount. It's not the first time this has happened, won't be the last...

 

I'm just wondering if I really did hit that ice patch or not, I didn't really notice that I lost traction for a second but I drive with people that always ask me "Did you feel that?" And I mostly say no and they tell me I started to drift a turn or something, so maybe I did, but what if I didn't? Could a band have slipped?

I've noticed that since this has happened the transmission has been shifting a bit harder nothing drastic really but enough for me to notice and my RPM's have been higher when the car is in O/D and the torque converter is locked up, plus its been shaking a bit more.

The whole shaking bit makes me think broken mount, but would the transmission start to shift differently so soon from a broken mount?

Are there more than one mounts?

I'm just worried about this....I definately don't have the money for a new transmission, unless I can find one for a few hundred bucks or get this one rebuilt by my shade tree mechanic for a few hundred bucks......He told me he rebuilt his 700-R4 which is now handling a 454 with nitrous and a newly added turbo charger(700+HP), so I know he knows what hes doing, all for 300 bucks, but I know hes gonna want more that just the price for new parts for it.

 

The only other transmission mount are the engine mounts. It could be a slipping band or something else. I know that the reason I finally yanked mine was that I couldn't keep the TCC locked... Running down the highway at 3K RPM kind of kills any advantage the 3.1 has over, say, a 454, in gas mileage. The hotter the engine got, the harder it was to keep the TCC locked (more gas pedal required).

Check your trans fluid... If it's brown, well, it's time to save some money up. If it feels grainy as you rub it between your fingers, well, um, that calls for , because that grainy stuff is supposed to be on the clutch plates (the friction material).

However, definitely check that mount. If you have a replacement, it can't hurt to change it as you don't know how old the other one is and how close it is to failure.

 

I checked it right after it happened. It was fine, it smelled like it was burning, and it was like a darker pink(like a redish color) but not brown or black, and it wasn't gritty. I got the tranny fluid replaced about 2 months or so ago and the guys at the dealer said it was perfectly clean of debris, no chunks or anything in the pan and it was acceptable for what it was. The only thing they saw as a problem was that the filter got knocked out but that was it, and I know that filter should be fine now, or at least I hope.

That fluids always smelled like it was buring though.....

 

I need to go adjust my TV cable, I've been reading up on transmissions all night long, and well I have my TV cable adjusted about 3 ticks out so give a nicer shift(at least I think) and well the mechanic that helped me do it the first time said it would be fine, but now I'm just afraid to run it with the cable set up to simulate my old stretched cable, which I liked a lot more than this new one The old ones plastic connector snapped a while ago while I was driving it......Had it rigged for a few days until the dealer could get me a new one....

 

So yeah I just got done looking at the mount.....it was done lol









Its all good now

Its a lot smoother now and no vibrations, it still engages a bit hard but oh well, but it seems louder, which makes the car sound meaner from the inside if you dont mind the noise, which I don't haha

 

You might consider strapping it down with a couple of big hose clamps from Home depot or Lowes, just wrap them around the mount. It will keep it from breaking in the future. I broke several before I did it.

 

The next time it happens I'm going to get more than a rubber/plastic whatever it was part.

It was actually better doing it with some help than just dropping it off at the dealer, I saved money and learned how to do it. It was actually fun lol too.

The guy that helped me took a look at my tranny too and noticed that the rear main seal was leaking a bit so thats next on the list. Its not bad he said but its starting to leak a bit.

 

Definitely readjust the TV cable... If it's messed up, the rest of the trans will follow sooner or later, as the trans uses the throttle valve and the governor to time the shift points (without having electronic controls). Do change your fluid soon, if you haven't already. If it smells burnt, that means you're wearing it out, and the internals don't like not being lubricated .

 

Just to add...
The TV Cable controls the Throttle Valve, which controls line pressure.
If your line pressure is too low, you'll fry your Clutch Pack in as little as 20 Miles.
If I'm remembering right, but don't quote me, late part-throttle shifts are OK as your line pressure is hi, but early ones are low pressure.

 

(Didn't want to get quite that complicated) But that's true.

 

FireInMe17
I'm not positive of the line pressure thing as it's been over a year since I dealt with it but I mentioned it as it will help you at least get your TV Cable into a safe adjustment area.

PLEASE check with a builder about line pressure and light throttle shifting before my mistaken memory fries your 700

Greg

 

Hold on, I have my textbook and GM auto trans repair book right here... I'll look the pressure issue up in a minute.

To adjust the TV cable, push in on the metal clip at the place where the cable housing mounts to the throttle bracket, and push the cable housing (where the actual metal braided cable comes out) back into the clip until it stops. Get in the car and push the gas pedal to the floor, hard. As the throttle lever moves, the TV cable housing will ratchet with it and stay where it needs to. This should be done with the engine not running and the keys nowhere near the ignition lock, BTW.

 

I reset it, and its back to where it should be, but the old TV cable, the original one was worn out and stretched to about where I had the new one adjusted to, and it ran fine and I had it tested by a Goodwrench mechanic and he said it seemed like it was perfectly fine.

When I had the 49.95 transmission special (New filter, remove pan, drain fluid, inspect internals/wires/govenors and cleaning plus refill) they said that nothing was on the fluid and it wasnt bad at all and they didnt see any thing to give them a red flag.

The only thing that they said was wrong was that the filter was laying in the pan and wasnt where it should be but it was fine, no scraps of metal or shavings or anything, just fluid.

So I dont really think that its really doing any damage to the transmission, plus I was driving it this way for almost a year.

But I'll go out and check the cable again and make sure that I had it properly adjusted, and look into getting new fluid for it soon. Just to be safe after all this stuff this week....

 

Well mine runs down the highway at 70mph with ~3000 rpm?.....

 

If you're unsure of what results you will obtain after you adjust the cable, as I was when I messed with mine, leave it alone until you know how it should respond.

As I said earlier, I forget which way to go with the cable.

If you don't mind my story...

I put a 700r4 in an old truck with a carb and I had to go through all the teething pains of adjusting it just right. I bought a conversion kit from Bowtie Overdrives and after using it for awhile, I decided to omit their carb base kit with the gaskets and TV Cable Mount location and just use a bracket for these trucks I found was very close.

When I did that new mount location for the TV Cable mount, I had to go through a very simple process of initial adjustment and then I pulled the detent out a bit more ( fine tuned the clicks over a few days ) to get exactly what I use now, 1 Year later and no failure.

I wish I could remember the rule for you but as I said earlier, line pressure is critical, to a point anyway.

If GM adjusted it, and pressure tested it, leave it for now until you know how to do it yourself. Really.
It's simple, but you gotta know how to read the car.
Sorry I don't remember which way to go with the part throttle shifting.
Maverick H1L stated he would post it if he finds it.
I will look myself now and post what I find.
Just don't touch it until you have the right answers!!!

 

Thanks a lot GregZZ4 for your help, but the Mr. Goodwrench that did it, did it right in front of me and he said it should be fine but he wouldn't adjust it to be out much further than what it was set to.

I have to go in soon(tomorrow) for PA State Inspection and I'll ask about it when I do.

Maybe I'll just ask him to adjust it to its only 2 "ticks" out instead of 3.

That should still give me the shift that I want and better safety for the transmission in the long run.


Oh and I have a story too for you fellows tonight!

I hit a deer.

Well yeah I slammed on my brakes and it hit the front bumper at about 30 mph, there was a small hole in the lower ground effect on the drivers side from when I got it which now has a small chip in it, and my plastic grill insert is cracked even worse now, but other than that theres no damage at all.

And well, now this just gives me a reason to get a new grill insert!

But boy did it ever scare the hell out of me, I saw it going to cross and I slammed on my brakes and when the tires locked up and started to squeal, it stopped and looked and gave the "deer in the headlights" look.

If I just would have held the brakes steady and not locked the tires I bet it would have kept moving thought, oh well the car survived pretty well actually so now worries!

 

Reminds me of a Bob Rivers Twisted Tunes song 'I Came Upon a Roadkill Deer' from one of the X-Mas Discs. Yes, I own it.

 

LMAO

I'm just glad that the car hit the deer and didn't let the deer hit the car, I was really impressed when the front end held up nearly flawlessly for what it could have been, its a TANK!

I'm planning on just beefing up the front end and maybe fabricating some metal plates to go on the braces so even when I scrape things won't bend or flex as much and it will hold up better.

Before I hit that deer I had always thought that if I even hit a rabbit it would mess up the front end but I guess not if I hit a deer at 30mph, lol.



But do you think that the transmission will be fine just turning it down a notch?

 

Maverick did you find some numbers?

 

First off, you've said many things, as we all have.

Start us off with a reply with clarified issues

 

You guys are my heros, and guys you have to give it up for Maverick H1L for all the help he gives everybody around here, I see him post detailed technical information in almost every thread in the V6 forum, and it really is impressive, and I'm sure very much appreciated by everyone in the forum for the help he brings!

 

Well when I say notch I mean a "tick" when the TV cable adjuster ratchets, before it was set to 3 "ticks" (or I guess notches by what I said earlier...) and I hope that setting it to 2 "ticks" will be better for it and calm the burning smell in the transmission fluid.

 

Don't be jealous, my '78 1/2 Ton @ 4200LBS does, on the highway, 16-1800 RPMs @ 70-80 MPH on a flat stretch with a 3:42 posi and 28 1/2 tires ( roughly ).

I love my fuel economy with my new 700R4.

 

Yeah well you've got a ZZ4 which is an AMAZING engine I might add....

I'm stuck with this little 3.1L V6......

I wanna do a rebuilt when I restore it, oh man right after I get out of college thats what its getting, no doubt, thousands of dollars with nothing to spend it on but loans and bills, oh boy! My car won't be getting neglected....thats for sure.

 

As I said before, we would try to find you the info about adjusting your TV Cable, but I am sad to say I haven't been able to find it yet.

When I did my adjustment, I called someone I know @ a shop and can't call him tonight.

When I put my 700R4 in my '78, I didn't like the conversion kit I bought as it messed with the carb gasket, so I found a bracket from a truck, DOESN'T APPLY to you.

When I got an answer from the shop, I did the whole push the TV Cable into the bracket and pressed the gas peddle until it ratcheted and I thought it would break from all the noise.

I drove it around the block and it was not happy, but was close.
Keep in mind that my situation was custom.

After I learned which way to go with the cable I was good to go with a couple or 3 extra clicks ( don't do this ). This was due to my bracket being in a different location than the stock one.

If you don't get a solid answer from Maverick looking at his manual,
I will call my dude and tell you which way is better with the cable.

Keep in mind that I don't want to call him unless I have to due to favours and so on.

 

Don't be so hard on yourself yet.
I bought this Engine when I was in my late 30's.
I'm not rich and had to wait like a lot of us poor Blue Collar dudes.

 

Alright, thanks a lot I really appreciate it. I just want to get these issues hammered out before its too late and I'll have to work on the internals of the transmission!

 

ALSO, let's not forget the fact that you have a '90 Camaro RS and I have a '78 Pickup!!!!!

 

OK, ask again....
what do you need to know?

 

I would love to get another thirdgen and stick a ZZ4 or an LS-Family engine in it and just have some fun with it, but I won't do that with this one, I want to keep it factory spec, and stock as much as I can.

I don't ever want to get rid of the car either, I talk to too many people that tell me they had one just like mine and they got rid of it and miss and regret it every day.

I hate not being able to drive mine everyday....

Eventually I'll get some dough piled up and I'll be able to get what I want out of a thirdgen. Any little bit of performance I can get out of it really goes a long way for me an I notice all of it.

Just replacing the transmission mount today made a big difference in the way that the car works, its amazing. I wish I knew more about cars!

 

Well I've had a lot of transmission questions since I snapped my mount last Friday and I just want to make sure that while I'm dealing with the transmission that I get it fixed up like I have been the engine.

The engine runs great and I love it, but I just want to get the whole rest of the drivetrain into proper performance/saftey operating ranges.

So far its going pretty good, the mount today was flawless, and I enjoyed doing it.

Next is the TV cable and the rear main seal.

But before I do the rear main seal the easier thing to do would be the TV cable, so thats where I'm at now.

 

Glad you love your car as much as most of these guys here do.
I want to buy a Gen3 convertable and joined this site to learn more.
As I have been here I have learned much and decided to help where I can, although I have made some mistakes already.

FireInMe17, you started this thread with some issues....

We should stick to your topic.

Greg

 

I love those pick ups!

My friend has an '85 C/K with a 90 6.2L Deisel V8 in it, and boy oh boy is that a sweet ride! Oh...and it has a 700-R4! haha

 

Alright sticking to topic now! Don't lock the thread mods! Were being technical!

I'll see what the dealer reports to me tomorrow and report back here when I get home!