I was cruising up to a light, going about 30mph. I dropped the shifter from 3 to 2, as I usually manually shift this 700r4 2-3-4 and 4-3-2 because I've never been satisfied with the way it naturally shifts (I let it handle the 1-2 shift but I take over for 2-3-4). Anyway I dropped it into 2nd and heard a bit of a bang, the car jolted, as if to start slowing down from the downshift, but then immediately stopped slowing down and it felt as if I was coasting instead of engine braking.

Now, whenever I'm slowing down and drop the shifter from 3-2 (usually about 30mph) I no longer get that nice solid SNAP down into second gear accompanied by a rapid deceleration. It still downshifts, and I still engine brake a LITTLE BIT, but it's NOTHING like it was before and clearly something inside the transmission broke. The downshift into second is veerrrry gradual and probably takes place a solid 2 or 3 seconds after I shift it, as opposed to before when it snapped down into second instantly upon moving the shifter into 2.

Other than that the tranny still shifts fine and operates exactly how it always has, this happened this morning and I finished my day (40 - 50 miles of stop n go traffic through pure city) without any other problems.

Any ideas what might have happened? Should I have a backup car ready?

 

it is very very bad to manually down shif but it is ok to upshift im not sure of you problem but what might help you on the shifting is adjusting the kickdown cable......

heres how if you dont know first you look at the throttle cable and the cable above it is the kick down cabe press the little button on the side and slide the linkage all the way back in then after you do that let go of the button then slowly give it full throttle and the cable will adjust itself then try drivin the car it should feel alot better and shift a little harder better

hope that helps a little

 

i doubt its a tv cable problem. im more led to believe that i could be the clutch pack thats responsible for the coasting in second gear. im not too familiar with the internals of a 700r4 but i have overhauled other transmissions before.

 

Sounds like a broken sprag to me, had it happen on my 3rd 700r4. It held together for another year, just no engine braking.

 

Its going to be an overrun clutch hub or a spag. I have had this happen before. It was a busted overrun clutch hub in my case. Time for a rebuild. Sorry about your luck man.

 

Sounds like the overrun clutchpack which is a small set has gone bad from the stress.

 

What can do to extend it's life? Just leave the shifter in OD and take it easy? How is it most likely to fail when it does?

 

It's most likely an overun clutch/hub failure. Yes, it has likely been over used/stressed from continuous manual downshifting. It is only a 2-pack clutch and is not designed for constant engaugement.

If it is a sprag failure you will soon have other problems.

 

Yeah I would almost put money on a shattered overrun hub. Since it just banged and started doing it. Let us know what you find. Let me know if you need one too I have a bunch of 700R4 parts lying around.

 

Yup, learmed the hard way too many years ago.
Wish I still had all the broken parts to show off =)

 

A complete overhaul probably won't be necessary. When the forward sprag breaks like this or the overrun clutches goes bad normally nothing else in the trans gets damaged. You should be able to do a clean patch by removing the pan, tcc solenoid, and tube to aux. valve body. Then pull the pump and release the band from the anchor with a pry bar. After that pull the band out and pull out the band drum and input drum. Inside of the input drum you need to remove the 3-4 clutches, then the forward clutches, and you can check the forward sprag that it only rotates one direction and that the o.r. clutches didn't get burnt. If it rotates free both directions all you need to do is replace it, install all the parts in reverse order with new pump gasket, pump o ring, pan gasket, and all should be good. This sprag also goes bad a lot in the newer Tahoes, and trucks when they think they're all that and try to do a burnout in the snow or when it rains-resist the urge.

 

What about all the trash that has made its way through the trans? I would pull the valve body and replace the filter screens in the case passages too. It is also alot easier to remove the band with valve body off so you can remove the anchor pin completely. You don't need to replace everything but I would at least reccomend a complete tear down and cleaning and replacement of the broken parts.

 

well if they wanted you to shift it yourself they would have put a manual tranny in it from the start. if u didnt like the way it shifted u should have got a shift kit. the valvebody gets massive amounts of unexpected pressure that its not ment for. so if one little piece breaks in a trannys the whole cookie will eventually crumble. so next thing to go will prob be the front plant. goto amco and have them rebuild it, it will cost prob around 1,200 bucks. and if u wana shift it ur self u can only up shift, and i wouldnt rec. that unless u got all the bells and whisles like the vette servo, sungear sun shell, shift kit, etc , new[strong] bands, corke parts. good luck-- and i say this not to come off like a know it all *****- iv been there first hand.

 

I didn't say to do the valve body removal because parts get mixed up too easily, and removing the band off of the band anchor isn't difficult with the valve body on. Removing the valve body would also require figuring out where all the check ***** go and would take the project to a whole different level than just pulling the pump etc.. You would also have to buy new valve body gaskets right?, adding to the cost. Take it to AAMCO? Fix it yourself or find someone you trust not just a random shop or person. Even rookies play pro ball right?

 

I am not trying to get in a pi$$ing match with you or anything but your way is kinda half a$$ed. Pulling the valvebody is not that difficult. Pulling the pump is far more involved than pulling the valvebody in my opinion. The checkball locations can be found online. He is going to need to buy a seal kit anyways and these usually come with all the gaskets and seals he would need. And like I mentioned before what about all the junk that went through the trans? Those valve body screens are most likely plugged too so he should replace those too. Oh well just my 2 cents.

 

the trans still upshifts o.k. so the filters aren't an issue. Under the valve body the filters are for the governor and t.c.c.. Removing the pump is a screwdriver away. and the pump filter can be checked without taking it apart. You can buy the pump gasket and o ring separately for approx. $5 versus 60-70 for a banner kit. Check ***** intimidating for some to do. The car has nice upgrades so a nice downshift isn't out of the question. The mileage of the trans wasn't disclosed so as the *** umption of the rest of the trans is still up in the air. I stand by the fact that when the forward sprag rolls normally no debris circulates. That could be determined when the pan comes off to remove the filter, tcc sol., and aux. pipe. I like saving money when possible within reason and that's my story and I'm sticking to it. Money isn't everything but having it is.

 

I too agree that if he did indeed take out the sprag that it's likely no "trash" has gone through the trans. Usually a sprag fialure just means the "dogs" have poped and everything remains inside the hubs. Even if it cracked/broke a hub, we're not talking about small/fine material that could go through the pump to have possibly been pushed into the tcc or gov screens.

IMO though, unless it's a very low mileage unit, now is the time to rebuild/upgrade.

 

WRONG

 

i have had many tranny guys tell me it is fine to upshift manualy but never downshif it, it puts to much stress on the tranny by downshifting

but i doo agree with others it is best to build the trans to shift the way you want it without having to shift manualy

 

Just start looking for another transmission. Call the junkyards or check CL or the classifieds here. There not that hard to find. I got lucky once and found one in a wrecked car that had an awesome shift kit in it. That transmission was a blast to drive. You just barely touch the petal and that car would take off or downshift instantly. Cost me 300 installed. Start looking