Rich B.

The story: (there's always a story!)

I started out for a ride last week, heard a funny noise, like I was dragging sheet metal, couldn't stop (no shoulder), went about a mile, downshifted into 2nd and the car slowed abruptly...got off the highway, looked underneath, nothing dragging...I linped home in 1st gear at about 10mph, put the Vette up on my garage lift, couldn't find anything wrong...stuck my finger in the trans filler hole, couldn't feel anything...opened up the gearbox drain, about a glassful of gear oil came out...no filings or grindings in the remaining [drained] oil or in the sump...filled it back up with gear oil, let it down and backed out...and couldn't get it out of reverse...

I still can't...disconnected all the shift rods, the yokes *seem* to be working correctly (they move anyway), and the clutch works fine (in fact, I had to cut a 2x4 to fit between the clutch pedal and seat frame to winch the Vette back into the garage - it only moves if the clutch is depressed)...

I did a Search here and elsewhere; found another owner whose DNE 4+3 wouldn't go into reverse, so I think I have actually broke something...I'll get the trans pulled out in a week or so, but in the meantime...

(1) Anyone else had this happen???
(2) 5speeds.com doesn't repair DNE 4+3's anymore; anyone know a parts and/or service supplier??? I have an email in to SK but no response as of yet.
(3) I know I need a driveshaft bushing and seal; GM discontinued the bushing; does anyone know if the auto bushing & seal will fit??? Or another source??
(4) Any other comments, links, or advice gratefully appreciated!!!

Rich B. - 1986 Corvette convertible; DNE 4+3; aluminum heads.

vettecrazy88

Try and get to CentralCoaster. He can probably help. While there are many genius' on this site, he's one I'm familiar with, and extremely knowledgable on 4+3's.

bogus

I agree, CC would be the man.

As an aside, I hate the 4+3... it hasn't aged well at all. Before rebuilding that pig, I would get a 5spd conversion. It will make the rest of the car that much more refined and a better overall drive.

all show and more go

ok,ur shift rods locked up somehow,u can do it the easy way and have this happen again (mainly if ur stuck in the middle of the road) jack up the car and wiggle rods hard enough and it will come out!

Harder way (should ultimitly fix the problem) 1)take out the drivers seat.
2)remove the inner panel(where the glove box is)
3)jack up the car and loosen the 2bolts at the end of each rod,there's a square metal box between the 2 bolts.
4) at this point the shifter assembely should be very visible and there are slots that line up at the bottum(not very helpful without pics,someone will prob post,ask agent 86 or someone with the service manual) i stuck a butter knife in it to line it up then tighten the bolts around the square blocks,and u should be good to go,like i said before i think agent 86 has pics.If u get this done right it will shift alot smoother!
im surprised i dont see this post all the time,seems like a common problem to happen to these cars after so many years!

all show and more go

the 4+3 sucks donkey nuts,its better as a plain old 4 speed(no problems,except the one stated above) my cars in the shop getting the overdrive hooked up(150$) if anything i would go with the zf6,or a perfect fit tremec 5spd!
if i met doug nash right now i'd kick him in the *****(didnt he have something to do with the creation of the delorean,wich gave us those terible back to the future movies,make that 2 swift kick to the *****)

Rich B.

Thanks for all the replies!

As I mentioned above, I disconnected the shift rods and the shift yokes all seem to be working. At least they all move (the shift yokes are inside the side cover; you can move them with the short links on the side of the sidecover independent of the shifter rods). I may very well have a broken or worn shift yoke; in any case, it's easier to work on it on the bench, so out it comes!

(The shifter plates are synchronized; I actually have the alignment tool.)

Yes, a $3500 5-speed Tremec + required accessories would be the way to go...

Rich B.

I just got an unexpected reply from Paul Cangialosi at 5speeds.com (unexpected because I mainly inquired as to whether they still did the overdrive rebuilds) -

They get stuck in reverse because the seal blows out of the OD unit and falls behind the reverse gear. Contact SK at 631-957-9427

Hmmm!!!

Well, it's definately gotta come out now...<sigh>...

CentralCoaster

I've got 4+3 in half as we speak. I'll take a look tomorrow and see if there's anything easy that can hold it in reverse, but as of now, SK's response sounds very plausible. Either way the trans has to come out if you can't shift reverse with the rods removed.

I'd like to know the p/n for that seal as well, I need to change one.

5speedC4

Dump that 4+3 and install the Tremec TKO 500 or 600 from Keisler engineering.

Or do the ZF6 conversion. Central Coaster has info on that conversion.

I have the perfect fit Tremec TK0 500 from Keisler Engineering, I love it.

I slam my corvette through the corners pretty hard and feel very confident in the transmission.

Rich B.

No problem! PM me and I'll send you my address to send the $3500 to!

**************************************** *************

Got the transmission out today. Took ~3 1/4 hours. (I have an Eagle garage lift + Harbor Freight hi-boy trans jack). It's been worked on before. Blue sealing goop between OD & gearbox, plus OD was painted blue at one time...

Remember the glassful of gear oil I drained out??? The OD had about a quart and a half in it...I talked to Brian at SK; he says this happens when the seal pops out...the fluid changes location...

Now I just need to get the OD detached and rebuilt. And decide whether it's worth the month or two to do a proper gearbox rebuild as well...

Over the years I've cracked and never-seezed pretty much every bolt needed to get the trans out, so no problems there. Pinion seal is leaking a bit. U-joints feel good. Haven't decided yet whether the friction plate and throwout bearing will be replaced - PO did a clutch job before I bought it...nine years ago...

Rich B.

I would appreciate any tips on problem areas...I'll be separating mine in a few days...

My Corvette Parts Manual says -

SEAL, OTPT SHF OIL (4.318) 3932255

While draining the oil out of the gearbox section, I felt a large washer in the sump...<sigh>...It's a thrust washer, which slipped out when the PO or his mechanic assembled the transmission incorrectly...The overdrive has been replaced, and if not assembled correctly (vertically, not horizontally), the thrust washer falls out...

There used to be a Tech Tip on this...but what happened to the Tech Tips???

trupp

I don't remember a tech tip on this but did recall the other forum having a very in depth article. Here is the link.
http://www.corvetteactioncenter.com/...Overdrive+Unit
Hope this helps.

Rich B.

Thanks for the link! David Fulcher used to post here quite often...I'm pretty sure that is one of the Tech Tips that used to be here in the C4 Tech/Performance section...there was one on the gearbox itself, too, IIRC...

I don't intend to get into the OD myself...I'll let experts rebuild that...but I will get that thrust washer back where it should be...hopefully, the case won't be too badly chewed up...

jhammons01

So we don't have to type it all over again

Rich B.

...???...

Anyway, I got the trans split apart today...it was the seal...the pieces are on the 2x4...



There is part of the seal still in the case...



Got the rebuilt/exchange overdrive in from SK on Friday. Looks good! I need to flush out the radiator cooler lines and replace some seals and gaskets in the gearbox, and I'm ready to...put it back in...

jhammons01

There were two other active threads at the very time you posted yours with the exact same topic being discussed. Not that you noticed.

Rich B.

You're right; I didn't... Thanks for bringing it to my attention! I posted a link to this thread for the guy who got no replies, but had the similar problem to mine...the other thread sounds like an adjustment problem with his short-shift links...

According to the guys at SK and 5speeds.com, locked in reverse/no reverse is an ongoing problem with the 4+3...due to the seal blowing out...mine seems to have run low on ATF due to a worn driveshaft yoke bushing...which overheated the case and caused the seal to pop out...

Brian at SK rebuilds these overdrives...here's a link to the causes of the overdrive failures, and SK's site as well...

http://www.5speeds.com/dne.htm

http://www.5speeds.com/nash.htm

http://www.skspeed.com/aboutsk/transshop/default.asp

Ray Quayle

Rich,
What did you pay for the rebuilt OD? Did you have to return your old one as core? Thanks for the great pics too.

Rich B.

Hello Ray! Long time no see!

Returning the core is optional; Brian at SK says they have "hundreds", but they will credit you if you return it, based on how bad it is...PM sent on the price...

Rich B.

Continuing on with this long dreary job...I got the gearbox cleaned up (inside & out), checked the bearings and synchro ring clearances = they're acceptable; and assembled the overdrive to the gearbox...vertically...I had my hands full of grease, kerosene, and oil, so no "action" pics, but here is the finished assembly, waiting to go in...



I work alone here, so I had to use a chainfall to lower the overdrive onto the gearbox...I heartily recommend the chainfall over using your hands/arms...there's just too much wiggling, aligning, and tweaking required...you need two hands free, at least...it slid down to about 1/4" from mating; I drew it on with the seven 17mm-head bolts to get it fully mated...(BTW, Sears sells a 17mm/19mm offset box-end 12-pt wrench that allows you to get to that bottom 17mm bolt easily)...

Mating the overdrive to the gearbox is done vertically [nose-down] so that the front reverse idler gear thrust washer doesn't fall into the case sump (which is where I found mine, courtesy of the PO)...that washer is the one on the far left, with the curious hex hole in it...the Torrington bearing and its thrust washer go on the opposite end of the idler gear shaft, inside the adapter plate space...



I pretty much expected everything else to be in good shape, since the gearbox was...but no, the throwout bearing has a groove worn in it, with a corresponding flat ground into the pressure plate fingers... ...so I have a "clutch kit" on order from RockAuto...should be here in a week or so...

I had a phone conversation with Paul Congialosi from www.5speeds.com on various subjects pertaining to rebuilding the Corvette gearbox & overdrive; he was *very* helpful and really took the time to answer my questions and explain what needed to be done, both for my particular trans and the 4+3 in general...both Paul and Brian at SK have been extremely helpful and patient in answering my questions, without trying to sell me anything I didn't really need...

I have a second transmission coming in, courtesy of idle shop talk in my local bar...Doesn't matter what it is; laptop computers, motorcycles, or Corvette transmissions...someone at the far end of the bar will hear you talking and say, "You looking for a Corvette 4+3 transmission??? I've got one on my garage floor...you can have it for $100..."...So now I have a spare DNE 4+3 out of an 85 (with TV setup)...plus three Honda CB550 motorcycles in boxes; and two Compaq laptops...with docking stations...