What are the failure modes of the 4+3?

I have looked and found that the annular bearing and thrust washer are common failures, do they give any warning that they are going or do they just suddenly fail?

I have an 86 with a 4+3 with 91K on it, as far as I know there has been no work done on it, I plan on doing a fluid and filter change soon and then at each oil change, to suck out what I can from the filler port and refill it. My concern is a failure that give me no warning and strands me away from home.

 

Your gonna have to do alot of reading and searching but here are a couple links to help
http://www.5speeds.com/nash.htm
http://www.corvetteobsession.com/Dou...formation.html

You will not be able to drain the fluid from the fill hole. The fill hole only lets you fill, you cant get a hose to the pan, too much stuff in the way.
dropping the pan is the only way to drain the fluid.
dont neglect your screen and particle magnet, there are plenty of posts on these in this forum.
There are no gaskets so use the right stuff to seal the pan to tranny, then let it dry over night before filling with fluid or you may get a leak

Mostly the first problem people post having is not being able to get into reverse or the OD engaging then dropping out then back in again. The FSM will have lots of info for you as well.

 

Thanks for the info, I checked those sites and it appears the the two main failures of the unit itself are the carrier bearing and the direct clutch washer. It says a failing carrier bearing will make noise while in direct drive and not in OD, but the only symptom for the direct clutch would be broken pieces in the pan. I guess that would be a good reason to drop the pan periodically.

 

I have a 1985 with a 4+3. When I bought it 4 years ago it had 68K on the clock and I had concerns after reading "how bad the 4+3 is" but I have had no problems and now have 85K on the car. The 5speed site above has a chart indicating how the overdrive should work if yours is working as it should I would not be concerned abour driving a long distance.

I would drop the pan and change the fluid and the filter, also clean the magnet. I use Mobile 1 in my 4+3 and it has worked good for me. I also installed a drain plug in the pan and drain an refill every spring. I drop the pan and change the filter every 3 years (10 - 15K).

If I ever have trouble with the unit I plan on replacing it with a Kaiser 5 speed.

I personally feel my C4 is a very reliable car given it's age and I an planning a 2000 mile road trip this summer.

Good luck.

 

the OD unit really isn't something that can be serviced in an average person's garage...its springs loaded and there are literally tons of pounds of force at work...if it fails, there are seveal things that could happen...i personally lost reverse and engine braking...but the 4 speed with no OD still worked...

the filter and fluid should be changed every 10K miles...i put in dexron III. thats about all you can do...if you change the fluid and find a ton of clutch material on the magnet, start saving for a new unit...

if you experience any problems, call Brian and S-K Speed in NY. Its the only shop that i will ever trust regarding the 4+3.

 

If the OD has not had a fluid and filter change in some time, you should do it now. As mentioned, you do have to drop the pan to get the old fluid out.

Changing the filter is easy, it pulls off going straight down. If you have a CarQuest store nearby, get p/n #85926 for a replacement filter. The filter is the same one used in the Ford FMX series of trannies that were found in late 60's to early 70's Cougar's, Torino's and some F-150 pickups. You can also find a FRAM filter by searching thru the filter catalog found at most parts stores. You will need to remove the rubber grommet from the old filter and reinstall it on the new filter.

There will be a small amount of tranny fluid in the cooling lines. There is an aerosol can available with a solvent cleaner that you can get to flush the lines or just use very low air pressure to remove the old fluid. This is especially important if you suspect there is any damage or if you see any particles in the old fluid.

Clean the pan rails and make sure they are straight. Also clean the mounting surface on the tranny case. Apply a bead of good RTV sealant ( I use MoPar RTV Sealant from the local Dodge dealer) around the pan rails and reinstall the pan. Don't tighten the bolts too much but get them all the same. 6-8 ft-lbs is the FSM spec.

Use Dexron II/III ATF for the refill; takes about 2 quarts. There has been some discussion over the years here about using synthetic ATF in the OD and the consensus was that it really shouldn't be used.

Once the fluid is in, turn a rear tire for about two minutes; this helps to pump fluid thru the now empty cooling lines. Top off the OD and you are done.

It would be a good idea to chenge the fluid in the 4 speed too. Drain using the plug at the bottom of the case and refill with a good 75W-90 GL5 gear oil.

 

ive noticed this 84 ive got has the oil cooler tied tagather...they unscreerude the hoses n ran em tagather...waht damage will this cause?? second kin i run n auxilary cooler?? (cheapa then new raditator) asuumin that leaked is why tied tagather ...thanks pappy

 

further diggin into my last post ...ive found the previous owners has installed a seperate oil cooler in front of radiator...like i were thinkin of doin...anybody see future issues with doin it like this??