4+3 tr ans

[retiredjumpmaster]

I have taken the advice of the posts and have bought a overdrive filter kit. I called the dealer they wanted 150. to install filter. Is this something I can do some of the locals said you have to pull driveshaft and cross member. From the pictures I have seen the pan is is pretty close to what looks like the crossmember.

I figuring I should change trans fluid too. What type of oil does it take .

Thanks for all the help.

David

 

[c4cruiser]

$150 at the stealership :eek That's beyond screwing over a customer. :eyerole

The OD pan will drop straight down with no problems. The exhaust pipes look like they are too close but there is enough clearance. There is no crossmember on C4's. If you have a convertible, what you are probably seeing is the X-Brace. It does have to come off to get the pan down but it's just a matter of removing the bolts at each corner of the brace and the nuts on the back half of the brace wher it attaches to the belly pan.

Otherwise the pan will clear the exhaust pipes and there is no need at all to remove the driveshaft. If you have a coupe, just raise the car and place it on jackstands and drop the OD pan.

Because there is no drain plug in the OD pan, you will have to remove all but one or two bolts (they need to be loose) so that the old fluid will drain out of the pan. A big plastic drain pan helps here if you do the job on jackstands. Once the flood is over, just remove the last bolts and empty the pan. Be sure to clean it very well.

The OD unit only holds about two quarts of DEXRON II/III ATF fluid. The cooler lines hold about a pint of that and you can use light air pressure to blow that old fluid out by disconnecting one line from the OD case. Use LOW pressure, about 5-7psi is all you need to remove the fluid from the lines.

Once you have the pan off, carefully straighten the pan rails if needed and make sure that the surfaces on the pan and the OD housing are completely clean. Use black RTV to re-seal the pan to the OD. If you got a gasket, I would toss it as most gaskets will not seal any larger bends, warps, or dings in the mating surfaces. The bolts should not be tightened too much but they do need to be equally tight. The RTV will seal everything up. Run a bead on the pan rails and immediately re-install the pan after inserting the new filter.

Hopefully you didn't buy one of the $25 filter kits from the accessory catalogs!! The 4+3 filter is the same filter used in late 50's to early 70's Ford FMX trannies that were found in some Cougars, Fairlanes, and a few F-150's. If you have a CARQUEST store near you get can the very same filter you ordered by asking for part # 85926. Should run about six to eight dollars. You can also cross-reference this number to other filter brands by looking thru the different filter catalogs hanging on the oil and air filter racks at parts stores.

The OD filter is held in place with a rubber bushing. The filter you buy for the FMX tranny does not come with a bushing as that tranny did not use one. If you got one with the kit, it can be re-used many times over. Simply pull the old filter straight down and insert the new filter.

For long life in the OD, you should change the filter and fluid every 15K miles or so. There is a fill plug on the passenger side of the OD unit. You will have to use a pump to get the new fluid in but it's just time consuming. If you blow out the cooler lines, fill the tranny up and then rotate a rear tire by hand for a couple minutes. That will fill the lines and then just top off the OD and you are done.

 

[retiredjumpmaster]

Thank you for the information my car is 86 coupe, you I don't know anything about the maintance I just bought the car. Should I try to change the transmission oil as well? I have read that you need to make sure you can get both plugs loose first?.

I belive I am in OD when I use the button on the shifter there is no difference in the rpm, but when rolling down the road at 60-65mph my rpm is about 2400. I am hoping that changing the filter will give me back the OD when the button is used. Any way thank you again for your help. Is there any certain spot to place the jack stands?

Thanks
David

 

[c4cruiser]

It is a good idea to get the OD unit flil plug loose before you try to change the fluid. Be careful as the OD case is aluminum. The OD fill plug is on the driver's side and is a square head plug next to the OD solenoid connecting wire. Same goes for the fill plug in the 4-speed trans. The 4-speed portion is actually a Borg-Warner Super T-10 and it will use 75W-90 gear oil.

With the tach showing 2400 RPM assuming you are in 4th gear, it sounds like the OD is not working. At 60MPH or so, 4th gear with the OD engaged should be about 1600-1700 RPM. You can easily test the OD operation by depressing the throttle in 4th gear at freeway cruise speeds; the system has an automatic kickdown sort of like an auto trans. If the OD is working, you will feel the "downshift" and once you release the throttle pedal, the unit should go back into OD.

There are a number of things that could cause the OD not to work. There is a solenoid and pressure switch inside the OD unit that is vislble when you drop the pan. Check for loose wires or connectors. The solenoid or the pressure switch may be bad. There is also a OD relay on the firewall next to the windshield wiper motor. That may be bad. It's a common relay to other components (the fuel pump relay is the same part #)

If you like working on cars, I would suggest that you get a real GM Service Manual printed by Helms for your 86. You can find them on eBay or in the parts for sale sections. You want the version with the RED covers, not the white covers. Red covered books are the production version and the white cover books are the preliminary versions. The manuals are a two volume set so make sure you get both. They are the same books that dealership service techs used. You may also be able to get them directly from Helm: www.helminc.com

For jack stand locations, you can place them under the frame pinch welds. Look at the jack placement points that are molded into the lower rocker panels. USe a floor jack at these points to raise the car. In the front, you can place a jack stand on the small vertical tab on the bottom of the frame just under the battery or about 4" in from where the tab curves inward.

At the rear, just a fww inches inside and in front of the rear wheelwell, you will see the same type of vertical tab wher it forms a square. You can place a jack stand under this area.

The C4 body is stiff enough that you can raise one side of the car at a time even if you jack the car up at the corner jacking points. I place a floor jack midway between the molded jacking points and raise the entire side of my 87 at one time.

You do need to look under the rocker panel to find a small threaded stud about in the middle. On the driver's side, it holds the brake lines in place; on the passenger side, it holds the fuel lines. Just position the pad of the floor jack either just in front or just behind the studs and you will be fine. Be careful to not have the pad of the jack touch the floor pan.

Here's a link to how the 4+3 operates: http://www.5speeds.com/43table.htm

This link to SKSpeed in NY state is a help if you need parts or tech information. www.skspeed.com

 

[retiredjumpmaster]

4+3 trans

So much information about this transmission, where can I get if I wanted the relay, the solenoid in the OD unit the parts you mentioned in your reply in your reply. I think I might be interested in changing out the parts when I have the car on stands.

I will order the manual for the corvette from Helms. Before I start to work. Would you be interested in giving up phone number. I have lots of questions and now wonder if I made the right choice for my retirement present.

Thanks
David

 

[johnny80]

Hooah!

Welcome Jumpmaster! My name is SFC Drummond, currently in Iraq for # 3 rotation.

The 4+3 is a quirky trans but reliable if you pull good PMCS. If you can, invest in the GM service manual for the vehicle. I have an 88 with the 4+3 and this site has been great. I have probably save thousands of dollars on unecessary/uneeded repairs because the folks here help me troubleshoot everything. Greatest site for corvette owners. It helps you talk the talk if you do have to take it in to a service shop. Missing my vette right about now. I am stationed out of FT. Lewis and this time of year is perfect for targa top off driving to MT. Ranier and the surrounding areas.

Hooah Airborne! ( I am a leg...but don't hold that against me)

 

[retiredjumpmaster]

Thanks for the advice. Because of this web site I did buy a GM manual and the posts here have given me a lot of answers to my questions. I found a parts house that has the filter and rubber gromment on the trans for the 4+3. I have bought 2 filters and neither have come with gromments. I bought vette as a retirement present for doing 20 with uncle sam. I wish you the best while out of country, and no that you are appreciated greatly by all of us here.

Hooah 82nd Airborne , I was a leg once to, but changed my evil ways.

David
SFC Retired

 

[Red G]

I've had decent luck with my remanufactured (late style) OD. I always run Mobil 1 ATF, changing it every three years since it would take me about a decade to hit 15k.

PS. I'd never jack up any Corvette without popping open the doors and hatch. There's more flex than you think!

 

[CAJUN C4]

The very best filter is what I installed on my 84'. Go to Jegs and buy a Perma-Cool External canister Auto. Trans. Filter Kit, P/N: 771-10678. Gives twice the Oil capacity and Much better filtering.

I think I paid $35.99 for it.