Have had a leaky rear main on '85 4+3 for some time. When I replaced the clutch and such
over a year ago, I almost attempted to change it then, but didn't. Can I drop the pan & oil
pump and replace the rear main without jacking up the engine? Can I do this with
transmission installed? If so, is the Felpro 2900 (2 pc, wide style seal with raised bead on
OD diameter) the right seals to use and should I use a pan gasket or just gasket maker?
Your help would be greatly appreciated.

 

You can change the rear main seal with the motor in the car but you have to drop the gearbox and bellhousing to access the rear main seal.

I changed my rear main seal when I did my clutch and flywheel last year - I figured it was cheap insurance so I didn't have to drop the box to do it later. I had the pan off but didn't touch the oil pump. I used a gasket for the oil pan with a bit of gasket adhesive used as insurance (not too much though). Getting the pan on is fun (making sure the gasket stays in the right place while installing the pan) but can be done fairly easily with the motor in the car. Can't help you with the rear main seal parts to use, 90's use a one piece seal so I have no idea about two piece seals.

 

Yuch! Don't know about a '90, but on an '85 that driveline support beam is a bj$%# to get in and out!
When I replaced the clutch a couple years ago I looked at it and almost did it then, but since my kid
was yipping about getting it back on the road, I gave in and bolted it up! Guess it's time to pay
the piper. You sure it's necessary to pull it cause I'm not as young as I used to be, and getting
that 4+3 back in there is not for the weak at heart!

 

i dont know if this is applicable, but i changed the rear main on an 84 camaro once i didnt have to pull the tranny, but i did have to jack up the engine to get the pan off

 

Yep, 90's still have that driveline support beam that is SO much fun to pull out. For what its worth, it gets a bit easier each time you do it. Also, if you use a jack on the bottom of the gearbox to 'adjust' the weight on the beam when you are manuevering it out it might make things a bit easier.
Puilling any gearbox isn't fun either...:rolleyes:

I don't know how you could get to the rear main seal without pulling the gearbox on a C4. Sorry, I think you'll have to pull the box...

 

Well, looks like I'll wait til we put it up for the winter. Thanks for the hints on the support beam. Since I had it out twice; once to do the clutch & transmission rebuild plus taking it back out when I heard a knock! Turned out to be the sheet metal plate on the front of the bellhousing was bent in ever so slightly, and hitting the flywheel when I started the engine. You can imagine how impressed I was after pulling the whole thing backout, finding NOTHING, putting it back, and THEN discovering the bent plate. Anyway, the second time it did go in easier, but wasn't the easiest install I have ever done. This time I will build a platform that will fit a large pin into my jack so I won't have such a balancing act to do putting it back in this time. Thanks for the help, even though you didn't tell me what I wanted to hear :>)

 

You might want to check with someone close who know's if your engine has the 2 piece or 1 piece rear seal. I don't know exactly when they changed them, but I know the 86 had the 1 piece. If 1 piece, then you probably would not have to remove the tranny to replace. As for pan gaskets, the new Felpro 1 piece setup looks like the way to go. No joints to leak. Good Luck.

 

You should have a two piece rear main seal on your '85. If so you can change it by removing the oil pan. I believe they went into the one piece in 1986. I changed the seal on my '85 last year and my '94 (big job) this year.

 

For future reference,ZR51 performance sells "support beam brackets".You get 4 tig welded stainless steel brackets that "tie" the beam down down at all 4 ends where the bolts go.
Web site is: http://www.ZFDoc.com
Ph# 602)319-6575 Bill Boudreau.

A good benefit of it is this...the top nuts are now encased inside the brackets so you no longer have to get your hand and wrench up in there to hold the nuts.You simply hold the bracket on top with your fingers and install the lower bolts through the beam and tighten to torque on the bottom.The bolts are encased inside the top brackets so they do not spin loosely.

These brackets are supposed to stop torque twisting of the beam and put the power to the wheels better.Im not sure how well they work for that,but the brackets alone make it so much easier to take the bolts and the beam out now when needed and reinstall is a snap.I have them on my 86 Coupe.

It took me over an hour getting the original bolts and nuts off the beam and about 10 minutes to reinstall with the new brackets.I had a hard time holding the wrench up there while loosening the bottom bolts.Now I can take the bolts out in a few minutes and reinstall everything fast.
:)