All,
Was searching for "-1" (dash 1) fill levels on the web, as my old Pantera ZF manual conveniently deletes any such info from it's "-1" section where you would normally expect it, and ran across this older post. ) You'd think that I'd have written this down somewhere after 16 years of owning the car...
Have just had my trans out and back in over the weekend, due to exactly what a poster further up the list mentioned...and then some! 1) too much oil and 2) too much of the wrong stuff in the oil!
I last used the "fill it up until it comes out the fill hole on the rear cover" method recommended by the ZF expert, and can hereby recommend that you NOT use this method. As correctly stated previously, this puts the oil level at "above" the level of the input shaft and input seal. Doing such, along with some other problems with the trans and pilot bearing, resulted in the soaking down of my very expensive double kevlar lined clutch disc.
This wouldn't have been so bad IF I had not added friction modifier to the ZF oil to cure my sticking clutch discs in the center spool. (posi-traction clutch discs to many of you....) While it did fix the sticky discs, when my pilot bearing and front main case bearing decided to act up, I flooded my clutch with oil. (I would leave about 2 tablespoons of oil when parked...and then sometimes nothing! But it was ruining my resto job on the chassis paint!!!
Now, being the handy dandy sort of guy that I am, I dutifully cleaned the clutch disc and every thing else with brand spanking new cleaning solvent (sort of kerosene based stuff) and figured that all would be well with the world!
I rebuilt my trans, fixed the crank in my engine, patched up another chassis crack, and just recently put it all back together to head off on a jaunt to Phoenix for the annual DeTomaso love in.
Well. Not so easy. During my first run outs for testing purposes, to put a few miles on the car to make sure that my work was proper, I found that at about half throttle and above, my clutch would simply let loose and slip like a bad powerglide automatic in a 57 Chevy!!!! At will I could dip into the throttle and hear the engine climb, or simply look down at the tach and watch it head for red line! Let up on the throttle and it would hook up and all would be well.
Short story was that I decided to go on the trip and as long as I didn't press it, the clutch held fine for all of the mountain passes etc that we hit. Just didn't want to have to accelerate quickly away from any mini-vans etc!!! Cuz you couldn't! Had a great trip save for my trans linkage trunnion loosening up in Palm Springs...but easily resolved.
SO, first, I would have to say do not use any friction modifier in a trans axle unless you are absolutely certain that your seals are top shape! Perhaps don't use a Kevlar fiber disc either...in case it does leak! I figure the Kevlar fibers retained the modifier lube, even though I cleaned the hell out of it, but being synthetic, it didn't respond as expected to the petroleum based solvent. My clutch guy recommended brake cleaner, but I had no way to get into the disc and assure that anything I sprayed into the bellhousing actually made it on to the disc!
That's what this last weekend was all about. I had my guy make me up a new clutch disc. 10.4" diam, double Kevlar linings. (They are smooth engaging and don't tear up the hard parts!) My son was home from school to help me get the rear engine covers off, and it was time to get this taken care of once and for all.
I roughed up the metal surfaces on the flywheel and the pressure plate using 80 grit emery cloth and an orbital sander, to get any of this residue off of the metal.....washed with brake cleaner, sanded, and washed it all down again!!
As I replaced my front main shaft seal once again, hey, the trans was out, the seals are cheap, and I had one in stock....so it's getting a new seal! I took the time to stare at the ZF and wonder about the fill capacity.....again. Before I left for Phoenix, I dumped the lube with the modifier in it, and filled with fresh 80W-90. Figured that I'd rather not try and make things worse..... (I again dumped the oil this weekend to get totally fresh oil in place! Old oil will get used in Ford 9" rears with posi that need the modifier to keep the units from banging themselves to death!)
As I looked at the markings that I made on my oil containers, to illustrate how much I used each fill, using the LBT recommended "fill it up until it comes out the rear plug" method I could see that I used almost 3 quarts of lube. Looking at the trans from the side, I could see that this level of oil, would be at or very near the top of the main shaft! I used casting bosses on the trans to use as guides while looking.....see pics later.
What appears to be the "more correct" fill level would be to fill via the rear hole until the oil reaches the bottom of the fill hole! This is about 3/4 to 1" lower and is a total PITA to get your finger down there while the trans is in the car..... I think I had been overfilling the trans by about 1/2 litre. (Bottle has both graduations on the side, English and us over here!)
The dipstick on the side of the trans is left over from something. Not sure what, but many Mangustas came with the side mounted dipstick, which if used, would over fill the case by a surely phenomenal amount of oil, resulting in a mess of catastrophic proportions as oil would be forced out of every hole and seal in the trans as pressure built up! I cannot say why it was not discarded and replaced with a plug of sorts...... I leave mine on for some stupid reason...probably because I don't have a plug for it......
I am working on a fab'ing up a simple dipstick and measurements, to use via the top cover vent/fill hole. Once I get oil back into it, I will graduate it and post the results.
Since this hole is so conveniently placed on the trans, I still say one of the best ways to check the oil level is to simply look in the hole and make sure that you are not covering the mainshaft! I don't know why I doubted myself.....every American car manual transmission I ever rebuilt, Ford Toploader, Borg Warner T10, Muncie, T-5, Tremec....ALL have fill levels just to the bottom of the mainshaft, input or output! None of them submerge the main shaft, only the counter shaft.
If you look at the pictures, (not quite at the optimum angle, but I didn't take new ones while it was out this weekend...ugh!) if you look at the case bosses at the same level as the unused bolt holes on the side bearing covers, I figure that this level is about proper. The casting line that is just above these points, goes pretty much uninterrupted all the way to the rear of the trans, and if I had better pictures, you would be able to see that this line is above or nearly above the mainshaft entirely.
Out for now!
Steve