side shaft play

The side output shaft has a tapered roller bearing and when properly loaded (shimed), I do not recall any wobble of the output axle. Although, Unless the bearing failed (unlikely), I don't recognize internally what would cause the clicking. If the tapered bearing's load was incorreect, it is likely that the interface between the pinion and crown gear would be off creating unusual wear on those valuable parts and most likely a whining noise. Then the tapered bearing is the least of your issues.

Thus, I would be more suspect of the u-joints and halfshaft.

Should you inspect the halfshafts and believe it is coming from inside the ZF, and if you are mechanically inclined and own a hydraulic press and have some creativity to fab some crude tools to faciliate pressing the tapered bearing off the output shaft, you can do this and save a bunch of moola. If you care to venture into your ZF and need an assist, feel free to give me a call 713.553.5475 - John

jt

I appreciate the offer for phone help. I live in the NE so we have about another month of good driving weather. I plan on tackling this over the winter. How much trouble can i get into pulling the side plate with the shaft out of the transmission?? Will i be able to inspect the bearings for wear or incorrect shims. The movement where the shaft exits the case is my concern. This is a new car, the zf was an NOS unit that had the ring gear flipped/wired and all new seals, the half shafts and u joints all new, The clicking and poping noise i'm hearing is while pushing the car arround not consistent just every now and then. the engine is too loud to hear anything with the motor running.

LLOyd

This link might help http://www.panteraplace.com/page10.htmand this http://www.panteraplace.com/page151.htm

Mike

thanks Mike

I think it demostrates with mechanical skills it can be done

I should be able to diagnois the issue at that point

LLOyd

I guess what i really need to know what is an acceptable tolerance for the shaft. Is 20/1000
too much play.

Lloyd

quote:

what is an acceptable tolerance

I suspect you'll need to call Butfoy or Quella for that answer.

Larry

Is the stub axle play in all planes or just back-front, up-down? You mention u-joints, they are true UJ's not CV joints correct? 3,000 miles isn't a lot, who rebuilt the transaxle previously and is there a warranty?

What angle do you have on you half shafts? I understand acute angles can be a problem with u-joints and that is why a lot of the GT40's are using CV joints that can tolerate more. Maybe that is putting excessive load on the stub axle.

Julian

Julian

NOS trans. Never was in a car. Pantera performance flipped the ring gear and replaced all of the seals. So there is no warranty. It does have movement in all planes and it is runninng true ujoints.
The problem is west coast for service. Pulling and shipping the entire transmission is going to be time consuming and expensive. I'm not aware of any zf shops in the NE.
Thats why i was wondering if i can pull the stub axle and send that for repair or is the problem deeper.

I have a private message into Lloyd B. to get his opinion

LLoyd G.

If Pantera Performance did the ring gear I'd be inclined to give Dennis Q. a call and ask his opinion as the axles had to come out for the flip and would have presumably been shimmed back to correct tolerances. Dennis usually stands behind his work.

You can probably get him to send out a new axle if needed on an exchange basis.

Lloyd Butfoy is good, but not renowned for answering his messages.

Julian

thanks julian i dealt with a bob byers at pantera perfomance
i'll try them

LLoyd

Lloyd, your axle play: was it in-and-out, or side-to-side? Some play will exist in any 38-yr-old transaxle from wear in the differential side-gears, both the teeth and the splines, and no one other than RBT will have new differential side-gears available. All other 'ZF overhaulers' do selective matching of used parts, or buy new stuff from RBT when rebuilding. But as long as no gear lube is leaking out of the side-seals, there should be no effect on reliability from a little motion.

Tell me- how do you manage to HEAR such clicking noises in a raucous mid-engined, fiberglas car? In a well-insulated Pantera, I can hardly hear the radio or CB!

boss

All play is side to side and no leaks.

You are correct with the noise the pistons could be changing holes and you wouldn't know it. I hear the pop or click while pushing the car under the lift where it lives. Not able make it happen. Just every now and then you hear that noise while under push power.

I wanted hear from one of the experts let it go until it leaks. I just concerned i'm damaging some expensive parts.

thanks for the response

LLoyd G

quote:

Originally posted by Lloyd GT40:
thanks julian i dealt with a bob byers at pantera perfomance i'll try them

Okay, Bobby is at 'Precision Pro-formance' in Brea, CA. When you said 'Pantera Performance' I assumed it was Dennis in Colorado Springs.

Julian

It really depends upon how sinister that noise is. When I hear a noise, I usually go looking for it too. It's rare that they fix themselves.

IMO, slight play in the drive flange isn't necessarily an indication of a problem. It's just a floating spline and is no indication of whether the carrier is shimmed at proper clearance. Quella has done a lot of ZFs, and though possible, I doubt he would make an error during a simple flip.

The ZF is a limited slip differential trans and of course when you turn, the inside wheel must slip because it travels a shorter distance than the outside wheel. This slip must occur either between the tire and the ground or in the clutch mechanism of the differential.

Years ago, I had buddy that was a drag racer set up the rear end in my mid-year vette for me. It drove fine cold but when it got heated up a bit, it would make a hell of a clunking noise while manuevering in parking lots. It sounded terrible and like it was coming from out near the rear wheel. Turns out, it was dragging the inside tire during low speed turns, stretching all the rubber bushings in the suspension joints to the max, and then the joints would catch up and let loose and make a hell of a clunk, some times several in succession. I chased it for a while thinking it was a bad u-joint. Being a drag racer, my bud was inclined to set up limited slip dif's a little too tight. I finally pulled the rear end and set up the clutch packs a little less aggressively and problem solved.

You mentioned your ZF is new. You likely have heim joints in your 40's suspension not rubber bushings. Maybe it's just got a tight differential pack and the heim joints do a good job amplifying the noise as it slips when you push your car?

Good luck.
Kelly

my mistake it was Bob Byers at precision pro-fomance in ca. It was a long time ago. 2001 to be exact. I found the transaxle three years before i got the car. Long wait list then took delivery 11/2004
LLoyd

the noise doesn't bother me as much as the play. The noise could be anything from the brake pads releasing to internals of the diff, Hiem joints. It has done it from the very beginning. I'm just anal with noises. The noise is what brought the attention to the half shaft.
Looking at the diagram of the parts it looks like there is bearing part number 912 in fig E of the manual. It appears to be a press on bearing to the stub. Wouldn't this bearing bearing control lateral movement.

LLoyd G

There's really no place where side-to-side play can develop except in the tapered bearings on the ends of the differential assembly, possibly from lack of preload. And I can't think of anything that would reduce preload except maybe using the wrong shims in the side plates, or a too-thick non-stock side cover gasket. Did someone work on this ZF to stop some leaks, perhaps?
If not, a popping noise at very low speeds can sometimes result from using 70W90 diff lube WITHOUT posi-lube. The limited-slip clutch plates stick together and when they pop loose, you might hear a noise. I always recommend using diff-lube WITH posi-additive in it.
Second possibility: if even one of the 16 halfshaft bolts are slightly loose, it can and has caused a noticable vibration under severe acceleration. I suppose its possible one might hear this looseness if pushing it around by hand. I first discovered this on a friend's car; close exam showed a cracked lock-washer in which most of it had fallen out leaving a gap between the companion-flange and the bolt head. A few weeks later, another owner that was present found one bolt on his Pantera that was loose. Both car's vibrations were completely fixed by simply tightening up all 16 bolts.

The floating axel is a press fit through the ball bearing inter-race and the outer-race of the ball bearing is a press fit into the flange (the cast iron side piece). When it is all pressed together there is a shim(s) to space the circlip so it fits tightly in the axle groove. This prevents the axel from moving in/out. If the axle is shimmed correctly and has not fretted away the axel surface or the side flange the only in/out play would be play in the ball bearing assembly. I do not recall my floating axel having in/out play when I was assembling it and I cannot feel any in/out play by tugging on the axel flange and U joint. There is a tiny amount radial play that is equal on both sides. It can be hardly seen and mostly is a “clunk” sound.

The ZF is a very built proof transaxle. The majority of problems are usually poorly adjusted shift linkage, poorly adjusted clutch free play (that many miss diagnose as bad synchros), leaking seals and an odd problem where the front bearing on the main shaft works its way backward out of the front case. This bearing problem is usually caused by installing a non-Pantera clutch system or a bad pilot bearing in the crank.


Mike

I should add that the floating axle is NOT under any pre-load. It is just held in place by the circlip holding it inside of the ball bearing. I guess that’s why they call it “floating”!! The ball bearing is a short distance behind the axel seal but on the inside of the flange. The pre-load is between the flange (the cast iron side piece) and the large single tapered bearing on each side of the differential assembly. The deferential assembly rides on the tapered bearings. It is a pretty cool design.

Mike

Guys lets back up here a minute the clicking noise is not my problem. The side to side and up and down movement of the shaft exiting the side cover is my problem. I don't believe this is related to my click. There is no in and out movement. During the hunt for the click is when i found the movement. So lets not get side tracked. My initial question was will i get myself into trouble removing the side cover to inspect the bearing. Could an out of balance half shaft wear the bearing in 3k miles. The manual is pretty vague on this process. I'm afraid of pullin the cover and something falling into the case requiring removal and teardown of the whole unit.

I'm curious to see the response to the guy that cracked the cover. He's going to have to remove it. Panter1887 provided an interesting link to the tear down
Thanks guys
LLoyd G

I went back and re-read all of the thread. As others have suggested you might want to give Bob a call, discuss your situation and get his recommendation.

Mike

My plan is to call Bob B. once the season is over here. We have about another month before the car gets laid up for the winter. We have such a short season here. It will be a winter project where down time is not critical. I was really trying to get as much info as possible to make an educated decision on how to proceed

LLoyd G

quote:

My initial question was will i get myself into trouble removing the side cover to inspect the bearing. Could an out of balance half shaft wear the bearing in 3k miles. The manual is pretty vague on this process. I'm afraid of pullin the cover and something falling into the case requiring removal and teardown of the whole unit.

No, removing the side cover won't cause trouble 'cause everything is snap-ringed together as an assembly. As long as you reassemble the side cover with a real ZF gasket (or reuse an undamaged OEM gasket), and don't mix up the shims that are inside the side cover under the snap-rings, the tapered bearing preload will be identical to what you had before. The only possible problem may come from the shim-washers that are between the side cover and the bottom cover, on the two long external tie-bolts. If you leave the shim washers out or mix them up with something else, when reassembling and torquing the long bolts, you can bend or crack iron side covers.
Note the inboard halfshafts do NOT run in tapered roller bearings. Each inboard stub axle runs in its own ball bearing and splines into the differential innards. The tapered roller bearings only support the differential. I suppose it's possible one stub axle could be worn a bit or the ball bearing & axle are victims of a tolerance mismatch, causing a tiny wobble that doesn't cause a lube leak. A missing snap-ring might also allow a small wobble. But unless you hear a grinding noise typical of a damaged ball bearing and find lots of steel in the magnetic drain plug, there's no reason to think an axle-support ball bearing wore out. It's far harder than the inboard stub axle surface. I hope you have a good set of snap-ring pliers 'cause some of the side-cover snap-rings are very large and very stiff!

thanks Boss simple and to the point. I'll keep you guys posted. One other word of caution is to only do one side at a time remove bothe and the ring gear drops. Sounds like a good winter project.

LLoyd