74 Duster 4 speed adjustments

Hi everyone, I know I haven't posted in a while; but I'm definitely in need of some help. So here goes. Bought a 74 Duster 360 4 speed car. Had a diaphragm cheapo clutch in it. What I've read says to remove the over-center spring and all should be well. Previous owner didn't do that, instead putting a metal bracket type stop on the pedal arm to limit travel and then bypassing clutch safety switch. Well of course the clutch was slipping and it was definitely odd to drive. My father and I decided to put a stock style 3 finger clutch in it. Perfection brand clutch kit 90338. 10 1/2 inch. Well, while it was up on the lift I replaced the rear main seal, motor and transmission mounts, bought new Doug's 453 headers and a new Hurst shifter that came with a lot of new clutch linkage parts. This is gonna be awesome , right? I even read on here about maybe having to modify the Z-bar, etc. Was prepared to do that, but as of right now, I don't need to yet. The reason you ask? I wasn't in the garage when Dad pulled the linkages and Z-bar out, so I don't remember what mine looked like before starting trans removal, etc. I would think its supposed to be level. Now it's ****-eyed forward and upward from a level position. My guess would be because of the stiff poly motor mounts changing where the motor rests at static. This cants the lower z-bar arm towards the bell housing, which actually gives me enough clearance for everything to move freely. I checked before hooking the linkages up. All linkages are now in place, but I cannot get the clutch adjusted to work properly. After reading several posts here and elsewhere, I've performed a lot of different adjustments. Setting the adjuster nut on the lower z-bar to clutch fork for 5/32", .050" clearance between disc and flywheel when the pedals all the way down, adjusting so that the throw-out bearing spins freely when clutch is disengaged and adjusting for 1" of pedal free play. If I set it so that ,at rest, the throw-out bearing spins free; I cannot get the car into any gear while it's running. If I go a little further, and push my luck with throw-out bearing clearance, It'll go into gear barely, and grind without ever going into reverse. We adjusted the new shifter linkage according to Hurst paperwork. That was easy. Where am I going wrong here? Dad says to keep adjusting the nut out so I can get it into gear, but then the throw-out bearing is riding on the fingers. That won't last long that way. I'll enclose pics that may be helpful. Last pic shows the rod that was in the car, next to last shows how the nut is against the washer. Not crazy about the angle, but that's where I'm at right now

Is the rod from the clutch pedal to the z-bar the correct length? the Z-Bar does look like it sits odd in the pivots. You do have the plastic spherical half moon pivots in?

My Z-bar did indeed hit my Dougs headers and needed modified. My car is currently part for TKO install so if you need pics or length measurements message me.

I've been told its better for the throw out bearing to ride the clutch a bit. Its harder on it to spin up then down to a stop then slam into the pressure plate finger and spin up again then it is to be tuning with the motor. You just don't want it to over "ride" the pressure plate.

Is it a real 360 4 speed car? Pretty rare if so.

If not (and sometimes even so), could be that the wrong pivot mount was used on the bellhousing side. Pretty sure a slant 6 mount will bolt up, but not be in the correct position. I will look at how mine mounts after I drive it home and see how it compares.

Pretty sure the factory procedure for the clutch was 1" of free play at the pedal. Have you adjusted it that way to see how it works?

I took a picture of my z-bar on my 73 it is on a slight angle. To adjust the shifter make sure the tranny is in neutral , there is a slot in the shifter you make yourself a pin and put it in the slot which lines up all the levers for neutral. Hope this helps you.

Does your bell housing mount look like this one? Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists

That is the correct one for a '72 and up A Body. Yours looks to put the ball above the top bolt, which would cause an angle.

Brewers also shows a '71 down mount that might be what you have. Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists

^^ That 72-up mount looks like it would place the Z correctly but guess what going to happen when the bell side of the Z comes down? Prepare to possibly modify the Z...

DionR said:

Does your bell housing mount look like this one? Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists

That is the correct one for a '72 and up A Body. Yours looks to put the ball above the top bolt, which would cause an angle.

Brewers also shows a '71 down mount that might be what you have. Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists

Click to expand...

Yes mine is the first one you have up.

The vin says it is a real 360 car, VS29L4*******. Everything looks stock in the engine compartment, the bell housing is correct and so is the trans. The pedal to Z-bar rod was never removed from the car, even though I got a new one with the new shifter parts. The plastic moon halves are brand new as are the ball studs( they are exactly like the old ones). The bell housing ball stud bracket matches the one I took out, I even tried the old one in place for conformation. When I adjusted for clearance on the throw-out bearing, it gave me approx. 1" free play at the pedal. The shifter was bench adjusted and rechecked once in the car and the rods hooked back up. Thanks guys for asking and answering questions, it helps me to verify that I'm covering all the bases. Dion, thanks for the Brewer's pic. It looks like I do have the wrong one, perhaps someone put it on for clearance with the old headers?

As far as the bracket, I can't believe the z-bar being crooked is causing too much problems. The adjuster rod is still a pretty straight shot to the clutch fork, not at a pronounced angle. I think I'm going to recheck the rod from pedal to z-bar to verify it's the right one. I mean it was already there so I didn't think I needed to change it. First thing tomorrow? If anyone needs pics to help me decipher this, please ask. Thanks again, everyone.

Just checked, trans has car's vin stamped on the side. Real 4-speed 360 car.

The Z-bar is just an equalizer. It it runs at some angle other than stock, then so be it.
The secret is in getting the .080 plate departure together with the proper freeplay.
This is the job of the ratio in the Z-bar. The outboard lever length is fixed, cuz the down rod has to stay in the hole. But the inboard lever length,controls the departure/freeplay.
It would appear that this new clutch of yours needs a new ratio. I think there are three 67 to 73ish A-body ratios; one for the slanty and one for the big boys, and one for the SBMs. The slanty will not interchange, cuz it is too long. The BB is all squirrely on the inboard end.Yours appears to be correct.
If the inboard ball is too high, it will steal ratio, by moving in an arc instead of fully longitudinally.
So, I would look to the ball height first. It should be the same height from the ground plane as the outboard one, and in plan-view, on an imaginary line 90* to the centerline of the vehicle, and ending at the outboard ball.
Once you have that set up right and you still have problems,then you may have to lengthen the arm.
That's what I think.

67Phish said:

Just checked, trans has car's vin stamped on the side. Real 4-speed 360 car.

Click to expand...

Sweat!! You know that's a 1 of 586 1974 Dusters, right?

Love to see more pictures.

Aside from your adjustment issues it appears that there are hairline cracks in your inner fender around the ball stud. Is it in the right location? Does it move around causing lost motion? Does the car have the correct doubler on the outside, under the nut?

IMO the z bar angle looks wonky. Something isnt right.

Also, if it hasnt been mentioned, the 90 degree bracket in the bellhousing that serves as the clutch fork pivot can crack, again flexing and causing lost motion.

IMO, I'd suspect the engine mounts for the driver side lift if you've done nothing with the bell side ball mount. Maybe a little repositioning the engine can help. Possibly a little lift on the passengers side will allow the driver side to roll down.
Ideally your looking for straight across in any view for the bell crank I believe. I like the bell side slightly lower myself.
Check to make sure, by hand pushing reward on the fork, that your release bearing contacts all three fingers at the same time. Just one of them off can eat up the disengagement clearance. The 0.060" plate departure is a starting point to adjust from. Try not to over adjust the 0.060" or you risk the finger backsides clipping the disc springs.
With the clutch engaged and pedal up the release bearing only needs to be off the fingers enough to clear any finger contact.

AJ/FormS said:

The Z-bar is just an equalizer. It it runs at some angle other than stock, then so be it.
The secret is in getting the .080 plate departure together with the proper freeplay.
This is the job of the ratio in the Z-bar. The outboard lever length is fixed, cuz the down rod has to stay in the hole. But the inboard lever length,controls the departure/freeplay.
It would appear that this new clutch of yours needs a new ratio. I think there are three 67 to 73ish A-body ratios; one for the slanty and one for the big boys, and one for the SBMs. The slanty will not interchange, cuz it is too long. The BB is all squirrely on the inboard end.Yours appears to be correct.
If the inboard ball is too high, it will steal ratio, by moving in an arc instead of fully longitudinally.
So, I would look to the ball height first. It should be the same height from the ground plane as the outboard one, and in plan-view, on an imaginary line 90* to the centerline of the vehicle, and ending at the outboard ball.
Once you have that set up right and you still have problems,then you may have to lengthen the arm.
That's what I think.

Click to expand...

No offense; I'm not understanding your statement. "If the Z-bar runs at some other angle than stock, then so be it." BUT, "If the inboard ball is too high, it will steal ratio, by moving in an arc instead of fully longitudinally. So, I would look to the ball height first. It should be the same height from the ground plane as the outboard one, and in plan-view, on an imaginary line 90* to the centerline of the vehicle, and ending at the outboard ball." Believe me, being a tool and die maker, I visualize and want that Z-bar straight. I personally think that when I get the car driving, the engine and motor mounts will all "settle in" and it will probably look a little straighter. Which will, of course, necessitate another clutch adjustment, AND lead me to believe I'll wind up modding the Z-bar like I've read so much about. OR, the engine doesn't move at all, I buy the correct ball stud bracket for the bell housing; then I have to mod the Z-bar anyway. I have no problem with doing that, It'll take me an hour to do at work; it's just upon mocking it up in the first place, I actually had enough clearance between the headers and starter. The motor mount bolt and washer centerlines look to be in the same place as before any changes, so we'll see. Today, I'm gonna take some stuff back apart and check some other stuff. Thanks again everyone!

67Phish said:

No offense; I'm not understanding your statement. "If the Z-bar runs at some other angle than stock, then so be it." BUT, "If the inboard ball is too high, it will steal ratio, by moving in an arc instead of fully longitudinally. So, I would look to the ball height first. It should be the same height from the ground plane as the outboard one, and in plan-view, on an imaginary line 90* to the centerline of the vehicle, and ending at the outboard ball."

Believe me, being a tool and die maker, I visualize and want that Z-bar straight. I personally think that when I get the car driving, the engine and motor mounts will all "settle in" and it will probably look a little straighter. Which will, of course, necessitate another clutch adjustment, AND lead me to believe I'll wind up modding the Z-bar like I've read so much about. OR, the engine doesn't move at all, I buy the correct ball stud bracket for the bell housing; then I have to mod the Z-bar anyway. I have no problem with doing that, It'll take me an hour to do at work; it's just upon mocking it up in the first place, I actually had enough clearance between the headers and starter. The motor mount bolt and washer centerlines look to be in the same place as before any changes, so we'll see. Today, I'm gonna take some stuff back apart and check some other stuff. Thanks again everyone!

View attachment 1715053566

Click to expand...

here's the deal, When you launch at 2500 and the tires hook, the engine is gonna torque over CCW from the front,to the passenger side, and pull that Z-bar into a new relationship. The TO bearing better stay off the clutch during this. And when you shift, the engine is gonna flop back down just long enough to make the shift, and then;streeeeetch, up it goes again,and dragging the Z-bar back up with it. So My thinking has always been that the angle at rest is not all that important.
But you can't have the inboard lever running laterally across the chassis, from inboard to outboard and back while clutching, cuz that steals travel. And your set-up doesn't seem to have enough of it. Either the pedal is not returning to the top, or the pedal ratio is wrong, or the Z-bar inboard lever is too short,or the fork is too long, or the clutch is not made for a Mopar.
Since you didn't have this problem with the old clutch........OK kidding on that one.
To repeat; I would look to the positioning of the inboard ball-bracket.
It appears to me that, the spool-mount K-frame takes a late bell #3515734 with it's own bracket, and
It appears to me that the Bisquit mount K-frame takes an early bell #2843887 and it's bracket.
And Brewers has nice pictures of those brackets. Your solution may be as easy as verifying the bell casting numbers.

BTW, My oem set-up has enough pedal-travel that I do not have to push the pedal anywhere near the floor, to achieve adequate plate departure , WITH the freeplay set to 1inch.

I get what you're saying, it's just I thought the two statements were contradictory. Here's the latest: Took everything apart again except the Z-bar, left that in place. Z-bar moved freely without being hooked to anything. Used the new pedal to Z-bar rod, but it was the same as the old one anyway. Put the old clutch adjustment rod pictured above that had been broken at some point and welded with a thick washer. (hey, it worked before, right?). What I like about this bar is it has the spherical half-ball at the end instead of the rubber insulator and thick washer. It also has 2 nuts to lock the adjustment in place. Started adjusting under the car for the supposed 5/32" free-play. Took it to right before the throw-out bearing makes contact with the fingers. Lower the car, have about an inch or so of free-play at the pedal. Start car, push the pedal to the floor; cannot get the trans in gear. Backing off on the pedal a little produces a little grinding, then a little more and then the car shifts nicely. Take it for a drive trying to only push the pedal to that sweet spot for shifting and bring it home. Start thinking, "I've gone too far". So I back the adjuster way off and sneak up on it again. Got it to about 1/4" of free-play down under, lower the car. Everything feels right at the pedal, start the car, go for a drive. No grinding, easy shifts; I'm getting excited now! Do a couple reverse shifts, back up, first gear, pull up. Start pulling out, wound it up a good bit, shift to second and WHAM! Pedal slams to the floor and now I've got nothing. Yank it out of gear and shut it down. Reach down, I can pull the pedal up by hand but something doesn't feel right. Look under the car, under the hood; can't see anything wrong, nothing visibly broken. Put it in gear, start it in gear and limp home; only a mile. I'm done for the day, need beer! Next morning, up the lift it goes (did I mention how I love my lift?). Now I find that the throw-out bearing has come apart! Calling Brewer's in the morning for a new throw-out bearing and the correct ball-stud bell housing bracket. I'm pretty sure once I get that mount I'm going to need to modify the Z-bar but, oh well. Trans is ready to come out, wish me luck!

Wow, that's a lot of bad luck!

67Phish said:

I get what you're saying, it's just I thought the two statements were contradictory. Here's the latest: Took everything apart again except the Z-bar, left that in place. Z-bar moved freely without being hooked to anything. Used the new pedal to Z-bar rod, but it was the same as the old one anyway. Put the old clutch adjustment rod pictured above that had been broken at some point and welded with a thick washer. (hey, it worked before, right?). What I like about this bar is it has the spherical half-ball at the end instead of the rubber insulator and thick washer. It also has 2 nuts to lock the adjustment in place. Started adjusting under the car for the supposed 5/32" free-play. Took it to right before the throw-out bearing makes contact with the fingers. Lower the car, have about an inch or so of free-play at the pedal. Start car, push the pedal to the floor; cannot get the trans in gear. Backing off on the pedal a little produces a little grinding, then a little more and then the car shifts nicely. Take it for a drive trying to only push the pedal to that sweet spot for shifting and bring it home. Start thinking, "I've gone too far". So I back the adjuster way off and sneak up on it again. Got it to about 1/4" of free-play down under, lower the car. Everything feels right at the pedal, start the car, go for a drive. No grinding, easy shifts; I'm getting excited now! Do a couple reverse shifts, back up, first gear, pull up. Start pulling out, wound it up a good bit, shift to second and WHAM! Pedal slams to the floor and now I've got nothing. Yank it out of gear and shut it down. Reach down, I can pull the pedal up by hand but something doesn't feel right. Look under the car, under the hood; can't see anything wrong, nothing visibly broken. Put it in gear, start it in gear and limp home; only a mile. I'm done for the day, need beer! Next morning, up the lift it goes (did I mention how I love my lift?). Now I find that the throw-out bearing has come apart! Calling Brewer's in the morning for a new throw-out bearing and the correct ball-stud bell housing bracket. I'm pretty sure once I get that mount I'm going to need to modify the Z-bar but, oh well. Trans is ready to come out, wish me luck!

Click to expand...

Hopefully you will get it sorted out! ( Always nice to have a lift. )

Update: If you look at my first picture at the top of the post, you'll see the throw-out bearing. Anything look different? It isn't made out of metal! It appears to be some type of plastic composite center section with the 1/2" bearing "pressed" on to a 1/4" shoulder and then a flimsy tin keeper thru the bearing face. Well, needless to say when I gave it some hard acceleration that thing flew apart easily. Ordered a new throw-out bearing(all-metal) from Brewer's. While I was at it, I also ordered the correct for 74 ball-stud bracket for the bell housing. When I mocked it up, I realized I did in fact need to modify my Z-bar to fit between the headers and mini-starter. Took care of that and everything is straight now. I did need to pull my steering column, the coupling was rubbing the header. Heated the tube and dinged it a little bit, no rubbing now. My next question is this. When adjusting for proper engagement/ disengagement, where is your pedal resting? Here's my deal; if I pull my pedal all the way up by hand, go under the car, the bearing spins freely and the clutch adjustment rod is free. BTW, I'm using the new rod with the ball and 2 nuts; NOT the rubber grommet and thick washer. Now, when I get in the car the pedal is above the brake pedal. Push it to the floor to start it, let it back up and it doesn't come way up like before. It actually rests a little below the brake pedal and operates fine, shifts fine, with no slippage. If I go back under the car with it in this position, I cannot spin the bearing by hand and the rod has pressure on it. Not a ton, mind you, but it doesn't flop around freely as before. Is this normal? I imagine as I'm driving around, the bearing, because it is against the fingers, is spinning along with the fingers. Is this gonna be a problem? Thanks in advance

If you removed the overcenter spring, then this is normal. On mine, I just installed a slightly stiffer anti-rattle spring underneath, to pull the TO fork forward towards the bell; anchor-holes are factory provided.
But this is not normal if the overcenter spring is still on there;you know, the big fat one on the pedal assembly.

A plastic TO carrier?!, I thought it looked odd, but I've never seen such a thing. That's whack!

Two things come to mind,
1)the TO must retract from the PP, or the continuous spinning will wear it out prematurely, and it may overheat.
2) You may not have to clutch it to the floor to provide enough plate departure to make the shift. With the recommended 1 inch freeplay at the top, seldom does the pedal require more than matbe 60 % of the remaining travel; except perhaps for reverse. Also, I don't run a full inch of freeplay. I run just enough to pull the TO off the PP. Adjustments are more frequent, but in my mind at least, the shift is faster,lol. Actually the departure starts sooner, ends sooner, and returns sooner, so my 64 year old leg can put in a good showing,lol.