Here's the situation:

1963 Dart GT slant 6 originally three speed column shift. Converted to four-speed by unknown past evil owner using a date-code Jan '72 A-bodycast-iron case A-833 and a '76 A/F body aluminum bell housing, using an adapter around the internal bearing retainer to fit. It has a 9 1/4" Borg and Beck three finger clutch.

A plate was fabricated to locate the bell housing Z-bar ball pivot higher in order to level the Z-bar with the fender ball pivot. Also, a longer release arm lever was stick-welded on the Z-bar closer to center in order to line it up with the release arm.

The clutch effort is really high, there is a suspicious grinding sound with the clutch pedal fully depressed and the damn relocated lower lever interferes with what little room exists for a decent exhaust system.

I have the engine out now and would like to fix this once and for all. I measured the release bearing travel and it's 1 5/16", with the clutch contact end of the bearing extending beyond the retainer tube at full extension.

Is this normal? I'm thinking that the longer lower arm is decreasing the leverage (resulting in higher pedal effort) and increasing the release bearing travel (resulting in the grinding noise).

Also, the "custom" lower arm is 1 " longer than the upper (clutch pedal) arm; should they be equal?

Finally, should I be able to use a 10.5" clutch with this bell housing? Would a diaphragm style pressure plate work?

I'm seriously considering a McLeod hydraulic release bearing, but the location and reinforcement issues of installing a clutch master cylinder have me spooked. Any experiences to share?

Thanks again for a great column.
Marc in SF

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Open the pod bay door, Hal.......

As you know, a lot went "wrong" when they tried to make the later set-up work in the earlier chassis.

In a "nutshell"... it sounds like the "z-arm" (bell crank) ratio has increased, causing extra peddle effort and too much clutch "finger" (lever) travel.

The "best" solution... find the correct cast iron bell housing, fork & and inner Z-bar bracket for the 64 - 66 A-body vehicles and swap those parts in.

"Plan B": Add some length to the upper arm of the z-bar to counter-act the ratio increase, caused by the lengthening of the lower arm.
DD

Appreciate your analysis and recommendations, Doctor!

I like plan "A" best; a question about the early cast iron A-body bell housings:
My A833 is a 1972 unit and has a 4.80" diameter input bearing retainer(currently fitted with an adapter ring to fit the 5.125" opening in the 1976ish aluminum bell housing)...will this trans fit the early iron bell housing?

Also, will a 10.5" clutch fit?

Thanks again,DD!
MD

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Open the pod bay door, Hal.......

My 62 Valiant uses the Aspen type bellhousing with an A833OD. The bellhousing came with a bracket to mount the inner pivot of the Z bar and everything seems to line up pretty well. My stock Z bar works with this bracket and everything seems to be in the right place and the clutch works smoothly. I might have had to shorten the z bar by 1/4" or so. Others may know where to find one of the brackets I am referring to. The pivot is at the top and the bracket is held in place with one large (13/16 head) and two 9/16 head bolts. You are limited to the 9 1/4 or 10" clutches with the notches in the cover with that bellhousing.

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If you didn't drive it there, it's not a street car.

"A plate was fabricated to locate the bell housing Z-bar ball pivot higher in order to level the Z-bar with the fender ball pivot."
This is good if done right, the Z-bar should be straight and square in every direction.

"Also, a longer release arm lever was stick-welded on the Z-bar closer to center in order to line it up with the release arm."
This is bad, very very bad. If you can find the original Z-bar or find one to copy to get yours back to stock it should take care of your problem. My guess is they did that change to compensate for not having a long enough adjustment on the clutch rod or for having the wrong length clutch fork for it to all line up.

If this is true the part you will need after fixing your Z-bar is
https://www.yearone.com/Product/1966-74 ... body/af256


"You are limited to the 9 1/4 or 10" clutches with the notches in the cover with that bellhousing" this is mostly true.

http://slantsix.org/forum/viewtopic.php?t=48219
http://www.slantsix.org/forum/viewtopic.php?t=49624
Before you do anything check the ford bolt pattern ( pic at the end) to make sure whatever flywheel you choose will have enough meat to safely machine in the new holes.

Thanks to all for joining in on this topic! I'm fairly new to Moparworld and I value experience; it keeps a dear school, but this fool will learn in no other.

I'm leaning toward Doctor Dodge's "A" plan of sourcing and replacing the bell housing/z-bar with stock early A-body units, but also good to hear that the late bell housing has been made to work with the stock z-bar. At some point I may want to experiment with an OD trans, and for that I believe I would need to use the 5.125" bell housing I have now.

My current setup has a fabricated bracket that relocates the ball joint bracket (source unknown, but it looks 'factory made' and has a "B" stamped on it) up about 2.5" from the original set of bolt holes on the bell housing. That sounds different from the Aspen bell housing setup.

ExnerGeek, would it be possible to measure where the centerline of ball joint on that car is located relative to the flat edge of the bell housing (where the dust shield bolts on)? Mine is 6 7/8".

Jerame, agreed that this is the heart of darkness in this mess! I checked the year one link and measured the clutch rod I have....it is 7"end-to-end, sounds like the right one. I wonder your observation about the clutch fork is the key; the clutch fork on the car now is approx 11/1/2" long. Are there any other measurements that would be helpful?

Again, many thanks for the help on this frustrating challenge.

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Open the pod bay door, Hal.......

The best I can give you on the clutch fork is a post from Dusteridiot:
"Is the 833OD throw out bearing lever unique to the OD bellhousing?

Good but loaded question...

If your bellhousing is a 1981-1987 A-833 OD with the ballstud clutch fork...then yes, only the truck version works and it is a longer fork for use withe the truck/van Z-bar...

The 1975-1980 units with the spring tab retainer (bellhousing has a iron angle with a square hole in it to hold the fork), then no...the late 60's to 1980 3 and 4 speed fork will work (note that the 3 speed fork has a little different configuration on the edges of the fork, but inserts fine and works fine...). The NP435 fork from a truck uses a different TOB and will not work for this application...but in the late 70's some trucks with the NP435 did get the standard A-833 TOB, and the long fork....

Other things to note: Using the longer truck fork has worked for some people but in a pre-67 A-body the installation of the fork may be difficult due to the earlier A-bodies location of the torsion bars....also if you do go that direction, look at the alignment of the fork and Z-bar/actuation rod...if they are at more than a slight angle (15 degrees or more), they may not stay together too long especially in spirited driving. "


My clutch fork (from the aspen my bellhousing came from) worked out well so I didn't have to go research it like a lot of the other pieces. (I started with an auto trans) I also used the aspen z-bar but had to put a large machined spacer on the bellhousing to move that pivot closer to the frame rail to make it work.
The Z-bar bracket sounds about right, the only ones I have seen that are not a bracket held by two bolts are on truck bellhousings. Yearone has some nice pictures of those as well.

Are the bushings in your Z-bar shot or full of mud? that could give a grindy sensation and excessive pedal effort.

Per part number, the bell housing is 1976 F-body, and has the "iron angle" clutch fork pivot. There is not a lot of clearance between the end of the clutch fork and the torsion bar...and this IS a 1963 Dart. I sure wouldn't ask you to remove your clutch fork to measure it, but can you measure how far out the clutch fork extends from the bell housing to the centerline of the actuating rod?

Thanks for asking about the z-bar bushings; they are in good condition, spotlessly clean and lubed.

If I have the correct clutch fork, then I guess I'll try re-engineering the z-bar to correct the unequal upper and lower arm lengths.

Given the space limitations around the z-bar upper arm and concerns about creating wacky angles at the lower arm, I'm now considering splitting the 1" difference in length by extending the upper arm 1/2" and shortening the lower arm by 1/2"; that will give equal lengths.

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Open the pod bay door, Hal.......

I will get you the best measurements I can on the clutch fork. For the Z-bar look at the pic in https://www.yearone.com/Product/1966-74 ... body/bh223
It seems to me that the pivot lengths were not equal on the early dart I was looking at but I don't know for certain.

I checked the dimension from the bottom of the bellhousing to the center of the Z bar pivot and it was 6 3/4" just like yours. You must have the same bracket I do so a stock Z bar, maybe shortened a bit, should work fine. I have over 100000 miles on mine. I did tear up a Z bar once but I have used McLeod and Weber clutches most of the time that require greater pedal pressure. I made some gussets that wrap around the tube and are welded to the arms to distribute the load better. My linkage clears Clifford shorty headers wyed into a 2 1/2" exhaust system but it is tight.

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If you didn't drive it there, it's not a street car.