Hey Guys,

I Started a new thread on this as the discussion got into it from a Different thread/title and I wanted some more relevant input towards a solution...

Here's the case...

Have a 1970 cuda running a '66 mild 426 with all new 143 tooth ram flywheel, an 11 inch ram clutch, ram borg and beck style pressure plate , ram throw-out and all new pedals/linkage/fork/adjuster/return spring... I verified with brewers that I have the correct 15 inch clutch rod and 9 inch z bar with the 1 1/4 lower offset for the 11 inch bell housing.

I'm having trouble getting the clutch adjustment.

All was good after install but the pedal felt a little weird and there seemed a hint of slip, so I poked around and realized my installer removed the over center spring... recommended for a diaphragm but not borg/beck, so I put it back in, and... pedal feels normal now, except... Now with the spring in, I am caught between adjustments.

At the recommended 1/4 in freeplay at the bearing (by ram) I have the common condition of the pedal not coming all the way up, the over center spring keeps the pedal pinned against the bearing. As I adjust the bearing clearance less it improves... but, I cannot get to the point where the pedal will pop up on it's own like it's supposed to, without running completely out of bearing clearance..

The car sits now with an 1/8th of bearing clearance and requiring a toe lift every time to get the pedal up. It might even pop up over a bump.. thats how close I am !

my questions:

1: Is there a simple solution I'm just missing here ? I did try a longer pedal to z bar rod, but it seems the play in the linkage (all new)is still too much to get the pedal back up past the over center point.

2: Can the over center point be adjusted or modified ? Anyone done this? Mine seems like there is no way to even get the recommended 1 inch play on the pedal...If I can get the "pull down" to start an inch later in pedal travel than it does now... all is good !

3: Does the direction of install on the over center spring affect it's over center point ? i ask because the service manuals and parts book all show the spring installed with the spring towards the firewall and the long part to the pedal... all pictures on the net show it opposite.. spring to pedal and long part to pin close to firewall. Much easier to install the latter way.

4: Anyone running a borg and beck style clutch without an over center spring ? I know guys remove it with a diaphragm.

Help on this topic appreciated... I'm sure allot of other "toe lift" clutches exist out there which owners would love to cure !

I don't look at the "free play" pedal adjustment or TOB clearance spec recommendations from the mfg,I start with the airgap of the clutch disc, see what RAM specs the air gap at?, if no specs are available, a BorgBeck cover is usually .040 to no more than .050 max, after the airgap spec is achieved and the clutch engagement and shifting into reverse and 1st gear encounter no clash, then look at what you have for free pedal play, and TOB clearances,and adjust those values without affecting the clutch airgap spec

Trying to set the clutch with pedal specs might result in you over centering the clutch cover on release resulting in a damaged cover, or warped cover ring

All of the factory OEM stick shift Mopar cars I've had needed less than .125 air gap between the throwout bearing and pressure plate fingers on the borg and Beck or Long style pressure plates to get the pedal to ride where it should Set it at the minimum(.060+ or -)air gap on the fingers and see how that does for your car

Is the release fork return spring in place? This is needed to return the pedal to its up stop.

thanks for the reply,

I'm not actually using the pedal specs to adjust, I just referenced where others say they should be ballpark, at adjustment... I know various setups can be totally different here and ram even states a pedal closer to the floor is usually going to be closer to what they call for. I was using the TOB clearance for my adjustments.

I've seen a couple different methods explained for setting by air gap.. one real involved with crank flange and compressed throwout calculations (outta my league) and another that basically says push the pedal to the floor and measure between disc and pressure plate while adjusting at the rod... which seems wrong if you are suggesting you can alter the bearing clearance after... cause you'd have to turn the rod again. Can you run down the steps to adjust by air gap ?

yes

Setting air gaps is all fine and dandy if you have access. But if you don't (like those of us with scattershields) then you have to use the pedal freeplay as your measurement - which I've always done anyway.

1" of pedal movement is just about right and everything should work fine and perform well.

The only time I had the pedal sticking as you describe it was because the plastic bushings in the bellcrank were shot and causing it to bind. So if everything isn't new, look for something binding.

Just to satisfy your curiosity, adjust all the free play out of the assembly and see if that little extra is enough to make the pedal pop all the way up.

Doesn't hurt to grease the pins where the O/C spring mounts - the spring does actually move on those pins during pedal travel.

FWIW - that small spring on the fork just keeps all the slack out of that assembly - it has no affect on the pedal.

Make sure you have a clutch pedal stop bumper on your pedal assembly. If it's missing it may have an affect on your adjustments.

I've never used the rubber dust boot on the clucth fork on a single piece scatter sheilds so I can use a mirror and a light to check the throwout to clucth finger clearances
The better choice is a two piece scatter sheild just for that reason, I'm putting one of those in my latest pump gas battle cruiser. Some idiot had cut the upper ears off that are needed to to keep it bolted together in case of a flywheel or clucth explosion before I got it That means it can never be SFI recertified anymore Not that I'm going to put a stick shift car together to race and be NHRA legal agian

You are getting some good answers here SMAC but all is assuming your linkage ratios are correct. Without the proper ratio you may be only able to achieve 1 out of 2 desired adjustments.

1st is throwout bearing clearnce. 1" factory recommended clearance is WAY TOO MUCH, for performance driving. Adjust until bearing spins and back off a bit.

2nd when the clutch engages. This is usually 1/2 to 2/3's up off the floor.

If you can not achieve both, 1 arm on the z bar may need its length modified or the length of the release fork. Changing any linkage rods does not change ratio.

You can run without the overcenter spring. Its only job is to reduce pedal effort from 1/2 way down to the floor, exactly when a 3 finger Borg N Beck needs help.

yeah the 1 inch was refering to the pedal play... don't worry i'm not trying to get an inch at the bearing ! Ram is calling for 1/4 inch there... what i have done is almost exactly what you said... I set the TOB clearance at 0, just touching the fingers (my pedal returns here) then i worked it out from there a few turns at a time until my pedal stuck... backed it up a turn and... the good news is, i have clearance and a pedal that returns... I can't fit my feeler gauge up there to measure it exact but i'd say I'm a little less then the .060 cab mentioned above. There is a slight gap basically just enough that the bearing is not riding on the fingers... not much more. Hopefully that will be ok. gives me about an inch of play on the pedal... but mostly linkage slop.

The z bar ratio could be out like you said but I am assuming the aftermarket pedals have the over center stud on the pedal a touch off (too low), if that stud is mounted higher, over center will happen a touch later in the pedals travel. so more up pull, for a touch longer.

Where is your pressure plate from? Maybe the finger to flywheel distance is too short. I think there is a spec for that height. If it's too short the overcenter spring will not return. Luckily this gets better as the disc wears.

If your bearing clearance is good and the engagement point is good. I'd just run with no overcenter spring. Just confirm the release fork spring is strong enough to hold the entire linkage assembly off the fingers.

This was a good read. I’m struggling with a strange problem now. Everything is brand new. Bushings, clutch, engine, flywheel etc. something in the clutch is pushing back on my TO bearing above 2000 rpms. No idea what’s going on. 1” of freeplay and that tension changes with RPM. Feels normal to 2000, then after that it stiffens up. So strange.

I will throw my 2-cents in here, for whatever it's worth.

a. I have run into this exact same issue with the "over center movement" of the clutch pedal where the correct adjustment is right at that "pivot point"...annoying.

b. If you're sure the clutch is adjusted how you like it at that point, then you could always rig up a longer "upper bump stop" to hold it down where you want it.

c. I personally prefer the clutch pedal as low as I can get it while still allowing enough pressure plate movement to go into 1st/reverse and not letting the throwout bearing drag on the clutch fingers....it's best for drag racing in my opinion.

d. You can adjust the pedal quite a bit up or down and the clutch will function just fine for daily driving.

e. Even with a 2-piece scattershield (Lakewood anyway), you can't access the pressure plate/disk to measure the separation, so 2-piece vs. 1-piece makes no difference.

f. Having all the bushings, clips, bushings in the z-bar linkage in place & greased is very important. I recommend the metal "1/2-ball" that replaces the rubber bushing in the release fork.

g. Just in general (probably doesn't apply here), if everything looks good, but the clutch still acts way off, then it may be the release fork church-key type spring or somehow the throwout bearing slipped off the fork.

Hope some of this helps somebody here