machanical linkage ?

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Abodyman

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Hello fellow gear jammers. I have a question about building a mechanical linkage for my drag truck. I realize for my Dart the best way to go is to use a hydrolic setup. In an effort to make my launch more consistent, a mechanical setup is the way to go. The problem is, my Dakota came from the factory with a hydrolic style (slave cylinder) setup...... I'm building my truck for a stick shift class, and the majority of the participants have all advised to go with a manual setup. From what I know, I'll need a Z-bar of some sorts, and a pivot point. Does anyone have any more information they could point me too. I will be using my 63 Dart's setup as an example. I plan on building something using Heim joints and tubing for strength. Thanks for any assistance in advance.
 
I'm not sure I agree that there's inherent advantages to mechanical. Especially if you are trying to adapt it into a rig not originally designed.

Some big issues with hydraulics to watch for:

The pedal stroke, cylinder bore(s) and fork travel must all be matched, else you end up with an "easy" pedal without enough travel, or way too much travel, and hire "Hoss" Cartright to operate the thing.

Too small tubing between cylinders. This restricts fluid and slows down action

Too LARGE and using hose which expands, which does nothing but "waste" pedal travel pressurizing and expanding the hose.

In this day and age where so many rigs came OEM with hydraulic, I'd think "juice" would be the way to go with this particular build.
 
67Dart273 You make some very valid points. Initially I felt the same way. The problem I have at the moment, is that the TB I have for it is a Ram style hydrolic. There is no clutch fork needed with this type/style TB. In any event. I'm trying to get the best setup possible, for consistent launches I appreciate your insight. If I were to stay hydrolic, how could I set it up so it is consistent at launch, and engage a 2Step switch for roll control?
 
I'm no expert on the aftermarket stuff. IE the concentric mount cylinder / TO units
 
If you want to avoid Hydraulic, go with a cable. Trucks are a bit iffy when it comes to linkage (mainly on off road rigs, but it applies to all trucks). Body flex can cause the linkage to bind up or move on its own.

My '75 D300 has that problem (mechanical linkage) sometimes the body flexing independently from the frame prevents the clutch from working.

My '84 D50 had a similar problem, I had a Challenger/Cuda Slapstik Shifter in it with mechanical linkage. When I'd pull up a hill at an angle (like a driveway) the body would flex separately from the frame and the mechanical linkage followed... Rowing the transmission from Drive to Reverse or Drive to 1st depending on which way the truck twisted. Not fun. I replaced the Slapstik Shifter with a Cable Driven B&M Ratchet Shifter
 
adiffrentcity said:
Is the truck gonna be carb'd?
Click to expand...

Nope. I'm running a FAST XFI setup on it.

74Dusted said:
If you want to avoid Hydraulic, go with a cable. Trucks are a bit iffy when it comes to linkage (mainly on off road rigs, but it applies to all trucks). Body flex can cause the linkage to bind up or move on its own.

My '75 D300 has that problem (mechanical linkage) sometimes the body flexing independently from the frame prevents the clutch from working.

Dusted, I don't anticipate flexing issues in my application. It is a drag race only Truck. I've installed new urathane body mount bushing. The engine is tied to the frame with a motor plate. The cab is also tied to the frame via the roll cage and out riggers. I also boxed the frame in completely, and moved leafs inboard. Once I finish up the suspension mods, the bed goes back on. The only way to remove it will be to cut the rear bars that come through the plexiglass. I've tried to stiffen up the entire chassis as much as possible to eliminate body flex. The next step is to dial in the linkage for consistent launches. My setup includes a 390 Ci stroker (magnum block) Edelbrok heads with 2.08 intake 1.65 exhaust valves, a custom ground roller cam 242/248 @.050 and I don't recall the LSA right now. All controlled by FAST XFI with a 1200 CFM 4 brrl TB. Out back I have a B body 8.75 currently being narrowed. 4.30:1 gears with a full spool. Once I get this clutch linkage setup, I may be able to get to testing before the season ends. If not, I'll have to wait.
Click to expand...
 
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