Need Some Help With Hanging Pedals

have done a lot of searching and still have not found two dimensions that would help with my 74 pedals going into my M38A1

Can someone measure for me on a 72-75 CJ5 ?

1. Dimension from bottom of pedal to bare floor
2. Dimension from underside of pedal to the angled portion of floor at a right angle from floor to pedal
Will attempt to attach pic showing what I need

 

Are you using the '74 sled bracket? (from the dash to the firewall).

 

Image of pedals
The complete assembly is a set of 72-75 pedals and bracket with the added piece that goes up toward the cowl
Tim
Does look like a sled!
Dennis

 

After installing many sets of swing pedals in various early Jeeps............one thing for sure is that no two installs are the same..........

You pretty much have to clear your firewall first and see what you have for space..........Up down / L & R. You also need to decide if your going to do a power booster.......which takes more room.
On the pedal set you have shown I believe the pedal foot Pad push point , to the fulcrum above that they both rotate on is about 16" long..........in a normal CJ-5 those pedals are usually about 2-3 inches too long at the floor and need to be cut off some or re-bent ..........reason being is due to the slanted floor below you will need enough swing to get the clutch pedal all the way to the firewall..........to release the ckutch........if the pedal arms are too long they hit the floor early.......that holds true for both mechanical linkage or hydraulic...

So it really boils down to trial & error fitting and not drilling any holes until you're sure about location. Also in the early Jeep the column will be in the way or want you to split the pedals each side of the column.........again sometimes you can bend the brake pedal to the right and make a dog leg out of it to get the pedal on the right side of the column..........but it is tight in there because of the throttle pedal..............Lots of folks go aftermarket on there pedal sets........or perhaps from an Import Truck which are much smaller....................Not hard to do just have to be patient and think out every step before cutting or mounting..

 

Pedal set in a CJ5...........similar bracket as yours....cut off to clear dash and a brace added above to the cowl to strengthen the mount thus eleminating having to install a large heavy plate on the firewall motor side to capture the Brake Master and pedal force...........Hope this helps!

 

From memory the height above the floor to bottom corner of rubber on my 1974 is 6 inches.
From the same point on the pedal to the angled floor is around 7.25 inches

Very rough dimensions and I can double check in the morning if it helps.

 

Everyone, thank you for the info! This is all very helpful!

Browncoat - yes if you can double check that would be very helpful.

Based on my preliminary fitment with a hydroboost type system (Elliott's adapter to an Astro van hydro unit) it appears that the brake pedal will likely be to the right of the column.......will have to check the gas pedal and possible brake pedal interference based on notes above!

I did plan on using the forward mounting point to lessen the leverage on the firewall..........great pictures tarry99!

tarry99 - did you have to modify the pedals to make them achieve the desired "throw" for the clutch? The pedal shape appears to be correct for clutch on left and brake on right of column without horizontally changing them. Was thinking of slightly moving down the pushrod point from the pivot to achieve about 1.5" of clutch travel. Realize this may increase the clutch pedal pressure somewhat. Also trying to leave the M38A1 light switch in place (will require splitting the attachment from pedal sled upward to cowl to fit).

Dennis

 

FYI..........Going off factory clearances on a 74CJ vs a M-38 will probably not compare very well.....as allot was changed in that cab forward when AMC took over....

As I mentioned above...........the pedal arm length will probably be too long to the floor and firewall , but that depends on how high up you can stuff the pedal set...........which that height will first depend on what's on the engine side of the firewall in the way of Master cylinder and Hydroboost system....................

You have not mentioned what type of clutch system will you be running? Hydraulic or manual linkage?.............

Keep in mind the longer the pedal is from the fulcrum point the longer the pedal has to travel to do it's work.............................1.5" of pedal or clutch travel as you state at the floor is not enough...........that would be fine if you had that much net travel at the clutch fork tip..............but it requires more travel at the pedal to net 1.5" at the fork either via manual linkage or hydraulics.

You also have to understand that whatever travel you have at the clutch fork tip.............get's cut by 50% once it enters the bell housing and gets to the throwout bearing as that ratio is 2:1....
1.5" of travel at the clutch fork would be great............it's just getting there that can be complicated.

Basically I like to start with as much travel as I can get at the clutch pedal to floor and firewall.............keeping in mind you can still adjust pedal ratios & lengths...............if you go hydralics then you can play with bore sizes to increase travel..........in both cases you also want to be mindfull of clutch & brake ratios at the pedals..

 

Tarry99 thanks for the inputs

The 1.5" is what I currently measure with the pedals mocked up in the space behind the dash for the clutch fulcrum point, sorry I was not clear in the earlier post.
The pedals have approx 6 inches of travel through their arch before hitting the floor - starting at roughly the same centroid as the floor pedals at their rest (fully extended into the cab?) position and hitting roughly at the same point the floor hit pedals when fully pushed to the floor.

The Clutch will be hydraulic so I can play the force vs displacement games if required.

Is 1.5" of travel into the clutch master sufficient? Would like to stay with a equal displacement clutch master and slave if I can. But as you noted could go with a bigger bore for the master to produce more travel.

So far this looks promising!
Dennis

 

My memory was not quite correct with the pedal heights Dennis.
I had them back to front
Height from floor is 7.25"


And the slope distance is actually around 6.25".

 

browncoat,
Excellent, thank you! Gives me another datum for the placement.
Dennis

 

Probably not........although close......Its a game of playing with the bore size on paper x the amount of travel...which equals volume.........take that number and see how far you can push the slave at the other end.

A bigger bore equals more volume which can mean more travel at the slave if using say a 7/8" bore master vs a 3/4" slave..........but sometimes the larger bore makes the the pedal to hard to push........again back to pedal ratios.......which on a hydralulic or mechanical system needs to be about a 6-7:1 ratio............And while on ratios you need to pay attention to the brake side also as to where your pushrod is going to attache to the pedal arm........for power brakes that needs to be about a 4:1 ratio...........lots of those pedal sets were for non power brakes so you need to check an see what you have ........If you look at the picture above.......the metal center of my pedal set was removed and a new plate installed that allowed me to move the master cylinder center line into a more correct position ratio wise.....and also to get a better center line push into the master piston......

I like using the 3/4" slave from Novak..........Novak Conversions :: Kit HCR3 that has a full 2" of travel.........expensive Yes....... but works........they also make an adjustable throught bearing with a threaded collar.......that also helps to get the correct free play in the system....

Again whatever you get for travel at the end of the throwout fork will translate to about 1/2 that amount in movement at the throwout bearing............for an average clutch pressure plate to release it takes about .500-.700 " of travel at the bearing........that includes whats lost in either flex or looseness along the path .............add in another .500-.750" minimum amount of freeplay at the pedal.........and you'll see why getting 1.5" at the Clutch fork tip is just a bare minimum....Good Luck!

 

Pay attention to the details as Terry mentions above. Allow some extra room for adjustment and freeplay. I went through all the calculations, many times, built my hanging pedals and used the Novak 3/4" clutch slave as well. What I didn't know was that the Novak slave comes with a different clutch fork that is longer so I lost some travel. Pulled the trans/t-case (again) to install the Novak adjustable throw-out bearing to regain every bit of adjustment I could. Worked out well in the end but was close to going the other way.

 

What did you come up with on mounting your pedals I’m running into the same problems. I’m using hanging pedals from a 77 cj 5 and will be using a hydraulic clutch system. Just mostly looking for pictures of pedal placement and did you have to shorten the pedal arms to get enough clearance to from them to the floorboard.

 

When I did my hanging peddle conversion I had to shorten the peddles. I’ll see I can find a picture of the final mounting.

 

We used a YJ pedal set in Steve's 71. Should be the same as the 76 and up CJ7/CJ5 pedals.
Your welcome to come down and take a look at them.
I did not shorten the pedal arms at all, just bent them, cut off the stock pedal pad cups and replaced them with flat stock.
Here are a couple pics. I basically just heated and bent the arms to match the firewall/toeboard angle when fully compressed.

 

Once again Kyle to the rescue... that's what I needed thank you.

 

Glad I could help.
You can come see them in person if you want, Steve's jeep is in the container next door.
I also have a title here that goes to the brown jeep you picked up.

 

Crumb cakes I forgot about the paper work . I'll give ya a jingle in the near future when work slows down and come get it..