Pressure Plate Swap...

[1955CJ-5]

There might be a wear advantage to the larger clutch....more contact area, less wear each time it's used.....the clutch just lasts longer....

The CJ-5 has a (nearly worn out) 9 1/4" clutch. I don't notice the difference..neither slips.....

[Carls_jeep]

Mark, for discussions sake, on some of the trails with large rocks in the way I have tried to pull them off the trail. Sometimes I moved the rock and sometimes the rock stayed and the tires dug deep into the dirt.

To be honest, I don't think a 2000 lb Jeep with a 60 or 75 hp engine is going to slip the stock clutch. As to pulling a stump, that I haven't tried but I have tried to move rocks much heavier than my Jeep and the rock didn't move and the clutch didn't slip but the tires sure did. Low gear, low range with a Lock Right in the rear axle just for you to know.

[athawk11]

Mark, no argument, just discussion.�

It looks like this upgrade option started in 1961. Prior to this offer, 20 years worth of Willys Jeeps were able to fight wars, pull farm implements, and travel the backcountry with no apparent need for the larger clutch.

Speculation� Kaiser was producing this larger clutch for the heavier wagon, FC, CJ5, and other vehicles.� Because they already had it, why not offer it for older vehicles?� It cost them a couple extra holes drilled into the flywheel.� It could offer additional income for the dealers offering service.� Consider your time at the parts counter at every auto parts store.� Buying a new battery?� Perhaps you would like to upgrade your cranking amps. Or buy a better spark plug.� Or store brand oil vs. Rotella T.

My point�guys like us are more than willing to drop more dollars into our vehicles whether there�s a chance at increased performance or not.� The automotive industry knows this.� And they probably understood this back in the 60s.

To your point on pulling farm equipment, stumps, and trucks from mud bogs�There are vehicles more suited to these tasks than a 70 year old Willys.� If I have these chores, and a choice, I would probably leave the Willys at home.

That said, I have no issue with you wanting this upgrade.� If it weren't such a pain in the a..., and there was a clear performance output, I would imagine that many of us would choose an upgrade like this.

Tim

[Mark W.]

Well as I said. The difference in cost for me having to buy virtually everything new save the Bellhousing and Plate (so the $100.00 the proper flywheel cost with shipping is more) is not that much. As to ever needing the extra 14% or friction material well unless I do it now there would be no opportunity to do it later.

As I have said on a couple other forums. When Chug A Lug is done I'll do a complete performance test and make sure everyone knows what the results are.

[Carls_jeep]

I totally agree with using what you have rather than making a lot of parts changes just to get back to original. After all, after 70 or so years of life of these Jeeps hardly anything is really original, unless you find a new Jeep in a crate.

[oldtime]

If changing to a 9-1/4" clutch I would choose the original Auburn clutch assembly and not the Borg Beck clutch assembly.

I wouldn't change over to a 9-1/4" clutch for any Go-Devil unless perhaps the engine was significantly modified for increased power.

I would consider the Auburn 9-1/4" clutch assembly for use with Hurricane engines if that jeep has optional traction such as wide tires  and/or limited slip and it also works hard such as plowing or skidding.

[Mark W.]

In my case I am using the 9.25" kit everyone sells for the CJ5

And yes oldtime my engine is going to be significantly modified it will be bored .060" over it will have the head shaved between .035" and .040" it will have a progressive two bbl carb on an aluminum intake manifold with a fresh air intake and free flow aircleaner, It will have a 4 in to 1 header Electronic ignition with a captive discharge spark box and vacuum advance, No fan, no fuel pump (reducing parasitic drag) And it will be tuned by someone who knows how to time and tune an engine.

on another forum one of the guys put his box stock Willys on a chassis Dyno the results showed 40.25 HP and 75. ft lbs of torque at 2200 rpm at the rear wheels. This would be approx. 80% of the actual HP of the engine due to the transmission, transfer case, and rear axle losses.. Engine HP would have been approx. 50 HP at 2200rpm

He then put an aluminum 8-1 compression ratio head on the engine. Did nothing else to change the performance of the engine. This resulted in an increase of 7.75HP and 20ftlbs of torque again at 2200rpm. Again using the 80% correction factor he made approx. a 9.5 to 10 HP improvement at 2200rpm.

Now remove the fan and the drag from the mechanical fuel pump. Improve the fuel air mixture with a much better carb greatly improve the exhaust system and improve the timing and ignition and yes I think a clutch with 14% more surface area will be called for.

Let you all know how it turns out when the thing is assembled and on the road in a couple years.

[oldtime]

I have friend who regularly races his flatty every year at the Gravelrama event in Ohio.
His L-134 is substantially modified.
He frequently runs it to 4000 RPM then dumps the clutch on take-off.
Needless to say he occasionally blows up the 9-1/4" clutches.
I sold him my genuine 6 spring Borg Beck clutch� because it was simply way too stiff for my needs.

By the way the Auburn clutch was a Dana Spicer product.

[aboyandhisdog]

Mark, your project sounds interesting.  I hope you'll start a thread with some pics as you go along.

[Mark W.]

I have been bloging my progress on the CJ-2A page Look for the Thread in the Projects section that mentions Chug a Lug

Heck here's a link

http://www.thecj2apage.com/forums/a-little-project-update-on-chug-a-lug_topic33676.html

Its going to take until the Spring of 2016 to have Chug back on the road so the thread might get pretty long by then

[Mark W.]

Mark, no argument, just discussion.�

It looks like this upgrade option started in 1961. Prior to this offer, 20 years worth of Willys Jeeps were able to fight wars, pull farm implements, and travel the backcountry with no apparent need for the larger clutch.

Speculation� Kaiser was producing this larger clutch for the heavier wagon, FC, CJ5, and other vehicles.� Because they already had it, why not offer it for older vehicles?� It cost them a couple extra holes drilled into the flywheel.� It could offer additional income for the dealers offering service.� Consider your time at the parts counter at every auto parts store.� Buying a new battery?� Perhaps you would like to upgrade your cranking amps. Or buy a better spark plug.� Or store brand oil vs. Rotella T.

My point�guys like us are more than willing to drop more dollars into our vehicles whether there�s a chance at increased performance or not.� The automotive industry knows this.� And they probably understood this back in the 60s.

To your point on pulling farm equipment, stumps, and trucks from mud bogs�There are vehicles more suited to these tasks than a 70 year old Willys.� If I have these chores, and a choice, I would probably leave the Willys at home.

That said, I have no issue with you wanting this upgrade.� If it weren't such a pain in the a..., and there was a clear performance output, I would imagine that many of us would choose an upgrade like this.

Tim

This clutch was never offered for older vehicles it was an option on CJ5's its a different clutch then used on the Wagons and Pickups which were 10" with the 226 and later 10.5" with the 226 and Tornado engines.

the 9.25" clutch was only 1960 or 61 to 1971 F head option.

The use of it in an older vehicle as I am doing is a hot rod thing where parts from something that was not original is being used to improve the vehicles performance.

[athawk11]

Again, I have no issue with your choice.  I have the modification you covet.  I doubt the PO was interested in the "Hot Rod" aspect that you mention.  This thing was trashed.  Guys interested in improved performance wouldn't normally treat their vehicle like this one was treated.  I believe he chose this route because the parts were readily available at the time of the mod.

I will also have a fairly unique opportunity to compare its performance with my other 3A that has a standard 8 1/2" clutch.  Should be interesting.

Tim