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Douglas

Centerforce Clutch for Willys MB

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Hi Moses,

 
I hope you can point me in the right direction, I’m nearing the end of a very thorough four year restoration of a 1942 Willys Jeep which I had shipped from San Francisco in 2008. 
I’ve made great effort to keep it all looking as correct as possible and do the best job I can. 
As I’m not a mechanic by trade, I farmed the gearbox and transfer case out. Now it’s in and running, there is a horrible noise from first and reverse, so I’ve resigned myself to pulling it all out and doing a post mortem. Naturally I’m more than disappointed as it’s a day away from being ready for the road and now summer is over here in London.
 
The reason I’m contacting you is that I have your excellent Jeep CJ 1946 - 1971 Rebuilder’s Manual, which has been very useful on some of the mechanical issues. I decided that if I have to pull the drive train out again, then maybe I’d sweeten it by doing the Centreforce clutch conversion you mention on page 242. I’m assuming this will work on the MB.  If so my question is, can you tell me exactly what is necessary regarding machining the Pinto clutch, and how you would mount the pressure plate in a lathe. 
 
There is a small garage down the road with a machine shop, and have found a Centreforce distributor in South East England, I just need to know exactly what is required to make it work as it seems such a great idea.
 
Any information you can give will be greatly appreciated.
 
Many thanks,
Douglas.

IMG_9156.jpg

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Hi, Douglas...Thanks for sharing your project!

I was very satisfied with the clutch upgrade as described; however, the machining can be an issue for many.  Drilling and tapping the required flywheel clutch cover bolt holes (using a bigger bolt circle and proper bolt size/threads for the Pinto clutch cover) is not a difficult task.  The new, tapped bolt holes in the flywheel can be performed by a qualified machine shop.  The key is to establish an accurate bolt circle measured from dead center on the flywheel or a common reference point.  A qualified machine shop has ready means for establishing the bolt circle diameter.  The clutch cover must spin on center. 

The clutch cover modification requires milling 0.100” off the face of the Centerforce Pinto pressure plate to get the correct “stack height” from the flywheel through the clutch release bearing. Centerforce performed this milling work for my project, and as you would imagine, they have fixtures and jigs to accommodate such machining.  If you do pursue this clutch cover and disc upgrade, with the increased disk surface area and Centerforce clutch cover design, consider having Centerforce provide a custom-machined clutch cover, ready for installation. 

I suggest contacting Centerforce regarding the project.  They can take the approach we did for the book project or perhaps have a more contemporary solution.  The gains are obvious, but the work involved and cost may not be justified.  If your MB has a relatively stock L134 engine, the original clutch design is adequate. 

Worth noting, you do not have 5.38 gears like later 4-cylinder Jeep CJs, and the 4.88 gears do increase the clutch load.  (Fortunately, the horsepower output is relatively low.)  I would definitely stick with the original tire diameter and not mount oversized (bigger diameter) tires.  The stock type clutch would have a tough time with the load created by oversized tires, and the engine would suffer, too. 

I’m guessing that you have restored the T84 transmission, a three-speed?  Or did you convert to a later T90?  You’re not retrofitting a T98/T98A or T18 four-speed in this case?

Moses

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I do still have the early T84, I had it re built at a transmission shop, thinking that it was a safer option, however it makes a nasty grating sound in first and reverse, so the theory amongst those I know who speak fluent Jeep is that they put the reverse idler in the wrong way round, so I have to see the current installation of engine and trans as a test fit. Disappointing at this stage.  I've contacted centerforce as you suggest, but I think you are right, it may well be more trouble than it’s worth for the amount of use I’ll be giving it. The tyres are stock size.

 I rang Centerforce technical dept. The guy I spoke to knew nothing about your previous project or book and said that they don’t do custom clutch components anymore. He said that they would dismantle the pressure plate assembly, do the machining and re assemble. Obviously something we can’t do at home. He said that machining the same amount from the friction area of the flywheel would have that same effect, I’m not sure about that. He also said that as the clutch wears, the fingers will get closer to the bearing, potentially giving a problem. At around £200 for the pressure plate, sadly I think it’s potentially opening an expensive can of worms.  It looks as if I’ll stick with the original design.

Bubba did fit 11” brakes from what I think was a Wagoneer, but I elected to keep them and rebuild them, apart from being bigger, they are self adjusting. I made the little S lines for the front so that they look more like the original as they had rubber hoses coming from the backplate instead. 

I’ll have to sign up to the forum and add the question for you. Your book is really good and has torque settings for parts that other books don’t list.

When this Jeep is done, I’m planning to do a little home brewed web site with lots of pics on Square Space or similar, I bought the domain name 42willys yeas ago, so I’m part of the way there. If that happens I’ll let you know. 

Apart from the obvious brakes I’m trying to keep the Jeep as period correct as possible, lots of expensive slat bits from USA, Australia, Europe. I’m also creating a used, un restored look, not the factory fresh look, I’ve cut out the rust, and filled Bubba’s many, many drill holes, it’s all steel, no filler on this thing. 

I don’t know it’s history, but am marking it up as my uncle Phil’s anti aircraft unit who went into France two weeks after D Day, as a mark of respect to him as he died last year. My aunt who died this year was a G.I. Bride, they met on the Tube here in 1945.

Many thanks again, I appreciate your help. 

Best,

D.

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Douglas...See my replies in your quoted post:

2 minutes ago, Douglas said:

I do still have the early T84, I had it re built at a transmission shop, thinking that it was a safer option, however it makes a nasty grating sound in first and reverse, so the theory amongst those I know who speak fluent Jeep is that they put the reverse idler in the wrong way round, so I have to see the current installation of engine and trans as a test fit. Disappointing at this stage.  I've contacted centerforce as you suggest, but I think you are right, it may well be more trouble than it’s worth for the amount of use I’ll be giving it. The tyres are stock size.

The T-84 is a somewhat easy transmission to assemble, similar to the T86/T90 but actually easier...The T-84 has a much weaker bushing (not needle bearings) arrangement on the counter gear.  The bushings do make it quicker and easier to assemble the gear set, as you do not need to hold needle bearings in place.  On the other hand, this bushing design places a time stamp on the life expectancy of a T-84.  You can rebuild this transmission yourself and likely would be very satisfied with the accomplishment.

 I rang Centerforce technical dept. The guy I spoke to knew nothing about your previous project or book and said that they don’t do custom clutch components anymore. He said that they would dismantle the pressure plate assembly, do the machining and re assemble. Obviously something we can’t do at home. He said that machining the same amount from the friction area of the flywheel would have that same effect, I’m not sure about that. He also said that as the clutch wears, the fingers will get closer to the bearing, potentially giving a problem. At around £200 for the pressure plate, sadly I think it’s potentially opening an expensive can of worms.  It looks as if I’ll stick with the original design.

Centerforce, like other companies in the post-Great Recession automotive aftermarket, is no longer the close knit community it once was.  I had great friends and nearly a two-decade relationship with Centerforce when we did the Pinto clutch cover modification.  Our pilot project has no legacy at Centerforce, which means that Centerforce sees no market for a vintage Jeep clutch upgrade.  It's time for us to move on.  Find a quality OEM replacement clutch assembly.  If you can find a savvy rebuilder, one upgrade is better springs that can be incorporated in the clutch cover build-up for additional clamping force.

Bubba did fit 11” brakes from what I think was a Wagoneer, but I elected to keep them and rebuild them, apart from being bigger, they are self adjusting. I made the little S lines for the front so that they look more like the original as they had rubber hoses coming from the backplate instead.

11" x 2" brakes are a classic and great improvement.  Make certain that the brake master cylinder can actuate the four larger wheel cylinders and not be short on fluid displacement volume.  If these brakes are adjusted properly, and self-adjusters are a big plus in this regard, that will reduce the fluid displacement demands. 

Your book is really good and has torque settings for parts that other books don’t list.

Thanks, Douglas.  I wanted the book to be a handy companion at your shop or work bench...

When this Jeep is done, I’m planning to do a little home brewed web site with lots of pics on Square Space or similar, I bought the domain name 42willys yeas ago, so I’m part of the way there. If that happens I’ll let you know.

We would be happy to mention your website when you get it online.  Smart domain name! 

Apart from the obvious brakes I’m trying to keep the Jeep as period correct as possible, lots of expensive slat bits from USA, Australia, Europe. I’m also creating a used, unrestored look, not the factory fresh look, I’ve cut out the rust, and filled Bubba’s many, many drill holes, it’s all steel, no filler on this thing.

First thing I noticed was the significant sheet metal work...Congrats! 

I don’t know it’s history, but am marking it up as my uncle Phil’s anti aircraft unit who went into France two weeks after D Day, as a mark of respect to him as he died last year. My aunt who died this year was a G.I. Bride, they met on the Tube here in 1945.

Very interesting history to convey here, Douglas...My wife's Uncle Roy and I were close friends, he landed at Normandy immediately after the first wave as part of a graves detail.  They were very busy, as you might imagine.  We're fortunate to have known or been related to these men.  Your MB is a great tribute!  

Many thanks again, I appreciate your help.

Best,

D.

Please keep us updated on Bubba...Wonderful project that brings a flood of memories for many of us!

Thanks,

Moses

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