MTFCA Forum

There is a fella in the classifieds looking to buy a TH400 clutch conversion, and he is getting a bunch of naysayer responses. I have been abusing a TH400 clutch set for 10+ years in my speedster, and another set before that for at least 5. Never had an issue... but others report repeated failures...?! What say you...?

Engine modifications and body styles provide a sense of load that the clutch experienced. Did you check the clutch spring pressure? How many friction discs were used? What TH400 friction lining did you use? Did you use new steel disks? What was the condition of the clutch hub/drum lug surfaces? What did the “burned” friction disks look like when removed? What did the steels look like when removed?

As a engine builder at my end of the world, I only fit the 400 or watts/jack rabbit, never had a failure yet. The only answer to a failure is simple, the owners have not been instructed on how to drive a Model T correctly. Some Utube posts with the titles of how to drive a Model T is a sure testament to back up what I say.

Never had a failure with either of our three Model T’s with the Turbo 400 Plates with the oldest installed in 2004.
As these are Automatic Transmission Plates, they are not designed to slip, but more so be applied instantly with great pressure
from a hydraulic oil pump. With the Model T, you shouldn’t “feather” the engagement of high gear but drop it in quickly.
The crispness of the shift will vary between the Green material plates to the Fawn coloured that are installed in the automotive version of the Turbo Hydromatic 400. My experience is the Green is
a firmer shift.
Slippage due to a weak spring, catching on damaged guides or driving style will soon soon burn up Plates that weren’t designed to slip.
Additionally, any hint of condensation / water in the Engine oil will cause the friction material to delaminates off the metal base of the plate.
Just my experiences .....
Alan in Western Australia

I do not know how the people drive these cars, the spring has been changed in all of them, these engines came from other engine builders from all over US, the square wafered ones seem to hold up the best, but the metallic material in them makes me wonder when they fail where is it going? The new Watts clutch has what it looks like brass in them, I have seen one of them destroyed with 50 miles on it, this one I think bit it from triple gear pin to tight. At one time I liked the looks of these newer clutches and was going to try one in my own but after replacing this many, I do not like wrenching on mine and would rather be driving it!

It is a love or hate thing from experience. I have used both Jack Rabbit and Watts but I believe as Joe has stated, Correct spring pressure and material used, and everything rebuilt correctly. I have never had any issues and I burn rubber!

Hank

Jack Rabbit and Turbo 400 are the same Green Plate. The difference is the Jack Rabbit has been professionally machined to
remove a few teeth making it a direct retrofit for the standard Ford inner plate. When using the standard Turbo one you have to
purchase the multi, fine spline Centre Hub or grind off the excess teeth. I have never seen the Watts Clutch so can not comment.
Alan in Western Australia

Alan Long wrote: ↑

Tue Oct 26, 2021 7:52 am

Jack Rabbit and Turbo 400 are the same Green Plate. The difference is the Jack Rabbit has been professionally machined to
remove a few teeth making it a direct retrofit for the standard Ford inner plate. When using the standard Turbo one you have to
purchase the multi, fine spline Centre Hub or grind off the excess teeth. I have never seen the Watts Clutch so can not comment.
Alan in Western Australia

Jack rabbits are renamed speedy t clutches. I have well over 10,000 miles on 1 set alone. Run em in all my cars. I built a die to accurately cut the notches for a contact @ all 6 tabs. (this was lacking in the early versions - hand filed) I have sold thousands of sets to the major vendors, still sell to some. Of course, there are "counter fitted" & "improved versions" The vendors prefer the heavy duty green/grey material, so thats what I provide. The tan lining seems to wear as well as the grey. Instructions are provided. They need to be read. I have only had 2 failures referred by a vendor. In both cases questioning revealed the installer was absolutely clueless on T's & didnt read the instructions. Constant parking brake cam contact has been @ the root of a few customer acquired problem clutches. They are a fine improvement when installed & operated correctly. IMO mandatory for a hand crank only T. Zero drag!
Like kevlar bands they are less forgiving & may not be for the inexperienced T owner. They are another love/hate product.

I saw the clutch that Joe is referencing, the clutch material on the disc was gone. You can go old school like I did some 20 years ago (still in the car, but I don't put nearly as many miles as before) using a hand nibbler and a bucket of old clutch discs that a transmission builder gave to me free and make your own, but like any manual clutch, if you ride the pedal or have a weak clutch spring they will wear quickly. Just my humble opinion, enjoy

What advantage do these offer over the Ford clutch?

TXGOAT2 wrote: ↑

Tue Oct 26, 2021 10:08 am

What advantage do these offer over the Ford clutch?

Zero drag. Even after a cold night, the clutch disks will separate for easy hand/electric starting. A positive, non slip lockup into high.

Several members in our chapter have had bad experiences with the T400 discs losing their friction coating. Poor driving habits? Weak springs? Maybe...

I have only used the original discs. Have never had problems with "free neutral" or a slipping clutch.

Jerry VanOoteghem wrote: ↑

Tue Oct 26, 2021 12:46 pm

Several members in our chapter have had bad experiences with the T400 discs losing their friction coating. Poor driving habits? Weak springs? Maybe...

I have only used the original discs. Have never had problems with "free neutral" or a slipping clutch.

I have not seen any disks that lost their friction material from delaminating, only extreme wear.
Nothing wrong with a good original set of clutch disks. However, few still retain the proper dishing that the were designed to have to work properly. A "burned up" stock clutch pack has flattened out, but still can be made to work. The do tend to be more prone to sticking when cold. You know, jack one wheel up to start. Park in gear overnight. But even as new they were prone to this. New disk sets are not made the same way & warp up when they get hot once.(a vendor asked me to not recommend bead blasting because it warped them) That might even be advantageous against extra cold sticking. No experience with them. I only use original outer disks & turbo inners.
Yes, burn up a set of 400's & you got no lock up. Pull it apart. Way less forgiving. Its all installer/operator error. I love kevlar also, but am careful for whom I install it for. Your choice, my choice. I have been very happy my choice & I am not wanting to change anybody's mind.
Its all about the drive. Lets go touring!!

Joe Bell wrote: ↑

Tue Oct 26, 2021 7:07 am

I do not know how the people drive these cars, the spring has been changed in all of them, these engines came from other engine builders from all over US, the square wafered ones seem to hold up the best, but the metallic material in them makes me wonder when they fail where is it going? The new Watts clutch has what it looks like brass in them, I have seen one of them destroyed with 50 miles on it, this one I think bit it from triple gear pin to tight. At one time I liked the looks of these newer clutches and was going to try one in my own but after replacing this many, I do not like wrenching on mine and would rather be driving it!

I have always shared your concern for the abrasive nature of the grey waffle disks. Early on, I made them from the lighter duty material for my personal use. Less abrasive like fiber & just as effective. After running the grey ones for many thousand miles, outlasting the engine they were in, I measured the used stack & found negligible wear compared to new. Re-used them. If they are allowed to wear down, that material has to get into the oil like anything else. Cylinder wall & drum iron band material, etc. It hopefully sinks to the bottom, but, should be cleaned up as you would the other stuff.

Other than driver/installation error, I have seen one with "other linkage" issues. Particularly, maladjusted parking brake lever/cam situations. (small drum brakes)The brake rods pull up the lever enough to touch the cam & create a slight continuous clutch engagement. That will do it. Obvious to most, but not all.
I have heard enough issues to conclude they arent for everyone. Neither is kevlar. Personally, I would not do without either.