400 turbo or Jack rabbit clutches

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Bob Broihahn-S.W. Wi
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400 turbo or Jack rabbit clutches

Post by Bob Broihahn-S.W. Wi » Fri Feb 21, 2020 7:21 pm

Looking for a little advice about installing a new clutch on rebuild of 27 tranny. I know this is a personal opinion topic but any pros or cons would appreciated. I'm at the point where I must make a decision soon, maybe the 400 turbo and the jack rabbit clutches are the same which I don't know much about. Any ideas will be given thought and I know the final decision is mine to live with. I have even thought about going back to what worked for 93 years.
Thanks in advance

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Re: 400 turbo or Jack rabbit clutches

Post by RajoRacer » Fri Feb 21, 2020 7:55 pm

Good attitude there, Bob !

I own 5 Model T's, including a OHV Racer & ALL have stock Ford clutches - you really can't go wrong considering the abuse they will take & withstand it !!! As you said, it's a personal choice and you will get other opinions, for sure.

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Re: 400 turbo or Jack rabbit clutches

Post by Stephen_heatherly » Fri Feb 21, 2020 8:59 pm

There really is no difference between the turbo 400 and Jack rabbit clutches aside from which center hub it uses. The turbo 400 uses a special hub with small notches all the way around for the lined plates and the jack rabbit discs have been modified to work with the stock Ford hub. Aside from that they're pretty much exactly the same thing. Having said that, it is completely unnecessary to install either of the two because there is absolutely nothing wrong with the stock clutch. You will find it works flawlessly and engages much more smoothly than the modern clutches. If everything is in good shape and adjusted correctly you won't have any of the issues that the modern clutches are supposed to cure. Others will disagree. This is just my honest opinion.

Les Schubert
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Re: 400 turbo or Jack rabbit clutches

Post by Les Schubert » Fri Feb 21, 2020 9:05 pm

I really like the Watts clutch especially for a high performance engine. It limits the torque loads on the rear axle gears (but not too much limit). I don’t know if it’s still available

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Re: 400 turbo or Jack rabbit clutches

Post by Scott_Conger » Fri Feb 21, 2020 9:16 pm

Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!

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Steve Jelf
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Re: 400 turbo or Jack rabbit clutches

Post by Steve Jelf » Fri Feb 21, 2020 9:59 pm

If I had a problem with the stock clutch I would have looked into the others. I haven't, so I haven't.
The inevitable often happens.
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Re: 400 turbo or Jack rabbit clutches

Post by Joe Reid » Fri Feb 21, 2020 10:07 pm

I had an engine rebuilt a couple of years ago and the builder used the jack rabbit clutch. It is really smooth, but it is just rebuilt. I have four other T’s with standard clutches and really have no issue. Keep them adjusted and they work fine.

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Re: 400 turbo or Jack rabbit clutches

Post by Joe Bell » Fri Feb 21, 2020 11:11 pm

The only problem with the modern clutches if they are ever slipped you can burn them up and then they need replaced and they are deep in the engine to do that. I know many people run them but in the last year I have replaced six sets of them in others engines, the wafered ones held better than the other modern ones but all of them where replaced back to steel that the customers wanted. Just my thoughts of them from having to repair them for people.

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Re: 400 turbo or Jack rabbit clutches

Post by Colin Mavins » Fri Feb 21, 2020 11:21 pm

We put turbo 400 disc's in the 12 in 1990 works great . we did it to stop the creep when starting ' before the rebuild when you started the car you put your leg on the front tire it would creep until it run for 10 or 15 seconds it does not creep anymore

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Re: 400 turbo or Jack rabbit clutches

Post by Kerry » Fri Feb 21, 2020 11:57 pm

To fry a modern clutch would be no fault of the parts, set up incorrectly or just the bad driver :D

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Re: 400 turbo or Jack rabbit clutches

Post by Stephen_heatherly » Sat Feb 22, 2020 12:00 am

If the plates are flat, the brake drum lugs are not badly chewed up and you have things adjusted correctly the stock clutch will not cause creeping. Besides if the car creeps before it warms up either your hand brake is not set or it won't hold. The car shouldn't move regardless how much drag is in the transmission.

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Re: 400 turbo or Jack rabbit clutches

Post by Kevin Pharis » Sat Feb 22, 2020 12:50 am

The TH-400 clutch disks used in both kits are designed for heavy duty and racing use. The “waffle” reliefs in the friction material serve several purposes;
1) Allow additional oil flow thru the clutch pack to lubricate and cool
2) Decrease clutch surface contact area to increase effective pressure at friction contact points
3) Provide shorter oil evacuation routes from clutch plates to allow more positive clutch engagement with minimal slippage

As far as I know, the waffle discs are aftermarket and were never factory equipment. Factory installed TH-400 discs had few or no oil grooves depending on application, and are intended to provide a smooth and gradual clutch engagement as the oil is squeezed out. In performance applications it is not uncommon for automatic transmissions to use an oil similar to SAE-30 motor oil, and these very same waffle discs.

When properly installed in a T, the waffle disks are well within their designed limits, and should provide a long life of positive clutch engagement. But by design, they will tend to have a quick, positive, or even grabby engagement.

I, and many others, have been using these clutch disks trouble free for years

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Re: 400 turbo or Jack rabbit clutches

Post by JTT3 » Sat Feb 22, 2020 1:42 am

I agree with Joe, I installed a set in a 26 roadster and within a year they stared to slip. It was a mess. Had to remove the engine and went back to factory disk. I was looking for a real neutral in all the wrong places when I decided to try the modern turbo 400 style.

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Re: 400 turbo or Jack rabbit clutches

Post by Henry K. Lee » Sat Feb 22, 2020 6:13 am

Been using Jack Rabbit clutches for over 25 years, about 35 plus installed to include 8 in our own cars. Never had an issue even burning rubber on hill climbs.

Hope this Helps,


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Re: 400 turbo or Jack rabbit clutches

Post by Craig Leach » Sat Feb 22, 2020 12:40 pm

I'm putting my reserve engine back together. After 7 years in my speedster I had a catastrofic low drum failure. I had made up a turbo 400 clutch set as per the MTFCA book. After a thorough inspection I elected to use them again because I could not find any defects. Did the same thing with the original Ford clutch in the front line engine that just went back in the car. It does feel to me that the after market clutch has the freest neutral and may be of benafit if you have a auxillary transmission when it comes to shifting. I have a Jack Rabbit in my firetruck with a Muncie and it dissenages exellant when shifting. I dought I will spend the time to cut all those teeth out of another set of 400 discs again. If I ever run across a 42 tooth hub Hughes has a set of discs they think will work even better than the stock 400 dics, they are thicker and you would use less of them kind of the same princable as the Watts clutch. Thanks for letting me get my $0.02 in.

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Re: 400 turbo or Jack rabbit clutches

Post by Mark Gregush » Sat Feb 22, 2020 12:46 pm

I did install a set of the turbo 400 disk that were converted to be used by removing some of the lugs. Shows how in the clubs transmission book. This was a used set when I got it and was even more used when I took them out. Even used, they seemed to work fine. As I recall they had the cross hatch design.
I also tried a set of the Watt's clutch disk (used too don't ya know). I lost my clutch using them when started slipping bad, over heated, swelled up and locked the clutch. Lots of smoke out of the breather on that one. :shock:
With the Warford, if I had on hand ether type I would consider going back to them to get a true free neutral. Other then that the original disk work fine except when cold and the car tries to run me over! :lol:
I know the voices aren't real but damn they have some good ideas! :shock:

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Re: 400 turbo or Jack rabbit clutches

Post by Kerry » Sat Feb 22, 2020 3:41 pm

If there are issues of slipping on the late clutch plates, I wouldn't be blaming them, if all adjustments are correct then it's the spring, It should have been replaced with at least a new 100-110lb one.

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Re: 400 turbo or Jack rabbit clutches

Post by Kohnke Rebabbitting » Sat Feb 22, 2020 6:32 pm

When I first saw that somebody was trying the 400 discs, I got a few, and machined some out. I put a set in one of my cars, and it worked perfectly, in all ways.

So we used them in our motor building, Guessing about 175, T engines or a little more, that had 400 discs.

I mentioned it to Birdhaven Auto, and Rick, and Joan said they would try them. Rick said he wanted to sell them under his own name, and they came up with the Jack Rabbit Clutch name. They sold a lot of clutch discs, and to other vendors.

Only had one set go out, because the owner didn't want to stop to adjust, as he thought after he got home, of 20 miles, he could do it then. NOT

The only reason I can think of for a smooth less shift, is the drum lugs are hanging up. They have to be in good condition, as all the discs have to release, not just some, same as the Ford discs.

Use only the grooved Discs.

The way we set the 400's up, they only have to be adjusted once, in no more then a 100 miles, and that has been, 1 full turn on the clutch fingers. That normally has been good for years.



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Re: 400 turbo or Jack rabbit clutches

Post by Duey_C » Sat Feb 22, 2020 6:58 pm

Like Kerry says, I should've just replaced the spring on my Crappy 24 to stop the slip. No $$$ right then tho.
I too had a book-modified set of turbo 400 discs (simple jig with a die grinder bit in the drill) with the smooth faces hanging in the shop and put them in after soaking for 24 in ATF, with the engine in the car. Every couple years I gotta lip-off about that. :lol:

Terribly grooved up drum, a very free neutral and like was said about a Panhard-Levasser once, The shifting is brutal.
Herm and others touched on that too. Sooo... I don't slip into high, I throttle down into high but never a slipper nor a nudger.
Since I lost my mind mind, I feel more liberated

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