Jack Rabbit or Turbo 400?

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A Whiteman
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Jack Rabbit or Turbo 400?

Post by A Whiteman » Sun Aug 04, 2019 7:30 pm

Your ideas and advice on the merits of the Jack Rabbit and Turbo 400 clutch plate sets would be appreciated.

My main issue is the clutch not slipping under load in Albert (1926 TT). I carry a bit of weight and the standard plates tend not to 'hold' over time, therefore 'strength' is my main goal. A 'free neutral' is a secondary consideration.

I have a 'new stronger spring' fitted and would like to try an aftermarket clutch, but which one?

Many thanks in advance
Adrian


Scott_Conger
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Re: Jack Rabbit or Turbo 400?

Post by Scott_Conger » Sun Aug 04, 2019 9:34 pm

Adrian

if the clutch is slipping under load, it sounds like your clutch spring is shot. If this is so, ANY clutch will slip. If it had been Jack rabbit or Turbo 400, slipping would have pretty much worn them out in no time. At least the FORD clutch can take the abuse.

If by "strength" you mean "durability" then stock Ford is the choice. If "strength" means no slipping, then it is a new spring that is in order (not new clutch material). Neither of those scenarios point to Jack Rabbit or Turbo 400. Those would be a choice for a freer neutral.

Bottom line, is that with Jack Rabbit, you MUST put in a spring that meets or exceeds original pressure at original deflection. Neutral will be improved with either choice. Just don't expect that they will hold up or be MORE robust than a stock clutch.
Scott Conger

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Re: Jack Rabbit or Turbo 400?

Post by Stephen_heatherly » Sun Aug 04, 2019 11:54 pm

Personally I would recommend that you replace the clutch spring and leave the stock clutch in the transmission after checking that all of the plates and the brake drum are good, of course. The stock clutch will work perfectly and never need attention for as long as you drive the car. There is nothing to gain by changing it.

Stephen


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Re: Jack Rabbit or Turbo 400?

Post by Alan Long » Mon Aug 05, 2019 3:20 am

In my experience Jack Rabbit and Turbo Hydramatic 400 are the identical friction material. The Turbo plates are available
in the Green Colour or Biscuit. The Green option are slightly harsher in engagement compared to the biscuit however both being designed for a Automatic Transmission are not designed to slip. If slippage occurs for whatever reason you soon destroy them where the original steel on steel will handle it better. Jack Rabbit have the inner teeth shaped identical to the original Ford inner plates however the Turbo are fine toothed.
Alan


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Re: Jack Rabbit or Turbo 400?

Post by D Stroud » Mon Aug 05, 2019 5:28 am

What Stephen said. If it ain't broke, don't fix it. Contrary to what has been posted on here as gospel, the original clutch can be adjusted to achieve a free neutral, that has been posted on here many times, just do a search. If you want a robust/tuff clutch, stick with the original one. JMHO Dave
1925 mostly original coupe.

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Re: Jack Rabbit or Turbo 400?

Post by A Whiteman » Mon Aug 05, 2019 6:28 am

Thanks guys, as I originally posted, the 'new strong spring' is fitted (first thing to do).
Strength I mean durability and resistance to slipping. The standard metal plates do tend to slip with time - they are under more load in my TT than in a car when in overdrive, hence my interest in the options. Metal plates can burnish and then are next to useless until replaced.

I have a good neutral (well adjusted plates) and that is not such an issue compared to durability.

From what Alan says, there is not much (if any) difference in them other than how they are fitted - so I guess the choice makes no difference.
I had heard the Turbo plates are thinner and can chew up the drum.

You all seem to say the metal plates are more durable, so that means perhaps the new plates would be a waste of time.

Any TT driver's experience here would be particularly helpful.

Thanks again,
Adrian


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Re: Jack Rabbit or Turbo 400?

Post by Stephen_heatherly » Mon Aug 05, 2019 8:11 am

If the stock clutch is slipping even with a new spring, something is wrong. How much adjustment do you have left on the pressure finger screws? I'd give each one a half turn in and take the truck for a test drive. A little adjusting is probably all that's necessary to solve your issue.

Stephen


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Re: Jack Rabbit or Turbo 400?

Post by Jeepbone1 » Mon Aug 05, 2019 1:45 pm

Are you positive that the brake handle is fully disengaged and not touching the clutch cam? I’d hate to see you take it all apart for a relatively easy fix.

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Re: Jack Rabbit or Turbo 400?

Post by ewdysar » Mon Aug 05, 2019 4:19 pm

Adrian,

We all know that the stock clutch should be able to handle all of the power that a well tuned stock engine can throw at it under normal operating conditions.

I hear you about the slipping, my well adjusted stock clutch will slip occasionally under heavy load, like when my Touring is carrying 4 adults and I do a “dump the pedal” shift to high under full throttle, going up the steep hill that leads towards my house. Usually a quick dip of the throttle allows the clutch to “grab” and carry on under full throttle the rest of the way up the hill. I can imagine that a loaded TT could have similar slippage due to the demand on the clutch. Upgraded engines, i.e. high compression heads or pistons, performance cam, carbs or exhaust, can all increase the chances of slippage n our T’s (and virtually any other car too, my 2014 Jetta TDi slips a little at full throttle since I installed a stage 2 tune in the car’s computer)

That said, all of my T’s have run stock clutch plates, so I don’t know if the lined disks will help with the slippage or not. But I do not assume that slipping is necessarily a sign of bad adjustments or failing parts. Since you mentioned overdrive, that does put more load on the clutch than the way the truck was set up at the factory. Hopefully, someone with experience with your specific use case (loaded TT with overdrive) can weigh in.

Keep crankin’,
Eric


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Re: Jack Rabbit or Turbo 400?

Post by Kohnke Rebabbitting » Mon Aug 05, 2019 7:48 pm

Bottom line, is that with Jack Rabbit, you MUST put in a spring that meets or exceeds original pressure at original deflection. Neutral will be improved with either choice. Just don't expect that they will hold up or be MORE robust than a stock clutch." End Quote.

It is NOT the Jack Rabbit Clutch that calls for the Heavy Duty clutch spring, all though, you can use one. That is the Watts clutch. The turbo 400, takes a New, or good original. Herm.

In my experience Jack Rabbit and Turbo Hydramatic 400 are the identical friction material. " END QUOTE "

There are two kinds of Turbo 400 Lining. The ones with grooves, and the smoother, thicker, lining, which should NEVER be used. Herm.

Jack Rabbit have the inner teeth shaped identical to the original Ford inner plates however the Turbo are fine toothed. " END QUOTE"

That is true, as all plates have the fine teeth, but the Jack Rabbit plate, has been machined. Herm.

I had heard the Turbo plates are thinner and can chew up the drum. " END QUOTE "

Just plain, NOT true. That wouldn't happen, no matter what you used for plates. Herm.


I got my first turbo set from a Guy that first had an ad, in Hemmings Motor News. I put it in one of my own cars. It worked so well, I put them in my own cars. All still the same today, with no problems, ever.

We cut our own plates, for my last two cars. After that, we cut plates for all the motors we built. I sold hundreds of sets to other vendors, also.
Rick at Birdhaven, didn't want to sell the packs, or sets, as a turbo 400, so Rick, and Joann gave the Jack Rabbit clutch its name, and sold them under that. WOW, did they sell the sets.

So, I had to hire just one Guy to make clutch sets. In all that time, we never got even one set returned, that was destroyed, and the only thing that will do it is adjustment.

Of all the motors we have built, one Museum, in Iowa burnt a clutch pack. Long story short. The town was 10 miles away, it was slipping when he left, was going to do it the next day, he didn't make it to town. If it needs fixed, don't wait.

Herm.

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Re: Jack Rabbit or Turbo 400?

Post by Henry K. Lee » Mon Aug 05, 2019 8:14 pm

I have to agree with Herm all the way! My Dad started using Jack Rabbit Clutches about 30 years ago, never a failure. We put them in just about all cars we restored and every car we own has them. Been doing hill climbs with serious burn outs, etc. not one failure to date even with abuse (Just don't tell Dad, it was his car).

Hope this helps and All the Best,

Hank

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Re: Jack Rabbit or Turbo 400?

Post by A Whiteman » Mon Aug 05, 2019 10:23 pm

Many thanks Herm, that is what I wanted to know, good summary :-)
Cheers
Adrian


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Re: Jack Rabbit or Turbo 400?

Post by Alan Long » Wed Aug 07, 2019 6:39 am

Further to Herms confirmation that Turbo and Jack Rabbit don’t chew up the drum. they can’t.... they are the inner
Plates and run on the clutch hub. The outer steel plates run on the brake drum. My experience is the green Plates with the cross hatch grooves are crisper when going into high than the biscuit coloured (softer one).
Another point is fibre plates of any brand or style will fail if they are allowed to slip or feather into high and / or
come into contact with water. The friction material flakes off when water is present.Prompt high engagement is a must if your using Fibre plates as there not designed to slip. Just my experience. Alan


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Re: Jack Rabbit or Turbo 400?

Post by noelchico » Wed Aug 07, 2019 11:59 am

I pulled my 23 engine several years ago to replace transmission output shaft and the slipping transmission that I had put turbo 400 plates into. The turbo plates looked good, but about 1/3 of the Ford steel plates were cracked. I suspect due to heat from the slipping transmission. I replaced the plates and went back to standard all steel Ford plates. I did not replace the spring, but should have. there is no slippage now. Has anybody else had a problem of the steel plates breaking? I was afraid if a chunk got out of the clutch pack and wound up in the engine it would cause all kinds of grief.


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Re: Jack Rabbit or Turbo 400?

Post by Kohnke Rebabbitting » Wed Aug 07, 2019 3:37 pm

noelchico wrote:
Wed Aug 07, 2019 11:59 am
I pulled my 23 engine several years ago to replace transmission output shaft and the slipping transmission that I had put turbo 400 plates into. The turbo plates looked good, but about 1/3 of the Ford steel plates were cracked. I suspect due to heat from the slipping transmission. I replaced the plates and went back to standard all steel Ford plates. I did not replace the spring, but should have. there is no slippage now. Has anybody else had a problem of the steel plates breaking? I was afraid if a chunk got out of the clutch pack and wound up in the engine it would cause all kinds of grief.
From my experience, many original Ford plates are cracked when we took them apart for rebuild. It seamed Good color plates were not cracked, and Blue colors, as in overly hot, had many cracked, were not saved any way. I beleave it comes from slipping, like you Guys.

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