4.0 clutch swap

[kaytor692]

so i plan on doing the 4L clutch swap in my 86 b2 in the near future due to the fact that my clutch crapped out. wanted to know if i should go with a ceramic clutch or a plain jane oem replacement? also if theres any specific brand or stage that work the best for a DD weekend wheeler.

any other suggestions on the swap would be helpful aswell
thanks

 

[4x4junkie]

Use a Luk RepSet clutch set (OEM).
The 10" 4.0L clutch already will have far more holding power than your stock 8.875" clutch. Using a "high performance" clutch here would do nothing beyond give you a harder & grabbier pedal to deal with.

 

[UrbanRedneckKid]

Unless you went with a Centerforce. They retain stock pedal feel, and use centrifugal force for more clamping power. More RPM= stronger clutch.

I've been satisfied with the Luk clutch, eventually plan to swap a Centerforce pressure plate, that is if my 302 doesn't come first.

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[kaytor692]

ok thanks ive talked to a couple guys a the local 4x4 shop and im gunna go with the luk setup

 

[UrbanRedneckKid]

That's what I would do. It takes a lot for the 4.0 to slip that clutch, more than a stock truck is capable of. It's perfectly at home behind a 2.9.

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[kaytor692]

good to here im only running 31s right now anyways. hows the wiring to do for the different starter?

 

[UrbanRedneckKid]

I forgot, it's been a few years since I had a 2.9. I may be wrong but...

IIRC, you just jump the small wire over to the big terminal on the starter, thus only using the fender mounted solenoid.

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[kaytor692]

oooh ok soo i dont have to rewire the hole starter circiut then thats good cause i hate wiring with a passion lol

 

[wildbill23c]

Will a 4.0 Clutch work with the 2.8L or just the 2.9L?

 

[4x4junkie]

I would think this swap would work on the 2.8, but I don't know for sure (might need to swap to a later slave cyl?).

Here's wiring for the 4.0L starter on a 2.9L truck:

 

[UrbanRedneckKid]

Junkie, your pretty much on top of everything you post, but I'm questioning the unnecessary wiring.

You can accomplish the same thing, just by jumping a wire from the big terminal to the little terminal right at the starter.

That's the way I wire all the racecars I do.

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[lil_Blue_Ford]

Oddly enough, the wiring for the 4.0 starter done the way 4x4junkie posted it is exactly how my 95 F-150 was wired up from the factory. Still not exactly sure what the point of doing it that way was, but apparently someone thought it was a good idea at Ford.

I suppose it would be possible to just jump the solenoid on the starter, I don't see why it would hurt anything.

 

[adsm08]

Wiring the 4.0 starter the way that Redneck suggests, by just jumping a little wire from the big terminal to the little terminal causes starter run on. It lets voltage generated by the starter while it is spinning down to re-engage it and keep it running for a few extra seconds after you let off the key. There is something a little different about the 5.0 starter that lets that setup work properly.

The way I did my starter wiring is still really easy.

Take the existing starter wire for the 2.9 and bolt it to the small terminal on the 4.0 starter.

Then get a section of double-ended (one eyelet on each end) battery cable approx 4.5 feet long. Add it to the same side of the starter relay (the piece on the fender that everyone incorrectly calls the "solenoid") and run it to the big terminal on the 4.0 starter.


The only thing you really need to be careful with using that method is the angle of the eyelet on the original 2.9 starter wire. It's kinda big and square shaped and if you don't watch when you tighten the nut it can spin the wire so metal is touching the other post or the block, both not good.

 

[4x4junkie]

A recent discussion on starter wiring:

http://www.therangerstation.com/forums/showthread.php?t=142852


Adsm, your method would work too, however I'd be afraid of that possibly putting too much load on the ignition switch contacts. I suspect this is why Ford chose to continue with the fender-mounted relay rather than just going straight to the starter solenoid (though I'll admit I haven't actually measured the current going to the solenoid, I wouldn't be surprised if it's 5-10 amps).

 

[UrbanRedneckKid]

Hmmm. That's something. Wonder why that starter acts that way. I've done numerous wiring jobs never even heard of that.

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[4x4junkie]

It's because the starter motor acts as a generator as it's spinning down. This creates a back-EMF that holds the solenoid engaged for several seconds after you let go the key if the wires are tied together like that. Meanwhile the starter pinion grinds against your flywheel (a very disturbing sound I might add lol).

IIRC, the link I posted mentions this.

 

[UrbanRedneckKid]

I get that. Just don't understand why don't other starters do that?

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[4x4junkie]

What other starters? You mean the stock 2.9L one?
The stock one doesn't have an external solenoid to engage the pinion gear like the 4.0L one has... Instead it has an internal mechanism that works off the motor's magnetic field to thrust the gear out, which retracts immediately when power is removed.
The 4.0L starter was deigned to be hooked to constant battery power and controlled via just the solenoid.

 

[adsm08]

Adsm, your method would work too, however I'd be afraid of that possibly putting too much load on the ignition switch contacts. I suspect this is why Ford chose to continue with the fender-mounted relay rather than just going straight to the starter solenoid (though I'll admit I haven't actually measured the current going to the solenoid, I wouldn't be surprised if it's 5-10 amps).

My current setup mimics the original 4.0 wiring in every aspect except the gauge of the wire going to the small post. Since the load will only draw the current that it needs to operate when more is available (this is why your 15 amp fuse doesn't pop when you turn the lights on even though the battery has several hundred) I don't see the use of the heavier wire causing any issues long term.

 

[4x4junkie]

My current setup mimics the original 4.0 wiring in every aspect except the gauge of the wire going to the small post. Since the load will only draw the current that it needs to operate when more is available (this is why your 15 amp fuse doesn't pop when you turn the lights on even though the battery has several hundred) I don't see the use of the heavier wire causing any issues long term.

Ah, OK, I guess I misunderstood your post, you took the BIG existing starter wire for the 2.9L unit (from the relay contact) and connected that to the small terminal of the 4.0L solenoid.
I read it as you took the little existing wire (control lead for the relay) and connected that to the 4.0L solenoid (which is what I was talking about could kill the ignition switch after a short time).

Nevermind.