I may have stumbled onto a solution to the pitiful fan-clutch dilemna.

I have found a source for direct-drive adapters with a Left-hand thread of 30MM x 1.5


Does anyone know what thread size fits the fan-clutch stub on our engines ??

Thanks.

 

According to Horton Fan the thread is M30 X 1.5 LH.

30 mm diameter
1.5 mm thread pitch (how far it advances in one revolution)
left hand thread

 

Oh goodie !!!


That means then we can use this :

http://www.summitracing.com/parts/FLX-852/


I am gonna risk $57 and see what happens.

It may also require one of their fan-hub spacers and maybe a 7-blade FLEX-FAN.

Who knows, the stock blades may fit as is.

 

I think you will find the stock fan won,t fit. The hole in the fan and the bolt circle will be too large. I got a viscous sever duty hub from NAPA that is doing good so far. I just wish I could find a fan with more pitch to pull more air than stock. The last hub I erplaced is through bolted and on the shelf in reserve.

 

Yeah; I decided that after closer examination.

No biggie, they have an awfully nice six-blade that comes in RED/Stainless.

The pinned clutch that I had been using on my personal truck finally egged out the holes through the soft aluminum bad enough that the bolts were rattling around; it had lasted for several years of hard use for a clutch that was headed for the scrap barrel --- in fact, that is where I fished it out of when I first pinned it.


I intend to order one of those direct-drive hub-adapters, the six-blade fan, and possibly whatever spacer I may need to get the blades clear of the other goodies.

If it fits and works out as good as I think it will, I may do likewise on the rest of the pinned-clutch trucks in our fleet and re-think my decision to go totally electric.

 

The 1st/2nd gen fans are the same pitch.
The clutch on the 2nd gens is a slightly heavier duty, due to the fact that they use STEEL blades, instead of aluminum blades.

Personally, I think a solid fan on one of these trucks isn't the best idea, because you have the peak torque of the engine at @ 2500 RPMs plus on the blades.
I've seen the consequences of those blades flying off and it isn't nice.

They have a clutch for a REASON.

Mark.

 

Think you might have a couple issues. I tried running a couple of my 7 blade fans, from various mopar cars and trucks, on the stock clutch. I tried this because my stock 89 fan was bent and twisted. What I found was that the fans did not have enough offset? They bolted on fine but when you then installed the clutch onto the hub the blades were hitting the harmonic balancer.

I can see that the hub you are looking at is going to bring the fan in even closer to the motor and you will more then likely have clearance issues. But with the close 4 bolt mounting flange you could probably use a stock fan spacer and move the fan out to where it might clear.

Good luck and keep us posted on how this comes along.

BTW I am running a 2nd gen fan and clutch on my 89 motor with no problems.

 

It'll clear that way, however, the NON-Intercooled fan won't clear on an Intercooled engine.
The blades are thicker and hit the balancer.

Wouldn't you know that the Non-Intercooled fan is a real PITA to come by, too.

Mark.

 

Hence the reason for the 2nd Gen fan and clutch on my motor....

 

I did not know there was a clearance issue between the non-I/C and I/C fans/clutches.

I had been swapping them back and forth on various engines around here and so far nothing has hit anything.

I had been curious as to why there were two separate part-numbers listed for fan-clutches.

One thing I noticed was that the non-I/C clutch says it will work from 1989 - 1993; while the specific I/C clutch says it fits from mid-1991 to 1993.

I have plenty of both around here, even a 2nd Gen. clutch or two; maybe I will pay closer attention to see any differences between the non-I/C and I/C fans.


I do know that the original fan on my 1989 engine that is in my Ford was badly bent and we ordered a new replacement from the Chrysler dealership.

The shiny new fan is all steel and said something about being "improved".

Other than not being bent all out of shape, I could see nothing different between it and the original one.

If memory serves, it seems like the cost was something like $38 or so.

 

I appreciate your concerns and I too have seen the carnage where blades have flew off --- not on anything of mine --- thank goodness.

During summertime heat, I have been running "pinned" clutches on several of our engines for a number of years with no ill effects.

We can see no difference in fuel-mileage between running the pinned clutch as opposed to the normal clutches of questionable repute that we run in winter-time.


Also, I have not experienced the dramatic power losses that many claimed I would have by running the direct-drive pinned clutches; the engine does not seem to notice.


From what I understand about viscous fan-clutches, there are three grades; normal --- which turn the fan at a maximum of 60% of driven shaft RPM; heavy-duty --- which turn the fan at 80% of driven shaft speed, and severe duty --- which turn equal to the heavy-duty, but have a larger heat dissipating area and more fins.

Even at full lock-up, these clutches only turn the blades at a given percentage of shaft speed.


All of the older/better trucks around here have always had direct-drive fans.

Back then, they didn't make them any other way.

These are on high-revving gas engines that often see 6000-RPM plus, and can acheive that 6000 in a heartbeat.

In all my long driving career, I have never seen or heard of one of those fans loosing a blade or self destructing; I am not claiming that they don't, just that I am unaware of it.

Curious it is that all the fans I have seen fly apart have been clutched fans.


Thanks for pointing out the issues about blade off-set; it will help me to make an enlightened decision about just which spacer to order when I order the hub and fan.

 

What is it about the I/C engine that causes non-I/C fan interference ??

Is the balancer of larger diameter on the I/C engine, thus requiring a fan of less diameter ??

Is the difference in the make-up of the clutch mounting stud ??

It seems like the I/C balancer is bigger around, hence the difference in recommended belt length.

Thanks.