Fan clutch

[dutchzcarguy]

16 hours ago, AK260 said:

melted one FET already with too small a heat sink

You use a FET? I would go for a thyristor.. And a fat heatsink.. 👍

[Zed Head]

The fan clutch is more like a torque converter in an automatic transmission.  It slips continuously, more so when it's cold.  I think that it's never "off" because it needs to pull hot air through the radiator in order to get the feedback it needs to operate correctly.  The fins on the clutch serve to absorb heat as well as release it.  It needs to absorb the heat in order to stiffen up and spin faster.

And it only needs to work when the car is not moving or moving very slowly.  No need to be at full throttle/high RPM if you're stuck in a traffic jam.

Just some thoughts.  The early mechanical feedback mechanisms on cars are pretty fascinating if you dig in to them.  Everything is going electronic now, it's just computer code, solenoids, and electric motors.  Even automatic transmissions have electronics inside with the ATF.  Kind of weird, really.

[AK260]

You use a FET? I would go for a thyristor.. And a fat heatsink.. [emoji106]

That’s a great idea! In fact, thinking about it more, I would imagine a lot of modern cars are using Thyristor based SSRs for modulating LED lights, motors, self-dimming fog lamps used with steering inputs etc. Will have to have a good look at that.

Dropped the Aisin clutch in last night but at 22:00 it was a little unfriendly to warm the car to full temp - to quote a wise man[mention=23570]siteunseen[/mention] “I have neighbours”!


Aisin V the other one I bought a few years back for double the price which never seems to engage.



A word of caution, the Aisin had a flange that is more than 2mm thinner than the stock clutch, enough to make my fan blades connect with the bolts on the front of the ATi damper - so more spacer washers went in between the fan hub and the clutch.

[AK260]

Duplicated post ... grrrr!

[siteunseen]

I try to buy Aisin when offered. My mechanic says they're OE suppliers to Toyota.

[AK260]

I try to buy Aisin when offered. My mechanic says they're OE suppliers to Toyota.

That’s great to hear! I wish the thumbs up icon on Tapatalk worked on the web view! But if it did, here it is ... [emoji106][emoji106][emoji106][emoji106][emoji106]

[siteunseen]

Working good. 5 thumbs up, that about as good as it gets.

[siteunseen]

I don't use tapatalk. I just get on the internet and go to classiczcars.com

Is tapatalk something special, should I be using it? Thanks 

Edited April 18, 2021 by siteunseen

[AK260]

That’s great to see! Normally when I use emojis from my iPhone on our other forum they don’t work, so I assumed they would t here either!

Tapatalk is a forum app for the phone and I REALLY like it and prefer it to web based forum UI.

The home page for me looks like this and allows me to quickly scan the forums I’m interested in / registered with without putting in login details every time. Sadly it was dropped from the UK Zclub forum which means I’m less on there than I used to be - as the mobile optimised web interface isn’t as easy / user friendly to use. :(

[siteunseen]

Here's what I see and I'm always logged in. 

I can have my laptop running classiczcars.com and someone wants a picture. I grab my phone take the photo and post it from my phone. Laptop and phone working at the same time. It's pretty cool looking at my laptop and see my post pop up from my phone. Silly what it takes to amuse me.

[AK260]

I’m going to steal some of these ideas for our webmaster to think about! That’s a much nicer view than we have. [emoji106]

Just been out for a quick one and sadly ran out of fuel about a mile in !!!! I need to pull the new sender and work out why it’s sticking at 3/4 - I suspect that last kink I didn’t fashion into a Z shaped one is the issue with the float pointing the opposite way probably sticking to something in the tank (it was a Datsun 620 truck one I modified to fit). At least now I don’t have to drain the tank to do it! The odometer was showing 165 miles since my last fill up, I suspect the lead in my right shoe is the cause of that one!



After being rescued by a neighbour with a Gerry can, I left it idling for 10 mins in the garage which normally would pull the gauge well past half way and close to 3/4. Well this time it only made it 1/3 of the way across and it wasn’t moving any further. So at least it seems my heat challenges are looking more resolved but I need to do this again on a hot day.

The Aisin appears to be constantly engaged as it feels just as vigorous cold or hot! Let’s let it heat cycle tonight and see how it does tomorrow morning.

But at 1/2 speed due to my just under half sized ATi crank pulley, even if fully engaged it’s still the equivalent of 1/3 speed on a normal sized crank pulley and I can’t hear it. So it shouldn’t be costing too many ponies if I choose to live with it! ;)

There is a nice bit of airflow if I put my hand on the front of the radiator, but there is an ENORMOUS dead spot in the middle of the fan, for obvious reasons! So when I fit the twin electric fans, I will ensure the flow in that area is improved.

[AK260]

The cleaners came just as I was planning on sitting at the laptop, so i HAD to leave the house and socially distance myself in the garage

Fixed fuel sender so that the float is now pointing left instead of right!




Filled up with an eye watering £80 of Esso 99 then went for a drive. Incidentally that’s their new fuel without ethanol! Next time you Yankee boys are complaining at the pumps, spare a thought for the rest of us paying $2 / litre and financing gold Lamborghinis in the Middle East oh and our thriving government with close to 80% tax on fuel!




With the fuel sender showing F now, I gave the car a bloody good thrash and then sat in a lay-by idling for 10 mins.

Normal driving, temps are now at 1/4 across.


Idling in the lay-by, it doggedly stuck to half or very slightly below (which is 85c I believe).

Then I turned the engine off for a couple of mins and let it heat soak. When started up again, the gauge was just past half way. In under a minute, it came back down to a half!

Ambient temp today is 17c here. Would be interesting to see if it does the same at 25c - 30c.

The good news is, when I got home, it was back down to 1/4 and I could stop the fan with my fingers without having them chopped off!! I tried cardboard and ended up with a bit of a mess. ;)

So the Aisin clutch is definitely working per spec!!! Yay!!! It’s the first time in my Z ownership that I have a fan clutch working as it should! It does however idle with a little more vigour than my other one, so there is noticeably more airflow through the rad.

The electric fans will now take a back seat until I sort out the next set of issues like lights working reliably on both sides of the car or dealing with rough idle / part throttle issues etc.