John..

Are the fans in the 928 S4/GT totally electric and mounted behind the radiator?

If so, how are they wired, i.e. thermal switch and then turn on with the AC, or what?

I need more space up front for a bigger charge cooler and removing my AC condensor fan is probably going to be required.

I thought I could upgrade to an S4 type setup and do some wiring and be done with it.

Anybody have any information?

MikeN

The S4/GT/GTS fans are totally electric and mounted behind the radiator. The fans/motors themselves are pretty straight forward, how they are controlled is relatively complex though, taking input from a control unit and various sensors......running at variable speeds depending upon the inputs, A/C on, etc., so taking the setup and installing it on an earlier model would be more hassle then it is probably
worth. Physically they would probably fit fine, and you could operated them at full speed with just a temp switch from the radiator and a relay, but this probably isn't the best solution.

Eric Dvorak

I sold my S4 fans last month to someone who was putting them in his 79', I ran into him at the Hershey swap and he said they dropped right in and ran the car cooler then before, I believe he wired them through a relay to a temp sensor that just runs them at full speed when called for.

John..

But this would open up LOTS of room for that 4.5" thick charge cooler I have been lusting after!

I saw in the manual where the voltage varies with coolant temp. That is probably way overkill, I could just use a on-off differential switch. I cna see the value in the varied voltage, as it helps to keep coolant temps steady.

There is a rolled over S4 at the pickin' yard just down from my house.

Perhaps it is time to go parts hunting?
It is conceivable I could get the control unit with it?

MikeN

You could probably get the control unit, but I don't think your year would support it without major effort. As Eric said, they should fit fine, and you can either use the switch you spoke of, or some type of simple relay/radiator temp sensor to turn them on full. There really isn't that much benefit to the "variable" speed
features.

Eric Dvorak

I still have the fan controls that I removed from mine if you interested (personaly I wouldn't bother) I also under stand the S4 and newer cars have a variable resistance temp. sensor in the lower front drivers side of the radiator, this can be replaced with the earlier cars snap disk style on/ off sensor (you should already have this) and wired through a relay.

ebs3349

I'm the one who bought Eric's S4 fans and installed them into my '79. Piece of cake ! No problems - only minimal cutting to trim-in the shrouds to fit. I wired them to run constant and full power by adding relay and heavier electrical wire/fuse to avoid any hot load on fuse panel. Good luck! Thanks again, Eric. These fans are hard to come by! Sorry, but SITM is not possible for me - other commitment. <img border="0" alt="[byebye]" title="" src="graemlins/wave.gif" />

John..

So, your viscous coupling fan is completely gone?

Did you use a new shroud, or keep the old one?

I was thinking I can wire just a simple relay so they trigger with the temp switch, and then also just have them on full tilt with the AC on. That should be as easy as two triggering circuits built into one relay with a hot line straight to the fan to avoid any factory wiring overload!

This should work just fine. maybe I can even get an aftermarket fan, but I'll have to see.

This makes designing and mounting a new, thicker charge cooler much easier than before. I can use the mounting tabs for the old condensor fan to hold the charge cooler. Callaway had it bolted to the bumper...hit anything and waste your condensor!

The boneyarr just has the motor, not the shroud. Car was roller hard and is a total scrap out.

ebs3349

Viscous fan completely gone. Bracket and all. New fans from donor S4 have shroud as one piece, fans and all. Also removed front auxiliary fan. This removal alone has greatly improved airflow for newer "puller" fans and my A/C has never worked better or been as cold as it is now. BRRRR....

John..

Sounds like a win-win for me too. That belt driven fan always hit my splitter pipes for the airflow to the turbos. That problem would also go away!

I say UPGRADE!

John..

I am making this mod to the Bastard. It just makes sense. The car close to home did not have the fans, it was smashed and rolled HARD. I have to purchase from an outside source.

Any help on wiring? Did you just use the hookup for the old aux, fan, or run new wiring off of a relay?

Jim bailey - 928 International

John why not move the auxiliary fan from the front of the radiator back into the schroud and try that

ebs3349

I ran new wiring off a new relay. Plus, mine being a '79, I used a heavier gauge wire. Just to be safe. Did this mod to mine last month. Daily driver with no problems.

John.

I don't think the aux. fan is big enough to move adequate air.

Anyway, now I am wondering what to do with the PS pump belt, since the fan was also driven off of this. Perhaps I can just get a shorter belt to fit?

Did you leave the fan bearing housing and pulley in tact and just remove the blades of the fan?

dr bob

There's a nifty fan conversion mentioned at the MSN DIY group website, using a GM fan and shroud from one of the V-6 front-drivers. Less than $20 at a boneyard and the car stays very cool according to the write-up.

If you decide to go with the S4/GT fan setup, consider two temp switches of something like that to stagger the two fans' operation. Just a thought.