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Am having trouble with fan clutches. Recently had the original fan clutch die. This was RB20 clutch with RB20 fan on front of RB25DET Neo transplanted in R32. Could not run the Neo fan and clutch at the transplant because they stand forward too far and get too close to the thick(er) radiator core on my car.

So new clutch was obtained. Brown box, to suit RB30 (notionally for a VL). Put it in, thought it was good. Turned out not to be. After the engine bay warmed all the way up the clutch would fully engage and roar like an old Falcon taxi from 2700rpm up. Cool days it would take longer, hot days it would happen sooner. And it would come and go. Sometimes you could take off from the lights and it would slip through each gear and be quiet, but the next set of lights it would roar the whole time, then back to being quiet again. Very very annoying, and really saps the cars will to rev past 3000 rpm too.

So, today I swapped in a replacement. Dayco branded, notionally to suit R31. Actual clutch looks identical to the brown box VL one, although there was a little nick in the bimetallic spring that I assume is a factory adjustment/calibration. Castings are the same - everything the same. Initially I thought it was better. But once the engine bay got hot it started locking on and being a taxi again. Behaviour basically the same, but a little different. This one would sometimes be quiet as it was revved up past 3000, but would actually engage above that. Sudden roar!

So the dilemma. Apparently, all these bloody RB30 ones are going to suck. I imagine that nearly everyone who has replaced a fan clutch in a Skyline has either gotten a secondhandy off a wreck or one of these RB30 ones. So surely I'm not the first person to suffer from this. What to do about it? Need to keep the clutch + fan height the same so to clear the radiator. Don't want to keep buying RB30 ones and testing them out.

I have seen some web pages where Landcruiser types open their Toyota clutches up and "adjust" them to make them activate earlier. Like this.

I suppose, given I've got a "spare" one sitting here, I could open it up and try to tweak it so that it doesn't open the valves until it is hotter. But that seems like work, and I want to avoid extra work. Plus I'd have to go find some silicone oil to refill it with on the basis of the assumption that I"ll spill it all when I open it up!

Any ideas if the bi-metallic spring can be fudged to achieve the adjustment? Any other ideas (except thermofans)?

cheers

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Checked the Davies Craig catalogue (http://www.daviescraig.com.au/Images/Categories/Fan%20Clutch%20Selection%20Guide%202011.pdf).

Replacement clutches for Skylines are different model from R31 / VL. According to the catalogue description, a VL / R31 unit shouldn't fit a Skyline RB engine (but maybe Neo is different).

Dayco don't appear to make one for the Skyline engines (no x-ref to DC model).

Iiiiiiiiinteresting. Didn't think of DC. I have been trusting the advice of someone who has always used the same type of clutch (as I have now) on all Skylines. Dozens and dozens of them.

As to the possibility of fitting between models.....all the RBs have interchangeable water pumps with the same flange on the front. Standard practice for putting a new water pump onto a Skyline is to get a VL one. So that's how the clutches can interchange.

I will most definitely obtain a DC clutch for an R32 as my next step though.

FWIW, the DC catalogue doesn't show a Xref to the Dayco RB30 clutch (115800) either. So the lack of a X-ref to Skyline ones is not conclusive.

Edited by GTSBoy

heres some facts

Vl hub takes a different fan bolt pattern. VL hub will fit SR20 fan and the new GKtech aftermarket fans but not any rb fan (other then the rb30 the VL has) just about every aftermarket supplier sells these hubs

R31 fan hub takes ANY rb fan, is shorter then RB20 and doesnt have external spring on it. very hard to get one of these aftermarket due to everyone sending out a VL hub. I just kept going to wreckers and grabbing 5 r31 hubs and then using the best one.

you can run two combos for best cooling... a r31 hub with an 11 blade latemodel RB25 fan or a VL hub with the GKtech fan. both will flow large amounts of air.

heres some facts

Vl hub takes a different fan bolt pattern. VL hub will fit SR20 fan and the new GKtech aftermarket fans but not any rb fan (other then the rb30 the VL has) just about every aftermarket supplier sells these hubs

R31 fan hub takes ANY rb fan, is shorter then RB20 and doesnt have external spring on it. very hard to get one of these aftermarket due to everyone sending out a VL hub. I just kept going to wreckers and grabbing 5 r31 hubs and then using the best one.

you can run two combos for best cooling... a r31 hub with an 11 blade latemodel RB25 fan or a VL hub with the GKtech fan. both will flow large amounts of air.

So will the vl hub have the trouble of locking up earlier than a rb20 or rb25 unit?

OK, so the one I put in first, though marked as VL, is effectively R31, because it is identical to the 2nd one I tried (marked R31) and both take my RB20 fan. And both have bimetallic springs, as they should regardless of whether the original R31 one doesn't. And they suck.

So that leaves me with trying a DC one in the hope it works differently, or scrounging a secondhandy. Secondhandy is already sourced, so that's actually going to happen before more cash is spent on new ones. Interestingly, the original Toyota ones for Supras are like $350 or similar (vs. $150 for aftermarket).....so one would have to guess that a proper Nissan one would also be expensive, but possibly more likely to work properly. That is also an option if desperation strikes.

Out of curiosity how much deeper is your radiator than an R32 GTS or GTR ? I would have thought that a 32 GTR one would be adequate for a Neo engine and not take up any more effective fan depth ?

Cooling systems can be tricky things because it doesn't begin and end at the rad core . Airflow has to be good in front of and behind the core in the bay because if it isn't the worlds biggest rad won't cool properly .

It can be very easy to overkill in some areas and that can have side effects in others . One thing R32-34 Skylines are not short of is radiator face area but as soon as you put non std things in front of them or compromise airflow behind them they may not work as well .

A lot of people find that the closer to the engine a radiator gets the worse the cooling tends to be and I think this may be because the post rad air has to turn sharper bends to get around the physical engine and fan hub . Its probably then harder for it to find its way out around the gearbox and tunnel and flow underneath .

If it were me I would be comparing the depth of you rad an a 32 GTRs one .

Then look at any cores in front of it ie AC and FMIC , how well is air flowing through them .

Neos have an 82C thermostat and I'd replace that with the 76C one if possible . Not the silly 61 odd C one .

If a genuine fan hub costs 350 and you want OE performance and reliability do that , even if if means buying cheaper from say the US .

Is there anything non std in your engine bay that would affect airflow through it ?

A .

No, there's nothing extreme going on here, and almost every other aspect of my cooling system is as good as you could want it to be. The reason I have a thicker core is simply because meany years ago the plastic tank on the standard rad died, and putting in a China rad was the best value option. That radiator was excellent, and recently died when the front of my car got hit (which is what also led to the later death of the original fan clutch - I HATE 80yr old drivers). So these two rads are about 50mm thick or whatever, which just brings the face of the core that bit closer to the engine. Which just means that you can't use other RB fans that push the fan further forward, because it gets scary close.

Let's be clear, I'm not having cooling problems. I'm only suffering from annoyingly conservative fan clutch activation points.

I actually don't have a problem with spending $350 on an OE one. I have, however, spent nearly that much on non-OE ones to this point, with only a certain % hope of getting a refund on the basis of not being suitable for task (which the supplier knew about), and would prefer not to have this turn into $700 still with an open ended question of whether it will work.

Edited by GTSBoy

I'm a bit finicky with cooling cores and I know for a fact that extra depth and or rows of tubes isn't always the best way .

People who've been in the radiator game for a generation will tell you that the hot side or top tank is always the one that dies on these OE type radiators and replacing them and if need be the core generally works out ok .

These Chinese radiators must really have some depth if they are 50mm (almost 2 inches) deeper than a std OE one ? I still have an R32 GTR Koyo radiator I bought brand new for my Bluebird FJ20 conversion years back and I haven't looked at it for a while but I seem to remember its core being ~ 20-25mm deep and I don't remember std GTRs being chronic overheaters .

Five cm is actually a fair bit of room to lose and I doubt Nissan had it that way in a car that had to mount and use three cooling cores by accident . Absolutely your call but its common to have issues std systems don't have when you go away from the way the factory had it .

My suggestion is to beg/borrow a std Skyline radiator and working hub and see if the problem still exists .

A .

Is there any chance I could get someone to measure the PCD of the water pump flange of their RB fan clutch?

I can confirm every other measurement, but the DC guide only lists flange diameter, not PCD.

From hole centre to hole centre across the water pump flange; I'm looking for a measurement of 61mm.

Cheers, Dale.

I'm a bit finicky with cooling cores and I know for a fact that extra depth and or rows of tubes isn't always the best way .

People who've been in the radiator game for a generation will tell you that the hot side or top tank is always the one that dies on these OE type radiators and replacing them and if need be the core generally works out ok .

These Chinese radiators must really have some depth if they are 50mm (almost 2 inches) deeper than a std OE one ? I still have an R32 GTR Koyo radiator I bought brand new for my Bluebird FJ20 conversion years back and I haven't looked at it for a while but I seem to remember its core being ~ 20-25mm deep and I don't remember std GTRs being chronic overheaters .

Five cm is actually a fair bit of room to lose and I doubt Nissan had it that way in a car that had to mount and use three cooling cores by accident . Absolutely your call but its common to have issues std systems don't have when you go away from the way the factory had it .

My suggestion is to beg/borrow a std Skyline radiator and working hub and see if the problem still exists .

A .

You don't seem to be listening properly. There is no problem with the cooling system. There is no reason to be worrying about the cooling system. The Chinabay cores are not 50mm thicker. They are 50oddmm thick (52, 54, 55, depending on which one someone has). They are much much better than the standard single row core in Skylines, which were adequate but offered little reserve capacity. Although I must say that they are some shit ones out there too. As with everything ChinaBay.

So I didn't lose 5cm of engine bay space. I lost enough room that I can't use the later fan that comes off the Neo that I transplanted because those fans are deeper and hence project further forward. Combine the two changes together and it gets too close for comfort. BUT THAT IS NOT A PROBLEM BECAUSE I CAN JUST KEEP USING AN RB20 FAN!

The only problem is the bloody aftermarket clutches that are available appear to suck the big one.

I would also like to ask you why anyone would pay a huge sum of money to get someone to crimp on a new plastic top tank to a new core just keeping the old plastic bottom tank? That would work out about 6 times the cost of dropping in a ChinaBay radiator. Nuts.

Do you have one decent clutch hub? Thinking laterally, rather paying up for a new hub is it worth considering buying a 42mm buck choy core?

The radiator is not part of the problem. Any RB fan clutch will physically fit. It is the fans themselves that change depth. So long as I have an RB20 fan (which I do) I'm fine. All I need is a fan clutch that doesn't think I'm driving an RB30 Patrol through the desert.

I have obtained a good secondhandy today and will swap it in soon as possible, then hopefully the problem will be history.

Edited by GTSBoy

You don't seem to be listening properly. There is no problem with the cooling system. There is no reason to be worrying about the cooling system. The Chinabay cores are not 50mm thicker. They are 50oddmm thick (52, 54, 55, depending on which one someone has). They are much much better than the standard single row core in Skylines, which were adequate but offered little reserve capacity. Although I must say that they are some shit ones out there too. As with everything ChinaBay.

So I didn't lose 5cm of engine bay space. I lost enough room that I can't use the later fan that comes off the Neo that I transplanted because those fans are deeper and hence project further forward. Combine the two changes together and it gets too close for comfort. BUT THAT IS NOT A PROBLEM BECAUSE I CAN JUST KEEP USING AN RB20 FAN!

The only problem is the bloody aftermarket clutches that are available appear to suck the big one.

I would also like to ask you why anyone would pay a huge sum of money to get someone to crimp on a new plastic top tank to a new core just keeping the old plastic bottom tank? That would work out about 6 times the cost of dropping in a ChinaBay radiator. Nuts.

I don't understand the point of this thread??

You know what you need to do, you tested two aftermarket clutches and they weren't right so either but a genuine one (which you said wasn't a problem) or a second hand one which you did.

Or were you asking if people have had the same issue with aftermarket clutches?

The point was to find out if anyone knew how to tweak the springs or otherwise knew of a solution that would work, seeing as I was invested in 2 of them already. Was trying to avoid the apparent endless cycle of obtaining another one to test (regardless of what type it was) and having to spend an hour or two swapping it in each time. Time I would rather spend with the kids.

As it turns out, the used RB25 one I put on day before yesterday works just fine, as you'd expect. So, crisis averted!!!!11juan!! Unless there was a problem batch of these Dayco ones, then at least the thread serves as a warning not to try using the Dayco R31 clutches on Skylines (or at least on Neos, if the higher thermostat temp has any impact on the temperature that the clutch sees).

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