Blue fan clutch mod...Thread has gone to hell, read at your own risk (1 Viewer)

[landtank]

the needle stayed about two widths under half.

This is what made me think you were over cooling, Cattledog mentioned the same thing when he downshifted and held it there for a bit when the clutch was over filled.

I'm thinking that 6K oil is probably what's going to reliably get the job done for a stock setup and 10k oil with a SC/substituted non-ringed fan.

As far as I can tell the stock timing has broken down like this


Mine - 120*
Semlin - 115*
Cattledog - 110*

My clutch for all practical perposes was useless, the other two had some cooling but did run hotter than what I'd consider normal. Of the three Cattledog had the best out of the box cooling which would make sense.

 

[Tools R Us]

This is what made me think you were over cooling, Cattledog mentioned the same thing when he downshifted and held it there for a bit when the clutch was over filled.

I'm thinking that 6K oil is probably what's going to reliably get the job done for a stock setup and 10k oil with a SC/substituted non-ringed fan.

As far as I can tell the stock timing has broken down like this


Mine - 120*
Semlin - 115*
Cattledog - 110*

My clutch for all practical perposes was useless, the other two had some cooling but did run hotter than what I'd consider normal. Of the three Cattledog had the best out of the box cooling which would make sense.

I agree, when testing shakes out, my bet is that 5000-8000 cst will cover everyone. 5000-6000 cst for those in cooler average ambient temps areas and 7000-8000 cst for those that deal with higher temps, SC's, big towing loads, etc. Mine is a big time wind tunnel under the hood when revved, it's a good thing that Toyota has good clips holding the wiring connections on, or they may get blown off! At this point I can't see 10,000 cst being "need" for good cooling and probably provides overkill under hood air circulation.

 

[SUMOTOY]

I agree, when testing shakes out, my bet is that 5000-8000 cst will cover everyone. 5000-6000 cst for those in cooler average ambient temps areas and 7000-8000 cst for those that deal with higher temps, SC's, big towing loads, etc. Mine is a big time wind tunnel under the hood when revved, it's a good thing that Toyota has good clips holding the wiring connections on, or they may get blown off! At this point I can't see 10,000 cst being "need" for good cooling and probably provides overkill under hood air circulation.

My concern is exactly the 'wind tunnel' under the hood during lockup. Run it to redline TRU, I figured with my 'operations check' on lockup it was right between 4500 and redline that I had multiple catastrophic failures with 10kcst.

I'd also look at the dimensions I posted earlier. Without the ringed fan, and your 3/8 dimension posted flex, you are at critical dimension in terms of interference. I was well into the radiator core (at least .500 in).

I also read an article that there are model airplane prop tachs that can be used on radiator fans to get rpm. Might be nice to have that data for lockup comparison to fluid viscosity.

Here I'm quite happy to be proven overcautious. From a physics standpoint, thicken the fluid, you have more coupling at higher rpm than you would otherwise.

Scott Justusson

 

[Tools R Us]

I hit 4800 rpm a few times when watching the tach, maybe more when not watching. Bounced the truck very hard and the foam blocks are still intact. This is about as hard as I intend to beat this truck, so I am confident that it will work for my needs with some margin for error.

Here is some data for you, is that enough, or do you need bent frame rails too for a "proper test?"

 

[medtro]

I have used any where from 4 - 5.5 bottles of 10,000 cst of Toyota fluid on several 80s, I have tried one of them with over 5000 RPM (with old back hub), no problem so far.

 

[landtank]

I'm going to step up the viscocity to 5K tomorrow. From Cattledogs report it seems 3K is borderline and from Tools the 10K is overboard. I'll also will be doing under hood temps this week as well.

 

[Cattledog]

Well I swapped in the 5000 wt OFNA silicon difflock oil this afternoon. I was OCD on the cleaning of the clutch to avoid mixing wts of oil due to the testing. It really can take some time to remove all the oil from the clutch. I refilled the clutch slowly to the bottom of the res. holes that also can take some time. The clutch was not filled Aussie style.

The results, The clutch engagement temp is the same as the second test. The needle will still rise about two width up with AC on full non recirc in park.

On highway the truck will cool right down to the middle of the gauge.

I did stop the fan at idle with the engine warm, no problem with a thick glove. I held the fan for about 2 minutes and released the fan. The fan clutch engaged and WOW that thing moved some air! Hard to objectively compare, but seat of the pants was double the amount of air was moved over equal time.

I also noted the gauge position after letting the fan go. The temp needle was around 3/4 high. As the clutch engaged the cooling by the fan was fast. Took less than 15 seconds for the temp to drop to middle of the gauge.

Last, I drove around at 40 mph and let the gauge settle to the middle. I then down shifted, the needle dropped about one width very quickly.

I am done with the testing and experimenting for now. I might put a temp data logger on the ac condenser for observation if there is interest. For my needs the 5000 wt should be fine. I would really like to try and do some towing to see the impact of the clutch changes.

Thanks

 

[Tools R Us]

That mirrors my results, unless the airflow is blocked or the fan is stopped the temps are much more steady. Before if it got hot at slow speed the only ways to cool it was to shift neutral and hold about 1500 rpms or shut it off and wait. Now it never gets there and if you cause it to heat the recovery is very quick, very nice added cooling capacity.

 

[SUMOTOY]

I hit 4800 rpm a few times when watching the tach, maybe more when not watching. Bounced the truck very hard and the foam blocks are still intact. This is about as hard as I intend to beat this truck, so I am confident that it will work for my needs with some margin for error.

Here is some data for you, is that enough, or do you need bent frame rails too for a "proper test?"

A proper test IMO, needs nothing to bend other than the radiator fan blades. A proper test needs only two components, clutch lockup and redline.

The pictures are nice, more appropriate to this thread might be my fan/radiator interference shots. I'll get those up with the measures as a data point.

I'm all up for 'testing', I just don't recommend the 10k cst in lockup and 5000rpm engine speeds. My front end is already bent up, prior to my radiator fan interference problem.

TRU, I'm not an enemy to good information and data. I'm a guy that put 10k cst fluid in his VC and found that under lockup and high rpm, the fan will bore the radiator. I also proved that's not 'just' a shroud problem as many proposed. I bored the radiator without the fan shroud. Then if you look at the measures I took, a stock fan (without the supercharger spacer) gets really close to the radiator under lockup and high rpm's. I'm glad it hasn't happened to you, but my data and multiple experiences of failure, certainly makes me think it's possible. I enjoy the thought of being a "special case", I just don't believe the data supports that.

SJ

 

[landtank]

Sumotoy, I realise that you had this problem but I'm concerned as to how much oil you added. From Cattledog's experience you could over fill the clutch with 3K oil and have it respond at high revs as if it was 10K oil. Now an over fill of 10K oil would definitely exceed what Tools has experienced.

I'm off to fill it up with some 5K

 

[SUMOTOY]

Sumotoy, I realise that you had this problem but I'm concerned as to how much oil you added. From Cattledog's experience you could over fill the clutch with 3K oil and have it respond at high revs as if it was 10K oil. Now an over fill of 10K oil would definitely exceed what Tools has experienced.

I'm off to fill it up with some 5K

Rick:
I've been filling VC clutches for several years. As a rule on VC's I don't cross the drive plate (something I was told many years ago, it changes the shear properties to the drive holes instead of the teeth). I suppose I could have, but I doubt it. 10k cst is like moving silly putty, so it would have been intentional.

I also drained the old fluid for a couple days before filling.

Lockup vs rpm is my only concern with higher cst fluid. I have a white paper that speaks to VC fan thermos with this other interesting tidbit:
"The hydraulic nature of a viscous drive prevents if from achieving a fully on or fully off operation. Consequently, in the disengaged mode, the fan continues to operate at speeds as high as 45 percent of the fully engaged rate..."

Reading thru all the 'data collecction' being very subjective (other than outright failure, I got that nailed) It might prove beneficial to work with fan speeds vs rpm, instead of glove tests and fluid swapping. Maybe C-Dan can find a TSB on that and/or cfm ratings of fans?

My concern is that I've tested and found failure in the absolute extreme. However, since it's still within the operating parameters of the vehicle, I shouldn't be experiencing this type of failure.

I'd also venture to say that a ringed fan might prove the best alternative for those wanting the VC setup. It may throw bits of fan during failure, but I consider a radiator puncture to be a critical breakdown. Costing a different VC to get destroyed rope towing the truck to effect repair.

Scott Justusson

 

[landtank]

I know how fond you are of all your past experiences and readily apply them directly to the LC. I however don't share this point of view. While some might apply, I don't think you can assume they all do.

In this particular case I'd bet you were over filling the clutch. These clutches aren't like others. In fact if you were to research how the Aussie's fill their clutches, which are made by the same company(Aisin) and bolted to the same vehicle, and applied that technique to our clutches, you get an overdrive condition as Cattledog experienced.

Now if you can say with 100% certainty that you were not any higher than what I've posted in the opening posts, then you weren't over filled.

 

[landtank]

I've just got back from a run with the truck with 5K oil in it and I'd have to say this is probably the minimum viscocity that you should have in your clutches.

Another point was when I drained the old oil it had darkened comsiderably. I don't know what this means, just an observation. The new fill went in clear and I'll check it after some miles.

I'll be changing the initial posts to reflect the oil change.

 

[cruiserdan]

TRU, I'm not an enemy to good information and data. I'm a guy that put 10k cst fluid in his VC and found that under lockup and high rpm, the fan will bore the radiator. I also proved that's not 'just' a shroud problem as many proposed. I bored the radiator without the fan shroud. Then if you look at the measures I took, a stock fan (without the supercharger spacer) gets really close to the radiator under lockup and high rpm's. I'm glad it hasn't happened to you, but my data and multiple experiences of failure, certainly makes me think it's possible. I enjoy the thought of being a "special case", I just don't believe the data supports that.

SJ

Tools does not have a supercharger. His fan is in the stock location.

 

[SUMOTOY]

I know how fond you are of all your past experiences and readily apply them directly to the LC. I however don't share this point of view. While some might apply, I don't think you can assume they all do.

In this particular case I'd bet you were over filling the clutch. These clutches aren't like others. In fact if you were to research how the Aussie's fill their clutches, which are made by the same company(Aisin) and bolted to the same vehicle, and applied that technique to our clutches, you get an overdrive condition as Cattledog experienced.

Now if you can say with 100% certainty that you were not any higher than what I've posted in the opening posts, then you weren't over filled.

LT:
I looked at your pictures you posted, and as a rule I fill below the drive plate. Not thru the holes, not over the top. Hard to "spill" 10k oil. Not sure what the aussie method is, I'll chase it down if it's in this link. Sounds like the definition of overfill to me.

I work on automobiles for a living, have for over 10 years. I'm also quite a nerd and overcautious when it comes to failure. I saw a lot of it, and only look at how VC's work under lockup conditions. You can change viscosity, which will affect lockup. To move this to beyond speculation, you either need to reach failure (I have several times) or you take some sort of measure given a set of changes. That would include engine rpm, accurate temps, and fan rpm. The conditions of my failure are documented.

Again, I found failure mode that's all. If you want to attribute it to overfilling above the drive plate, I'm comfortable that you hold that opinion. I'm also quite comfortable that under the right conditions of VC lockup, the radiator fan becomes an auger. With or without the SC spacer, we know fan flex takes place. How much? Well, you either need for it to fail or set up some conditions that indicate otherwise. Redline it with a corresponding measure of fan flex would be the first step. Right now I haven't seen either. It's not the fluid I worry about, it's assessing the risk of it.

Scott Justusson

 

[Cattledog]

Rick,

What brand oil did you use? Did you clean the clutch with solvent? Hexane worked well for me. I will be pulling the clutch in about a month too. Worst case the silicon fluid should thicken with the heat cycling. The shearing might lower the viscosity but not much I see heat cycling being the bigger issue for the silicon fluid. I need to find a viscometer and heat cycle and test the cheap fluid. Toyota's 6000 cst fluid is a sure bet for temp and shear stability. I may order some later.

Also, I noticed that when the clutch was "clean" the hub would spin like a normal bearing, fast while holding the housing.

 

[SUMOTOY]

Tools does not have a supercharger. His fan is in the stock location.

Dan:
My concern is based on my measures. If you read my report, it shows fan flex being critical beyond the SC fan spacer. IOW, given the depth of the fan auger, I ccorrected the measurements for the spacer, the fan is really close to the radiator at lockup and somewher above 5000rpm engine speed.

I also suspect that the radiator caused fan blades to snap before the fan reached full flex. Hence my concern, SC spacer or not.

SJ

 

[cruiserdan]

My bad then. I did not read it that you believe the fan will strike when it is in the stock location.

 

[landtank]

Cattledog, I just drained it. I'm a big beleiver in no chemicals unless absolutely needed. I got the same OFNA oil you did only drove to Nashua to get it .

The housing also rotated very easy once the oil was out.

 

[SUMOTOY]

My bad then. I did not read it that you believe the fan will strike when it is in the stock location.

Dan:
Post #78 in this thread, copy of 2-10-2006 post: "Conclusions"

Keeper of Parts, your excellency, I believe it was originally written as a response to you back in February...

My bad... is apparently doing the right things, then breaking them. I may need to steal Photoman's "if it ain't broke, fix it till it is..." I certainly qualified using my fan as a way to modify my radiator application.

SJ