Thank you all for taking time.
Yes, I appreciate and understand the differences between viscous and non-viscous fan clutches (thermal/non-thermal), just pondering choices of HD or RD.
And unusually, intuition tells me the earlier viscous version is wiser than the thermal which seems a quirky contraption. However all dismiss its quality, robustness and effectiveness. I guess it makes sense when you think about it.
Again, I own a '72 S1 XJ6 with the old saloon type metal fan.(same as on 420/MkX, S1 XJ-S and others no doubt such as 340 etc).
@Breen60 : Paul do you remember the part no. for that Dayco? Regular or Heavy duty? Do you recall?
At any rate, I don’t wish to return to a topic discussed ad nauseum, in part by me!
These threads are worth perusing for those interested.
https://forums.jag-lovers.com/t/s1-xj-fan-replacement-with-electric/361976/17
In the end it is personal preference/experience to large extent.
Just need to experiment.
I am re-hashing the same thought process/dilemma, and again returning to the same conclusion… Restore all to original spec…
Although the elec fan upgrade does appeal to me, I’ve never had a problem in the past with my old Jaguars running as original. And I have restored entire block and cooling system already, and anticipate no problems even in TX heat.
YET … I am drawn to the idea of efficiency of course and as a perfectionist, the best option.
But I still read reviews of electric fans dying, and in TX traffic I can’t have that.
I may install a small elec. fan in the front of the AC condenser when I get there.
And if I replace with good elec fan unit, I need new alternator, new wiring, etc…$100 here and $100 there adds up, and I have much else to do yet.
An interesting note, I have read from apparent well respected Jaguar restorers addressing those who are considering adding electric fans to the older models such as the Mk2 and XK that the airflow has a dead area at those grilles /front radiator areas at 70mph.
Vis a vis, continuous fan operation is necessary even at speed to pass air properly and cool on those models.
Anyway, reading past threads there are some discrepancies I’d like to address.
The 2705 recommended for the S1 XJ6 is not heavy duty, it’s regular duty.
~3" long.
I received the 2747, and it’ll be too long at 3.5" for my Series 1 XJ6 and I’ve returned it.
(Amazon, free returns and job security for someone I guess)
It is also 7.5 " diameter…too large for this older metal fan style.
The clutch on my car was perfect at 2.5" in length. And I wouldn’t go larger than 7"dia.
And I think going longer than 3" will be too long.
I ordered the Hayden 2765 (Regular Duty) per past posts I’ve read here. ~2.5" long.
HOWEVER, one must be aware that on these older cars the pilot hole at clutch base (where attaches to water pump) is .63" (5/8"), this 2765 model has .75" hole.
Therefore it needs that bushing that many come with which fits within to attach to the earlier models (.63 water pump shaft) such as mine.
Strangely past posters stated how difficult it was to find this Hayden model 2765.
I don’t know how that’s possible. Internet has MANY vendors for them.
However, just came across a post at Summit Racing directly replied to by Hayden describing a shorter version of the 2747 (heavy duty)…the 2947. (see below)
A perfect option for those wanting a heavy duty. Again, many V12 XJS guys prefer HD…
I’m uncertain and am going to play with the Regular Duty and see what I think.
This 2947 is not listed on the Hayden Fan Clutch part list dated 2007 found on their site. Must be new.
(VERY useful list I might add. Lists ALL dimensions…)
https://www.haydenauto.com/upload/HaydenAuto/Documents/Cat_Hayden/2007-hayden-fan-clutch.pdf
They recommend the 2705 (regular duty) for 71-73 XJ6 models…but I have to be a wiseguy and try something else…
Of course I understand they do not “lock up” entirely.
I am simply trying to find some perfect balance, not wishing to sap HP, be too loud, steal mpg…load the motor unnecessarily,etc.
Going electric, well, one needs a good quality fan$$ or you are gambling/wasting time, then I must update alternator, wiring, install relays and so on…and I already have a lot to do yet and it adds up and that can be never ending.
And I already gotta deal on an original rebuilt original Lucas alternator from a Lotus …so heck with it.
So we’ll see how it goes…
In the end, for S1-S3 XJ6 Hayden options are:
2705 Regular Duty .63 pilot hole, 3"length (S1 specifically) 7"dia
2765 Regular Duty .75 pilot hole (needs bushing) ~2.5" length 7"dia
2747 Heavy Duty .75 pilot hole (comes with Bushing for .63) ~3.5" length
I measured 7.5" dia. on mine received.
2947 Heavy Duty Same as 2747 shorter version. How short? Pilot hole dia?
Dunno need to call Hayden.
Again, Regular Duty locks up ~60-70% hot, Heavy Duty 80-90% when hot.
Horses for courses.
Ok, that’s all I know.
P
EDIT: Hayden 2947 Specs found. Possibly great HD clutch option for S1 XJ6 and earlier metal fan models.
Specifications:
- Mounting Hole/Stud Qty: 4
- Bolt Thread: 5/16" - 18
- Clutch Type: Thermal
- Color: Raw Aluminum in Color
- Description: Fan Clutches
- Drawing Type: C
- Duty Rating: Heavy Duty
- Fan Bolt Circle : 3.250"
- Fan Mount Dia. : 2.622"
- Fan Mount Height : 1.09"
- Material: Aluminum
- Meets or Exceeds OEM Specs: Yes
- Mount Dia. : 2.59"
- Mount Type: Flange
- Mounting Hardware Included: Not Included
- New or Remanufactured: New
- Original Equipment Replacement: Yes
- Overall Dia. : 7.2"
- Overall Height : 2.707"
- Performance Rated: Yes
- Rotation: STD
- Style: Heavy Duty
- Type: Thermal