Transaxle temperature readings

[bluefirefly]

[insyncro]

How cool is TOO cool?

Is there a thermostat plumbed in?

[Jon_slider]

Testing update.
Going over highway 17 I could not get the transmission temperature above 140°.
I used fourth gear, I allowed high EGT of 1250, I mashed the pedal at low RPM of 2000.

I should have been at 190°, could not make it happen.
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[snowsyncro]

This is encouraging.

Great test, glad you did it, but hopefully you won't want to do this any more...

[tschroeder0]

Great thread.
I am curious what people are thinking the problem here is (if there is indeed a problem)?

I am assuming it is trying to abate the 3-4 slider failure since this seems to be the most common failure right? If that is the case then what is the main culprit, a high average oil temp, or as Doug pointed out the occasional very high gear face temps?

Does lowering the average oil temps have much of an effect on the gear face temps under high load?

Just wondering out loud, in my case( no pun intended) I am a pretty easy driver much of the time, but when travelling around here i spend a lot of time heading over passes large and small, in third gear pushing pretty hard for, at times, up to 10 miles at a shot.

I guess I am weighing out the extra work and worry over more fittings that could possibly fail and leak, against what it is that would add some real longevity to the tranny...???
Thanks,
Todd

[gears]

Heat build-up in 4th gear and mainshaft ball bearing (due to lack of adequate oil splash) is the biggest issue being addressed. If I had to chose between cooling the oil and merely circulating it to where it's most needed, I'd likely chose circulation. (This isn't to say that cooling the oil won't cool 4th gear, too.)

The ultimate system IMO would circulate all the time, while cooling some of the time .. because as some have pointed out, the optimum temperature for the oil is probably higher than 150*. I believe some EP additives don't perform until a specific temperature is reached. Sorry I can't be more specific with that temperature (and I could easily be wrong).
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[insyncro]

Very curious to know if the oil is being sprayed by an internal "Squirter" and aimed or just flush mounted at the case?

I personally would rather have my fluid reach my designated operating temp and stay as close to it as possible.
Not up and down from each extreme.

Many more variables come into play with this mod, IMHO.

Keeping the fluid from being sprayed in certain areas is a must for longevity.

It has been shared with me today that a Syncro box is undergoing a full Herman currently...hopefully we will hear about that from the builder.

[Jon_slider]

more testing results

drove from San Jose to Big Sur
Hottest the tranny got was 155F, when it was 90F outside, going 71mph, about 30 minutes into the drive. Once I got back to the coast, tranny temps dropped below 140F

hard shot to focus while flying, top gauge is tranny temp of 155F, bottom gauge is showing EGT 500f post turbo, equiv to 750F pre turbo as most peoples EGT probes are mounted.

I believe the cooler is very effective, it makes shifting very easy.

Before the cooler, at 170F tranny temp, 3rd gear was notchy. Its smooth with cooler lube.

First problem report, on the way home from Big Sur around 8pm, I noticed that the cooler ran all the time, even when the lube temp was 90-100F. The maximum temp achieved was barely 120F on the freeway at 70mph.

Not sure where the failure is that is making the cooler run full time, yet, but full time is too much. At the moment the radiator and the lube pump are both on at the same time.

Per gears suggestion, Im tempted to test unplugging the radiator and running just the lube pump and see how much regulation that creates..

ah the wonders of things mechanical
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[Jon_slider]

Today I tested the Tranny Cooler with its radiator fan off, per gears suggestion, with just the pump running. Max temperature achieved was 140F @ 70mph when outside temp was 65F, a differential of 75F.

I then tested the same no fan, yes pump configuration going over highway 17, and max temp achieved was 140F, @ 55mph uphill, when outside temp was 60F, a difference of 80F

So here are some differential temperature preliminary benchmarks

1. No cooling system, 100F differential @ 70mph flat freeway, 120F differential going over HWY 17@55mph

2. Cooling system radiator fan On, pump on, freeway differential 65F, hwy 17 differential 65F

3. Cooling system radiator fan Off, pump on, freeway differential 75F, hwy 17 differential 80F

I look forward to getting a working thermoswitch installed, so I don't have to keep switching the system off and on by hand. If the pump runs full time, even with the radiator fan off, below 45mph around town, flat ground, operating temperatures drop below 120F.

It also appears to me that below 45mph, no cooling system is needed. The majority of the heat build I see, is above 50mph uphill, and above 65mph flat ground.

The biggest factor in tranny temp is outside temperature. the tranny cooler is predictable at obtaining a temperature differential.

By looking at my tranny temperature, I can come within a few degrees of guessing the outside temperature, and vice versa, once the configuration differential is applied.

Example, no cooler, 70F outside, flat freeway at 70mph, predicted tranny temp will be 170F.

Another example, cooler radiator fan and pump on, outside temp 70F, flat freeway 70mph tranny temp will be 135F. etc.. its all about temperature differential..

The good news is the system as installed in my Syncro, is completely effective at accomplishing the goal of eliminating temperatures above 160F, all the way up to outside temp of 95F @ 70mph. Outstanding!
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[hans j]

Finally tested mine again.

Road is Parleys Canyon between SLC and Park City. About 2300 foot elevation gain, last couple miles 6% grade.

Tested at work first when I picked up my IR gun, about 80* out and measured about 95*F on case under the drive flange and on the 4th gear housing. I used the same places for all measurements.

First stop up the freeway, 60mph, 4th gear (3200rpm), 1050 EGT - measured 136*F on trans.

At the top of the hill, 60 to 55 mph (2/3 way up to keep egt down), 4th gear (3100rpm), 1250 EGT (the max I allow it to go) - measured 147*F on trans. Outside temp was around 70* or so at the summit.

There's my input on it. And I'm running Motul Gear 300 75/90 oil.
_________________
1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181

[Jon_slider]

> about 80* out…136*F on trans.

a difference of just 56 degrees! wow! thats awesome.. it seems very low, but, there may be saveral factors different than my configuration..
1. I have a skid plate over my tranny, very close, disallows airflow cooling
2. you might have been driving for less than 30 minutes, which in my configuration is how long it takes, minimum, to get up to max temperature..

> measured 147*F on trans. Outside temp was around 70*

a difference of 77F, outstanding for no cooler installed

IF outside temp goes to 95F, your hill climb temp would be 172F, based on your temperature differentials. I do not think you need a cooler at all. Congrats on great motor, tire size, and gearing choices. Thanks for taking the time to share info.
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[hans j]

I still want slightly taller gears but stock gearing it tolerable if you don't want to win any races. I also fully balanced my internals so I don't mind running it at higher RPMs.

I was probably driving for barely 30 minutes by the time I got to the summit. I do need longer driving tests though. I did have a gummy shifter issue driving back from Arizona last year, but now I have better fluid and replaced shift bushings.

I have a skid plate too, but skipped the differential housing since that hung down lower, also to keep air flow on the fins. There is a picture of it somewhere in my gallery.

I'll also be doing the SA aluminum main bearing housing and possibly also ceramic coating the gear and bearing housings with a heat transfer product (discussed in the billet main bearing housing thread). I'll also have the holes plumbed for a cooler, even if I don't need it.
_________________
1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181

[outwesty]

Im curious what your engine oil temp readings are with the 5 cyl. I realize this engine is a different beast but curious. Do you have an oil temp gauge ? I just got back from the coast(4cyl AHU) and I'm at 250-260 degrees cruising 75-80MPH. at 65 I'm closer to 230. Cruising around town I'm down to 215. I have the larger B5 passat heat exchanger and a very small 8x12 radiator with a thermostat controlled mocal sandwich plate.

[hans j]

[Jon_slider]

note,
with radiator plugged in and uncovered, and cooler pump running full time, tranny would not exceed 140F on highway 17 and on freeway at 70mph, and tranny temp would run below 120F around town.

test report

covered radiator with foil, and unplugged its fan, ran the pump constantly, to prioritize feeding lube to the 4th gear main bearing constantly, without additional cooling.

It was a hot day for Santa Cruz, 80F. Tranny temp maxed out at 155F at the top of the Highway 17 hill. (That hill would produce 200F tranny temp with the circulation pump and radiator off)

Similar to the hill results, on the freeway at 70mph, tranny temp did not exceed 155F with just the circulation pump running and the radiator covered and unplugged. (With pump and radiator off, freeway temp would have been 180F)

I am happily suprised how much cooling the circulation alone provides. And I especially like that the recirculation return lubricates 4th gear. It is very reassuring to know that 4th gear and main bearing are being actively lubricated at all times.
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[gears]

Excellent. This is pretty much what I expected would be learned from this test. Halting heat build-up in 4th gear reduces overall temperature dramatically, even without an active cooler in the loop.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[insyncro]

I pulled my fan from the cooler as I needed it again on another machine.

I no longer add a fan to the fender well coolers on the 911s I support unless they are doing endurance races.

Last week I had a long talk with a Chap from Mocal.
He loved hearing that trans and diff cooling is helping.
He sounded willing to put together a spec system and offer some discount if multiples are purchased.
They replaced two HD pumps for me and we're really psyched to hear I had scavenger filters attached

[kpbo]

Thanks for all the great info Jon! I'm thinking of something similar, but would really love to avoid running hoses/radiator/fan up front... Given your good results w/o a fan and functioning radiator, I wonder if anyone has considered an cooler that doesn't rely as much on direct airflow, e.g., something like this:

http://www.summitracing.com/parts/mrg-7365g

Similar to what Go Westy specs for their external auto transaxle coolers...
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1987 Syncro Westfalia w/ 'AHU' TDI

[insyncro]

I have had engine oil coolers fail when used with heavy weight oil like trans fluid.

The Summit cooler looks like it is for ATF and the GW one is sold for an automatic.

I know the pump must be ready for the task.

What is the consensus on fluids and type of coolers?

[gears]

Insyncro, are you using an in-line scavange filter? What type (make & micron)?

We typically advise coolers for track cars racing longer than 20 or 30-minute races. Active LSDs add 70*+ to the oil temp.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com