quote:

Originally posted by 329L:
The beautiful thing about the Transynd is, the fluid will cool back down naturally when not being worked. Ive noticed for the last several years of using it, that the trans temps come down MUCH better coming back from a run than MOST other fluids do.

Nuz,
You dont have to run the fluid temp up to get a consistent transmission. If you switch to the Transynd, you will find your 1st pass will be much closer to the next runs. I have found the converter stall doesnt move anywhere near as much with temps with transynd, compared to other fluids.

Thanks, Jeremiah. For years I'd puzzled over why my first pass of the day would be quite different from later runs, and suspected trans temp.

Thank you for all the thoughtful responses; I am grateful for every one.

I just ordered a case of 3 x 1-gallon jugs of Castrol TranSynd 668 fluid. $129 from Walmart, including tax and free shipping.
A single gallon from my local O'Reilly's is over $62, incl. my 'good guy' discounts.

Expensive, yes. But then I think of all the money I lost when I went out in the first money round..... If I only had a slight edge...

The many other alternatives suggested here may in fact be just as good, if not better, but the most votes seemed to point toward the TransSynd as a start point.

I ass/u/me the 668 to be compatible with my GM transmission.

When I change the fluid, I think I would have to pull my transmission to get the converter out to better drain the transmission. Ugh.

I think for now I'll take my chances on just draining the pan and refilling it, allowing the older but still fresh, cheap, synthetic fluid to dilute the new fluid a little.

I don't know yet if I dare to turn over the engine a turn or two just to try to drain out more of the old fluid.

The subject of ATF has never come up in the circle of racers I hang with.

I ran into trouble getting type F around my area, and using all these "trick of the week" fluids years ago and decided that I would find a suitable replacement at Wally World so I could grab it off the shelf and go. The Valvoline Maxlife full synthetic ATF has worked great for me in my glide and 800+ HP BB for hundreds of passes every year. I pull it apart every couple years to look at, replace some seals and put it back together.

Valvoline ATF

Cant remember when I replaced the clutches and band in it but it was years ago.

A properly built trans isn't picky about what fluid you run in it until you start trying to build boost or get into the big HP.

I'm still using the ATI Super F Synthetic 20W. I drain the pan & replace 4 quarts annually.

I said I would change out to the 668 but haven't done it yet.

https://www.atiracing.com/prod...ransparts/superf.htm

2BKING

quote:

Originally posted by Brandon@BTE:
https://www.allisontransmissio...ds/on-highway-fluids

Castrol's variant is the most one we see used, but a 668 spec fluid is the best you can buy.

I agree with Brandon and a former member here on the Allison Transynd fluid.

quote:

I just ordered a case of 3 x 1-gallon jugs of Castrol TranSynd 668 fluid. $129 from Walmart, including tax and free shipping.

A Smoken Deal! NICE!!!

I've been using the Mobil versionof transynd for quite a few years. I won't use anything else now

Back when I raced, I switched to Schaeffer All Trans Supreme synthetic. Never had an issue with it.

Fluid can be a great tuning aide too!

Well, I tried the Castrol TranSynd 668 fluid at a three-day event over Memorial Day weekend. This fluid may have helped narrow down my ET variation.

Though the results are far from conclusive, I concede that I was only able to change about half the fluid, simply draining and refilling my stock transmission pan. So the new fluid is diluted with cheap, synthetic fluid.

I would have had to pull the tranny I guess to try to drain more fluid from the converter.

My transmission never got very warm; at the start of the day it would get up to perhaps 105 degrees after a pass. Later in the day it might get up to 135 degrees.

I may try to rig up some sort of transmission cooler by-pass to shunt some fluid around the cooler to better warm the tranny. I'd shut off a valve when it got hot enough.

quote:

Originally posted by Bad Nusz:
Well, I tried the Castrol TranSynd 668 fluid at a three-day event over Memorial Day weekend. This fluid may have helped narrow down my ET variation.

Though the results are far from conclusive, I concede that I was only able to change about half the fluid, simply draining and refilling my stock transmission pan. So the new fluid is diluted with cheap, synthetic fluid.

I would have had to pull the tranny I guess to try to drain more fluid from the converter.

My transmission never got very warm; at the start of the day it would get up to perhaps 105 degrees after a pass. Later in the day it might get up to 135 degrees.

I may try to rig up some sort of transmission cooler by-pass to shunt some fluid around the cooler to better warm the tranny. I'd shut off a valve when it got hot enough.

If you're running a stock style radiator with a trans "cooler", run it through there.
As original equipment it's designed to help the trans warm up, as much as to cool it. It's really a temperature stabilizer as much as anything.

quote:

Originally posted by Goob:


If you're running a stock style radiator with a trans "cooler", run it through there.
As original equipment it's designed to help the trans warm up, as much as to cool it. It's really a temperature stabilizer as much as anything.

Thanks, Goob. That hadn't really occurred to me; I think I will try that next. I can keep my engine coolant to 160 degrees, even when hot-lapping.
Will need to figure out what I need for fittings to adapt my -6AN steel-braided hoses to the radiator.

When I first converted my S10 from street to race-only, 12 years ago, I selected the biggest, plate-type tranny cooler I could find, thinking transmission heat would be a problem. And I fabbed up a mounting so it would not have to hang on the radiator, wanting to be able to pull the radiator with greater ease in less time.

And I didn't want to use the internal transmission cooler, knowing that it would be messier to pull the radiator.

Interestingly, I moved the trans cooler to a point behind the radiator, to draw some heat at that point, but it still stays cool.

Thanks again.

I failed to mention earlier; when I switched over to Castrol TransSynd 668 tranny fluid, it seemed like my stall speed dropped by about 100 or 200 RPM. I was pushing through my brakes at the starting line.

Anyone else notice that?

quote:

Originally posted by Bad Nusz:
I failed to mention earlier; when I switched over to Castrol TransSynd 668 tranny fluid, it seemed like my stall speed dropped by about 100 or 200 RPM. I was pushing through my brakes at the starting line.

Anyone else notice that?

I do not think my stall changed any.

Wal Mart branded Type F. The local one always seem to have it on the shelf. If I made power, or ran more stall speed, I might consider something else. Take care. Tom Worthington

Yes, mine also tightened roughly 150 rpm switching from napa type F.

quote:

Originally posted by Bad Nusz:
I failed to mention earlier; when I switched over to Castrol TransSynd 668 tranny fluid, it seemed like my stall speed dropped by about 100 or 200 RPM. I was pushing through my brakes at the starting line.

Anyone else notice that?

The transynd is a little heavier than a dextron vi/mercon lv. 100-200 rpm isnt out of line.

I've raced two weekends now with the Castrol TranSynd 668 ATF.

The jury is still out, but it seems that my ETs have tightened up some, in spite of having to buck a rather high, variable headwind in the quarter-mile.
Must compare my 330', 660'and 1000'split times yet.

My 60-foots were all over the map, but that was prob. due to other things going on, including new DA drag shocks or something.