Does anyone know the optimum operating temperature range of the 901, and/or the the temp. at which accelerated wear becomes an issue?
Has anyone run an oil temp gauge on their 901 transmission?
Thanks Guys,
I'm always amazed with the amount of knowledge residing in this thing of ours ( couldn't resist the movie reference ). The reason I inquired is I'm running a 4.3 V-6 and its' exhaust runs closer to the case and generates considerably more heat than stock. You're replies lead me to think that although it might be a nice safeguard, it probably isn't a necessity (after all I've run it as-is for several years now), at least until I have more opportunities to really run it hard.
Scott
i have a cooler and pump on my transmission plus a temp guage. The highest i have seen my temps street driving are only 150F after flipping the pump switch they fell to 135 in a few minutes.
Having the exhaust coated is definitely on the to-do list. I'm convinced excessive ambient engine compartment temps. are a major bane of conversions, shortening the life of; alternators, starters, batteries etc. I've fab'd heat shields, but aren't convinced of their efficacy.
Which brings up another question that perhaps should be asked in a new topic (if so, tell me).
Any improvements over the 75-90w originally called for? Broader Ranges? Synthetics? Additives?
...back in 2000 or 2001, I had talked with an engineer at ROYAL PURPLE, about using their stuff in my 915. He was saying that the lubrication boundary layer was so thick that it wouldn't allow the dog faced gearing the 915 to shift easily. They had no problems with the Borg-Warner and other styles. Even with the Funny Car transmissions, that usually remove every other tooth of the syncros.
Several racers had called and conveyed their problem. Royal Purple suggested using their ATF version of the lubricant in the 901/915 transmissions. Some changed to the ATF, some didn't and changed to SWEPCO thinking that the ATF fomula wasn't up to snuff.
So I've had my car running now for about a year. I used an infrared temp sensor to 'shoot' several points of interest on my car to check cooling ability. I have installed the flaps on the underside of the car and did notice a drop on temps, as it helps evacuate the heat under the car.
Concern? or Acceptable? I did a drive the other day when it was 90 degrees here in Seattle. After street driving, I immediately used the temp sensor to check engine oil temp at the filter (186) and concerning was the transmission housing at 200 degrees. Is this radiant heat from the exhaust warming the housing or is there something else going on?
IAMCHAPPY is seeing 150 street driving. Why am I hitting 200? Thoughts?
150 to 210 is the range that my box shifts smoothest. That said there are a lot of factors into temps for any given car. Driving conditions, lube type, LSD or not, and driving style all contribute. I used an infrared thermometer for a good while but was never satisfied that I got good readings since the ground clearance limited the number of places I could get a good shot at it. In other words, there was too much variation in the readings to trust them. My temps with the installed sensor/gauge are lower than those I got with the infrared thing.
I figure the 993 engine driven like I stole it puts enough stress on the R&P that I want as slippery and cool a trans fluid as I can build into the car. The excellent clutch-type Guard LSD just furthered the cause.
Also I installed a temp sensor (shown in the thread below) in only one place, where the speedo gauge would go. That works for me because I use GPS as my speedo and don't even put a speedo gear in my transaxles any more.
Next time I take the box out I'm going to put sensors in each compartment just to see if there are significant differences.
http://www.914world.com/bbs2/index.php?showtopic=161520&st=0
Chances are you're fine without a cooler, even at 200 degrees if your box shifts well. I'm also convinced that there is a lot of exhaust-heat soak if the car is in town sitting at red lights and hardly moving... not much of a factor on the open road. I run synthetic fluid in mine.
Initially I used it because, with a high torque engine driven with authority, I would be protecting the R&P and they're more expensive than synchros. But I also discovered (although this is prior to having a temp gauge) two things.
1. My temps dropped about 10 degrees on average and
2. My synchro wear didn't increase at all. About that ...
Number 2 is conditional: There are plenty of folks that will tell you synchro's will wear badly and dog teeth, because the synchros don't hold as well, will suffer if you run synthetic. They might be right for most folks.
All I can tell you is that I haven't found it to be the case. But I'm certain it has everything to do with shift technique, i.e. smoothness and reasonably "slow" shifts, but I can't prove it. Not enough data points.
Good luck
Thanks you have lots of perspective and it make sense. I have not seen the temps get over 200 with the infrared sensor, suspect you're correct on the temps being lower inside. You've got the proof with your temp sensor.
Running 200 degrees on a 90 degree day after an hour of driving is expected.
Thanks!
200 is fine
street cars won't have a problem with temp
track cars will
its not entirely about the radiant heat or the torque for them
I hit 250 on my track car (with a guage) and a 2.0/6
its oil... anything approaching 230 is a problem
I don't think the speedo drive is a particularly good spot to measure temps because it does not see much oil and is far from what creates the heat.
I measure temps in the fill plug. Stock 3 liter motor running Miller's transmission fluid. It's a track only car. Without cooling, it will go north of 275 pretty easy. With a cooler and a blower on the cooler, it will run 250 if you are really pushing.
200 is pretty normal. In my experience, shifting problems start around 250+
forgot to add that my 250 is with a cooler on the track
I use redline light weight "shock proof"
I see about 105C (about 220F) on the track, 2.7 with ZF LSD and Motul FF-LSD synthetic oil. No cooler though. And no problems shifting.
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