Rusty Bowtie
General Category => GM Tech Questions and Answers => Topic started by: Cool53 on December 23, 2013, 07:40:53 PM
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Building a trans run-in stand now. Believe it or not, I have people buying transmissions, even shops that install them incorrectly and burn them right up. So this stand will allow me to run them in, make sure everything is ok, then show the customer exactly what he needs to do to make a proper installation. I will use a big brake rotor and caliper for a brake, will go to a pump later. Then I'll be able to add the necessary electronics to measure power output. This project will allow me to tune carburetors after a rebuild,curve distributors, and check alternators after I build one. Fun project.
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Jef....thats pretty cool! What's your recommended procedure for transmission run in for the guys who aren't lucky enough to have a run-in stand?
Moose
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Jef
I see your test stand engine has an electric water pump. Have you ever run one of those successfully on the street ? I've always wanted to give one a try.
Moose
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Jef,
Very cool stand! Nice work,
Tom
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That's a great looking setup, and should save you some headaches in the long run.
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On the wart pump, I have used the same pump for 10 years and it's still working well. If you run higher rpm like I do it helps eliminate cavitation by maintains constant flow. I wire the pump and cooling fan together so that if the engine calls for the fan when the engine is off it turns the pump back on, too, eliminating thermal rise after shutoff.
With aluminum heads, good timing control, Evans NPG+ coolant I can run just under 11.5 compression with no worries. Have to keep an eye on A/F ratio, too. 12.6/1 is about as lean as you want to get at WOT. Timing kills engines way before mixture, though. It's work to keep everything where it needs to be, but well worth it.
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Breaking in most transmissions is usually a function of varying driving routines for a few hundred. I use Trans Gel when assembling a transmission so changing the fluid isn't a bad idea either. I install spin on filters on most installations which makes it easy to change and the filter works better than the one in the pan.
On a 4L60 or a 4L60E you can break in the band by using a pry bar and pressing the servo cover in while the transmission is spinning in first gear. Firm pressure for a few seconds will do the trick. But the band runs on the reverse input drum which is sheet metal, so don't overdo it. Anytime you rebuild one of these transmissions it's a good idea to replace the reverse input drum. I have a lathe so I can refinish some of them. And don't run a wide band,mother tend to just run on the edges. I talk too much!