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Old 08-29-2006, 11:46 PM   #1
Bus Nut
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Join Date: Nov 2003
Location: Twin Falls, Idaho
Posts: 806
Improving the longivity of an auto trans

Things to improve the life and reliability of an Allison trans.

Seperate the trans cooler from engine cooling system
Install new trans cooler at radiator or mount unit with large cooling fan with shroud.
Install fan motor control switch at driver's seat.
Install large trans external filter assembly.
Acquire new or used deep trans oil pan to increase oil capacity.
Change all trans cooler lines to at least 3/4 tubing.
Install new trans temp guage to indicate oil temp in oil pan.
Carefully check and adjust shift linkage for proper detents on trans.
Check trans fluid every time engine oil is checked.
Trans fluid indicates oil condition.
Trans fluid smell check is important.
Synthetic trans fluid is best as fluid cannot be scalded but very expensive.
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Old 08-30-2006, 11:26 AM   #2
sportyrick's Avatar
Join Date: May 2006
Location: mid Mo.
Posts: 241
Year: 1976
Coachwork: bluebird
Chassis: F33695
Engine: 427 chevy
Rated Cap: 84
too cool transmission

Transmissions are made to run the same temperature as your engine, too cool a transmission won't boil the absorbed moisture out of the fluid and the clutches will swell and get soft which ruins them over time. That's why you have the line running through the radiator, to heat the transmission up quickly to reduce acid and moisture buildup, also to maintain a constant temperature/pressure in the valve body. Cold fluid makes for sluggish shifts and more clutch wear too. A temperature guage is a good thing and with the information you aquire with it you can make an informed decision as to if and/or how much additional cooling you need for your transmission. If your transmission is running the same temp or less than your engine you don't need any extra cooling, a higher temp means you need ADDITIONAL cooling added to the transmission coolant line going TO the radiator, not the return line. Yes a cooler transmission does help the engine run cooler. sportyrick
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Old 08-30-2006, 01:36 PM   #3
Bus Nut
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Join Date: Nov 2003
Location: Twin Falls, Idaho
Posts: 806
I disagree

It is my view that most decisions in building any vehicle are financial. Many vehicles could be made to last or operate for a longer time period. The method currently used to control temps between the engine and trans are financial decisions. The number one reason for trans failures is heat. A very bad situation to correct is a failed coolant heat exchanged. Usually the trans will have major problems after the heat exchanger is replaced. Having a trans cooler system that is seperate from the engine is very superior in many ways. The trans does not need any help achieving a good operating temperature. In many cases, a quick oil temp system can be created. Controlling the oil circulation can be used to allow oil to warm quickly. Most commercial systems are created to be cost effective and produce revenue for the maker. The failure rate for seperated cooling methods is much lower than the co-joined coolant systems. Rarely are auto transmissions failures
caused by internal mechanical problems, as heat destroys everything.
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Old 08-30-2006, 03:37 PM   #4
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Join Date: Apr 2005
Posts: 274
The reason for a heat exchanger is consistent transmission operating temperature, therefore consistent performance by maintainig tolerances. Quicker warmup is also a result, as the transmission will generate very little heat by itself until the vehicle is in motion. I agree an independent system can work well, but should be regulated somehow to maintain a consistent and adequate (high enough) temp. I can say from monitoring trans fluid temps in drag racing applications, that too cold DOES hurt performance. I don't believe the heat exchanger design is strictly a financial one. My opinion, and it is just that, an opinion: The heat exchanger design works well and should be monitored and additional cooling should be added IF NEEDED. But, we can all agree that TOO MUCH heat is the enemy.
Brad Davis
79 International Wayne
"Big Blue"
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