I have noticed an ever increasing number of Fiero swaps using higher and higher power levels. As we continue to push the envelope, with all the boosted 3800s and LS options available, tranny selection is still very limited. Stock transaxle swaps are not going to handle the power levels we have in our minds. So what do you do?
For the purpose of drag racing, the popular choice seems to be going with an Auto. A beefed up 4T65e HD from ZZPerformance or similar is a good example. Since there are plenty of threads on that, I would like to concentrate on those of us who prefer the metallic raw driving experience of Manuals.
If you don’t want to do extensive mods and you are only making moderate power levels, there are a few things to do. The following should be good for an increase in wear resistance.
- Replace worn motor mounts and trans mounts with Poly ones. Any uncontrolled movement is bad and Poly absorbs shock load well. Solid mounts are a cheap alternative for many engine swaps but they can slightly increase shock load levels.
- A good synthetic fluid is a must. Redline produces a line of lubricants designed for high load applications called ShockProof gear oil. It has a simulated 250 weight with the viscosity of a 90 weight. The draw back is that it can decrease the life of your synchronizers when used alone. There is something you can do make the synchros compatible, which I will get to shortly.
- Clutch selection is vital. A clutch should be matched to your trannie’s torque capacity and/or engine output. It is a safety margin that you’re looking for. A full metallic faced, solid hub Spec Stage 5 clutch with a Super Clamping pressure plate, capable of handling 700 Ft lbs, would be a bad choice for a 400 Ft lb engine. The on/off characteristics of a mismatched clutch will cause unnecessary shock load wear. If sized properly the clutch might slip and save your tranny in a high torque high traction situation.
Before I continue, I would like address the misconceptions of some people when it comes to factory torque ratings. Let’s use the G6 6-Speed with a GM torque rating of 290 Ft lbs. as an example. That means that the trans is rated to handle 290 Ft lbs of tantrum-throwing teenager abuse for the warranty required 100,000 miles. Applying 390 Ft lbs to the 6-Speed will not kill it (I would have already destroyed mine by now if it would) but it will most certainly reduce the expected life of 100,000 miles to probably closer to 50,000 miles if abused. Higher consistent torque applications will exponentially reduce the life of the tranny until the point of immediate failure. The 6-Speed could probably even handle 600+ Ft lbs for at least one or two good romps before grenading. So, keeping the trans alive for as long as possible under high torque loads should be the goal.
So if you decided that you want to push things to the max and you are ready to get inside the tranny, here are some tips.
- Selecting a low mileage or new trans is first. If you can’t get one, a high mileage one may work, but you never know how much life is left in it. A thorough inspection and worn part replacement may be required
- All parts should be cleaned and the factory gears should be deburred with a scotchbrite wheel.
- The trans case and internals need to be Cryo-treated to improve the internal tensile strength of the metal.
- Next, the gears and shafts should be two-step shotpeened. First using a 330 size shot and then a 220 sized shot to get into the valleys. An R65 steel shot with an almen intensity of .025 or higher should be used.
- The gears and shafts could then be REM treated, which is an Isotropic super-finishing process that smoothes the microscopic surface imperfections.
- An expensive final process that will effectively double your useable torque capacity is a process that a company in Southern California does.
http://www.wpctreatment.com/ You will need to treat ever metal part including your case and synchros for maximum durability. As a bonus, the characteristics of this process will make your synchros engage smoother and compatible with the Redline fluid.
All the above are to decrease wear and friction while increasing tensile strength. To maximize efforts, the tranny should be professionally blueprinted and reassembled with tighter thrust bearing clearances than factory to minimize axial gear spread caused by helical cut gears. The WPC process above will also help with this, reducing the chance of splitting the case.
I did the best I could to condense this info to a helpful quick reference.
Thanks for reading.
Sources:
http://www.taylor-race.com/index.cfm Quaife LSDs and blueprinting services
Sentra SE-R Articlehttp://www.evansperformance.com/ Cryo REM
http://www.peentech.com/ Shotpeening
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87 GT Tilt Clip-Widebody-RamAir-Fastback-GlassHatch Powered by SBC 383 6-speed w/ NOS
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[This message has been edited by ClayTonto (edited 02-18-2010).]
