Tuned beyond stage 3, blew the tranny and lost 3rd gear - 255awhp/285tq 2008 LGT 5EAT
 

At 73k I took my car to EFI Logic in Bethel, CT... Pete there did a phenominal job tuning my car.

At 73.5k I entered my car into the NER 1500 mile rally, awesome 0-60, awesome tune... went from (Mustang dyno) 230awhp to 255awhp, from 230 torque to 285... (sucks the 5EAT eats so much power at the interface)...

Spirited driving all around, broke some new personal records, and I was pleased as punch at the conclusion that my car performed and hung in there so well.

At 75k I bring the car home, and begin work on repairing parts that failed during the rally... an axle, windscreen, TMPS sensor, repaint the nose, replace various plastic bits that fell off the underside, etc.

In 5 days I have an appointment at Bertera Subaru in Hartford, CT to do a complete 5EAT flush with the better Subaru ATF specifically for the 5EAT.

Last night I replace the axle on the passenger front and it got rid of the grinding noise I had in low gear (cv boot split open and sprayed grease all over the control arm and DP)

I believe I am starting to hear the 'wah-wah-wah' of a wearing wheel bearing, but I'm not sure which one it is yet.

Now I've noticed (since the CV boot first broke, and even post axle replacement) that the steering wheel hops wildly at 3500-3700 rpms in 3rd gear.

1st gear 0-redline, perfect
2nd gear shifts into perfect, shift to red line perfect
3rd gear (if throttle over 50% 0-3499 rpms fine, 3500-3750 steering wheel hops) 3751-redline perfect
4th gear - perfect
5th gear - perfect
reverse - perfect

As posted above, I have a transmission flush due in 5 days for a complete system change and then I plan to do a drain and fill every 10k after.

Diffs are untouched... stock oem and I've never checked fluid or anything, but dealership did it at 30k and then again at 60k. I was planning on draining these and putting in motul's synthetic gear oil specifically for our diffs.

Any ideas what can cause such a wild vibration and steering wheel bounce? It really jumps up and down, but only in that range and once you pass 3750 it smooths out like butter

I'm praying that it's just the fluid change or maybe the dif fluid....

I'll take a video of this at lunch today.

The transmission fluid is not going to end up being the problem.

well this developed from nowhere. according to the timeline above it started happening between the time around the axle failure. The tranny fluid has about 40k miles on it now and is brown

Its probably your choice of motor oil

It didn't develop from nowhere you just replaced an axle :spin:

It sounds like a vibration or resonance. Go ahead and have the fluid changed and see if it solves the problem.



:lol:

motor oil since 1st change has been Motul synthetic 8100 5w30

75000 miles and 0 problems until the last week

:spin:

Not true rao. I made it through a 1500 mile event with no problems. Around the time that the cv boot cracked is when it started. Axle replaced, problem persists.

It's a very narrow band that it happens and only if the throttle is greater than 50% in that narrow band.

I'm thinking it's more vehicle or wheel speed based than it is engine RPM. Since it's easy and cheap, have the dealer do a rotate and balance and see what happens after that.

Did you use an axle from Subaru, or a "reman"/"Lifetime" axle from a box-parts store?

I can also duplicate it if I'm doing 65, then go to pass someone without flooring it. Only seems to happen in 3rd. I'll video this at lunch in a few minutes and post the findings. I'll do 2nd gear pulls, 0-75, highway speed to passing speed and hopefully it can narrow it down.

I have read that all of that stuff is 3rd world crap :eek:

dealership wanted 280 for the axle. I got the axle from advanced down the street here through multiple people recommending it due to it's warranty. Now that I know how to quickly change it out I have no problem doing it again if the problem is indeed the axle.

But the same symptoms persist from the OEM axle with 75k miles and this new one with less than 100 on it.

There is an entrance ramp I get on in middletown, ct that requires me to go from 0-65 dead stop into traffic and this is where I first noticed it.