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Discussion Starter #1
As I mentioned in my main thread and my cooling thread, my 24 Hours of Lemons team took out our tbird for the first time on the track this past Friday. It worked way better than we expected.

While perhaps more of an annoyance and performance limitation than an overall realiability concern, we experienced some annoying behavior from our 4R70W transmission in this 95 Ford Thunderbird that I wanted to check in with you folks on...

NON ISSUES
1) Cooling: Using our A/C condensor as an ATF cooler worked awesomely. On the highway, our ATF temps were ~150. On the track, it stayed mostly at 180F and barely peaked over 200F under the worst condition. We aren't worried about this part of the transmission system.
2) JMOD worked perfectly fine.

CONCERN
3) Car doesn't upshift at WOT as often as we want.
Alan @ Dirty Dog was right. At least at Thunderhill, we spent a LOT of time in 2nd. One slightly annoying thing was that on some of the straights, the stupid transmission wouldn't shift into 3rd even at ~4000+RPM without us letting off the gas and hammering back down the pedal. At that point, we would be pretty much running ~80MPH and the engine was definitely struggling to accelerate the car beyond that speed (likely b/c we were pretty far outside our power band). It took a little practice but eventually we could get the car to decide to upshift when we wanted and and everything would be fine.

Q: Do you guys think replacing the gears and going from 3.27:1 to 3.73:1 (so the engine will spin ~15% faster for the same speed and the car will want to upshift more often) help up address this concern? My guess is that we'd trade potential reliability (we know our 3.27 rear diff works, we've never modified a diff before so we are introducing a new point of failure) for increased acceleration and the car potentially spending more time in 3rd than 2nd.

From what I understand, this might not be an issue at Infineon b/c the track is MUCH more curvy with fewer straights. Esp if we risk screwing things up by mucking around inside our rear pumpkin. The team is divided but i'm personally leaning towards the "if it aint broke, let's not try and fix it BEFORE our Lemons debut."


Thanks in advance for your comments.
Regards,
-g
 

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Discussion Starter #3
If you are talking about going from 15" wheels to 17", we could but we aren't willing to due to cost.


If you are talking about the overall diameter of the tires (while still remaining on a 15" wheel), that's our plan.
http://forums.tccoa.com/showthread.php?t=135611
 

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I'd go the rear end route, if it was me.

The tranny planetaries aren't fully lubed in 1st and 2nd, only in 3rd and 4th, from a post SirWill made years ago.

Slammin in 2nd will eventually fry that planetary, imho.

Maybe it's not as much of a problem as I think... :zdunno:
 

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I'd go the rear end route, if it was me.

The tranny planetaries aren't fully lubed in 1st and 2nd, only in 3rd and 4th, from a post SirWill made years ago.

Slammin in 2nd will eventually fry that planetary, imho.

Maybe it's not as much of a problem as I think... :zdunno:
How you get there is a variable, but I agree that you would want to be in 3rd most of the time.
 

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....we've never modified a diff before so we are [potentially] introducing a new point of failure....... Esp if we risk screwing things up by mucking around inside our rear pumpkin.
IMO, the IRS 8.8 ranks right up there with the Ford 9" and the Mopar 8 3/4 in the ease of setup....if for no other reason than you can do it with the relative comfort of having it up on a sturdy workbench.

You don't want to setup a Dana 60. lol
 
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