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Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

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Old 02-06-2007, 12:59 AM   #1
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Default Thrasher shift kit, mini-review

I recently installed a Thrasher shift kit in my 98 LeSabre'* 4T65E. Got it for $90 delivered direct from Thrasher Charged Engineering (through EBAY). It included springs, shims, a tranny filter/seal (appears to be good quality), piston seals, a separator plate with bonded gasket material on both sides, and a free T-shirt!

I considered TransGo 4T65E jr., but it doesn't include a filter or separator plate, and is therefore IMO way overpriced at about $80-90 delivered.
I considered the Intense Street/Strip kit, but the only significant difference I could see between it and the Thrasher is that the Intense includes some sandpaper and some me, these items weren't worth the approximately $40-50 more the Intense kit would have cost versus the Thrasher. I've also heard that the washers in the Intense kit sometime bind on the accumulator piston rods...

Supposedly, any of these kits can be replicated with less than $20 worth of springs and shims (according to certain webpages I've seen)...but it was worth it to me spend more to get a "proven" kit with all the extras.

I installed it at the "medium" setting. Including dropping and cleaning the pan, install, filter change and ATF refill (AND the install of a Tru-Cool tranny cooler simultaneously), it took me less than 90 minutes to complete...and about half that time was spent obsessing over whether the hard tranny lines were re-seated properly

The plain brown box and parts in ziploc bags was less-than-awe-inspiring. The instructions were adequate (if unclear in some sections), and the off-center Xerox-of-a-Xerox-of-Xerox hardcopy with washed-out pictures was a bit off-putting. Invest in some packaging equipment and a color printer, guys!

My goals for this "mod" were two-fold:
1) Performance: Better, safer entering and passing on the freeway through less "laggy" shifting.
2) Maintenance: Improved life of clutches.

As for performance, the transmission feels like brand new again. Shifts are crisp, quick, and ultra-reponsive. WOT shift points are now dead-on and consistent at 1-2 5700rpm, 2-3 5400rpm. All shift "lagginess" at any level of throttle is gone, and I now power smoothly right up to 90 mph on the on-ramp (minimum safe speed to enter slow lane in *. California). This mod did EXACTLY what I wanted, and it makes me want to do more mods to open the intake and increase the torque peak slightly, to get rid of that slight bit of engine "gasp" at the tops of the gears. If my Scantool could read shift times (detailed in another thread ), I would have provided before and after data...

As for the claim of improved clutch life...well, once the novelty wears off and I can keep the pedal off the floor, maybe we'll see!
(Besides, the new tranny cooler will probably do more for that)
2004 Buick Lesabre Limited, Gran Touring; Bone Stock

1998 Buick Lesabre Limited, Gran Touring; Mods: Poly sway bushings/endlinks, Tru-Cool trans cooler, Thrasher shift kit (med), PLIM, front PEM; Mods in progress: Alot of stuff, but slowly...
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Old 02-07-2007, 12:55 AM   #2
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Good deal, sounds like its doin' what it'* supposed to!
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