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T-stat question + a few other things

3K views 4 replies 2 participants last post by  drewsk 
#1 ·
Saw a scary post about the engines in our cars sometimes having head gasket issues? Mine has been fine so far. Got 118,000miles. 2007 LT 3500 flex. Got an Overkill 87 octane tune ECU in the mail to me right now....hopefully that goes well. Wondering if I should replace the t-stat with a lower temp one as insurance?

I also got a Transgo SK4T65E shift kit+accumulator gasket kit from a friend of mine but have been hesitant to install it because the springs in the kit are weaker than the factory ones. Can anyone attest to the pros/cons of installing this kit? I'm just wondering if it would be good or bad, longevity-wise, for a transmission that works fine. I've read quite a bit about this kit and it seems like a good thing to do....but not much real-world reviews aside from a few youtube videos.

All I've really had to do was change the fluids/filters and the front brake pads so far. Also cleaned out the MAF and TB real good. I'm honestly trying to bulletproof this car as much as I can. I've owned it since August and I definitely enjoy driving it soooo......any advice in this regard is much appreciated!
 
#2 ·
You don't remove the springs in the accumulator pistons you add the kit to supplement the stock springs.. And I can atest that the kit solved harsh shifting on my 4t65e and have read numerous testimonials stating it prolongs the life of the trans..
 
#3 ·
OK, instructions not too clear on this and I may have not described it right. Good to know. I assumed the springs above the pistons are factory but the ones below are all kit springs...is this not correct? That's basically what the diagram shows.
 
#4 ·
Come to think of it... I totally forgot something it came to me as I was re-reading this. There are small springs on top of the accumulator that you do not replace but there are larger diameter springs that are replaced inside the piston bore and then an additional set of smaller diameter springs that are added to supplement the larger springs in the piston bore. Sorry it's been about 3 years since I installed this kit myself. As I recall it was very important to scuff the shit out of the piston bore walls too but I can't remember why now.. There are a number of different people on here who added that kit.. g25racer, Grimsin I believe and a few others including myself. Like I said I think the kit is great and for the price it's doesn't hurt to add when you plan to perform your scheduled Trans maintenance. When I initially got my Impala I was getting an occasional harsh shift from stop. That occasional harsh became more frequent then it became every drive. I added the kit and I can't recall it happening again during next 3 years that I owned it.. I added the kit at around 105k miles and I traded it with 154k back Late march / early April.
 
#5 ·
Well I did some tranny improvements today....including the transgo shift kit

Here's what all I installed:
Transgo SK4T65E shift kit (1-2 and 2-3 accumulators)
Sonnax diff tube retainer kit (TSB)
~8 quarts of Valvoline Maxlife Dex6 full synthetic (I let it drain for quite awhile)
Allomatic US-made trans filter
New accumulator gasket
Added a stronger magnet to the transmission pan (TSB)

I did score the accumulator piston walls real good with a scotchbrite pad, yes this is definitely recommended. I was going to install new accumulator piston ring seals but the ones on there were actually perfectly fine. So the only new gasket I had to use was the big rubber/metal one that goes between the two accumulator halves. I probably didn't have to install that gasket even, but the original one had some obvious compression in it so I went ahead.

The original springs under the pistons are NOT used. You just use the ones from the kit as stated in the instructions (total of 2 under piston for 1-2 and 3 under piston for 2-3). You should only have 2 springs left over from the kit. Also there are 2 .750" spacers that go under each piston and one shorter spacer that goes above the 2-3 piston. The springs above the pistons are left OEM.

I did not realize how loose fitting the diff tube is in the accumulator until messing with it today. I HIGHLY recommend everyone get the sonnax retainer kit to avoid burning up your diff.

The Allomatic trans filter fits very nicely into the tube hole in the bottom of the trans body, much tighter fit than even the AC Delco one I had put on there several months ago after I serviced it when I got the car. Definitely not gonna suck air in. Seems to be a well-made filter.

The fridge magnet that GM put in these transmissions is WEAK. No wonder they have a TSB. They get saturated very quickly, supposedly. Mine had very little wear in the 4 months since I did the first change.

Fluid is literally clear-red now. I drove around for probably 2 hours tonight. Can't say how it compares to a brand new 4T65E but my 119,000 mile one feels great now. Under normal driving the shifting does not feel very different, only slightly faster than before which is okay. Also my 3-4 shift has not had any issues so I am not concerned with removing the side cover. However, under heavy throttle it shifts significantly faster. Under WOT the shifts are practically instant but still quite smooth. Forcing a 3-2 or 2-1 downshift is a HUGE improvement as well...transmission is much more decisive in selecting gears. Makes it up to 4th lockup just as it should. I already am very happy with this shift kit.

My Overkill 87 octane ECU should be here Tuesday. That's next :)
 
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