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Bonnie is pushing 150k mi these days and I get the occasional hard shift, especially in stop-n-go traffic. I did a fluid filter change right after I got the car with 99k on the clock. I thinking I should start making prep for possible trans overhaul or swap so I wanted to float some ideas.

Single row final chain; This feels like a worthwhile upgrade and from all info I've read I think my 2004 SLE came with the 3:05 ratio. I'm pretty sure my 2001 Grand Prix GT had the 3:29 and I was thinking it made sense for the heavier Bonneville to have the steeper gearset. My GP still got excellent hi-way mpg so I don't think 3:29 would kill the mpg on Bonnie either.

Other upgrades; I'd like recommendations for other mods. I don't race the car and it gets pretty normal street use but I have occasionally tickled the idea of a turbo kit for the L36 when it comes engine time. So for street use, anything else over stock I should consider?...or just step up to the HD trans (since I assume my L36 isn't hooked to one of those)

Trans source; Instead of having a local shop overhaul my existing...well swapping to HD makes that moot...or is there a better source/value for just buying a bolt-in trans. Something like a ZZ or other supplier?

Speedo?...if you change final drive, what has to be done to correct the speedo?

Thoughts?

The big difference in the HD trans is the differential, everything else is the same as the standard. Source a U-pull differential and parts and turn your 4t65e into the HD version, for a fraction of the cost of another unit.

You can modify a combination of 440-t4 (4t60) parts to get the single chain. You would need to find the 3.06 trans for the single chain setup. I think it's fairly simple machine shop work. Is there another option (1" ZZP chain for $1000 pre-order?)

But the Gemini chain (replacement for the dual chain) would work out good as well, and no modifications to fit.

I would recommend to support a reliable local shop (if that exists) and tell them you want upgraded parts. They should include the Sonnax trans fixes as part of the rebuild, and all the updated parts that address the major issues, add in the hardened chain and and you're all set for the 300whp area.

Turbos are fun. Anybody that can tune a turbo build can adjust the speedometer reading to match the FDR should you change it.


I recommend that you decide what power level you want and plan everything based on that.

To cure the occasional hard shift, you can install a trans-go shift kit. It only adds a couple minutes to a normal fluid/filter change.

3.29 gears will help move the Bonne a little better. I doubt you'll notice much of a drop in fuel economy on the highway at all.

The only difference between a 4T65 and a 4T65-HD is the differential, which is a little beefier. That is stressed under launching. With a turbo set up I would suggest a 300M input shaft and a heavier duty chain. New clutch packs and other misc items would also be recommended. You can make a stock trans last but you have to be careful. The input shaft is usually the first thing that goes when you put lots of power down. If you restrain yourself to only doing pulls in one gear, you might be alright. Turbos are easier on the trans because they don't typically produce neck snapping torque. A trans cooler will help too.

A great rebuilder for these transmissions is Triple Edge Performance. They offer a variety of options to suit your needs, be it just a DD rebuild or if you need something to handle a good bit of power.

Speedo can be adjusted easily with a tune.

*EDIT* *dang* it Matt. I always get beat on my phone.. Haha

Triple Edge Performance, has a "Back to Basix" trans that is probably cheaper than any trans shop

thanks for the info guys

I've both heard and read that installing a shift kit will improve trans life, but I always thought that applied to a new/rebuilt trans you were installing. Adding a kit to a high miles trans wont contribute to its demise? LOL

Is there a how-to thread or video on YouTube about the install? I would have no probs doing another fluid/filter change since I've put roughly 50k on the car since purchase.

That most transmissions fail due to clutches slipping, the shift kit is very effective at combating that, this is one thing that can really help extend the life of the trans as long as the clutches aren't starting to slip. That's mainly because a nice smooth shift is slipping the clutches in a slower, smoother transistion, during the shift. There is always a tradeoff; some hard parts will be stressed more with a firmer shift. But with the 4t65 that's not a problem until you start making more power.

http://www.pontiacbonnevilleclub.com/fo ... 10193.html

This should help you. The shift kit stresses the input shaft but at near stock power levels it's not necessarily a big deal. TransGo is the ideal shift kit. It will help, but it won't cause nasty shifts.

I have a ZZP/TransGo/Homemade randomness hybrid shift kit and I lay a patch between gears at WOT... Hahahaha

Ok, just ordered a Transgo kit...what the difference with this T304 AC Delco filter I keep seeing?...and I assume most here recommend sticking with a Delco filter.

Found a thread and another how-to thread on the GP site...pretty sure I can handle this install.

Where exactly does one buy the TransGo kit? I've only seen the one from Intense, or are they one in the same?

I usually run a Wix filter. If you feel the need to get a Delco filter, go for it.

If you want to change gears, you're going to need your tune adjusted. For a highway runner, 3.05's are plenty. 3.29's would be a worthwhile upgrade if you're drag racing...

BonnieBoy08 wrote:Where exactly does one buy the TransGo kit? I've only seen the one from Intense, or are they one in the same?

I ordered my 4T65e TransGo kit from Amazon for $40

00Beast wrote:I usually run a Wix filter. If you feel the need to get a Delco filter, go for it.

If you want to change gears, you're going to need your tune adjusted. For a highway runner, 3.05's are plenty. 3.29's would be a worthwhile upgrade if you're drag racing...

I'm not locked into a Delco filter, I had just heard in the past that some of the part store brands were very cheap and skimped badly on the filter media inside. Then again, Delco out-sources replacement parts so who knows exactly what you get anymore? LOL

I remember reading the tune would need to be changed, but thanks for pointing it out again. I'm not planning on swapping gears until I change/overhaul the trans, and I agree the 3:05s do make sense numerically for a highway car, especially in a flat land kind of area.
However, a lot of the roads here in Virginia tend to be hilly (not mountainous! LOL) but with Bonne being a bit heavier than the GP, I think the gearing could help. The reason I say this is recalling how the GP would climb hills on the interstate at 70mph and never come out of high gear (or converter lock-up) whereas Bonnie does a lot of up/down shifting on the grades, even between here and DC, let alone the Blue Ridge or PA hills. I think it might help the in-town mileage also. Either way, if mpg stayed about the same and the car was a bit more responsive, I wouldn't complain over that either.

My TransGo shift kit arrived, except when I opened the box it wasnt a TransGo kit, and it was for the 4L60e trans and not the 4T65.

SO...I'm shipping it back today for a refund

I looked on the ZZ Performance site and their shift kit shows what looks like little sleeves or bushings as opposed to springs. Is their kit as easy to install as the TransGo? Or I just need to find another source for the TransGo kit?

Don't get the ZZP one, buy the Intense one, it comes with upgraded springs also.

3.29's would hurt in-town mileage...

The ZZP shift kit is garbage. This spring I'm gonna go with a TranGo and a trans cooler. I think eBay has TranGo kits too. Or you can buy the whole shift kit from TEP.

I found the TransGo kit on eBay so I went with that one...and I popped for the ZZP finned aluminum cooling pan...gotta love tax time

Ghosthawk wrote:and I popped for the ZZP finned aluminum cooling pan

I'm jelly. Those have the drain bolt which is an awesome thing to have.

Hmmm, so tempting! Sets a guy back a few bucks though. Might be worth it. My taxes won't get done til the beginning of April