Write-Up: 4T65e-HD Transmission Rebuild

Write-Up below: https://rivperformance.editboard.com/t7473-write-up-4t65e-hd-transmission-rebuild#146378

I am interested in doing an 4T65e-HD rebuild in the near future. It's nothing imperative, just something I want to do. With over 55k miles on my current rebuild, I know there are some original parts in there that will need servicing eventually. For now, my current trans is working fine accept for an occasionally slipping TCC lock-up.

Having no experience in the area of trans rebuilding, I'm relying on my shop manual and some assistance from anyone who's had their hands in an automatic transmission before. I plan to photo-document the process for other members interested in taking on a rebuild.

I plan to communicate with Triple Edge Performance and Transmission Center before attempting the rebuild, but first I will ask a few questions of our members:

• Are there differences between Riviera 1997, 1998, and 1999 HD transmissions? If so, what are they specifically?

• What is typically expected when buying a "core" transmission? Does it include all of the gears and old parts, or can I expect some parts will be removed (not counting differential and torque converter)?

• If I receive a core torque converter and differential, are these parts considered okay to reuse, or should they be rebuilt? What's involved in rebuilding these items?

Thanks in advance for any help. I don't know for sure when the rebuild will happen, or if it's for sure, but if we can answer some of these questions, maybe someone else will beat me to it. I think it could be a neat winter basement project for spring installation. Thanks again.

This will be of interest to me Aaron. I've wanted to attempt a transmission rebuild one day. I can tell you this, you should never reuse a torque converter especially if it came from a failed transmission. It may have metal inside, and that will go right into the transmission ruining all your work. A converter shop can cut it in half, clean and replace any parts necessary, and weld it back up. I would do this with any Rebuild.

...and I would say no to reusing a differential. Everything was so lightened and shrunken when they went to transverse mounting and combined the diff into the trans, some of us have already learned how delicate they are in the first place.

Thanks for the TC info, Larry. I am thinking about getting a core trans unit sans torque converter and differential, use my OEM diff, and buy a new #7TR. 4T65E, 245 MM performance torque converter unit from PATC ($399). It looks like this...



...so I will assume it does not include the impeller pump/housing?

Mark, I am still using my OEM differential with 200k+ miles - it was not replaced nor rebuilt with my transmission. ZZP built a drag car around a stock diff. They seem pretty robust to me?

That's funny, 'cuz I had it in my head that you were the one who was warning Travis or somebody about doing burnouts, because the diff was a weak point...

Because I'd read that somewhere in here, I even asked my tranny guy about it the other day and he agreed. It was he who said what I posted about the shrinking and weakening of the parts. He doesn't think he ever saw the "real" diff on a Turbo 425 or 325 blow out.

I have warned against doing single-wheel burn-outs; I read a long time ago from INTENSE or ZZP that spider gears perish from this activity. I rarely do burn-outs, but when I do, I make sure to spin both wheels. There's a technique to it.

ZZP's twincharged GTP broke into the 9's back in 2005 using a stock differential - Link

I never did get around to rebuilding the trans. Turns out everything is still working almost two years later, aside from the TC lock-up clutch. After talking with a few people, I learned the difficulty level is high, and tools are specialized. The tools alone for this job are around $400, according to one source.

But for anyone wanting to take on such a project, I found a write-up for rebuilding a 4T65e-HD from a '98 Regal GS. Looks very complex and time-consuming!

http://pontiacbonnevilleclub.com/forum/viewtopic.php?f=8&t=1483

I figured i would ask a couple of questions that i havent found on here. my car has 142000 miles on it and i am wondering generally how long do the transmissions last.? my transmission seems to be ok BUT ive thought about it and if i plan on modding car maybe i should start backwards? Preventative maintenance basically. I've looked online ant intense and zzp and basically a trans will cost around 2100-2600 dollars.? does that sound right? The other question is gear ratios, there were options for the dual chain 2.93 and 3.29 gears then i saw a 3.69 gearset... what would be the benefit of the on a relatively stock riviera. Last but most important, wheres the best place to go to get a trans rebuild? any experience and feedback is appreciated.

highwaywarrior wrote:

I figured i would ask a couple of questions that i havent found on here. my car has 142000 miles on it and i am wondering generally how long do the transmissions last.? my transmission seems to be ok BUT ive thought about it and if i plan on modding car maybe i should start backwards? Preventative maintenance basically. I've looked online ant intense and zzp and basically a trans will cost around 2100-2600 dollars.? does that sound right? The other question is gear ratios, there were options for the dual chain 2.93 and 3.29 gears then i saw a 3.69 gearset... what would be the benefit of the on a relatively stock riviera. Last but most important, wheres the best place to go to get a trans rebuild? any experience and feedback is appreciated.

just my personal opinions obviously...

- if you keep the fluid changed (every 30-50K) with Dexron VI or other synth fluid, don't hold your breath waiting for the 4T65 to fail. It's a pretty sturdy transmission.

- if you modify the transmission be sure you know what your goal is. as installed the Riv's transmission is pretty hot

- if you search this site you'll find a thread showing how one member wired up a sport/econ control on the transmission. These transmissions have the capability, the button just is not included on the lever ha ha.

- best place to go for a rebuild is someone near you who knows what he or she is doing. Next best is a swap with a Jacobs or other reputable re-manufactured unit. Be sure you understand if you're getting a transmission built for speed or for durability/fuel economy.

I am on my 2nd rebuild of the original transmission. 1st rebuild was due to TCC lockup failure, rest of transmission actually was OK but at that time we cleaned it out thoroughly and replaced the frictions and steels with HD parts. It ran longer rebuilt (over 150,000 miles) than it did new (about 90,000 miles). It failed the second time essentially because a new tech at the shop that originally rebuilt the unit, when I brought it in for a maintenance fluid and filter change, put in Dex III with an additive - I had told him to use Dex VI but he ignored me... so they rebuilt a second time at a discount (essentially we split the bill). Upon inspection, the frictions were still good but the torque converter had grenaded, filling the frictions and valves with shrapnel. Even after 2 cleanings we could not get all the shrapnel out so we had to toss the original valve body. (I also got a set of blue urethane cradle mounts in the deal). So this time I got a remanufactured valve body and torque converter in the rebuild and replaced internal frictions and steels same as before. So...

- don't put anything in the transmission other than the factory (Dex III) or the revised factory (Dex VI) fluid


...just sayin', based on my experience.

Albertj

..my two cents,do install a trans cooler with integral fan. it makes a world of difference.you might have to remove the 2 cross braces infront of the ac condensor to hook it up.

like this

http://www.jegs.com/i/JEGS+Performance+Products/555/60346/10002/-1

youll also need a temp probe like this .youcan program it to come on at different settings

http://www.jegs.com/i/Flex-a-lite/400/31147/10002/-1

thanks for the replies guys, being that i bought this car with no records im changing every fluid and filter etc. that way i can document everything. what is the benefit of the intercooler with fan?

highwaywarrior wrote:

thanks for the replies guys, being that i bought this car with no records im changing every fluid and filter etc. that way i can document everything. what is the benefit of the intercooler with fan?

depends on your point of view. If you drive spirited across hot high desert, maybe. If you're in a normal clime, not really. The other thing to think about is if you add a cooler you are adding a failure point - more lines to crack or break, admittedly if the cooler is put in right odds on a problem are low.

All good points on trans coolers. If you drive 'normally' as in how 95% of people do, there is no need for a cooler, IMO, on a healthy transaxle. If you do anything outside the general realm of what the car was designed for, as in racing, towing, mountain driving, severe hot weather, or a combination of these, a cooler can be a good thing. If you are planning on taking many trips over 200 miles, a cooler is good insurance. If your transmission is getting close to the end of its life, a cooler can extend the need for rebuild or replacement.

More on coolers: https://rivperformance.editboard.com/t1748-write-up-transmission-cooler-install

Gear ratios, which I assume we're final ratios, can make your car accelerate more quickly, even stock. The result with shorter gears is more torque delivered to the wheels. This comes at a price, fuel economy and top speed are decreased. So on the freeway you would cruise at a higher RPM with a 3.69 final gear.

I have 3.29 gearing in my trans and enjoy it. It's a little bit quicker to accelerate but costs a few extra RPM at highway speed. The 2.93 gearing gives you a useless (in the USA) top speed...

As far as your order of events - you may be pleasantly surprised how long your transmission holds up. Mod lightly at first, save up for the trans, but don't fix it if it ain't broke. The only reason I rebuilt mine was because I happened across a fantastic deal on a used race-built trans and decided to go for it. When I did the rebuild/merge of the transmissions I opted for some upgrades (hardened input shaft etc).

oh wow awesome answers fellas thanks, i normally drive up to nj ( 273 miles from where i am stationed) atleast twice a month, i do love the rush i get when passing people on the highway etc.. maybe ill just do the mods i have listed and go from there. thanks