Michael_

https://www.tciauto.com/buick-oldsmo...n-package.html

I wrote an email to TCI about a week ago but still no response.
Does somebody know? It's an interesting transmission.

joe_padavano

I'd be more worried about using the OD stage in a 4L80E to gear split. The stock OD clutch pack only has two discs. It's not designed to take the torque of lower gear acceleration. Yeah, I'm sure there are ways to fix this with aftermarket parts, but geeze, I don't think I've ever spent that much money for a running car.

matt69olds

The gear ratios are different between the TCI 6 speed and a stock 400. First gear is much lower, the gear spacing is closer also. For the money they are charging, I would hope your not simply buying a 4L80 with aftermarket planetary gears and done valve body changes. I would expect some overdrive clutch upgrades (both friction and mechanical upgrades) and some upgrades shafts.

I have built a few 4L80 for people with some power. The stoutest one I have had my hands in made right at 900 rear wheel hp, this was in a mid 2000s Chevy truck with a turbo big block on E85. At the time he said he “only” had plans for 700-750, but he keeps cranking up the boost. So far, it’s holding up. That’s one of the disadvantages of turbo engines, it’s so easy to make power.

Sooner or later something will break. When it does I’m sure he will cring at the cost of the aftermarket shafts and other parts

BillK

Have you tried actually calling them ? I have found that to be the easiest and fastest way to get questions answered.

1-888-776-9824

joe_padavano

To me this is the real issue. With the torque curve that an Olds 455 makes, I have a hard time seeing where these "split" ratios add any value, especially for the eye-watering price. Lower first is nice, but you can get the lower planetary gear sets without the need for splitting gears.

olds 307 and 403

That sounds perfect with a highway gear like 3.08 with the 2.97 first and up to 850 HP. My only issue, like Joe said, way too pricey. Over 7K for a trans, cooler and controller. Yikes! You still need, I assume, a 4L80E converter, probably another $500 minimum, more like $1000 if you want the extra strength lock up clutch and billet body. Also the manual paddle shifters, if you manual control are extra as well!

joe_padavano

TCI sells a low gear planetary with those 2.97 first and 1.57 second ratios. That setup by itself is $1300. With 27" tall tires and 3.42 gears that puts you at 40 MPH at 5,000 RPM in first, 5,500 RPM at 80 in second, so you're looking at two gear shifts in the quarter. If you have a six speed vs. four speed, that's THREE gear shifts in the quarter and the car is likely less quick as a result. In both cases, the OD gear is the same 0.75, so that's about 3,000 RP at 70.

Same setup with 3.08 gears puts you at 45 MPH at 5,000 in first and close to 95 in second (in the four speed configuration), with just over 2,000 RPM at 70 in OD. You're right, that might be the sweet spot. I'm still not seeing where you need the gear splitting.

oddball

It would be shocking if the trans doesn't do lockup. Can't find any useful docs about the trans or the TCI controller, so who knows....

Joe, I've never had my hands inside one of these, but all the teardown videos I've seen show 4 frictions and they're pretty big. We're not talking a stock 200-4r here. Given the size of the overdrive planet I figure there's a pretty good chance it would survive well.

A big chunk of the extra cost is the bellhousing conversion. Looks like that runs ~$1.5k-$2k by itself.

joe_padavano

The original one in my 1999 truck puked the OD clutch pack and there are only two plates in it. I know the 4L80E/4L85E has been a work in progress with pretty much annual changes, but that's what was in mine.

matt69olds

Sonnax makes a auxiliary valve body that engages the overdrive coast clutch in s as lil the forward gears except overdrive. The idea is to help take some of the load off the sprag. I wouldn’t be surprised if the TCI 6speed does something similar.

The overdrive clutches on a 4L80 are pretty big, as is the piston that applies them. I’d be willing to bet you would roll the sprag or snap shafts long before those slip. Btw, there are 3 clutches.

I can’t help be wonder if the 6 speed is more suited for road race applications. With the power that can be made today, the trend is to actually take some gear out of the transmission. In the case of the 400, first gear is 2.48. The most common aftermarket gearset is a 2.10, I think planetary gearsets with ratios as high as 1.90 are available. The ideal is to close up the gear split, while taking first gear ratio out. The REALLY fast cars eliminate 2nd gear entirely, make the 400 more like a Powerglide. That eliminates sprag failure, eliminates a bunch of weight ,basically anything needed for 2nd gear is eliminated. I have never built one, but there is a display case in the showroom at Coan Engineering with all the parts on display. There is also kits available to put a lockup converter on a 400. It’s not intended for street use, but it does add a few mph on the big end.

Michael_

Why not? Is there a downside for normal driving?
TH400 + lockup converter + gv overdrive + cooler is another option i'm thinking about because if my cutlass was a big block car, it would have had it from the factory so its simple to install and i know these can take a lot.

Yeah i don't know about these TCI ones.
Not a lot of data and experience out there yet.

Despite i also tend to think 3 speed + overdrive is probably sufficient, they put 6 speed manuals in the vipers.

joe_padavano

The torque multiplication of the torque converter mitigates the need for more gears. And the T56 in the Viper had TWO overdrive gears. In fact, with 2.26 first it was a surprisingly close ratio box.

matt69olds

The lockup kits are very expensive, as are the converters. Needless to say, putting a lockup system in s transmission never designed for it takes lots of custom parts.

The “not recommended for street use” disclaimer might have something to do with the cooling. Maybe the way the cooler flow/lockup system has to work restricts internal cooling? I have never personally seen the lockup, nor do I personally know anyone using one, so I have no real world info to share.

A VERY well built 4L80 would be much cheaper than the 400 with lockup. In all reality, you could probably buy 2 well built 4L80s and have plenty of leftover cash for gas and tires. The 400 lockup system is really intended for the class racers looking for every advantage, regardless of cost.