T 400, Btr, C4

[jimking19]

I'm looking at options for a gearbox after mine let go and have noticed there are three types of autos that people talk about. I wanna know what the difference is between them and also what auto do I have (standard BA box)? The transmissions are called T 400, BTR and C4.

The problem with mine is that it started slipping into 3rd and then suddenly I lost 3rd and 4th gear altogether. I'm being told that the C1 clutch pack is stuffed but no one has looked at the car yet.

[gregor]

The BTR is the 4speed BA box. t400 and c series boxes are tough and are usually built (manualised, high stall) for drag applications. I think most of them are a 3 speed but I could be wrong.

For your power level a built BTR would probably be ok, but if you're really into the drags one of the other boxes might be worth it for future use. Not really the sort of thing most people would fit to their daily though.

[Henz]

Your standard box is a BTR, the C3/C4 conversion is pretty popular for conversions in these, and I think people have bolted up T400s as well because they can be built to handle more hp than the C series boxes.

^^Beat me to it.

Edited 17/02/10 06:13 AM by henz

[jimking19]

Thanks gregor and henz. I want a box that can handle 330rwkw easily, as that's about the power I've got. Is a built BTR still alright for that? It won't be a daily driver per se, but will get driven fairly often just for fun/ cruising.

What should I be looking out for in the way of what work will be done to the box? Kevlar bands and clutches, what else?

[Henz]

Built 4 speed will handle it easy. May as well go for a 2800 stally as well if you dont drive it everyday.

Not sure what exactly goes in the boxes

[jimking19]

Wanna hear from someone that's had a BTR built, who did the work, had any problems, generally what the experience was. Also is there a reputable shop around western suburbs melb? And generally what are people's opinions on what path I should take...

[Rhino1980]

An awesome combo if it would fit would be a TH400 + gear vendors overdrive.

[straughsberry]

Depends what you call awesome! While a TH400 can be build very strong, it is more parasitic than the BTR. And for the great majority of people making 300-400rwkw in our cars, it will probably make you go backwards when compared with the BTR.

And while the GVOD doubles your available ratios and will handle 1250hp in it's basic form, there's a quirk when you have to shift out of overdrive and shift your auto up or down at the same time. You have to switch the OD out and shift the box at the same time. There is no way to time the 2 shifts so you get a double shift quirk happening. That is what put me off a Powerglide/GVOD combo.

Yes a BTR can be built to handle that power. Having a well built box is a great part of it but getting the shift strategies right via the tune is also very important.

C series, TH400, TH350 and Powerglide boxes are all "old school" and do not have an overdrive. So while they all can be built to handle a fair bit more power then the BTR (TH400 and Poweglides well over 2500hp), your fuel economy will suffer because you'll only have a 1:1 ratio in 3rd as well as some of these boxes being parasitic. Expect about 3000rpm at 100 km/h. I know of a story where a 4l80e (a newer 4 speed electronic shifting version of the TH400) was swapped out for a 4l65e (a newer 4 speed electronic shifting version of the TH350) and 150hp was picked up at the treads.

People are holding around 400rwkw with a well built and tuned BTR.

Edited 17/02/10 07:46 AM by straughsberry

[Rhino1980]

True they are a bit of a power robber and also quite heavy. By awesome I mean tough, reliable, cheap parts, readily available, can be easily fully manualised, can be fitted with a high stall convertor without problems etc, mainly raw power handling capability. Way over kill for 310RWKW though. I've never killed a 400. A 350 is less parasitic, shorter, lighter and still an excellent box too.

What about an early TH700R-4 (non electronic) these can be built very tough these days, as can a TH200 4-R.

[straughsberry]

As you mention, the 700r4 is basically a non-electronic 4 speed TH350. After the 700r4 came the 4l60 and 4l65e. The newer 60 and 65's have detachable bell housings and other improvements. There are a lot of interchangeable parts between all of these boxes and I'd dare say a built 700r4 is much like a built 60/65 except it is shifted non-electronically. The good thing about the 60/65 is you don't have to use a manual valve-body to shift manually so you can have both manual and auto shifting available. In manual mode, you can spool the turbo up in second then wack it into first as you take off. That kind of setup is more suited to a daily driver and is the way I am going