What's new
By:
Filters

School me on turbo 400s.

HELL BOUND

HELL BOUND

Well-known member
Joined
May 27, 2020
Member Number
1574
Messages
481
What do I need to know before I buy one. Any years better than others? I see different atlas adapter kits. I thought a atlas would bolt right up? Can I use a 2wd and swap output shafts? What rebuild kit have you had good luck with?converter? I've always had a stick. And all my searches come up with pirate4x4 for results. Not gonna go down that rabbit hole. It will be going behind a 5.3 hopefully somewhere around 500 maybe 600 hp is the goal.
 
I have exactly what you need. Brand new Jakes Performance "Rock Crawler" K case TH400. RMVB with engine braking AND a 2.75 first gear set. I have all the paperwork from Jakes and the trans is still in plastic.
 
The Novak Guide to the GM TH400 Automatic Transmission (novak-adapt.com)

Novak is pretty awesome

The 400 transmission has a main case of cast aluminum alloy with a length of 24-3/8" long. Its aluminum case is essentially smooth. The rear mounting face of the transmission has a hex bolt pattern with ribs running forward longitudinally. The fluid pan shape is irregular (see image, left), being likened unto a distorted Texas pattern. The TH400 is the largest of the common GM auto transmissions, but still surprisingly compact in light of the immense power they can handle.

There are two significant variations of the TH400. The TH375 was a version of the transmission used from 1972-1976 in smaller displacement cars. It is identified easiest by its "375-THM" designation cast in the underside of the tail housing. The TH475 was an extra-heavy-duty version, and was found in larger trucks from 1971 on.


If you are trying to determine the TH400 from another in a vehicle, a fast way to tell is to look at the kick down mechanism. The TH400 uses an electrical slide switch, which is controlled by the throttle linkage. The TH350 uses a mechanical cable kick-down mechanism that is attached to the throttle linkage.



This transmission makes an excellent conversion transmission due to its adaptability into most Jeeps longer than CJ5s. Both 2wd and 4wd versions of the Turbo 400 can be used equally well, and there are no inherent advantages to either one once you have installed our adapter assembly.

2wd transmissions feature conical shaped tailhousings and an output yoke, which are replaced with a typically shorter 4wd style output shaft (included with our adapter assemblies) of varying lengths and spline counts, depending on the application. The HydraMatic can be adapted to the popular Jeep (and many IH) transfer cases,

Essentially all factory GM 4wd applications available with an OEM configured TH400 have adapters and transfer cases that are prohibitively long for a Jeep, and transfer cases whose sizes and gearing fall short of desirable for most Jeep applications.
Click to expand...

basically, any year is supported and for the low low price of $570, novak will sell you all the things you need to make it a short output 4wd style, and apparently there is also a longer output 4wd style.

Adapting the Turbo Hydramatic 400 Transmission to the Jeep Dana Model 300 Transfer Case & FSJ NP Transfer Cases (novak-adapt.com)
 
One 4wd version of the TH400 is ready to bolt up to our 134-B adapter kit. Disassembly of the transmission is unnecessary as the 32 spline 4wd style output shaft is correct for this kit version. Partial disassembly of the transfer case is necessary to install a new matching 32 spline Dana 300 input shaft machined from triple-alloy gear steel which provides a superior upgrade.

The input shaft installation is a 1-2 hour bench job and usually includes either a simple gasket and seal replacement or preferably a full rebuild of a tired D300. Bearings and pre-load are involved with this job. It is not requisite that you rebuild your Dana 300 to successfully complete the conversion. However, it is certainly worth consideration especially if your transfer case leaks or has many years of service. Our superior quality Dana 300 gaskets & seals kits and our all-inclusive master rebuild kits with stronger Novak manufactured center pin are highly recommended for this purpose.

th400_np208_style_output_shaft.jpg
The NP203 version of the TH400 output shaft features a very short 32 spline sections measuring 1-1/4”. The extended length Novak input shaft engages this shaft perfectly. No other TH400 output shaft is compatible with this kit.
Click to expand...


well hell, apparently if you get a TH400 that came in front of a NP203 then it will already be short and 32 spline. that's nice.
 
Th400 basicaly the same after 1968is. First couple years 65-67 used a different filter setup but otherwise the same.

203

2wd truck and early 4wd are 4" ish output and virtualy interchangeable

Late 4wd 2.5" output

Car 6" tail shaft

Th375 is basicaly a th400 with a long 6-9" 27spl input. Also rumored to have lighter duty guts.

Th475 p30 chassis with drum brake on tail shaft. Itlooks longer but its still a 2wd truck 4" output and has straight cut gears and the strongest guts.
 
SLOWPOKE693 said:
I have exactly what you need. Brand new Jakes Performance "Rock Crawler" K case TH400. RMVB with engine braking AND a 2.75 first gear set. I have all the paperwork from Jakes and the trans is still in plastic.
Click to expand...

How much? I could use that
 
Thanks guys. Slowpoke let me know the price also. I was looking at picking up a builder off Craigslist for cheap just so I'd have a mock up trans that I could build later.
 
I searched around for awhile to find a TH400 for plans to rebuild. Not a lot around locally. After hearing about the amount of stock cases breaking from the weight of the transfer case and or doubler regardless of how It was mounted. I decided I would probably end up having to replace it at some point in time due to the case going out. I started looking into the 4L80 which is the TH400 with an overdrive, many of the internals are the same. It has the stronger stock case and the overdrive 4th gear which allows for better gearing options. There are many non computer controlled options to fire the solenoids or full manual valve bodies. The only downside I see is the longer length which was worth it. If you go 4l80 make sure you get the later years as they include all the upgrades. I used a Jakes Performance rebuild kit which is the guru of 4L80 and TH400 transmissions. It still takes a lot of time to figure out how to rebuild it properly, but it takes the headache out of figuring what parts are needed. Half the info out there is for street use not for off road use. The on an off throttle with engine braking changes what mods are done. Some mods that a street trans uses will not work or be good for an off road trans. Jakes has an off road valve plate vs the normal street plate and the check valve layout is different. Jakes gives you the specials instructions for the parts they include in the kit. You will still need to know how to rebuild the trans though and if you add any other parts or upgrades how they come into play with the rest of the parts. Jakes sells a generic rebuild manual which is a good way to start figuring out how to rebuild or what grades or options of prebuilt trans means.
 
Theres the guy on pbb that made a manual shifter with switches to create a stand alone stock 4l80.

I have the transo fmvb and love it. No gain in mpg but it drives solid and shifts firm. Rock solid if you disconnect the vac modulator.
Its been in 2 ccdrw chevys and never given me any issues with about 40k on it.
 
total newb said:
Th400 basicaly the same after 1968is. First couple years 65-67 used a different filter setup but otherwise the same.

203

2wd truck and early 4wd are 4" ish output and virtualy interchangeable

Late 4wd 2.5" output

Car 6" tail shaft

Th375 is basicaly a th400 with a long 6-9" 27spl input. Also rumored to have lighter duty guts.

Th475 p30 chassis with drum brake on tail shaft. Itlooks longer but its still a 2wd truck 4" output and has straight cut gears and the strongest guts.
Click to expand...

Not always.... In GM vehicles, I believe this holds true.
But TH400s also came behind other makes, such as AMC. The AMC had two versions of the TH400, and early one with a 2 inch adapter ring around the bell housing (from the AMC to GM) and a later case which bolts directly to the AMC engines. The AMC case has an extremely long output, but the GM output is a direct replacement, however since it's the first item dropped into the case, it'll require a rebuild to install it. Once in, the ATLAS or Novak adapters work fine. The only tricky part is the AMC case is rotated slightly to gain clearance for the front driveshaft to transmission pan. This will cause the GM to Atlas adapter to be 7 degrees (or some weird number) off of level once everything is bolted up. I used an axle shim to level it to my crossmember and all was good.

I'm not 100 percent sure, but I always remembered there were three of the four wheel drive output lengths, and a fourth length for the two wheel drive versions on the GM cases.
 
total newb said:
Theres the guy on pbb that made a manual shifter with switches to create a stand alone stock 4l80.

I have the transo fmvb and love it. No gain in mpg but it drives solid and shifts firm. Rock solid if you disconnect the vac modulator.
Its been in 2 ccdrw chevys and never given me any issues with about 40k on it.
Click to expand...

4-Speed Shifter Cruis'n USA, 20-10141 - 50-8496-00 (suzohapp.com)

this is by far the coolest shifter for a full manual "dumb" electronic transmission

2015_3_32.pdf (windows.net)


4l80e-4th-gear-and-tcc-problem-running-from-4l60e-segment.png
 
TreeClimber said:
Not always.... In GM vehicles, I believe this holds true.
But TH400s also came behind other makes, such as AMC. The AMC had two versions of the TH400, and early one with a 2 inch adapter ring around the bell housing (from the AMC to GM) and a later case which bolts directly to the AMC engines. The AMC case has an extremely long output, but the GM output is a direct replacement, however since it's the first item dropped into the case, it'll require a rebuild to install it. Once in, the ATLAS or Novak adapters work fine. The only tricky part is the AMC case is rotated slightly to gain clearance for the front driveshaft to transmission pan. This will cause the GM to Atlas adapter to be 7 degrees (or some weird number) off of level once everything is bolted up. I used an axle shim to level it to my crossmember and all was good.

I'm not 100 percent sure, but I always remembered there were three of the four wheel drive output lengths, and a fourth length for the two wheel drive versions on the GM cases.
Click to expand...

Well theres also bopc bellhouse th400s. Op said 5.3 so i kept it gm simple
 
bdkw1 said:
I'll take how to blow up your T400 for 500$ alex.
Click to expand...

The quote was pulled from Jakes Performance. From the research I have seen the majority want engine braking and a manual controlled valve body usually in reverse pattern.

Offroad and Rockcrawler TH400s


Rockcrawler 400 – 450 HP/TQ capable


We offer a TH400 setup for Rockcrawler and off-road applications. This is similar to our Stage I build but uses a HD “K” case 4×4 TH400 core with a reverse pattern manual valve body that retains engine braking. We can upgrade this unit to our other level of builds as necessary for you big power off road guys. Price is $2500.
Offroad Stage 2 TH400


This build is based on our standard Stage 2 build. It starts with a 4×4 core and HD case. We use a reverse manual valve body with engine braking, a wider 1.25″ intermediate band for engine braking with HD material. A 34 element sprag, offroad specific clutch materials, lubrication modifications, and torrington bearing upgrades are added. Upgrades are available for bigger power combos. Price is $2650.


Maximum Effort Offroad TH400


We’ve pulled out all the stops on this build. It is built specifically for the harsh conditions experienced in offroad competition. We start with a new Reid Racing case for a bulletproof foundation to prevent stress cracks and case failure common when used in rough terrain and/or with a transfer case attached. We include a Reid Super Bellhousing and a new roller tailhousing (where applicable). The next key ingredient to this package is the spragless design used instead of the typical roller clutch or sprag design used for 2nd gear. This requires the state of the art billet aluminum Griner valve body to control shift timing and includes a direct drum assembly that eliminates the failure prone sprag. An important additional benefit of this design is the extremely strong engine braking ability. Most TH400’s with engine braking rely on the OEM design 1″ wide band. This does not, it uses the entire 2nd gear clutch pack to give the same capacity and strength to engine braking as it does acceleration. Additionally we use 300M input shaft with larger splines in the forward drum, 300M alloy intermediate shaft, and billet alloy steel forward hub. We add torrington needle bearings in several key locations to deal with friction and thrust loading caused during heavy deceleration. We make several lubrication improvements, pump modifications, and other improvements to help with lubrication and cooling issues seen in offroad competition. As always, all new clutches, steels, bands, and soft parts. Clutches are specific design that we use for offroad builds. Custom length output shafts and planetary ratios are available. 6 month warranty. Pricing begins at $8000.
 
HYDRODYNAMIC said:
The quote was pulled from Jakes Performance. From the research I have seen the majority want engine braking and a manual controlled valve body usually in reverse pattern.

Rockcrawler 400 – 450 HP/TQ capable

Pricing begins at $8000.
Click to expand...

The pertinent points. A, below his power estimates. B, way above his price point. C, he was talking about stock case trans.

Trust me, in something heavy with a lot of power you do not want engine braking. It will destroy the trans no matter who built it. I have had a trans run the 1000 without issue. Change drivers and that same trans is done in 200 miles. Driving style is the culprit.
 
bdkw1 said:
Rockcrawler 400 – 450 HP/TQ capable

Pricing begins at $8000.

The pertinent points. A, below his power estimates. B, way above his price point. C, he was talking about stock case trans.

Trust me, in something heavy with a lot of power you do not want engine braking. It will destroy the trans no matter who built it. I have had a trans run the 1000 without issue. Change drivers and that same trans is done in 200 miles. Driving style is the culprit.
Click to expand...


Either you are horrible at reading and quoting or you work for MSM.
Two of the engine braking builds are stock HD/K cases. The stage 2 build is dyno tested and rated at 750HP.
Add the billet input and intermediate shafts and it goes up to 1000HP for heavy vehicles.
Only the all out race build is a Reid case and $8,000
What was the build spec on the 1000 trans that blew up? What was the driver doing to it?


Rockcrawler 400 – 450 HP/TQ capable
HD “K” case 4×4 TH400 core Price is $2500.

Offroad Stage 2 TH400
It starts with a 4×4 core and HD case. Price is $2650.

Maximum Effort Offroad TH400
Reid Racing case and Reid Super Bellhousing 6 month warranty. Pricing begins at $8000.
 
Last edited:
Maximum Offroad Transmissions - ULTRA4 / PreRunner / Crawler TH400 and 4L80 builds are all engine braking with options for electric, reverse, or forward valve bodies
 
I don't know that engine braking is all that important in a race vehicle, especially short course. on the gas, on the brakes.

cruising down the highway and around town? sure.
 
YotaAtieToo said:
4l80e or 6l80e/90e ftw why only have 3 gears in 2021?
Click to expand...

I dont see a point to have overdrive in a trail rig that won't see the street. Plus start pricing a 4l80e and then you have to pay extra to control it. Just a bunch of extra cost for no reason to me.
 
HELL BOUND said:
I dont see a point to have overdrive in a trail rig that won't see the street. Plus start pricing a 4l80e and then you have to pay extra to control it. Just a bunch of extra cost for no reason to me.
Click to expand...

You can get a manual valve body, but yes, you're right, I didn't realize the ratios were identical except for the OD.

6l80e ftw :flipoff2: 4:1 1st is kinda a game changer imo. With a stock 2.7 case you're lower than a Th400 and 4.3. Then you have a much more usable high range. But ya, you have to control it.
 
YotaAtieToo said:
You can get a manual valve body, but yes, you're right, I didn't realize the ratios were identical except for the OD.

6l80e ftw :flipoff2: 4:1 1st is kinda a game changer imo. With a stock 2.7 case you're lower than a Th400 and 4.3. Then you have a much more usable high range. But ya, you have to control it.
Click to expand...

I agree, I dont believe anyone makes a controler for them yet but it's just a matter of time.
 
HYDRODYNAMIC said:
What was the build spec on the 1000 trans that blew up? What was the driver doing to it?
Click to expand...

Culhane built Ried case, full 300M shafts and billet internals.

Driver A goes into the corner on the brakes still in 3rd. At the apex he drops it to second and stands on it.
Driver B comes in hot slams it down into second to rotate the rear around and stands on it.

Also, rating trans capability's by HP is the biggest joke there is. Is that 1000HP at 2500RPM or 7500RPM or 10K? cause there is a huge difference between the 3. TQ kills trans, not HP.

We have used Culhane, Kroyer and Mogi, none of them ever recommended braking with the trans, they all specifically recommended against it.
 
bdkw1 said:
Culhane built Ried case, full 300M shafts and billet internals.

Also, rating trans capability's by HP is the biggest joke there is. Is that 1000HP at 2500RPM or 7500RPM or 10K? cause there is a huge difference between the 3. TQ kills trans, not HP.

We have used Culhane, Kroyer and Mogi, none of them ever recommended braking with the trans, they all specifically recommended against it.
Click to expand...

Good point about the HP. It’s about all the builders list, unless you dig through the parts list to find out what they are putting in them or what mods are being done and can correlate that to driving style and power.

Miller and Slawson both run Maximum who builds with engine braking. Maximum also has an Ultra4 car so it’s not like they don’t know the particular driving style. Maybe Ultra4 and Baja style are different enough to make a change for some drivers.
 
You must log in or register to reply here.
Top Back Refresh