How much HP can a stock TH400 handle?
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About 400-450 HP/TQ is the limit on the stock TH400. With ONE almost free modification and some minor valve body calibration changes, 800 HP on an otherwise stock TH400 is not a problem if it’s assembled well (good endplay, etc), and the 34 element sprag is a wise addition above 450 HP or any drag usage.
What does a sprag do in a transmission?
A sprag is a one-way mechanical clutch used in many automatic transmissions as a method of allowing the transmission to smoothly change gears under load. Allomatic sprags are full-hardened, individually loaded, and made with high-quality maraging steel that provide higher fatigue limits than stainless steel.
What is a 34 element sprag TH400?
The 34 element sprag has over twice the holding power of the stock sprag. Eliminates intermediate sprag failure due to excessive torque input. The TH400 34 element PATC sprag replaces the stock 16 element unit, increasing the torque capacity by 110%. Standard in all PATC TH400 race transmissions.
How many sprags are in TH400?
TH400 Aluminum Direct Drum with Pro Mod Sprag Our best TH400 direct drum is a hybrid aluminum and steel design. It still has the 36 element sprag and the five clutch intermediate pack, but the clutch drum portion is constructed from 7075-T6 hard anodized aluminum.
How good is a TH400 transmission?
It is widely regarded to be a supremely durable and legendary transmission. The TH400 is conservatively rated at 450 ft. lbs. of input torque.
How can I tell if I have a 400 Turbo transmission?
Another quick way to identify a Turbo 400 is to look at the kick-down mechanism. Unlike the Turbo 350, instead of a “kick down” cable, it uses an electrical slide switch, which is controlled by the throttle linkage. Generally, in ’68-’71 vehicles, the switch is located on the carburetor.
Why do sprag clutches fail?
The cause of sprag failure is most likely due to low battery starts. Other factors can hasten sprag failure, including: Starting without the choke, Starting in gear, using an oil of too low viscosity(the lower the viscosity = a higher viscosity number /// 80w is less viscous than 20w).
How do I know if I have a Turbo 400 transmission?
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.
What is a drum in a transmission?
The transmission drum is an important part of an automatic transmission. It connects the transmission’s central or sun gear to the exterior half of the clutch pack. In automatic transmissions, gears do not move other than to spin, so a different method is used to engage and disengage transmission gears.
Does a TH400 transmission have overdrive?
But the TH350 and TH400 three-speed versions (and their two-speed Powerglide cousin) fall short when it comes to highway cruising. The reason for this is the conspicuous lack of an overdrive gear. Back in the late-’60s gas was cheap and highway cruising speeds were lower.
Which is better TH400 or 4L80E?
4L80E vs. Though 4L80E race transmissions are quite similar to TH400 in terms of strength and parts used, however, there are differences, such as the added overdrive gear, advanced electronic controls, and a lock-up torque converter. 4L80E transmissions have nearly 25% overdrive and are 4 inches longer than the TH400.
What is a TH400?
TH400’s are what we cut our teeth on. We have extensive experience building the TH400 for all types of applications. We do stock rebuilds all the way up to 3000+ HP Pro-Mods.
What is a stage 5 TH400 upgrade?
Fully rollerized upgrade (includes all thrust areas between drums, planetary sets, case, center support, and pump, and direct drum stabilization) Stage 5 TH400 uses a Griner* G20 billet Aluminum valve body and eliminates the intermediate sprag.
How much hp can you rebuild a TH400?
We do stock rebuilds all the way up to 3000+ HP Pro-Mods. Our “stock” rebuild is strong enough for over 600 HP repeatedly yet functions like a stock transmission. Our TH400’s use exclusive proprietary parts that are only available in our builds as well as techniques that your normal transmission shop or builder is likely not aware of.
How wide is the clutch band on a TH400?
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.