Moving on to the main transmission case, there are two clutch packs, one in front of the input shaft hub and one behind the input shaft hub. The one in front is commonly called the direct clutch and the one behind the shaft is commonly called the forward clutch. This terminology is a little confusing but the way I remember is the forward clutch is for forward movement and only disengages when in reverse.
Direct Clutch Pack:
- Has a smooth drum that is wrapped with the 2nd gear band.
- This clutch pack is engaged when the transmission shifts into 3rd gear.
- Stock 47re has (4) frictions in this clutch pack.
- Stock 48re has (5) frictions in this clutch pack.
- There are many different aftermarket drums, pistons, plates, etc for this clutch pack, it's probably the most modifiable pack in the transmission.
- This pack takes a lot of abuse especially on misadjusted transmissions because the 2nd gear band holds the drum stopped in 2nd gear and this clutch pack engages the drum and makes it spin in 3rd. Commonly there is a small bind-up on the 2-3 shift that really puts a lot of wear on this clutch pack, especially if the 2nd gear (aka intermediate) (aka front) servo is worn and leaky.
- Hydraulic pressure pushes a piston that engages this clutch pack.
- If the pump stator and or bushing in the drum is worn, hydraulics leaks cause a loss of pressure behind the piston making this clutch pack susceptible to premature failure.
- In short, if you do anything in your transmission, you should at a minimum upgrade this clutch pack.
The cheapest way to gain more clearance in this pack for additional frictions and steels is to install a different reaction plate. The stock reaction plate is about 0.280" thick. You can buy machined, stepped, altered plates for about $30, or you can buy a used pressure plate from the forward clutch pack for about $4.
In the picture below is the stock 0.280" reaction plate vs a used pressure plate from the forward clutch pack.
Upgrading this pack is really simple, you can use stock .085" thick frictions and steels and fit 1 extra friction and steel for a total of (5).
Or you can buy stock .070" steels and .065" frictions and fit a total of (6) frictions and (6) steels. If you really want to go extreme, you can fit (7) of the super thin alto frictions and (7) kolene .068" steels but those parts alone will run around $110.
For my truck, I installed (4) 0.065" frictions, (2) 0.085" frictions, and (6) 0.070" steels. There is a clearance specification for this clutch pack so depending on the make of the frictions, sometime you have to get creative with the thickness of the frictions and steels to make the clearance meet specification. On my 47rh transmission in my other truck for example, I used (3) 0.64" frictions and (3) 0.096" frictions with (6) 0.070" steels.
Then top off the clutch pack with the stepped used plate that came from a forward clutch pack pressure plate.
Then install the waved snap ring and verify proper clearance.
In this picture you can see the groove in the drum where the snap ring rides. Proper clearance for the clutch pack usually happens when the top of the reaction plate (used stepped forward clutch pressure plate I purchased for $4) is just below the bottom of the waved snap ring groove. As you can see in the picture, there is enough clearance and I of course double checked this with a set of feeler gauges.
For those wondering where to get different thickness steels and frictions, Wittrans.com has a great selection. Another bit of useful information is that the direct clutches and steels and forward clutches and steels are the same profile, just different thickness so they are 100% interchangeable. Typically the forward clutches are much thinner and therefore you can get more of them to fit in the direct drum.
