47re Clutch Pack Upgrades

[zstroken]

Originally Posted by Big Blue24

The arrows point to the small corner than needs to be ground just a little to gain clearance for the wide snap ring. I just used a 4-1/2" grinder with a 1/8" thick metal cutting wheel and slowly made an approximate 0.030" deep cut and worked my way around the entire pressure plate. It is possible to install the snap ring without grinding the plate but makes the clutch pack a little tight which would cause it to drag a little in reverse, not a good idea for a daily driver that uses reverse regularly but running an unground/unmodified pressure plate hasn't been a problem for my drag race truck.



With increased line pressure, this pack seems to do fine with the stock (4) clutch count in 47re and 48re on diesel applications up to about 500 HP rear wheel horsepower, after that it's probably a good idea to upgrade this pack.

Note that you also have the older style return spring.

[Rich Buckley]

heres some pis of bent od plate from high line pressure.

[Rich Buckley]

Originally Posted by Big Blue24

Forward Clutch Pack:
- This pack is located right behind the input shaft hub.
- Stock 47re has (4) frictions
- Stock 48re has (4) frictions with a different spline count so if you buy a 48re rebuild kit just remember to buy extra clutches for this pack that don't have the 93 center splines like the 48re clutches.
- This pack is applied in all forward gears and it's not a shifting pack so it's not subject to as much wear as the other packs.
- This pack is released when the transmission shifts into reverse.
- This pack is the most difficult one to upgrade since space is very limited.

I upgraded this pack from (4) frictions and steels to (5) frictions and steels for 25% increase in clutch capacity by purchasing a used forward clutch pressure plate and using it as a stepped reaction plate. This drums snap ring groove is machined a little tighter than the direct drum and it's nearly impossible to install the snap ring without grinding a little bit of the inner corner so the plate has a wider flat stepped portion for the snap ring.


The arrows point to the small corner than needs to be ground just a little to gain clearance for the wide snap ring. I just used a 4-1/2" grinder with a 1/8" thick metal cutting wheel and slowly made an approximate 0.030" deep cut and worked my way around the entire pressure plate. It is possible to install the snap ring without grinding the plate but makes the clutch pack a little tight which would cause it to drag a little in reverse, not a good idea for a daily driver that uses reverse regularly but running an unground/unmodified pressure plate hasn't been a problem for my drag race truck.



With increased line pressure, this pack seems to do fine with the stock (4) clutch count in 47re and 48re on diesel applications up to about 500 HP rear wheel horsepower, after that it's probably a good idea to upgrade this pack.

you have to check that the plate does not hit the back of the shell.

[mondtster]

Originally Posted by BigDodge

you have to check that the plate does not hit the back of the shell.

Yep.

[npe3484]

Originally Posted by zstroken

Direct is the forward most clutch pack.

Right, but the order he listed the packs in doesn't quite make sense. Most people would list them off in order from front to back. I was just trying to get some clarity. Things can really get confusing at times with all the different terminology that is used for the same clutch pack.

Either way, I'm still curious how he fit 8 clutches/steels in one of the main case clutch packs.

[npe3484]

Originally Posted by mondtster

Yep.

Can you explain that a little bit more? Are you saying that enough material must be ground off so that the beveled top of the plate doesn't hit the shell?

[mondtster]

Originally Posted by npe3484

Can you explain that a little bit more? Are you saying that enough material must be ground off so that the beveled top of the plate doesn't hit the shell?

Basically, yes. Some combinations of parts don't have enough clearance to keep them from rubbing. You should always check, don't assume.

[Dazed&Confused]

nice thread

[Rich Buckley]

Originally Posted by npe3484

Right, but the order he listed the packs in doesn't quite make sense. Most people would list them off in order from front to back. I was just trying to get some clarity. Things can really get confusing at times with all the different terminology that is used for the same clutch pack.

Either way, I'm still curious how he fit 8 clutches/steels in one of the main case clutch packs.

custom made billet durm and piston!!!

[Big Blue24]

All right, you caught me, all of the forward clutch pack pictures are from my 47rh build, I didn't remember to take pictures of the forward drum.

As far as clearance, I measured 4 mm space between top of the reaction plate ridge and shell surface. Sufficient in my opinion.

[maxedout03]

Do you have any problems when using the forward plates to stack extra clutches with fairly high line pressure? Any issues with plate warpage or bending in a daily driver?

[1/2TONCUMMINS]

Great thread.

[Big Blue24]

Originally Posted by maxedout03

Do you have any problems when using the forward plates to stack extra clutches with fairly high line pressure? Any issues with plate warpage or bending in a daily driver?

I haven't had any problems in my daily driver or my race truck, but others have had problems around 200 psi line pressure. I don't run that much in either of my trucks, my Junker only makes about 195 psi line pressure because that's all I can get out of it, it doesn't have all of the top of the line leak free servos/accumulator and it has a stock pump setup. So far, it's sufficient pressure.

On my daily driver, I just rebuilt the tranny over thanksgiving so it only has about 900 miles on it. So far, so good, but I haven't maxed out the pressure on it just yet either, it only makes about 300 to the wheels and it was working fine (no slipped or burnt clutches) at 115 psi line pressure before I tore it down so right now it's running just 170 psi line pressure.

All that said, the stacked clutches and plates won't cause problems, it's the stepped pressure/reaction plates that can bend a little per BigDodge's posts about his race transmission running 200+ psi line pressure.

[mondtster]

Stepped plates have the potential to break too, a guy I was helping diagnose some tranny issues had it happen to him. IMHO it came from high line pressure. It should be noted that this stepped plate was not one from the forward pack but a modified plate out of the direct drum.

I have seen no issues running the stepped forward plates, provided there is clearance for them. I usually set my line pressures fairly conservatively compared to what is being discussed here though.

[maxedout03]

Thanks for the info guys! Another thing, I used the forward plate in the direct drum(drum with tangs for drive shell) and can not get the snap ring in the groove due to clearance issues from the swapped plate. The flat plate has no clearance issues for the snap ring. You guys ran into this?

[maxedout03]

Also what do you set the clutch pack clearences to with extra clutches added? Do you set them a little looser or not?

[maxedout03]

Is it ok to run the thinner forward clutches and steels in the direct pack to stack even more? Or is this not such a good idea. Makes me wander if the thinner clutches and steels would hold up in the direct pack. All info and knowledge is appreciated guys!!

[maxedout03]

Do you think I should do the direct drum mods also? Drill the holes on the outside for fluid evacuation and the inner for more even apply pressure. Does this make a noticeable change?

[Big Blue24]

Originally Posted by maxedout03

Do you think I should do the direct drum mods also? Drill the holes on the outside for fluid evacuation and the inner for more even apply pressure. Does this make a noticeable change?

I didn't do the drum mods on my daily driver because I didn't have enough time to fiddle with it when I pulled the tranny, built it up, and reinstalled over Thanksgiving holiday.

I will say this, my race truck with the drum feed and evacuation mods has a firmer 2-3 shift so although this isn't conclusive evidence, I am lead to believe that these modifications helped.

It is just fine to use the thinner clutches and steels, in fact, that's exactly what you get when you buy the alto power packs (thinner clutches and steels) although they are a little different friction material.

The only downside to using the thinner frictions is they are usually smooth and not waved or textured. Smooth clutches take longer to squeeze the fluid away when the tranny shifts. This isn't a problem on the forward clutch since it's always engaged (except for reverse). The direct clutch (3rd gear) is a shifting clutch so the smooth clutches will make it slip just a little longer while fluid is evacuating between two smooth surfaces instead of a textured clutch surface (kind of the same idea behind AquaTread tires, they have grooves to funnel the rain water away from the tread).

Trust me, 5 skinny smooth clutches will lock-up and last longer than 4 textured clutches. And since you can easily fit 6 clutches in there, smooth vs textured is a moot point (non-issue in all but the most extreme builds).

All that said, you can buy skinny textured clutches, they cost a little more, have a little less friction area so less overall torque capacity but they do engage a hair quicker.

[Big Blue24]

Originally Posted by maxedout03

Is it ok to run the thinner forward clutches and steels in the direct pack to stack even more? Or is this not such a good idea. Makes me wander if the thinner clutches and steels would hold up in the direct pack. All info and knowledge is appreciated guys!!

Yes it is ok to run the thinner smooth frictions, yes more frictions are better, and yes more frictions will last longer than less frictions.