Question: 48re

[motoking_1990]

I know this is not a cummins thread. Its just easier for me to ask here instead of making an account of another forum. Don't know much about these trans. Are they worth building, can they hold power say 600-900 hp, should they be swapped out for another trans? Reason I ask is a buddy just got an 05 and isn't sure whether to build it or put a different trans in. Thanks, Greg

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[JoshH]

They can be built to handle that much and more. You'll need billet shafts and a few extra billet goodies, but there are several good companies who make parts for them.

 

[onebaddmaxxx]

The heart of a 48re a good valve body. The person setting it up better know what they are doing.

 

[mike diesel]

A properly setup 47/48RE are pretty much the bees knees behind a high hp diesel.

There are quite a few dmax's that have them swapped in.

 

[motoking_1990]

Interesting I wouldn't have guessed they were very good. Everyone I ever talk to always say they should've put an allison behind the cummins and scrapped the 48s. This guy actually rebuilds transmissions for a living. He mainly deals with gm vehicles though. He wants to make sure it can be done before he wastes his time with it.

He has rebuilt tons of allisons when he was in the dealership. I told him I was thinking about refreshing mine. Of coarse he is willing to build it but, I know that when it comes to my truck, I want someone that builds these things everyday to hold the hp/tq I'm hoping for. If that makes sense. Sure he can build a stock trans but can he do what I need.....probably not. He hasn't had enough experience with high hp builds for him to touch mine.

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[WolfLMM]

Interesting I wouldn't have guessed they were very good. Everyone I ever talk to always say they should've put an allison behind the cummins and scrapped the 48s. This guy actually rebuilds transmissions for a living. He mainly deals with gm vehicles though. He wants to make sure it can be done before he wastes his time with it.

He has rebuilt tons of allisons when he was in the dealership. I told him I was thinking about refreshing mine. Of coarse he is willing to build it but, I know that when it comes to my truck, I want someone that builds these things everyday to hold the hp/tq I'm hoping for. If that makes sense. Sure he can build a stock trans but can he do what I need.....probably not. He hasn't had enough experience with high hp builds for him to touch mine.

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The reason you hear that is: for towing and what normal people use their diesel trucks for, the Allison is a far superior trans.

Racing is a whole different ball game.

 

[motoking_1990]

So for racing the allison doesn't contend well?

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[Evan@InglewoodTrans]

So for racing the allison doesn't contend well?

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It's doing better then it ever has in the racing scene but it's still not a race transmission by any means. However we are still going to try and run mid low 8's with the Allison this year.

 

[Mike L.]

I build a lot of 47/48 RE's and they can hold a lot of power.

 

[dunnc1991]

See them swapped into high hp powerstrokes in place of the 5r.

 

[mike diesel]

Interesting I wouldn't have guessed they were very good. Everyone I ever talk to always say they should've put an allison behind the cummins and scrapped the 48s. This guy actually rebuilds transmissions for a living. He mainly deals with gm vehicles though. He wants to make sure it can be done before he wastes his time with it.

He has rebuilt tons of allisons when he was in the dealership. I told him I was thinking about refreshing mine. Of coarse he is willing to build it but, I know that when it comes to my truck, I want someone that builds these things everyday to hold the hp/tq I'm hoping for. If that makes sense. Sure he can build a stock trans but can he do what I need.....probably not. He hasn't had enough experience with high hp builds for him to touch mine.

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Sounds like you need to find a new builder if he's asking you if a 48re can be built to hold power so he doesn't "waste his time"....

 

[motoking_1990]

It's doing better then it ever has in the racing scene but it's still not a race transmission by any means. However we are still going to try and run mid low 8's with the Allison this year.

Mid/low 8s is fast in my book. Especially in a truck at that. How far have people pushed them? Have they hit into the upper 8s? What is restricting them?

Sorry for the questions Evan, I am curious and like learning. Anything Duramax and Allison performance related really spikes my interest.

I build a lot of 47/48 RE's and they can hold a lot of power.

Why is there such a bad reputation for these trans then? Do they not hold much torque over stock? If that's the case they are not much different than any other trans.

My dad recently trashed the trans in his 1 ton dodge van. Has the 318 and I'm thinking it may have a 47 or 48 not sure. Was thinking about tearing into it to find the cause. Had to be a hard part, Planetary or something. He planning on scrapping the thing anyway.

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[motoking_1990]

Sounds like you need to find a new builder if he's asking you if a 48re can be built to hold power so he doesn't "waste his time"....

Never said he was building anything of mine. He's a really good friend raised me for a couple years when I was younger. What I think it boils down to is money. I don't think he wanted to drop a bunch into a trans that has rumored to be junk. Which Mike and Evan have said can hold power.

My thinking is he needs to do some more research into it before he rebuilds. Decide what his goals are for it and go from there.

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[mike diesel]

Mid/low 8s is fast in my book. Especially in a truck at that. How far have people pushed them? Have they hit into the upper 8s? What is restricting them?

Sorry for the questions Evan, I am curious and like learning. Anything Duramax and Allison performance related really spikes my interest.

Why is there such a bad reputation for these trans then? Do they not hold much torque over stock? If that's the case they are not much different than any other trans.

My dad recently trashed the trans in his 1 ton dodge van. Has the 318 and I'm thinking it may have a 47 or 48 not sure. Was thinking about tearing into it to find the cause. Had to be a hard part, Planetary or something. He planning on scrapping the thing anyway.

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The main issue with an allison is that it has to go to neutral between each shift. That's just how it operates. The previous clutch pack has to release before the next clutch pack can be applied or you end up tieing up 2 gears. They can shift plenty fast but it will never shift as fast as a 48re will.

 

[IdahoRob]

If it's mostly a street truck, then the Allison is king and the 48re isn't in the same class of the Allison. If it's a race truck, 48re is a very good choice as long as it is built properly. I haven't heard of anyone running faster than high 9's, and at not consistently. Lots of mass, clutch on clutch, and a smart computer don't make for the best racing transmission.

If it's driven on the street more than 25% on the time, keep the allsion. These guys are building them very strong.

48RE in action behind a Dmax so you can see the quickness of the shifts.
https://www.youtube.com/watch?v=SFMBaVOK0Mg
https://www.youtube.com/watch?v=EWxA5cNXZes

 

[motoking_1990]

He bought a 05 dodge 2500. So it looks like he is going to build the 48re then.

I didn't even know the allison shifted in neutral in between shifts. I noticed the let off in between gears. I thought it had a kit or was part of the tuning. The old ve pumped 1st generation cummins shifted like that as well.

Comment at the end of the second video gave me a chuckle. Rofl

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[Evan@InglewoodTrans]

Mid/low 8s is fast in my book. Especially in a truck at that. How far have people pushed them? Have they hit into the upper 8s? What is restricting them?

Sorry for the questions Evan, I am curious and like learning. Anything Duramax and Allison performance related really spikes my interest.

The mid to low 8's is just the goal we have this year for Mike Graves new truck and it won't be full bodied truck. Mid 9's is the fastest at the moment I believe. The overall design of the Allison is its limiting factor but we are finding ways around it. With Mike Graves truck we were able to run 10.13-10.2's at a few different tracks just about every pass when it was turned up then giving it a whiff of nitrous at the end of the year it ran a 9.73 at 145 on the same trans it had since July. C3's were on there last leg when I refreshed it for this past year. This year once it was back together with new turbos it ran a 9.73 again on the same tune it was running 6.4 on at Rudy fuel only. I have no doubt it could be faster with a purpose built race transmission but that's not what Mike wants to use just yet.

Here is a video of a 6.4 pass at Rudys this past fall. https://m.youtube.com/watch?v=fa-eP9aAtwo