45rfe trans upgrades

[truthman]

Firstly I just registered here so I am a newbie! Anyway to my question.

I've read some on how the stock trans for my truck (645rfe) can only handle up to 400ish whp. This has me thinking I should upgrade/rebuild it as I plan on adding a supercharger.


So far I don't have much other than exhaust, CAI, and soon to be shorty headers.

I plan on the boost and possibly a complete performance rebuild on the engine with ported polished heads and a new cam(possibly). This is way down the road though. I haven't decided on centrifugal or roots because I want to see how much it would cost for the trans.


Can anyone point me in the right direction as far as what I should need?

 

[Pull Ya]

Talk to Matt at Moe's Performance. He will have the answers to your questions, and his information is backed by personal experience.
Jay

 

[SlowRoller]

And like Jays sig says: Remember, going fast cost money, so just how fast do you wanna go?

 

[truthman]

And like Jays sig says: Remember, going fast cost money, so just how fast do you wanna go?

Trust me I know it will cost, that doesn't scare me. What does scare me is me putting all my money and work into making it fast and having the trans break on me.

 

[Hemi450hp]

In all honesty, your driving style will be more of a factor in keeping your transmission in 1 piece than the brand of transmission you buy. Do not do any WOT downshifts out of overdrive, and don't hold WOT into 4th gear, and you will be fine. If you do either of these things, then the transmission will fail...doesn't matter if it is stock or built.

 

[popcenator]

So WOT from 4th is not reconnected? I read with the ERS set to 3rd or 4th is alright. But that could be wrong. I try and stay out of 5th or 6th as much as possible.

on the move..

 

[Hemi450hp]

If you launch from a dead stop and just go through the gears...1-2-3-4. Running into 4th at WOT, you are likely at speeds of over 130mph. That is what you need to avoid.

 

[popcenator]

But say passing on the interstate, I usually shift into 3rd or 4th before I step on it. Should I avoid 3rd altogether?

on the move..

 

[Hemi450hp]

If you are going 60mph on the interstate, then you are probably in 5th gear. I always drop down to the gear you would be in if you were going WOT from a stop, which with your 3.55's should be 2nd gear.

 

[ST-8]

Cost me a trans doing wot into 4th a few weeks ago. You really learn how to drive these things right after you blow a couple up.

 

[popcenator]

So if I'm going 65 which is my usual pace, and I am looking to pass someone, I should be dropping the ERS to 2nd? I'm glad this thread came up because I was just going to ask you this myself. I just get a little nervous dropping it that much at that speed.

I'd like this transmission to last. So this is great advice. Could I have been doing any harm going WOT at 65 mph in 4th?

on the move..

 

[ST-8]

Before I knew better( an even after I did) I still did wot downshifts when at highway speeds If you downshift manually, let the truck get into the gear it needs to then go wot you really will help the trans out.

 

[Hemi Ram]

Ok... so I'm confused.. why can you not just board it and let the truck do its thing? I really never full throttle my truck (my 67 Charger yes, but not my truck) so not really an issue but why does this damage the transmission? When cruising down the highway with the cruise on it does some pretty radical downshifts at times maintaining speeds up hills etc.. is this the same?

Sent directly from my thoughts using tinfoil antennas and a stainless mixing bowl helmet.

 

[hemidup]

Ok... so I'm confused.. why can you not just board it and let the truck do its thing? I really never full throttle my truck (my 67 Charger yes, but not my truck) so not really an issue but why does this damage the transmission? When cruising down the highway with the cruise on it does some pretty radical downshifts at times maintaining speeds up hills etc.. is this the same?

Sent directly from my thoughts using tinfoil antennas and a stainless mixing bowl helmet.

The 2 weakest clutch packs in the 45 series transmission is the OD clutch pack then its the 4c. This series of transmissions needs to use two clutch packs together to make a gear. Its a clutch on clutch design and in my personal opinion a very poor design when you want to put added power to it and the worse part is that its fully computerized controlled. Without a tuner you have no way to raise your speed limiter so you'll probably never use the 4c clutch pack being limited to a 105 mph. The 2nd prime kick down is worse combo of clutches in these transmissions since that gear uses the very smallish size 4c clutches and the weak OD clutches.

 

[schwarz]

Before I knew better( an even after I did) I still did wot downshifts when at highway speeds If you downshift manually, let the truck get into the gear it needs to then go wot you really will help the trans out.

Total noob question but how do I manually down shift with a 3rd gen?

 

[powderbrad]

In all honesty, your driving style will be more of a factor in keeping your transmission in 1 piece than the brand of transmission you buy. Do not do any WOT downshifts out of overdrive, and don't hold WOT into 4th gear, and you will be fine. If you do either of these things, then the transmission will fail...doesn't matter if it is stock or built.

So runningv through the 1/4 needs 4th. That sucks.
ive done a few hwy pulls shifting into 4th wot.

Hmmm...

 

[BlownGP]

This still makes me scratch my head every time this comes up.

I understand the reasoning, I'm just dumb founded on what gear to be in.

Mine seems to shift in 5th at 65mph. So if I wanted to go WOT, I would need to shift down to 2nd gear. Isn't that kinda low for 65mph?

I've been actually playing with the manual shift more, trying to figure out the perfect time to shift and downshift.
2nd prime still ***** me up every time though.. haha

I'm more of a visual learner so that's probably why this is hard for me to understand. lol

 

[popcenator]

This still makes me scratch my head every time this comes up.

I understand the reasoning, I'm just dumb founded on what gear to be in.

Mine seems to shift in 5th at 65mph. So if I wanted to go WOT, I would need to shift down to 2nd gear. Isn't that kinda low for 65mph?

I've been actually playing with the manual shift more, trying to figure out the perfect time to shift and downshift.
2nd prime still ***** me up every time though.. haha

I'm more of a visual learner so that's probably why this is hard for me to understand. lol

As with most things, the more I try it the easier it gets, but I'm still not completely comfortable with shifting. But yeah, 2nd seems like a low gear to be in at 60-65mph.

on the move..

 

[truthman]

In all honesty, your driving style will be more of a factor in keeping your transmission in 1 piece than the brand of transmission you buy. Do not do any WOT downshifts out of overdrive, and don't hold WOT into 4th gear, and you will be fine. If you do either of these things, then the transmission will fail...doesn't matter if it is stock or built.

Good to know, Thank you for your input.

 

[SlowRoller]

Trust me I know it will cost, that doesn't scare me. What does scare me is me putting all my money and work into making it fast and having the trans break on me.

Sounds like it will break either way, at least until the 'learning curve' is met,, so probably best not to be scared of the inevitable,,,