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greenwayer 06-13-2013 11:18 PM

Strength of 545rfe
Hey guys,
How much power torque and Hp wise can the 5-45 rfe in our wks really handle? I know by the name it should handle 500 ft lbs of torque but does this really hold up in reality?


greenwayer 06-14-2013 05:10 PM

Re: Strength of 545rfe
Anyone know?

jeepgcoman 06-14-2013 05:46 PM

Re: Strength of 545rfe
With proper care and maintenance, the 545RFE is a fairly bulletproof transmission, and should handle most anything you can give it with a normally aspirated 4.7 or 5.7, but not as it is set up from the factory. The factory programming.....shift schedules and torque management, are set up more for soccer moms, and the "average Joe". When you start throwing a bunch more power at it, you'll need to increase the line pressure, change the shift schedules to take advantage of your mods., and decrease the torque management, so it will shift firmly and not retard the throttle as much on the up shifts.

On my slightly modified 5.7 (signature items below plus 85mm TB and 25% UD Pulley) I've added the Sonnax Line Pressure Booster (~15-30 PSI increase) and use the Superchips Advanced Transmission Tuning Application to modify my up and down shift schedules, as well as light and wide open throttle torque management. You could also get one of the Diablosport Tuners and a Chipmaster Revolution (CMR) custom tune. They can make all of the appropriate adjustments with the tune. With these mods. you wouldn't even know it was the same transmission.

greenwayer 06-14-2013 06:09 PM

Re: Strength of 545rfe
I'm thinking of doing a 6.4l striker how do you think it will hold up to that? We are talking 450+ horsepower at the crank

jeepgcoman 06-14-2013 06:23 PM

Re: Strength of 545rfe
You might be pushing it a little with that much hp. I am guessing mine is now at ~375-400 hp. at the crank, and it works far.....for the last year and a half. If it were me and I was doing what you're planning, I'd do the same mods. I have, and if it blew, I'd sign on for a Sheradon Stage II or III unit. That should end the worries for sure.

greenwayer 06-14-2013 09:32 PM

Re: Strength of 545rfe
Yeah I will do the sonnax and the tune. If it blows up I don't think I have enough money to by a sharadon tranny but instead I will go to the junkyard and pickup a NAG1 w5a580. Does anyone know if the nags mate to the nv246 transfer case?

jeepgcoman 06-14-2013 10:34 PM

Re: Strength of 545rfe
I don't know, but if it does, I'll be one of the first to get one. I have the NAG1 in my Hemi Magnum and it is day and night better than the 545RFE. One problem you're sure to have is the TCM. It is separate from the PCM on the NAG1. Don't know if you can mate any other PCM to the WK chassis without lots of grief.....unless maybe one out of an SRT Jeep will work.

jjt250 06-15-2013 01:47 PM

Re: Strength of 545rfe
I can't tell you about the strength of the 545FRE but the NAG1 should mate up to the NV245 transfer case as I have that exact set up on my CRD (Diesels came with the NAG1 and NV245). The computers will be the hard part. However, I read that SRT8 guys (same tranny) sometimes start to see problems with just bolt-ons with their NAG1 transmissions. Now there are upgrades that could be made to the NAG1, but it might be more economical in the long run just to get a built 545FRE if your stock one goes out. Also, tuning options for the NAG1 transmission are limited (at least for the CRD).

jeepgcoman 06-15-2013 02:18 PM

Re: Strength of 545rfe
Very true on the NAG1 tuning options. That's probably the only thing I don't like. Both tuners for the gas guys only allow canned torque management settings. Wish I could set the shift schedules for the NAG1 on my LX, using DiabloSport tuner, to match what I have set on the WK, using the Superchips tuner. The absolute best things about the NAG1 (with either tuner) is the complete control the "true" autostick gives, and the instanteous WOT downshifts. The so called autostick on the 545RFE's is not really an autostick and all the WOT downshifts, especially the 4th to 2nd prime, are about as bad as it gets.....takes ~2-3 seconds to figure out what you want it to do. I've messed with the SC ATT App. trying to fix it, and haven't been able to improve it.

greenwayer 06-15-2013 06:55 PM

Re: Strength of 545rfe
Well the 545rfe will cost me about 3k for a sharadon stage 2 built one, which will double the cost of my stroker, on top of that sharadon doesn't even offer any sort of warranty. Your probably right the electronics to get a nag to work will be an out right mess. But the fact it supports the nv245 is a step forward i guess. BTW jeepgcoman can you send me a copy of your transmission tune?

jeepgcoman 06-15-2013 09:19 PM

Re: Strength of 545rfe
The trans. tune is set up for my mods. and probably wouldn't work well on a 5.7 that doesn't have a higher lift/longer duration cam installed. You'd also need to have the Superchips tune with the Advanced Transmission Tuning Application, or it wouldn't do you much good. Also, the Diablosport for 1, 2, and 3 up shifts uses RPM settings, and all the settings on the Superchips are by speed, so you'd have to convert the speeds to RPM if you're using the DS tuner. Not a big deal though.

What I did on mine is make notes on when I wanted it to up shift (speeds) in all gears, how I wanted it to down shift, which shifts needed to be firmer, and anything else I didn't like. Then I graphed the stock up/down shift schedules and torque management %age settings, and also graphed the way I wanted it to work. I also had some crude Superchips Beta graphs that helped clue me in to how things should be set up......i.e. downshifts should not overlap upshifts on the graph, and the closer the down shifts are to the up shifts on the graph, the more sensitive down shifting is to the slightest increase in throttle. I got it pretty close on the first try, but have made slight adjustments off and on for about the past couple years. (First rendition was 5/21/10, and the last, prior to minor tinkering was 3/12/12.) I must have it about right now, because I haven't "tweaked" it for at least 6 months now. I like the setting so much now that, when I drive the LX with the NAG1, I think something is wrong, because all it's shift schedules are similar to the stock 545RFE. I think the lack of quick, responsive light throttle downshifts annoys me the most on the takes a bunch of throttle to get it to go down.

greenwayer 06-15-2013 11:03 PM

Re: Strength of 545rfe
Oh I see, sounds like a lot of trial and error. How much Hp does yours make with those mods? Also, the guy at sharadon told me that my stroker will easily make 515+ Hp and even more torque because of the huge stroke. So know I am really concerned about the trans and will likely have to buy sharadons tranny.

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