Worth a Sonnax Zip Kit?

[dashhho]

My 2005 B4000 with a 5R55E has ~140k miles on it. I live in a mountainous area and the constant downshifting has me concerned on how long this tranny will last until I burn it up. I was looking at the Sonnax Zip kit, it looks like it can be mostly installed without pulling the tranny - would this be worth putting into my tranny given the mileage? It looks like transgo also makes a kit but I'm not as crazy on it. My main thought is minimizing the pressure loss and the firmer shifts will help burning the clutches out of this tranny. Any help or criticism is appreciate.

 

[Dirtman]

There are parts of the zip kit that are worth it, and then there are parts in the transgo kit that aren't in the zip kit that are needed. Both fix some inherent problems to the 5r series trans.

I installed the transgo kit and then some of the sonnax parts in mine. (Most notably the o-ringed end plugs to prevent pressure loss) I'll have to look and see what other sonnax parts I used with the transgo kit.

Here's the problem if you want firmer shifts. It is good in theory BUT you can install the heaviest springs in the shift kit for hard shifts but the transmission is computer controlled with adaptive shift control, meaning the computer adjusts the pressure and shift points to keep the shifts smooth. Once you install the kit the computer simply overrides what you've done by adjusting the pressure to bring it back to shifting as it was stock. If you clear the adaptive shift memory it will shift like a rocket for about 50 miles before the computer re-learns. The only way to keep the shifts firm after installing the kit is to delete the entire adaptive shift program which I have not been able to figure out how to do. I don't know if something like an SCT tuner is capable of this.

It was still worth it for me even though it doesn't actually shift any firmer, it still feels "crisper" but my valve body was having issues before I did it. The one thing you absolutely must do without question if you do this is DO NOT USE THE VALVE BODY GASKETS IN THE KIT!!!! Go to Ford and get the steel bonded one piece separator plate gasket! The 3 piece gasket/separator plate are known to blow out and cause pressure leaks. The one piece bonded gasket/separator plate is nearly bulletproof.

As for whether it's worth it on a tranny with 140k, yes. Even if you have to rebuild the tranny down the road you still have a nice fresh valve body to use so it's never a waste.

If you are in there, you might as well replace the EPC solenoid while your at it (it's recommended by both the sonnax kit instructions as well as the transgo kit instructions,), if not the whole set. And don't buy China garbage solenoids from eBay.

 

[dashhho]

Thanks Dirtman. Shall we call it the Zipgo kit? Great info and ill look into those changes. I guess the other option is a....manual tranny ha.

 

[dashhho]

One issue I had experienced a few weeks ago that came to mind today. I was travelling uphill and kept the accelerator at the same level. The truck naturally slowed but the tranny never downshifted, instead the engine started to lugg (stutter/shake) and that triggered me to lay off the gas and stomp on it - this always trigger the tranny to downshift. Naturally I lay off the gas and romp it to trigger the downshift when going uphill to try and stop the tranny from burning up with constant up/downshifts.

Is this a bad sign on the tranny? Again - I live in a mountainous area so its probably near the extremes of the shifting issues.

 

[Dirtman]

One issue I had experienced a few weeks ago that came to mind today. I was travelling uphill and kept the accelerator at the same level. The truck naturally slowed but the tranny never downshifted, instead the engine started to lugg (stutter/shake) and that triggered me to lay off the gas and stomp on it - this always trigger the tranny to downshift. Naturally I lay off the gas and romp it to trigger the downshift when going uphill to try and stop the tranny from burning up with constant up/downshifts.

Is this a bad sign on the tranny? Again - I live in a mountainous area so its probably near the extremes of the shifting issues.

I don't really know if its a sign of an actual problem. I've had my truck since brand new and its always needed a bit of coaxing to downshift on hills. Usually just a slight jab of the throttle though, nothing drastic.

Unrelated to the downshift issue but do you have an auxiliary cooler on it? If not you should install one asap. A real cooler will do more to prolong the life of the transmission than anything else you can do, especially if you're in the mountains. The factory setup is criminally insufficient.

 

[dashhho]

I don't really know if its a sign of an actual problem. I've had my truck since brand new and its always needed a bit of coaxing to downshift on hills. Usually just a slight jab of the throttle though, nothing drastic.

Unrelated to the downshift issue but do you have an auxiliary cooler on it? If not you should install one asap. A real cooler will do more to prolong the life of the transmission than anything else you can do, especially if you're in the mountains. The factory setup is criminally insufficient.

Checked quick and there is a cooler infront of the AC coil. It is 10" x 7" - I'm guessing it is stock . Looks like Hayden sells a bigger one ( 11" x 11") for ~$60.

 

[Dirtman]

Do the lines still run through the side of the radiator before going to the cooler in front on the AC condenser? If so it's most likely aftermarket, in any case as long as it has that "real" cooler and not just the built in part of the radiator it's good. I think my aftermarket one is 10x7 and works perfectly fine, my trans temp stays around 175f even loaded going through hill country with the 10x7 and that's basically as cold as the fluid can get. (It's thermostat controlled so it won't even send fluid to the cooler below 170f).

 

[Roert42]

I think tow package 4.0 came with external trans cooler from the factory.

I just drive around with O/D off when i'm in a hilly area, which is most of the time.

 

[Dirtman]

Maybe dunno. I thought by 2005 "tow package" wasn't really an actual option. They all came with class IV trailer hitches by then, even the 4 cylinders which weren't rated to tow squat.

 

[Roert42]

Maybe just the 4.0 auto then.

 

[dashhho]

Mine's got 10" rear drums - maybe that's part of the "tow package" as they also have a 9" rear drum option. From the look of the install it kinda looks factory but I could be wrong.

The tranny seems decent so ill go ahead and get the kits and figure it out. I'll see what ford wants for the valve body gasket and EPC solenoid.

 

[Dirtman]

The 10" drums are just standard for the v6 trucks. 4 cylinder trucks had the smaller brakes.