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-   -   Kickdown problem? (http://www.ramforumz.com/showthread.php?t=124320)

BigZach 10-22-2012 10:29 PM

Kickdown problem?
 
My transmission shifts fine in till I have to stomp the pedal like to pass someone or jump on the freeway. It feels like it over revs and doesn't shift till I let off the gas. It does it around 45mph and up.

ramvan2500 10-22-2012 10:55 PM

Quote:

Originally Posted by BigZach (Post 918311)
My transmission shifts fine in till I have to stomp the pedal like to pass someone or jump on the freeway. It feels like it over revs and doesn't shift till I let off the gas. It does it around 45mph and up.

Well you shouldn't just stomp on the pedal, these transmissions in stock form cannot take the abuse over and over. But a problem that you describe could be many things, most likely it's the valve body preventing a direct 4-2 downshift, it's built to do 4-3 then 3-2. A forced downshift 4-2 can cause issues, many times the front bad will apply before the OD clutch is able to dis-engauge. It's normal though for it to sound like it over-revs. Try doing a partial pedal for a 4-3 downshift, then once it goes into third stomp down on the pedal. It's the safe thing to do.

It is possible that the front servo is leaking, Sonnax makes a very very nice part it helps cure the long slide 2-3 shift, increases the band apply force by around 15% (according to sonnax- haven't measured myself yet). It's the sonnax front servo kit, has everything. Good little kit, it's about 110 bucks but it's a good investment, for one it reduces direct clutch wear cause by the long slide 2-3 shift, gives a more clean and firm shift (the firmer the better). And quick shifts as well.

BigZach 10-22-2012 11:08 PM

How hard is that servo to install? Could 33" tires cause issues with the transmission? What am looking for when I drop the valve body? Thanks for the quick reply.

ramvan2500 10-22-2012 11:31 PM

Quote:

Originally Posted by BigZach (Post 918379)
How hard is that servo to install? Could 33" tires cause issues with the transmission? What am looking for when I drop the valve body? Thanks for the quick reply.

33" Tires wouldn't cause the issue, the only thing 33" tires are going to do is slow down the acceleration and top speed of the vehicle. It will also make slowing down more difficult.

I will give you a link to the instructions to install the servo, this is from sonnax.

http://www.sonnax.com/system/instruc...-01K_SK-IN.pdf

It is a very easy thing to install, you just need a inch-lb torque wrench, torx screw driver, and c-clamp (8"). Part can be replaced in a matter of an hour to hour and half.

BigZach 10-22-2012 11:41 PM

Thanks! All right when I get the money I'll get that servo. Anything else I should check out while I'm in there?

ramvan2500 10-22-2012 11:44 PM

Quote:

Originally Posted by BigZach (Post 918444)
Thanks! All right when I get the money I'll get that servo. Anything else I should check out while I'm in there?

Yes there is one thing you should check while you have the valve body removed, check the 3-4 accumulator shift spring. They are prone to breaking causing 4th gear shift issues.

Here is a link which includes a picture of the spring location and the what PDF's of what the spring does.

http://www.sonnax.com/product-lines/...ion/parts/1708

Gen1dak 10-22-2012 11:54 PM

When was the last time it was serviced? Could be as simple as needing a band adjustment. The kickdown band can be adjusted externally without dropping the pan.

BigZach 10-23-2012 12:44 AM

I just dropped the pan and put a new filter and fluid in it two months ago. I didn't even know there was such thing as a kickdown band adjustment till I started searching today. It probably needs to be adjusted. @ Ramvan2500 thanks for the link I'll check that out when I get the valve body out.

Gen1dak 10-24-2012 03:47 PM

Well once you open it up don't forget to adjust the rear band too as it can only be done with the pan off.

ramvan2500 10-24-2012 04:38 PM

Quote:

Originally Posted by BigZach (Post 918529)
I just dropped the pan and put a new filter and fluid in it two months ago. I didn't even know there was such thing as a kickdown band adjustment till I started searching today. It probably needs to be adjusted. @ Ramvan2500 thanks for the link I'll check that out when I get the valve body out.

Yea not a problem, I didn't want to say do a band adjustment because usually in all the TF's I rebuilt and serviced and hell even modified generally if the band is in need of an adjustment you won't have a very nice 1-2 shift and 2-3 shift. Forced kickdown shifts aren't always as smooth as we want them to be when it comes to a stock TF. The biggest issue is with 2nd gear with these transmissions and on top of that the 2nd gear problems usually cause wear to the rear clutch. The issues that cause common problems with 2nd gear are.

1. Direct Clutch Inner Lip Seal Leakage, this is due to improper machining of the drum.
2. Front servo Pin boss wear, causes leakage and this is when you get that long slide 2-3 shift, a soft 1-2 and 2-3 shift, and a the obvious kick down issues. Long slide shifts are a big problem and not just for the chrysler transmission, the powerglide was coined at one time as the Slip and SLIDE powerglide, ahehe. Long slides with the TF's cause excessive wear to the rear clutch because the band isn't able to release in sync with the application of the clutch, so you get a large shift overlap that causes clutch damage.
3. Rear planet gear wear, this can almost never be avoided. Because helical planetary gears have a tendency to walk, thrust washers are used to set endplay and to prevent them from reciprocating within there ring gear, but the issue is they still are allowed to move which causes a shear stress (big one) to the teeth which causes them to wear, and wear is normal but it's uneven wear and eventual leads to chipping.
4. Many of the stock bands have lubrication slits, Borg Warner makes a very nice aftermarket replacement band that doesn't have these large oil slits but has very small oil holes and a journal. Basically the aftermarket band has more friction area than the stock band.


There are tons of other issues, I am sure. But the above are the ones I always run into when it comes to 2nd gear. And I hate long slide shifts because in a race you want to spend more time in a single gear than to be stuck between two. Shorter shifts times basically. But other than trying to win a race, it's the wear that occurs which is the most important. If it wasn't for all the slipping and sliding then the clutches would practically last forever.

And I know for a fact that you are having a long slide 2-3 shift because Chrysler never made an attempt to correct the issue, which could of been done by machining a grove in the covers bore and snaking an o-ring in there which is essentially what the sonnax front servo cover is, I prefer to buy the kit because it has a larger area so the apply pressure is higher and well you will get a stronger 2nd gear. If you tow or race, the stronger 2nd gear the better.

Speaking of issues with these transmissions, they also don't cycle fluid when the converter clutch is engaged. Most people would say you don't need to circulate fluid if the clutch is engaged. I say you do because the clutch is friction based, has a reaction plate and friction disc, so there is going to be some slipping, less than a non-lockup converter. But most engineers and even I don't even bother to include lock-up converter clutch slippage because it's so minimal, but it's still there. And where there is coupling that can be removed there will be friction, and where there is fiction there is heat. This is a primary reason that the converters don't last long in these transmissions. Sonnax (surprised yet?) has a replacement valve to correct this.

Another big problem is that these transmissions don't provide a lubricant feed while in park, this is the primary cause of excessive input shaft bushing failure.

Another thing, not much a problem but could become one is the anti-drain back valve that everyone talks about. It restricts lubricant flow and if the valve because clogged you won't have any flow and well essentially you run without lubricant to the essential components such as the clutchs, bushings, and bearings... The common fix is to simply remove it. The only issues is the converter will drain overnight, but the converter will quickly refill when you put the vehicle in gear. But again no lube feed in park so you have to put it into any gear other than park to fill it up. Which leads to another Sonnax valve, the manual valve and pressure regulator valve. The sonnax PR valve stops PR valve buzz and has a built in anti-drain back valve. The PR replacement valve by sonnax also helps with the harsh reverse shift and allows lube flow in park. The sonnax replacement manual valve allows for converter fill in park.

Overall the TF or say the 46-48 RE/RH's are good transmissions, but with a little money can be made into solid as diamond transmissions.


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