Hoping some folks might advise me on this recent issue I have developed, didn't want to hijack the other transmission discussions.

Its an early 99 F250 SD 4x4 5.4l that I ordered new. Tranny has been very smooth since day 1, just over the past couple months has started shifting harsh most of the time, only on 2nd to 3rd upshifts. Its has 150K, well maintained. Filter changed by ford dealer at 30K and 130K miles. Last time they added 9qts of MercronV, first time this tranny saw synthetic...might be the clue. I drain and re-fill the pan (has drain plug stock!) once or twice a year with 5qts mercron3.

Using tuning software in the past, it acts like it would if I tried to adjust up the shift pressure from stock...I never understood why people did that, as it made my transmission shifts very harsh if I tried any setting but stock shift pressure.

Thanks!
Neil

 

MERCON V is not necessarily synthetic. I suspect you have an accumulator valve that is sticking in the accumulator body.

 

Thanks Mark...I thought Mercon V implied synthetic.

I can get a low mileage stock VB from a lightning for under $50...is this a good fix? Or what would you recommend?

Swapping a VB doesn't look hard, a shift kit may be too much for me...

 

I don't know what a Lightning valve body would do on this trans. If it were mine I'd check the sticking valve. There are aftermarket bodies available, I've never tried one.

 

Ok thanks. Looks easy to pull the accumulator apart and clean...is that the fix?

Or once the main valve is worn, its best to a) use that Sonnex type valve solution Pop mentioned or b) replace the VB?

Neil

 

Yes, and either one will fix it.

 

Cool. I ordered the sonnex kit for $20...might as well do that and try to correct what I have before spending dough on a VB when I like the stock springs.

I'll post the results next week!

NC

 

I have my accumulator on the bench, pulled the shift valves to clean them before I got the main valve (with Sonnex replacement in hand)...and found the 2-3 valve spring broken in half.

Would you recommend Mark:
1) taking the 2-3 spring from the lightning VB I grabbed for $30, and replace the broken spring in my VB...plus the new sonnex valve
2) do a whole shift kit
3) swap to the lightning VB (the lightning folks change the VB more often, why there are plenty available cheap) I didn't think the stock VB would be different?

Thanks,
Neil

 

I don't know if the valve bodies are the same or not. The Lightning valve body will bolt to your trans, but will it have the right pressures? I don't know.

You can take the spring if it is a shift valve. If it is an accumulator valve it may create harsh or soft shifts.

 

Yeah its a shift valve spring that broke in half...will pull it from the lightning. Since I have it apart and the new sonnex valve in hand, I might as well swap it also? Or would you just fix the broken spring? The new valve is .427 diameter, and will only very slightly boost line pressure like 3%.

Thanks,
Neil

 

Good call on being cautious with the lightning VB swap Mark, as it turns out the accumulator valve itself is different...w/ no grooves at all. The shift springs were identical, so I used the shinny new ones from the lightning VB...and did the sonnex valve also.

All back together, easy job, runs great! And will never pay anyone to change my trans filter again!

Thanks again for all the help!

 

I am currently having the same issue with my 4r100. I am going to look at it on Saturday. Does anyone have a diagram of the accumulator apart?

 

TransGo | TechSolutions

Try this video from Transgo website, it helped to see the accumulator being disassembled first.

Its very straight forward.

ncon

 

Awesome. Thanks for the link!