....OK, maybe I am a bit parinoid. Will I hurt my 4R70 tranny ini my '01 SCREW if I manually downshift it?

When I see that I need to stop, I gently push the OD button on the end of the stalk, When that shift has engaged, I then pull the shift lever down to 2nd gear. I rarely need to downshift to 1rst gear, but occasionally do.

When I have a green light, then I move the shift lever back to Drive and push the OD button again.

Will this cause any damage to my tranny? I ahve 170K on it, with fresh fluid and filter and it shifts wonderfully right now.

 

Our "mechanic" at work told us to turn off the overdrive on our F150 7700 work trucks when driving down the steep grade on one of our local highways, as he felt people were warping brake rotors riding the brakes.

I don't know the answer to your question, but I figure brakes are much cheaper/easier than transmissions to replace/repair.

 

no it will not hurt anything to manually shift like that.

there should be a fail safe to prevent you from doing any harm. this fail safe prevents the transmission from shifting down when there are excessive rpms.

 

Anybody else have any thoughts????

 

well i dont see how it could cause any damage, there are fully manual valve bodies out there so i would assume you would be okay

 

Is this something you do on ocassion or is it every time you slow down? I have no knowledge of it will hurt anything but I know I am not a fan of it. The brakes do a wonderful job if you let them. Not preaching just more curious on why someone would do it. I thougt that was the whole ideal of an automatic tranny.

 

i tend to do it often. especially loaded, i use compression to help with braking some as my brake system needs pm'd badly...

 

I tend to do this every time I have the room to slow down with the tranny without causing the engine rpm's to go above 3K. So....when the light changes and I can downshift without causing excessive rpm's I do the manual downshift. It saves wear and tear on the brakes.

Just worried that it might be causing some wear and tear on the tranny.

Oh, how I wish I could get a manual tranny in the F150....and now they are going to disappear on the Super Duties as well. What is Ford thinking????

 

If your tranny is a 4R70W (which i'm pretty sure it is unless you have a 7700) then manual downshifts shouldn't be a problem if its newer than 1998.

Jerry W. (creator of the J-mod) says this in his thesis on the 4R70W. The second to last paragraph on this page he answers this.

http://www.tccoa.com/articles/tranny...on/page6.shtml

I just happen to be rebuilding my tranny at the moment and remembered reading this.

- Erik

 

Thanks scruffy....I knew the 4r70 was a bit more advanced then the 4r100 as far as electronics, and this confirms it. Good read.

 

No damage will happen to the transmission it is made to down shift for steep downgrade but you can red line the engine if you going too fast and cause engine damage so, keep the RPM below 7000.

 

Would this be the same for the newer 4r75w trannys in the 3v 5.4s? I was always told its not healthy for them, but its useful to help with braking when hauling a load. The thing is the 4r75ws dont have a very high reliability according to most of the 04+ owners.

 

4r75 vs 4r70, better quality steel parts in the 75's

 

Thanks. I dont take chances with such expensive repairs, so when I hear rumors and study up on them I play it as safe as possible.

 

A stock torque converter can't handle much over 5400, which is why that's what the rev limiter is set to. I'm pretty sure the electronics WILL upshift the trans regardless of lever position if it goes that high.