As I was very aggressively accelerating my '02 Harley F150 up the pretty steep freeway onramp (that was curving sharply toward right, if that matters) I heard and felt strong thump (so strong that it scared me) that sounded as coming from transmission during upshift right when I hit the top of the ramp.

Can anyone tell me what might be the cause for it and would there be any damage due to it?

Thanks!

ZoranC

 

I have the same thing happening to me in my truck. Mine only seems to happen between 1st and 2nd gear, and only if my foot is on the gas, If i accelerate and then let off, and the truck shifts while I"m off the gas it is fine, but on the gas it is pretty loud/hard. I am planning on taking it in next week to have it checked out. I will let you know what happens.

 

SSR, does that happen to you during any acceleration or only when up the hill/slope/onramp? My wife says she experiences similar thing in her Mustang when by coincidence she takes the foot off the gas pedal right when tranny tries to shift. I tried to reproduce it today but onramp was packed with cars. I will keep trying and also take it up some long steep slopes in the neighborhood. Let me know what they told you about yours.

Thanks!

ZoranC

 

It happens only under acceleration. The harder the acceleration, the harder the thumb and the louder. If I take my foot off the gas right before it shifts, then it shifts fine. I tow with it, and it is worse when I have a trailer on it.

 

What I meant to ask is: Do you get this only when accelerating up the hill or on flat straight road too? I don't have a single problem when on flat straight road (shifts are aggressive, but no thumps).

Thanks!

ZoranC

 

Sorry, I mis understood. I do get them on flat roads as well as on ramps, although I think its a little worse on the ramps.

 

Thanks! I will start paying attention to flat surface. I might go and find good place to try what happens if I stand still or roll at low speed and then slam pedal to the metal. I guess if it shifts through that without thumps I am good at least on those surfaces.

ZoranC

 

I get the same kind of thump or I call it bang shifting. Miine happens mostly when I take my foot off the gas right before it shifts allthough I have felt it when I keep my foot in it.

I can kind of expect that out of my truck though. It's a 97 with 140K and mostly original. I blame mine on worn u-joints, sloppy rearend, and more than likely a very worn tranny. A new 02 shouldn't be doing that. Is that a 1 piece driveshaft or a two piece? Also, I can't hel pto think that maybe the factor of going uphill which loads the truck and the turn creates some sort of bind, but that's doesn't explain it on straight uphills and flat surfaces. I would have a dealer look at.

 

KYFordFreak,

Thanks for the reply. It happened only once, on curved uphill. We resolved the mistery, though. If you are curious check out reply by Ken800 under tread with same name as this one in 'Harley Davidson' forum.

Thanks one more time!

ZoranC

 

my 98 does it. I call it a "hard" 1-2 upshift. Happens under heavy throttle. It's more pronounced now whlie running A/C. Under moderate throttle, doesn't happen. Mine has 175,000 km (about 110,000 miles)

I attribute it to age and mileage.

 

J-150, thanks for the thought. However, this is '02 with approximately 3K miles on it when it happened. I don't know what caused and my later efforts to reproduce it failed.

Thanks again!

ZoranC