Loud Slam

[KStromberg]

So I took the car out for a short drive today and came up to a stoplight at the end of an offramp and SLAM! it felt like someone rear-ended me when the car downshifted into first. I actually looked in my rear view mirror and verified that wasn't the case because I was that convinced that I had been hit. I noticed a veeeery slight rotational type of squeaking at around 28 mph when I am driving through neighborhoods. Very hard to hear, but it is there.

Am I dealing with a potential u-joint failure? It "tinks" when I put it into reverse. I have been running the same spicer solid ujoints since 2010 and it the car has seen plenty of spirited driving since. I have 4.30 gears. Opinions? All seemed well on the remainder of the ride home and it didn't do it again. Would excessive pinion play in the rear differential also cause this?

 

[Right on the Mark]

Would excessive pinion play in the rear differential also cause this? No

U-joint problem you would have crazy vibs. I would check them out thou. When my old AOD went out it did the bang downshift.

 

[97MarkJA]

Would excessive pinion play in the rear differential also cause this? No

U-joint problem you would have crazy vibs. I would check them out thou. When my old AOD went out it did the bang downshift.

+1 my 5.8l f150 did the same thing, and sometimes on the up shift as well. Broken sun gear where the dogs go into the basket.
You could email Alan at dirty dog and see what his thoughts are. He's usually pretty helpful.

 

[driller]

The 'think' and 'squeak' is likely a dry u-joint cup, not related to the slam.

 

[Dave 88 LSC]

Dont laugh. But about 10 years ago I was driving my 88 LSC, car full of people and as I was crossing Whitestone Bridge in NY we heard a loud bang/jerk. I thought the rear blew up or we got hit somehow. Slowed down and limped it off the bridge. Long story short, one of the bolts from the gear came off and got crunched between pinion gear. Rest of the bolts were loose too.
I felt fortunate the rear didnt lock up. I had 3.73 gears put in but a reputable shop weeks earlier.

 

[the1andonlyGR81]

if it slammed after you stoppedm my tranny did that the night before it died. did you check fluid intrans?

 

[KStromberg]

if it slammed after you stoppedm my tranny did that the night before it died. did you check fluid intrans?

To be honest, I didn't even bother to check the dipstick. When I was coming to a stop after this happened, I could hear some noise in the rear differential area whether it be in the differential or the ujoint at that end of the shaft.

Too be honest, I hope it is not the transmission because I have probably 85K miles on it and it came out of a civilian Crown Vic more than likely driven by an older person. I didn't feel anything out of the ordinary at all with the transmission or the shifting after this happened. I proceeded back to my parent's house with the car because that's where I store it, and now it once again sits. I stewed about it for awhile and have pretty much gotten over my anger about it now LOL. I'm going to take it to the guy who did fantastic work on the car this last fall and have him look it over.

I personally don't think it is transmission-related, but if it is, then I have a whole nother ball of wax to deal with, and with the upcoming coil conversion and front end work to be done before race day, I might just lose my temper a few more times.

 

[driller]

No need to worry about it, if it's the transmission you will know soon enough. Just be prepared and don't baby it - drive it like you stole it. Better to know now than at the track.

I don't want to hear any whining about how you couldn't get in the low 13s because of yada, yada, yada...

 

[ford nut]

No need to worry about it, if it's the transmission you will know soon enough. Just be prepared and don't baby it - drive it like you stole it. Better to know now than at the track.

I don't want to hear any whining about how you couldn't get in the low 13s because of yada, yada, yada...

+1
Its part of racing, just assume something is going to break.
Its going to be in the 70s at the end of the week :dancefool

Take it out and try to make happen again.
Better to find out now.

 

[97MarkJA]

+1
Its part of racing, just assume something is going to break.
Its going to be in the 70s at the end of the week :dancefool

Take it out and try to make happen again.
Better to find out now.

LOL... It'll work till it breaks.