Highrpm

I have an 84 with 5.0 that I recently picked up. It drives nice until you get to about 70 mph and then it shakes from something in the driveline I think. It doesn't appear to be a steering issue however I have not ruled the idea out. The guy that had the car some time ago had a 351 in the car but left everything the same from what I can tell. It has a Tremec 5spd, stock driveshaft, 8.8 rearend with 373 gears.Does anyone have any ideas? I havesome of my own ideas but could use a little help figuring this one out. Thanks.

ZachW04Stang

Could be a lot of things, bent or out of balance driveshaft. If you have a stock one they tend bend from racing on slicks. U joints can also do it. How do your motor and tranny mounts look? Tires could also just be out of balance.

Highrpm

Mounts are all brand new on the engine but I'm not sure on the transmission. Tires are ok. I was suspcious of the driveshaft being unbalanced or bent. I don't know if he ever ran slicks on the car but I would guess he did because the car is all set up for racing.

wildsurfer92

yea check and see if your wheels are balanced properly

tmajikman

check the air preesure in the tires also. you never know. that was my problem.

ZachW04Stang

I think a ford racing driveshaft is a good investment if you have a 351. Its a lot stronger then the stock ones. The only problem with the ford racing driveshaft is the u joints that come with them suck, I destroyed both of them in 1 trip to the track. I've replaced them with Precission u joints HD 1330's and they've held up so far.

Highrpm

Well I think that I'll have to get a new driveshaft and see what that does for me. Thanks for your input.

Nike2141

I had a buddy with that exact problem. The fix for him was a transmission issue. He had to replace a cracked portion of the transmission case. He had tried the driveshaft switch, wheel balancing, changed the fan...ect and it ended up being a very inexpensive part. I will talk to him tomorrow and get the exact name of the peice.