sross4141

ok i have a quick question. i have a 88 5.0 and i just got the gt40 upper and lower intake manifold, what is better to get the gt40 heads or get the stock heads redone with a port and poilsh and a valve job, and wen i get over 65 on the freeway my whole rear of the car starts vibrationg, how to fix

88 orangepeel notch

I'm gonna take alot of flack for this but I'm running p&p E7's and am very happy with dyno #'s, and track times. If you have the money definitely get a set of aluminum heads (name brand), major weight loss and major hp gains. If your still running stock gears, that would be my first mod before digging into motor, best bang for buck.

You have to figure out what's causing the vibration. Where do you feel it vibrating, steering wheel or body (seat, floor, etc). Look for wheels out of balance, if your at a steady speed no load on drivetrain, check u-joints.

sross4141

ok, thanks. but it only happens wen im at 65 and over, it feels like it might be the springs, but im looking at the gt40 heads, for cheap

88 orangepeel notch

Springs aren't going to cause a vibration, you need to look for something in driveline that spins/rotates. Something is not in balance (wheel) or worn out (u-joint). Good luck, and post back when you find the problem to help the next guy who reads this.

The heads may give you maybe 10-15 more hp. Gears will "feel" like you have 100 more hp.

95 BLOWN GT

if budget is an issue get the gt40,s redone..

lxman1

Mine had a vibration at 75-up. Found out the driveshaft was bent a bit. (Was a good excuse to buy a Ford Racing aluminum driveshaft)
Have the tires balanced. Check for play in the u-joints. Jack the car up on a lift or put the rear up on jack stands. Start the car and put it in 1st gear. Watch the driveshaft to make sure it doesn't have any wobble in it. If all of that checks out, you may have an issue in the rearend such as a bent axle, bad bearings or badly worn gears.

tinman

I'd look at the rear wheels/driveshaft first.
Sounds almost like a rear wheel is loose to me........