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  1. #1

    Default Driveline vibrations at high speed

    Hey, long time no post, but I've got the capri on the road with the roller 302 and t5, 8.8 rear. I'm running the stock shaft from the 4 speed and the 7.5 with the current setup.

    I'm experiencing driveline vibrations above 50 or so. It gets worse the faster you go, and the clutch in or put at any rpm does not affect it. So we are looking st output shaft of trans to tires for an issue.

    I have rebalanced the tires, the u joints don't seem obviously loose, and there's nothing blatant staring at me.

    I'm thinking it's driveline angle or the shaft is just out of balance.

    I understand the U shape angle these fox's come with, but I dont really get what's acceptable for angles and the tremec app gives you angles but does not work for non z type angles.

    So my output is around 4-4.5* down
    Driveshaft is around 3.5-4* down (it is slightly different from the angle of the output shaft)
    Pinion is around .5-0* pointed down (toward the ground)

    So we have a u shape, but what do these angles equate to?
    I have all stock everything from the control arms to the crossmember and trans mount (4speed mount on the t5).

    Any help is appreciated so I don't go pulling driveshafts for no reason and still have the angles off.
    Thanks!
    1979 Capri RS 302/4spd- Rough (but free!)
    1982 Fairmont 200/c5- Rough, but running
    1987 Olds Cutlass 403/t56/4.10 Dana 60
    1972 Plymouth Satellite wagon- AACA HPOF, all original, my grandpa bought it new.
    And many more...

  2. #2
    FEP Senior Member
    Join Date
    Mar 2008
    Location
    darien il
    Posts
    514

    Default

    According to Currie, the average car crafter should strive for between 1 and 3 degrees between the tailshaft of the transmission and driveshaft, and 1 to 3 degrees between the driveshaft and pinion. Furthermore, the two angles should be nearly equal (between 1 and 3 degrees), but always opposite, with mine when i was chasing the vibration, i also replace the drive shaft to the aluminum. that and other things finaly got it.

  3. #3

    Default

    Sounds like a bad u joint.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    K&N filter in a stock dual snorkel, GT40 heads, Edelbrock 3721 intake, MSD 8456 Dist., MSD 8227 coil
    Comp cams XE254H, hypereutectic pistons
    Hooker Super Comp Shorty Equal Length Headers, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace, 3.73 rear.
    Ford Performance Springs, Firehawk A/S 225/55r16 on LMR TRX r390 wheels (street)
    Federal 595 rs-rr 245/40r17 and 255/40r17 on OE cobra r wheels (race)
    AOD rebuilt with a 6 clutch direct drum, Koline steels stacked with 8 clutches, Kevlar band, superior shift kit, new torque converter. --Everything else stock and fully functional.

  4. #4

    Default

    The equal and opposite is what I've always done. But from all my reading, the nose down pinion I'm seeing on this car is normal for a fox body and acceptable. I'm just not sure how exactly I'm supposed to set this up to work.

    As for the joints, they aren't new but I see no noticeable slop in them. It is a stock shaft but I didn't have any issues before I changed literally everything around it.
    1979 Capri RS 302/4spd- Rough (but free!)
    1982 Fairmont 200/c5- Rough, but running
    1987 Olds Cutlass 403/t56/4.10 Dana 60
    1972 Plymouth Satellite wagon- AACA HPOF, all original, my grandpa bought it new.
    And many more...

  5. #5
    FEP Power Member 87gtVIC's Avatar
    Join Date
    May 2009
    Location
    Whitestone, NY
    Posts
    1,053

    Default

    Will mention u joint as well. Had a faint sound and vibration at higher speeds. Front u joint had one dry cap. That was enough to cause some noticeable vibrations. It had no slop but was very stiff because of no grease in the cap. Not too hard to just check them. Pull shaft out and if there is any rough spots while manipulating the joint you have an issue.

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