So my car's been doing this for a few weeks now. About a month ago a friend and I put 390 Motive gears (ya I know not Ford Racing) and got the proper backlash at .011 and ect... Did the breakin procedure correctly. The gears seemed fine until a few days later we all decide to go down to NED and pulling onto 93 with hard acceleration I got a really bad vibration that feels like it's more in my shifter.
To narrow down possible problems I had rear tires rebalanced, changed the u-joints in driveshaft on both ends, and checked the rearend out. Pulled the cover and the backlash was still .011 and no broken pieces of anything spilling out. No metal shaving s out of the ordinary. I am running Royal Purple as well. We did notice that the driveshaft going into the tail end of transmission has a slight movement but not sure if it was like that before and if it's normal to have any movement.
Besides forking out money for another transmission which shifts fine and has no noise with no grinding with an occasional grind in 2nd gear witch is probably my fault, what else is going on with my car? And if you guys think without looking at my stang could be the transmission where can I find one? (used or rebuilt)
Tire pressure is fine but tires are a little worn. They were like this beforehand with no vibration. It also does it in nuetral as well cause I tried that already too. There is no noise either. I feel it like 10x more now that I have the Steeda in which kinda sucks because it's a lot stiffer with no slack like the crappy stocker.
Try an aluminum driveshaft if you don't already have one in there. Fox bodies for some reason have vibration issues when installing gears. I did 3.73 gears years ago in my old 90 L.X. As soon as I took it for a ride it vibrated badly. I swapped in an aluminum driveshaft and the vibrations went away completly. I drove it for 5 years after and no vibrations at all. I still have the rearend and the driveshaft. They are goin in another fox that I'm building.
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337 C.I.D.
390 R.W.H.P.
362 R.W.T.Q
11.44@120 in the 1/4
7.35@ 95 in the 1/8
1.60-60'
N.A.
1988 L.X. Hatch 5.0L 5-Speed, 85,000 original miles
I'm not questioning anyone I'm just curious in how it causes the driveshaft to vibrate after gear install. If you guys think that I'll give it a try cause a transmission costs alot more. lol Possibly more torque being forced on the driveshaft from gears??
I'm not questioning anyone I'm just curious in how it causes the driveshaft to vibrate after gear install. If you guys think that I'll give it a try cause a transmission costs alot more. lol Possibly more torque being forced on the driveshaft from gears??
Harmonics. Same reason the dogbone can be removed from the rear axle if you have an aluminum DS.
Was the DS reinstalled 180* off?
You can try this lengthy process to narrow it down.
PINPOINT TEST A: HIGH SPEED SHAKE DIAGNOSIS
A11 REAR TIRES
l Engage drive train while vehicle is raised on hoist. Carefully accelerate the drive wheels while feeling for vibration.
l Is vibration felt?
No GO to A14.
Yes GO to A12.
A12 DRIVETRAIN
l Remove rear wheels, secure brake drums, if so equipped by installing wheel lug nuts, reversed. Carefully accelerate the drive train while feeling for vibration.
l Is vibration felt?
No BALANCE rear wheels. PERFORM Road Test
Yes GO to A13.
A13 REAR DRUMS OR ROTORS
l Remove the brake drums or rotors. Carefully accelerate the drive train while feeling for vibration.
l Is vibration felt?
No REPLACE drums or rotors. PERFORM Road Test
Yes GO to Driveline Vibration Diagnosis .
A14 WHEEL BALANCE
l Balance all wheels not previously balanced. Road test vehicle.
l Are wheels balanced?
Yes Vehicle OK.
No GO to A15.
A15 SUBSTITUTE WHEELS AND TIRES
l Substitute a known good set of wheels and tires. Road test vehicle.
l Is vibration felt?
No INSTALL the original tire/wheel assemblies, one by one, road testing at each step, until the defective tire(s) is identified. REPLACE tire(s) as necessary and RETEST.
l Verify that the observed condition is not a high speed shake caused by wheels/tires.
l Is observed condition a high speed shake caused by wheels or tires?
Yes REFER to High Speed Shake Diagnosis for drive-wheel runout and balance procedures.
No GO to C2.
C2 DRIVESHAFT
l Inspect driveshaft for undercoating or physical damage. Check index marks (yellow paint daubs) on rear of driveshaft and axle companion flange. These marks should be no more than 90 degrees apart.
l Are marks no more than 90 degrees apart?
No GO to C3.
Yes CLEAN off undercoating or REPLACE damaged driveshaft. If index marks are misaligned, GO to C6. CHECK for vibration at road test speed. If still present, GO to C3.
C3 DRIVESHAFT RUNOUT
l With vehicle on hoist, measure runout at front, center and rear of driveshaft. Maximum runout is 0.89 mm (0.035 inch).
l Is maximum runout 0.89mm (0.035 inch)?
Within specification GO to C7.
At front or center out of specification GO to C4.
At rear out of specification MARK the rear runout high point. GO to C5.
C4 DRIVESHAFT RE-INDEXING AT TRANSMISSION
l Note or mark indexing of driveshaft to transmission and axle companion flange. Disconnect the driveshaft, re-index 180 degrees at transmission only and reconnect. Check runout at front and center of driveshaft, maximum runout is 0.89 mm (0.035 inch).
NOTE: While driveshaft is removed from vehicle and manipulate U-joints in each direction of rotation. If a U-joint feels stiff or has a "lumpy", "gritty" feel in any direction, replace U-joints or driveshaft.
l Is it within specification?
Yes CHECK for vibration at road test speed. If still present, mark rear runout high point. GO to C5.
No GO to C6.
C5 DRIVESHAFT RE-INDEXING AT AXLE
l Note or mark indexing of driveshaft to axle companion flange. Disconnect the driveshaft. Re-index 180 degrees at axle and connect. Check runout at rear of driveshaft. Maximum runout is 0.89 mm (0.035 inch).
l Is it within specification?
Yes CHECK for vibration at road-test speed. If still present, GO to C7.
No GO to C6.
PINPOINT TEST C: DRIVELINE VIBRATION DIAGNOSIS
C6 AXLE COMPANION FLANGE
l Compare the two high points of runout marked in Test Steps C3 and C4.
Marks within 25 mm (1 inch) of each other REPLACE driveshaft. RECHECK vibration.
Marks 180 degrees apart REPLACE axle companion flange. CHECK driveshaft runout and road test for vibration. If still present, GO to C7.
C7 DRIVESHAFT VIBRATION
l The driveshaft can be re-indexed at both the rear axle and transmission to minimize system imbalance. Refer to driveshaft indexing procedure.
l Is driveshaft balanced?
Yes Vehicle OK.
No REFER to Driveshaft Balancing Test Step F1 , if vibration still present.
C8 AXLE PINION NOISE DAMPER
l If vibration still exists after balancing driveshaft, install an axle pinion damper, as outlined.
l Is vibration still present?
No REFER to Group 05.
Yes Vehicle OK. REPLACE driveshaft if vibration still persists.
Wow, nice write up but very long indeed. I found 2 driveshafts to try out tomorrow to see what happens. One with with dampner and one without.
What's the purpose of the dogbone wieght?
did u make shure ur driveshaft bolts are tight? usualy when u do gears, ur supposed to drive ur car around then tighten the bolts back up after 100 miles or so, this is wat dez told me to do, just make shure theyre all tight thats the 1st thing i wuld check
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"Nothing says "I LOVE YOU HONEY" like a smack across the dome with a camshaft"
-G.M.
put an Aluminum driveshaft in...problem solved....everyone ive dont gears in i had to also put in a driveshaft or it vibrated at highway speeds......put it this way...you got stock 3.08s in your car....you notice it vibrates at 140mph...well put 410s in it and it does it at 80mph
It's so hard to say because it's been leaking from the tailshaft seal where the driveshaft goes into the transmission. And I just replaced that seal when I did u joints last week. The bearings or something must be shot in tranny. And it seems if I put in an aluminum driveshaft in it just covers up the problem right? There will still be a problem somewhere?
We were going to try out a couple diff. driveshafts for my car but couldn't get to it cause we were busy working on my friends car. Idk maybe today.
about a month ago i did 4.10s in my 89 and i had the exact same problems.. vibration at highway speeds and i was told to have the driveshaft rebalanced but instead i just put a used one on it it was the problem!
Probably oringinal. All suspension is stock. Eventually everything will be replaced, well that's the plan anyway. So when we race at the track I have to deal with it for a couple seconds hoping nothing breaks lol.
I really don't think that'll be the problem. But if it is I won't find out till next year when I spend money on the stang again. It parks in my garage when winter comes so I don't want to spend my money quite yet. Only thing I might get this year will be an aluminum radiator cause mines about had it. So I'm hoping it'll last through our next meet next month.
yesterday is history tomorrow is a mystery
337 C.I.D.
390 R.W.H.P.
362 R.W.T.Q
11.44@120 in the 1/4
7.35@ 95 in the 1/8
1.60-60'
N.A.
1988 L.X. Hatch 5.0L 5-Speed, 85,000 original miles
