Vibration after gear installation

Yan88gt · 08-18-2001, 11:25 AM

I've just put a new 3.55 gear in my car. When i go at 85 mph i feel a little vibration and i push the clutch or put the car in neutral ,it vibrate very bad. I've check the u joint, wheel bearing, the mark on my driveshaft ,everything is O.k. My wheels are balanced. The car was running great 2 days ago with my old gear.

MiracleMax · 08-18-2001, 01:16 PM

Try removing the axle damper (the big weight looking thing near the front of the center section on the diff), they're tuned to different gear ratios.

93CobraR · 08-18-2001, 03:31 PM

Either try rotating the drive shaft 180 degrees, and if that doesn't take care of it an Aluminuim one usually does.

------------------
87 GT, Cobra R's,GT-40 heads,Crane 2031,1.7's, Edelbrock intake, long tubes,BBK cold air, Mass air,pulleys,Pro 5.0, King Cobra,Lakewood Lift Bars,50/50's,subframes, 4.10's.
Best time 12.759
Best MPH 106.79
Best 60' 1.695

Visit my site at:
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Yan88gt · 08-18-2001, 08:20 PM

Thanks to Miracle max and 93cobra but it will still vibrate.Does everyone had this problem? Is it normal or what? Do i have to live with this problem? It shack VERY BAD at 100mph +

Wildhorse91 · 08-19-2001, 01:22 PM

I HAD THE SAME PROBLEM UNTIL I WENT TO AN ALUMINUM DRIVESHAFT. HOWEVER IF THE VIBRATION COMES IN WAVES(VIBRATION INCREASES AND DECREASES) IT COULD BE YOUR HARMONIC BALANCER. BELIEVE IT OR NOT YOU CAN TWIST THE OEM DRIVESHAFT. TO CHECK THE DAMPNER: START YOUR CAR AND POINT A FLASHLIGHT ON THE DAMPNER. IF IT IS GOING OUT IT WILL WOBBLE LIKE A BENT BICYCLE RIM. WORKS BETTER TO DO THIS WHEN IT'S DARK OUT SO YOU CAN SEE IT MOVE BETTER. IF IT IS THE PROBLEM, DON'T WAIT TOO LONG TO CHANGE IT. IT WILL COME APART. THE DAMPNER IS A TWO PIECE DESIGN. ALSO EXCESSIVE HARMONICS CAN BREAK DOWN YOUR MOTOR.

skiwesser · 05-22-2006, 03:37 PM

rotating my stock shaft 180* helped a ton when I had 3.73's put in, prob put shaft on in wrong position to start with, took weight off of housing, but my aluminum shaft made it smooth as stock.

tmoss · 05-22-2006, 06:24 PM

Any time you change to a 3.55+ gear, you should have your driveshaft precision balanced. The guy who did my gear install said it should go hand-in-hnd with a gear change. It took my vibration away - cost was $50.

Jeff Chambers · 05-23-2006, 06:53 AM

Your problem is in the pinion bearing preload. You didn't crush the sleeve to the proper running torque on the bearings. When you decel, the pinion is sucked deeper in the mesh and unloads the rear pinion bearing. Time to take it back apart again.

mustangII460 · 05-23-2006, 08:39 PM

I quit using crush sleves on the pinion long ago for this reason. A spacer kit is made to replace the crush sleve.

I recomend http://www.fortesparts.com/ for the part if you don't have a source.

rwhite65 · 05-23-2006, 11:17 PM

You guys may have just solved a problem I have been chasing for ever! I have had the same problem ever since I bought a 4.10 third member for my eight inch about 8 years ago. I have tried everything and never been able to find it.....now I just gotta find someone to help me

I love this board.
Ryan

Coupe50h · 05-24-2006, 11:43 AM

good thread.... I need to look into that spacer, I re-used my crush sleeve, so far everything's fine....but I have something wrong with a carrier bearing, since i hear a whine only whine when i make right hand turns, Things arent caddilac smooth in my car at over 105+ mph with 3.90 grs, but having the aluminum d/s helps alot, problems can be in the u-joints as well.

08-18-2001, 11:25 AM	#1
Yan88gt Registered Member Join Date: Jun 2001 Location: Quebec canada Posts: 92	Vibration after gear installation I've just put a new 3.55 gear in my car. When i go at 85 mph i feel a little vibration and i push the clutch or put the car in neutral ,it vibrate very bad. I've check the u joint, wheel bearing, the mark on my driveshaft ,everything is O.k. My wheels are balanced. The car was running great 2 days ago with my old gear.

05-22-2006, 03:37 PM	#6
skiwesser Registered Member Join Date: Sep 2000 Location: rock hill,S.C. 29730 Posts: 420	Re: Vibration after gear installation rotating my stock shaft 180* helped a ton when I had 3.73's put in, prob put shaft on in wrong position to start with, took weight off of housing, but my aluminum shaft made it smooth as stock. __________________ 88 GT: subs,pullies, 1 3/4 longtubes, flowmasters, AFR 165's,T,F #1 cam,Thyphoon intake, 24# inj., 73mm C&L,65mmT.B., 190LPH pump, Eagle sir rods, forged pistons in a newly rebuilt 306. DYNO TUNED TO 300.97 RWHP 337RWTQ

05-22-2006, 06:24 PM	#7
tmoss Registered Member Join Date: Mar 2003 Location: Saint Louis, MO Posts: 634	Re: Vibration after gear installation Any time you change to a 3.55+ gear, you should have your driveshaft precision balanced. The guy who did my gear install said it should go hand-in-hnd with a gear change. It took my vibration away - cost was $50. __________________ Tom (Torque) Moss 88Gt 5spd Vert, FLowmaster Catbacks, stock cam advanced 4° @ 108.5° ICL, NMRA prepped GT40P heads 1.85/1.55 valves and 1.7 rockers, MAC P headers Jet-Hot coated, 97 Exlporer intake (ported lower), TB and injectors. 277RWHP/330RWTQ (SAE). http://www.fastlanecars.com/

05-23-2006, 06:53 AM	#8
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: Vibration after gear installation Your problem is in the pinion bearing preload. You didn't crush the sleeve to the proper running torque on the bearings. When you decel, the pinion is sucked deeper in the mesh and unloads the rear pinion bearing. Time to take it back apart again. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

05-23-2006, 08:39 PM	#9
mustangII460 Factoy Five Roadster Join Date: May 2000 Location: Sevier Co,Tennessee Posts: 1,681	Re: Vibration after gear installation I quit using crush sleves on the pinion long ago for this reason. A spacer kit is made to replace the crush sleve. I recomend http://www.fortesparts.com/ for the part if you don't have a source. __________________ Frank

08-18-2001, 01:16 PM	#2
MiracleMax Registered Member Join Date: Apr 1999 Location: Hayes, Va, USA Posts: 798	Try removing the axle damper (the big weight looking thing near the front of the center section on the diff), they're tuned to different gear ratios.

08-18-2001, 03:31 PM	#3
93CobraR Registered Member Join Date: Oct 1999 Location: Cincinnati, Ohio Posts: 1,575	Either try rotating the drive shaft 180 degrees, and if that doesn't take care of it an Aluminuim one usually does. ------------------ 87 GT, Cobra R's,GT-40 heads,Crane 2031,1.7's, Edelbrock intake, long tubes,BBK cold air, Mass air,pulleys,Pro 5.0, King Cobra,Lakewood Lift Bars,50/50's,subframes, 4.10's. Best time 12.759 Best MPH 106.79 Best 60' 1.695 Visit my site at: http://www.geocities.com/cobrar93_2000/MyPage.html

08-18-2001, 08:20 PM	#4
Yan88gt Registered Member Join Date: Jun 2001 Location: Quebec canada Posts: 92	Thanks to Miracle max and 93cobra but it will still vibrate.Does everyone had this problem? Is it normal or what? Do i have to live with this problem? It shack VERY BAD at 100mph +

08-19-2001, 01:22 PM	#5
Wildhorse91 Registered Member Join Date: Aug 2001 Location: lake charles, la. , usa Posts: 3	I HAD THE SAME PROBLEM UNTIL I WENT TO AN ALUMINUM DRIVESHAFT. HOWEVER IF THE VIBRATION COMES IN WAVES(VIBRATION INCREASES AND DECREASES) IT COULD BE YOUR HARMONIC BALANCER. BELIEVE IT OR NOT YOU CAN TWIST THE OEM DRIVESHAFT. TO CHECK THE DAMPNER: START YOUR CAR AND POINT A FLASHLIGHT ON THE DAMPNER. IF IT IS GOING OUT IT WILL WOBBLE LIKE A BENT BICYCLE RIM. WORKS BETTER TO DO THIS WHEN IT'S DARK OUT SO YOU CAN SEE IT MOVE BETTER. IF IT IS THE PROBLEM, DON'T WAIT TOO LONG TO CHANGE IT. IT WILL COME APART. THE DAMPNER IS A TWO PIECE DESIGN. ALSO EXCESSIVE HARMONICS CAN BREAK DOWN YOUR MOTOR.

05-23-2006, 11:17 PM	#10
rwhite65 Ride Hard Join Date: Oct 2000 Location: Wyoming IL Posts: 1,094	Re: Vibration after gear installation You guys may have just solved a problem I have been chasing for ever! I have had the same problem ever since I bought a 4.10 third member for my eight inch about 8 years ago. I have tried everything and never been able to find it.....now I just gotta find someone to help me I love this board. Ryan __________________ 65 Fastback 91 roller 306, H/C/I AOD-Bauman, PI Stallion, 4.10's and traction loc 04 Grand Cherokee Freedom Edition 79 Ford F-250 4x4 - Restored

05-24-2006, 11:43 AM	#11
Coupe50h Registered Member Join Date: Aug 2002 Location: SanAntonio, Tx Posts: 957	Re: Vibration after gear installation good thread.... I need to look into that spacer, I re-used my crush sleeve, so far everything's fine....but I have something wrong with a carrier bearing, since i hear a whine only whine when i make right hand turns, Things arent caddilac smooth in my car at over 105+ mph with 3.90 grs, but having the aluminum d/s helps alot, problems can be in the u-joints as well. __________________ X-Texas highway patrol ssp 1990 coupe - exploder Gt-40 iron heads, Explorer intake, 19 lber's. E-cam. crane 1.7 rollers. 190fp. 75mm maf. 65mm tb, tubular subframe connectors, mac cai, Asp crank pulley, T-5, king cobra clutch, flowtech 1-5/8 unequals, mac X-pipe Frpp driveshaft, lakewood Lca's. race weight 3,160 12.69 @ 107.35, 1.71 60' 26x8.5 drag's 3.90 gear 13.20 @ 106.91 - 235/60/15 firestones 2.3 60' 3.27 gear

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