vibration-help or opinions needed

[84hotairgn]

looking for some help or opinions on my vibration that starts around 70mph and gets worse with speed.first i should give a little history.bought this white 87 t off of craigslist in vegas early 2015.only test drove on surface streets so i never felt the vibration.has old school performance mods like ta49,bigger down pipe-brand unknown,42lb injectors,hooker cat back,etc.had an old len freeman sticker on the back window so i assume the trans was built by him,vigilante convertor,stage right trans brake.had alot of stuff i removed like vacum pump,fuel pump booster,etc.car runs good know and shifts fine.on jack stands with tires/drums removed vibration is there.drive shaft was rusty/original and i had the local drive shaft shop retube and balance the shaft-no change.noticed play at tail shaft bushing so i replaced it and when shaft was out i noticed witness marks on slip yoke where bushing rides.vibration is harmonic when on the gas and just a vibration when off the gas and shakes the whole car.after less than 100 miles the tail shaft bushing is eaten down to copper in spots and worn.since the drive shaft has been balanced/replaced and this is done with the yoke installed i suspected a problem inside the trans and had my local trans guy tear it down then i took the output shaft to a machine shop that put it in a lathe and said the most runout they found was .004 but there setup wasnt the greatest.the trans guy said he doesnt see anything else out of the ordinary except some worn clutches/steels.no twisted teeth on the output or yoke,and yoke diameter is in spec. these marks are only on half to 3/4 of the yoke.visually i dont see that its bent.its fairly inexspensive to replace but i dont want to have the trans put back together and have the same problem. the ony other large rotating mass in the trans is the drum and i dont see anything indicating its bent or warped.any help would be appreciated.

 

[mikestertwo]

Two things come to mind....pinion angle....or... bad pinion bearings (side play). When you had the car up on jack stands were the stands under the frame or the rear axle tubes?

 

[84hotairgn]

They were on the axle tubes and i already rebuilt the rear end all new bearings,gears and posi.pinion angle has also been checked.

 

[84hotairgn]

TTT. Anyone? Was hoping some tranny builders could chime in or someone that has had this issue

 

[No disintegrations]

How about when revved in neutral to verify its not engine or convertor? I think you prob tried it already though.

 

[84hotairgn]

Yeah,tried it. No vibration from engine or convertor

 

[nat86]

I'm chasing something similar to this changed drive shaft no change aligned engine to rear end no change turned converter one turn then bolted back up no change. Slow off and on vibration feels like in the drive train never did this until I changed engine transmission converter

Sent from my SM-N910T using Tapatalk

 

[nat86]

Pinion angle hhmmm

Sent from my SM-N910T using Tapatalk

 

[fastblackracing]

One other area to look at is the u-joints being centered with respect to the yoke and tube.
The factory u-joints and yoke and tube assemblies as I understand are put into an alignment
fixture and then the glue was injected to hold everything.

replacement u joints rely on on the circlips to center and the surfaces they register to
are not machined true so the yoke can be off center to the shaft and they may be able to balance
the shaft but it will still rotate in a orbit from the shaft center line.

I would get a magnetic dial indicator and get under the car with it and measure the actual
run out of the shaft in 3 places.... right near where the tube terminates to the yoke ends about
1 inch back on each end and then in the center....rotating the shaft carefully by hand so as not to
induce side pressure readings from pushing on it.

Also not normally an issue except for 2 piece splined shafts the u-joint must be in phase with each other
so they pitch forward and back at the same time....looking down the shaft the eye loops that the joint caps
go in must be 100% in alignment or time with each other, if one eye is rotated a few degrees or more off the
other the joint the angles do not complement each other and can vibrate......I see this problem mostly
on industrial equipment and 4 wheel drive stuff with 2 piece shafts that can assembled wrong usually
1 or more spline teeth off from the other end.

Also what where your pinion angle and the trans tail shaft angles and what did you reference
the angles to?

It is also possible that you have some side angle stuff going on from the engine/trans not being
square and centered to the rear end with respect to each other..... Not just up and down angles
that can cause this but side to side as well.

The angles need to end up being opposite of the other end...if one end is 3 down the other should
end up 3 up under power for the u joint to cycle properly through out the rotation...same goes
for the side to side alignmen

Does it have stock control arms and original mounting points?

Things usually have to be off a measurable amount to produce the symptoms you describe....
Keep digging and measuring and you will find it.....HTH FBR.

 

[nat86]

Fixed my problem it was one little spot wear the crs transmission shield was touching the floor board lol vibration Galore

Sent from my SM-N910T using Tapatalk

 

[Chuck Leeper]

Trans out? Run the engine and see if it vibrates?
Check the balancer. Is it the right one? Loose? Cracked?
Same for the flex plate.
Check the crank end play.

 

[84hotairgn]

Wow thanks for all the replies. Pinion angle was .6 of a degree I believe.haven't checked side to side. All control arms and mounting are stock, no excessive movement in any of the bushings or mounts. Freewheeled engine with no vibrations. Slip yoke is suspect but vibration was there before shaft rebuild. I have ordered a new slip yoke and pinion yoke but the trans is apart and the builder showed me the direct and forward crutches are alto red and have hot spots along with the steels so I need to buy a rebuild kit as he only does stock rebuild kits and as I stated previousley it was built in the early 2000s by Len Freeman so I was wondering what rebuild kit to go with? I was looking at ck perf and extreme but have read mixed views of alto reds. Any advice?

 

[84hotairgn]

Update. After having the trans rebuilt and replacing the pinion yoke and the trans slip yoke the vibration is still there. The builder said he saw nothing unordinary besides worn parts.he didn't have a lathe so he couldn't check runout of any internal parts,I took the outputs aft to the machine shop but they couldn't find anything. If I remove the drive shaft and put a slip yoke in the trans I can still feel the vibration but not as intense which makes sense because it can't travel through the drive shaft right? If it were the vigilante convertor then I should be able to feel in in park or neutral revving the engine right? What inside the trans could cause this?

 

[achalmersman]

Was the TC replaced during rebuild? Does this happen only when the TCC is applied? If so run it up to the vibration and then gently apply the brake to get the TCC to unlock. Hard to believe you would feel a TCC shudder with no load on jack stands but Im just throwing the idea out there. Oh and if you do that with the wheels off just a reminder to put the drums back on....

Sent from my VS990 using Tapatalk

 

[Gene Van Horn]

Bent axle or tube??

 

[achalmersman]

Bent axle or tube??

He said he still feels it with driveshaft renoved

Sent from my VS990 using Tapatalk

 

[Gene Van Horn]

Broken engine or crossmember mt?

 

[84hotairgn]

Tcc was disabled and vibration still there. Engine and trans mounts are good. Thanks for the replies.

 

[84hotairgn]

Tc was not replaced,has anyone seen problems with the vigilantes? This one has to be older as the trans was last rebuilt by Len freeman in 2003

 

[achalmersman]

Where are you located? Im sure somebody would be willing to loan you a TC they have laying around just to try and see if its the source of the vibration. Im sure your sick of pulling the trans but im sure you dont want to drop 500-1k on a converter and it not fix the problem. If you're within driving distance of DE you're welcome to try my D5 I have thats a known good unit.

Sent from my VS990 using Tapatalk