This may sound silly but did this have the weights on the rear of the transmission or rear end? And are they still there? I am also fighting a vibration problem and I have changed everything that spins. The only thing I can think of is there was weight on the rear of the transmission that got chucked. (oops) And mine is like yours at an idle at 65mph it's the same. Had 3 drive shafts 2 transmissions 2 flywheels
I did a auto-5 speed swap- before I did it everything was smooth as silk.
Please let me know what you find Lee

 

it had the weight on the rear end but I threw it to. I am begining to wonder if maybe it has somthing to do with driveshaft length. when I get it cured I willl let let you know what i find.

 

Read http://www.tccoa.com/articles/tranny/transmission/page17.shtml it's most like a driveline critical speed issue necessitating a driveshaft change to an aluminum or carbon fiber one.

 

Have you tried to index the driveshaft on the pinion flange?

Rotate it 90 and test.

 

Your biggest problem, as you'll find in the TCCOA article linked above and written by a ford driveline engineer, is your steel driveshaft. Balancing won't cure it. You need an aluminum driveshaft, properly indexed to the pinion flange. ANd check your pinion angle while you're in there.

 

this is the exact problem I am going through right now. My car had 3.08's and ran smooth. I put 3.55's and now I have a vibration at about 65mph. All new bearings and ford racing gears. It has been driving me mad! I am going to look into an aluminum shaft. Why on most cars does this not happen though when changing gear ratio's?
thanks for the help

 

I have the same issue but it happened when I put a reman trans in

 

How do you properly index your diveshaft to the pinion flange?

 

Under the grime on the pinion flange is a white paint dab. You match that as close as you can with the greenish yellow dot on the body of the driveshaft.

 

I just had a steel shaft made for mine. Crap! I hope it works out ok.

 

and what if there is no white dot or greenish dot on the ds?

 

There will be.

 

From '92 service manual...Section 00-04

Driveshaft Indexing Procedure

The first check to be performed when driveshaft vibration is suspected is re-indexing the driveshaft at both the rear axle and transmission.

A vibration free driveline can result from the driveshaft indexing procedure when minor driveshaft imbalance is cancelled by minor system runouts.

1. Raise vehicle on hoist. Refer to «Section 00-02». Remove rear wheel and tire assemblies and rear drum or rotor assemblies. Place floor stands under suspension arms to support rear of vehicle. Note or mark index of driveshaft to transmission and axle companion flange.

2. Mark one hole position on driveshaft yoke at rear of driveshaft with the letter A and the eight circular flange holes (starting with the mating hole with driveshaft position A) from one through eight. Position A-1 is considered the original index position.

3. Disconnect driveshaft, re-index 180 degrees at axle position A-5. Check for vibration at road test speed. If vibration is still present, evaluate positions A3 and A7.



4. If further improvement is desired, evaluate remaining positions that are located between the best of the two previous positions, A-3 and A-7. If vehicle tests satisfactorily at any point during this procedure, do not proceed with any further steps.

5. If re-indexing at axle is unsuccessful, disconnect the driveshaft, re-index 180 degrees at transmission and connect. Check for vibration at road test speed. If vehicle tests satisfactorily, do not proceed with any further steps.

NOTE:
Remove driveshaft from vehicle and manipulate Universal joints in each direction of rotation. If a Universal joint feels stiff or has a "lumpy", "gritty" feel in any direction, replace Universal joints.

6. If re-indexing at both axle and transmission is unsuccessful, refer to Driveshaft Balance Diagnosis as outlined.

NOTE:
Original equipment driveshaft-to-axle companion flange retaining bolts (N-800594-S100) are Loctite coated and do not require a lockwasher. If these bolts are removed, they may be re-installed, if additional Loctite is applied. New and used bolts must be tightened to 95-129 N-m (70-95 lb-ft).

 

thought I would give a progress report. after changing everything listed and checking pinion angle. pinion angle was 2degrees nose up ,I changed it to 3degrees down. ran on jack stands still has vibration, decided to road test it barley has any vibration in it but is still evident about 65 mph that there is still some there.
I am going to performance plus on friday to get a new aluminum drive shaft for it and I will try that some time this weekend. I will update progress report after that.
thanks for all the info it has helped in diagnoseing this problem.
thanks
Steve

 

just wanted to let everyone know that I put the aluminum driveshaft in and VIBARATION IS GONE. finally thank you for the advice. one problem cured on to the next
thank you
Steve

 

Steve, thanks for the update and I'm glad you got the issue resolved.

 

Thread jack!

I installed my driveshaft spacer and still had vibration issues. I just finished rotating my driveshaft 180 degrees and I have yet to road test it; I will respond with my results later.

However, I snapped some pics and I want some opinions. I still think I am not getting enough engagment, even with the spacer. I have replace the tailshaft bushing, and had my driveshaft completely serviced; new joints and balance. Let me know what you guys think.

 

Are those pics with the rear suspension hanging or on jack stands. If the later seems like too much yoke is exposed.

Even if hanging it looks excessive. What's your combo, car, trans, etc?

 

That's with the axle on a Jack, that's as if I were driving. Read above for what I have.

 

The vibrations are only noticeable above 85 mph now, whereas before it was above 70mph...

 

So what about my slip yoke engagement? Is it not enough?

 

That looks like it's not in far enough.

I was under my car yesterday putting in my AL driveshaft...and it's engaged about 1" more than yours is

 

That ds is from a foxbody, bur is it possible I got one from a 4cyl auto? (they're shorter) if that's the case, can I just get a longer slip yoke? (I spent $100 on that one getting it completely serviced)

 

Bump

 

Bump x2

what do you guys think about my ds problem? Did I get one from a 4cyl auto?

 

Measure what you have the correct length is 45.5" long (CL to CL of U-joints). (From FRPP catalog re: HD ALUMINUM DRIVESHAFT)

 

So I finally got around to taking measurments, and here is what I got:
length of exposed yoke: 1.5"
cl of ujoint to cl of ujoint: 45.5"