100mph 347 vibrations shift lever vibes bad .

[5ohjoe87]

Ok I just had a 347 stroker engine built in August And decided to wind her up a little. However Bad baaaad vibrations are effecting the car mostly aproaching at 3000 rpm in fifth gear around I guess 100mph. The shifter lever vibrates so bad my hand goes numb and the whole car feels as if it's going to vibrated to pieces if I dont back off or the trans is going to explode. However at idle in nutral when I rev to 3000rpm the car is smooth with only a hint of vibration. No bad vibration is felt in any gear except in fith and a little in 4th on the highway aproaching 3000rpm and above 3000. The engine is a 347 stroker that I find odd that the machine shop used my stock 302 balancer and flywheel. The flywheel was machined basicaly by the machinist making indentations during the recipricating balancing procedure in the flywheel removing material . The car has a z303 cam 290 duration and .552 lift and edelbock victor jr heads so the car jiggles a little at idle. The vibrations seem to be vehicle rolling in motion specific also the t5z was replaced with a new t5z I only have 100 miles on the new trans and king cobra clutch. My old 90 gt with a built engine and aod never vibrated. I ran that Mustang up to 5000 rpm in overdrive bad to to do but she lasted.

 

[jd351]

Sounds like the shop ballanced the reciprocating assembly, so I doubt it's the engine. Do you have a new D/S? Old ones can get pretty bad, have had lots of vibration with the original steel D/S. May try to replace this with an aluminum FRPP unit, or take a look at the u-joints, they may be bad. Otherwise I would think trany is bad, but doubt that.

 

[TrickStang37]

yeah, what he said.

 

[5ohjoe87]

I have the ford aluminium driveshaft however it was on the car when i got it no telling how old . I do know that with my old e camed supercharged gt 40 long block I had no bad vibes this summer I had a gps in the car and well clocked in some scary speeds aproaching the limit of z rated tires without any vibes. I guess I will have the u joints checked. How do they check to see if the driveshaft is balanced? If it is the driveshaft this may sound funny but are there any exotic metal shafts or ones made of carbon fiber?

 

[Sir Hacksalot]

yeah, what he said.

Hey Trick,

I sent you a PM about your combo...I was wondering if you got it.

If not, do you have any numbers and/or times on your car with that set up you have in your signature?

Hax

Sorry for the threadjack.

 

[hllon4whls]

Try re-indexing the Drive shaft. Mark where it is now and turn it 1 bolt hole in reference to the diff and repeat until vibration goes away. Might have to do this 4 times, but besides the testing it will only take a few minutes.

To make sure this is clear you need to unbolt the DS from the rear hold the rear fixed. Turn drive shaft. Bolt together. Test. Repeat.

Mark your start point and verify the way you move this and I believe that it will help.

 

[90Notch]

Pin down where the vib is coming from,

you said that in nuetral and you rev to 3000rpm there's no vib? This tells you that the vib is related to the drivetrain and not motor.

Exactly when does the vib occur, at a specific speed or rpm? It sounds as though rpm but you don't mention if it goes away as rev continue to increase.

From what you said I would look in this direction (or combination) first:

Pinion depth not set properly, worn bushings (check trans , trans cross member, rear upper & lower CA's, worn U joints or strange pinion angle. The frequency that an AL driveshaft would vibrate is pretty high RPM and they don't need to be indexed. You should still run the dog bone in rear diff.

 

[5ohjoe87]

uhh oh the dog bone is missing. I hope this is what was causing the comotion. Is the primary function of the dog bone to reduce harmonics? I also am getting alot of diffrent opions about aluminium driveshafts.
Some people say they need indexed others say no. I am going to try a ford tech line and see what they say unless anyone reading this is a tech. I saw some ad in the past that sold carbon fiber driveshafts anyone ever hear about these units or see them? I would imagine I would gain some tq and hp because they are lighter.

 

[TrickStang37]

sorry didnt get back at ya, the car was solen back on april 28. I actually just got the car running again today for the first since. everything was stolen except for the stock shortblock. $6000 later (liability only), the car is back!! before i used to run the street heat intake w/ 3/8in spacer, 65mm TB, 1.7rr, 73mm MAF w/stock intake track and stock radiator. the best I ran with that set up was 13.38 @ 109ish dont remember exactly. the 60' was OK (2.2x) but spun 2nd REALLY bad. as you see, now im running 1.72rr, track heat intake, no spacer (trick flow egr this time), 70mm TB, 76mm MAF w/the aluminum C&L piping. that + aluminum radiator.

The car idles much better this time. Feels good to have her back, still need to repaint the bitch though.

 

[94Silverbullet]

suscribing..

I've got a very similar problem.

Mine did it with both the stock and the aluminum DS.

It also did it with the old and new Tranny.

 

[JimBowy]

i'll add my comments later

 

[hllon4whls]

I will resuggest indexing the drive shaft. It would take me longer to drive the car on ramps and get my tools down to the driveway than to unbolt and rotate the thing 1/4 turn. What is there to lose? Mark, turn, test repeat. Possible easy way to lose the vibration.

 

[5.0fox]

i think i am having the same exact problem above 100 mph it shakes so bad that I have to get on the brakes. I think it might possibly be a tranny problem by the way the shifter shakes extremely hard.

 

[Matt90GT]

Index the driveshaft. Great suggestion there.

Also check all your motor mounts, tranny mounts and the bushings that mount the tranny bar to the unibody. If any are suspect, replace.

 

[JimBowy]

I don't think my problems are directly related to the rest of these guys. But I have vibrations in the car at any speed. They get worse as you get faster though.

In neutral with the clutch engaged/disengaged I get the same result. Very little vibration until 3,000 rpm. It continues to get rougher until you approach 4,000. At about 4,700 she's shaking hard. The shifter is vibrating with 1/4" of play. I know my powersteering needs pulley needs another bracket connected to it. This should solve some of the problem?

This must be engine related though, right? BTW I'm using Polyurethane motor/trans mounts.

 

[90Notch]

"In neutral with the clutch engaged/disengaged I get the same result."

Motor is out of balance. As for guy who's car vibrates at 100mph above in any gear, that's a suspension/alignment issue.