Vibration normal and 2 other questions

[MoeJr]

I computer balanceed all my tires and just had 2 new ujoints put in the drive shaft of my 84. However when on the hiway at 65+ the car vibrates in the body not the steering wheel which is why I had the ujoints done. Is this normal? I thought maybe it was cause the 84 suspension is so stiff. Thoughts on this are greatly appreciated.

Also what is the stock rearend ratio for an 84 Vette Automatic? I have seen 2.73 or 3.07.

How do you adjust the wiper arms so the wipers won't fly off the edge of the window? My Drivers side goes right off the window and gets caught the passenger side is fine.

 

[c4fan]

To adjust the windshield wipers you must pull out the little screen right in front of the drivers side wiper and there is a little nut on the linkage that you loosen to adjust the wipers. I had the same problem with my 87 and after adjusting them have not had a problem since. As for the vibration, hopefully another member will be able to help you out. Good luck.

 

[geekinavette]

Moe,

I had the same problem with highway vibrations, mine started at about 70 MPH. The problem turned out to be from the wheels being slightly out-of-round. They will still balance...but of they are not looking specifically for this condition then it might go un-noticed when on the spin balancer. The stiff suspension is very unforgiving when your wheels are just a little out-of-round. I picked up a set of '86 wheels and that cured it right away. Also, if the car has sit for a long time the tires can flat-spot causing a vibration.

The standard rear gear ratio is 3.07:1. There were two other gear options:

RPO G95 - Axle Economy Ratio (probably the 2.73 or thereabouts)
RPO G92 - Performance Axle Ratio (3.31) supposedly there were only 410 produced with this option.

If you haven't already, check out the 1984-1996 Corvette Specifications page, from the C4 Technical Discussion forum.

Bill

 

[JonM]

You may wish to check the wheel bearings along with all the bushings under the car. Remember those bushings are 18 years old. Have you checked alignment? This is why I ask...84 is nortorious for having a bad intermediate shaft (I'll show a pic below) if the shaft is bad (gets worst when it gets colder) you get looseness in the steering (see red circle) when you bring it up to speed and your front end is not aligned, you will feel vibration.

 

[MoeJr]

I will look at all that stuff. It is almost time to put it away for winter anyhow. I checked the bushings the other day while I was under the car and they looked good and not dry rotted. I didn't think about the wheels bein out of round. These wheels are not the originals they are 86 with the all silver center caps. I will replace the intermediate shaft while I am at it. I know my rear shocks are marginal so all 4 will get replaced during winter storage. I know 84 suspension is not the most forgiving so I expected road vibration but wasn't sure how much to have. This seems to be just a touch excessive. I'll keep ya posted.

 

[vigman]

Did it do this BEFORE you did the drive shafts?

Enquiring minds want to know!

Vig!

 

[MoeJr]

Yes Vigman it was there before I did the driveshaft. I am gonna replace all 4 shocks as the backs are looking a bit old and also look at the intermediate shaft. Any other ideas keeping em coming. Thanks.

 

[JonM]

The intermediate shaft is not available anymore. If you find that yours is loose, let me know and I will give you a suggestion as to what I did.

 

[LarryBible]

There is much more to wheel balance than most people realize.

It is very common for the guys at the tire stores to static balance the wheels and use weights ONLY on the inboard plane of the wheel. This is most common with alloy wheels because the tire store guys don't want to hear the complaints about scratching the wheels.

As a previous poster pointed out, the stiff suspensioned Vette shows up improper wheel balance more than other cars. Additionally, the Vette suspension is nimble and shows up dynamic imbalance. Dynamic balance is ignored when weights are ONLY used on the inboard plane of the wheel.

To properly balance the wheels you MUST use weights inboard AND outboard, in dynamic balance mode on a properly working computer balancer.

If indeed the wheels were balanced on two planes, by a competent operator with a computer balancer, you need to find a Hunter GSP9700 balancer. This machine can check for out of round tires, out of round wheels AND bad tires with stiff spots. Sometimes it can even correct the tire vibration by telling the operator to exactly what position the tire should be rotated to minimize vibration.

You can locate a shop with a GSP9700 by going to www.gsp9700.com. There is a locater there in which you enter your zip code and tells you the shop you can go to.

For most situations the 9700 is overkill, PROPER two plane, dynamic balance will get the job done.

Good luck,

 

[MoeJr]

Thanks guys. Larry I found someone very close to me that has that Hunter gsp9000 balancer and I am gonna call today to have em done. Thank you for the tip.

 

[MoeJr]

Larry I got the tires balanced on that gsp9700 and it made a world of difference. I would say it took 95% of the vibration away and the last bit that is there is resonance vibration I atribute to lousy hiways up here and shocks that are barely passable and will be replaced in the spring. I am also going to look at doins the suspension bushings over in spring. Car gets aligned Monday and that should help too. Thanks for the tip.

Moe

 

[geekinavette]

Good deal Moe! Did they happen to mention anything about noticing any "hop" in the wheels due to being out-of-round? (just curious).

The other factor you're dealing with is the incredibly stiff suspension of an '84...especially if you have the Z51 option.

Bill

 

[tkrphxr]

Vibration

I had a buddy that chased a vibration in his 73 for over a month. He went thru drive line axel shafts wheel balance and out of round on tires and wheels. Turned out the tailshaft bushing in the trans was worn. Best I remeber it would start about 45 to 50 and would vary a little depending on the gas tank being full or on the low side. Sounds weird I know but might be worth checking if all else fails.:crazy Good luck Charlie

 

[MoeJr]

All the wheels had some hop in them. The tech put the specs of what he did on the back of the tire not that I could tell what they meant. It really did make alot of difference. I know 84 is stiff and I keep that in my mind. My shocks are getting close to needing to be replaced which they will be in the spring. It is getting an alignment Monday so I know it will be in tip top shape. I also goona do the bushings possibly in the spring. Hopefully oncemy build sheet and window sticker cone in from NCM I will know what suspension I have. I will also check the tail shaft of the tranny. Thanks for the tips and I'll keep you posted.