Vibration after an hour at highway speeds

[70bigblockdodge]

There are ones that have a spring in the rear section with a rubber mounted tube inside, I tried to get one of these shortened guy called said they are a pain in the a$$ so I just found a different one to shorten, I would take it to a drive line shop see what direction they suggest.

 

[C Body Bob]

This happened last year when I drove to Nat's but my transmission and suspension were toast then. It almost feels like flat spots on a tire when they are cold but this happen after an hour after driving 70 plus mph.

Anyone think I could have a bad tire? They are new BFGoodrich Radial T/A. Just driving around home no problem and once I do get the vibration I need to drop to about 55 before it isn't noticeable.

One thing I have done when checking driveshaft issues is to get a band clamp large enough to fit the shaft. Put a small weight under it & clamp it down. Mark the position & drive car. Note change. Rotate the clamp & weight about 1/4 inch & continue untill it either shows improvement or you make it all the way around & no change. Just something you can try while still driving the car. Be sure to mark the starting point & any changes better or worse.

 

[Zymurgy]

Good possibility for vibration source. I decided to take my tires off the car to see if I can find any visual issues. I discovered on my front right tire the brakes are catching when I spin the tire. I already discovered this problem once before and backed off the auto adjuster until it spun freely.

Now how do I resolve this? Some addition information. 1. I still have air in my brake lines and they need bleed again. 2. This is the only "new" brake drum. 3. I have not replaced my bearings, but they were in good shape so I only repacked. 4. All the brake components are all new.

My first thought after bleeding the brakes is take the "new" drum in to have it turned. Any other area to check for this dragging wheel?

 

[C Body Bob]

Do a run out on the drum while on the lathe. Make sure its true. Or well <----- within specs. Parts quality is somewhat shabby these days. Make sure there is no grease or oil on the lining. Will cause the brake to grab. If there is a stain use a piece of lite sand paper & scuff very lightly. Also if I remember corrrectly. Dont you have mag/aftermarket wheels? If so make sure the wheel is & lugs are centered correctly. If any of the wheel holes are a bit ovaled it can casue the rim to mis align. If this is the case. Tighten that lug last. Check that tranny mount too. Remove it if you can. I have had them where they looked ok, but came apart when I removed it.

 

[1970cat]

if you can find a place that will arc your shoes to the drum, that car will stop as good if not better than disc brakes. if you take the drum off and the shoes are worn on the very front and rear edge, but no wear in the center then they aren't making full contact with the drum. i doubt that is your vibration though

 

[C Body Bob]

if you can find a place that will arc your shoes to the drum, that car will stop as good if not better than disc brakes. if you take the drum off and the shoes are worn on the very front and rear edge, but no wear in the center then they aren't making full contact with the drum. i doubt that is your vibration though

This is very true. I always use a bit of white lithium grease paste on the backing plate where the shoe rest on it. You will see these small raised bumps. It helps it move in a more fluid & accurate motion. Just dont get any on the lining.

 

[Zymurgy]

if you can find a place that will arc your shoes to the drum, that car will stop as good if not better than disc brakes. if you take the drum off and the shoes are worn on the very front and rear edge, but no wear in the center then they aren't making full contact with the drum. i doubt that is your vibration though

Matching the shoe arc to the drums, that's cool I didn't know this could be done. I have one place in mind that might do this.

 

[65sporty]

Ck that brake really close drum, shoes, adjuster, wheel cylinder. when you get the vibration does the steering shake or pull when the brakes are applied? if the drum is out of round and adjusted too tight the more you drive the more it will heat up and the vibration will start. sounds like you may have found your problem. good luck

 

[Zymurgy]

Update, I took Goldie to have her aligned finally this week. Drives straight as an arrow and they found 3 out of the 4 wheels were out of balance. My vibration was all in the tire balance.

I drove home on the freeway keeping a constant 80 for 5 or 6 miles, solid as a rock, could not be happier. The best riding car I own. Have I said enough, I love this car.

 

[thrashingcows]

Great news...glad it was something as simple as wheel balancing.

 

[Stormer]

Congrats, Mike. I just put new rubber on my 300 & eliminated a highway vibration.

 

[Zymurgy]

Congrats, Mike. I just put new rubber on my 300 & eliminated a highway vibration.

Did you keep the current wheels or are they new too?

 

[Stormer]

Did you keep the current wheels or are they new too?

Same wheels, just balanced with new rubber.

 

[Zymurgy]

So there are at least 2 smooth driving '66 300's in central Ohio. :yaayy:

 

[Stormer]

So there are at least 2 smooth driving '66 300's in central Ohio. :yaayy:

I've used mine as my daily driver pretty much since I bought it. Finally got the timing dialed in so it starts halfway decent...

 

[Zymurgy]

My cold start isn't as good as it was before hand, but starts with a bump after it is warm.

I wish I could use it as a daily driver, but I did drive it to work on Monday. I had 6 5 gallon paint buckets, 6 single gallons, a huge rubber maid container, and spare tire in the trunk and I still had room to spare. I just don't have a place for ladders.

 

[LocuMob]

Good to hear you ironed out the kinks. I'm afraid I'm going to I've to upgrade to radials sooner than I'd like to as my old polys are balance and still cause vibration. I have to thank my alignment person as well, he adjusted something, timing or carb and my cold starts are easier than ever. I had to relearn how to start my car! Enjoy cruising around in Goldie!s