Hi all,

I installed the Edelbrock no-hop bars on the 70 this last weekend, and I have a new vibration problem that happens at speeds over 60mph. It did not do this before the install.

I have a 12 bolt, stock control arms, stock springs,poly bushings, ride height, and gas shocks.

I am guessing the no-hops changed my pinion angle? Anybody have experience with the bars doing this and if they did, do I need adjustable uppers to cure this?

Any help would be appriciated smile.gif

The no-hop bars did indeed change your pinion angle upwards. Your vibration might be an indication of a bad u-joint. If you haven't replaced them recently, it's good cheap insurance & easy to replace. Let us know the outcome.

Craig, I agree with Greg possible ujoint going out .Had the same viberation over 60 took the shaft out rear joint was ready to fall out. Replaced front and rear back to normal... :D Ralph

Craig, is it possible you when you installed the driveshaft upon job completion, it was 180 degrees from when it came out? If so, that could be your problem. It's cheap to try anyway.

Hopefully that works. If not, :(

Alan - is installing the drive shaft one way or another an issue? I've never paid attention to that.

Criag I just installed Edelbrock adjustable upper control arms, and I also have vibration problems about 60 mph. I am pretty sure its my pinion angle which is the cause, adjustment to the correct angle should be the cure. I also like the comment about changing U-joints I think I may do that also. How is the Car running? The 427 BEAST!

Originally posted by K_Janisch:
Alan - is installing the drive shaft one way or another an issue? I've never paid attention to that. In my experience, yes. Driveshafts come from the factory balanced and phased correctly with pinion yoke. From my experience, driveshaft balancing weights are not placed so that the shaft is balanced no matter which way you put it in the pinion yoke. That is the reason the 'shaft works smooth one way, but turn it 180 degrees and it produces a vibration. This happens a lot when the original 'shaft is balanced. Even new aftermarket 'shafts act the same way (the Denny's 'shaft I got for my 1994 Impala SS did the same thing - smooth one way, but produced vibrations when turned 180 degree at the pinion yoke). Sometimes, after balancing a driveshaft you'll get lucky and put it in the pinion so the 'shaft is smooth. For an experiment, try turning the shaft 180 degrees at the pinion yoke and you should notice a difference.

Overdrive transmission are very sensitive to vibrations as well (Craig has a 200R4). In overdrive the shaft is turning much higher than engine RPMs and therefore is the reason a high-speed balance is needed if you're going to drive in the 100+ mph zone. I'm not saying Craig's problem is definitely the driveshaft being 180 out of phase, but it's worth a shot. Just keep this in mind when you have vibration problems with the driveline smile.gif

Craig,

I would check the pinion angle and get the adjustible upper arms if it needs to be corrected.

I had this problem on my old El Camino with the lakewood No-Hop bars... It wore out u-joints pretty quickly...

Also, this year I had a similar vibration (but about 45-50+). I went to do a burnout in front of my house and snapped the rear u-joint and toke out the pinion yoke. Luckily nothing else was hurt.

I am pretty sure this was pinion-angle related because when I installed my Richmond, I dropped the mount pad on the cross-member so the shifter would sit lower in the console. This changed the whole angle of the engine/trans.

I am getting the Edelbrock adjustable upper arms this year...

U-joints are cheap and easy to change.

I guess nothing to lose trying Alan's rotation idea, just a few minutes of your time...

Thanks much for the advise guys, as I suspect the pinion angle has probably changed causing this. If it was a u-joint, I don't think it would have just happened after the install? Or did the slight increase of pinion angle amplify the bad joint?

Al, I will give the 180 swap thing a try tomorrow night, it is really easy to do plus that gives me a chance to inspect the joint more carefully. I like the way the car reacts under power now, the whole car lifts and want to grab and go. Neat feeling compared to the front lift and rear squat I am use to.

Tony, how can I check the pinion angle? I have heard that one can get a protractor and a simple string/bob weight and do it that way? Either way I would like to know where I am sitting with my angle now.

Tristan, thanks for the advise bud. The car is running great :cool: It has allot of power, I just need to hook it. That is why I installed the no-hops, on a quest for the holy grail of traction smile.gif BUT it still has serious traction issues, I need tires! Plain and simple, I am trying to push too much power through those 295's and need a softer tread.

On a side note, I was reading Harold's advise in the performance thread about increasing the lash on solids to 'tone down' the ramp a bit for better idle and more low end. I changed from .025 to .030 lash, tell ya what it worked! Idle is slightly better,(still nasty) is not a choppy below 2000rpm under light throttle, and takes slighly less throttle at speed (freeway) I think that is cool stuff. it sounds like a sewing machine though.....

Craig, to check the pinion angle, this is what I bought Magnetic Protractor (http://www.powerhouseproducts.com/store/merchant.mv?Screen=PROD&Store_Code=PH&Product_Code=POW301375) . I got a cheap one at Harbor Freight for $5 though and it works great.

Here's an article from Car Craft on how to set the pinion angle Setting Pinion Angle (http://www.carcraft.com/howto/91758/)

Here's another good article Pinion Angles (http://www.drivetrain.com/driveline_angle_problem.html)

With the magnetic protractor it's easy to check the pinion angle. I've used a drafting protractor and nut hanging on a fish line before, but I like the magnetic protractor better. Changing the angle will require the upper adjustable control arms. I might strike a deal with you on my BMR upper adjustables ;) . I've been looking into getting the Edelbrock ones.

Al, your awesome man, I will get to check my pinon angle very soon like Monday or Tuesday. I will take you up on the BMR's if you are considering the Edelbrocks which are nice pieces :cool: I did see Jegs had thier own line of adjustables for $155, those would be my next choice if I had to buy new. But if I had the extra cash I would be buying the Ededlbrocks for sure.

Thanks again for all of your help I very much appreciate it guys. I will post back with the pinion info, and if it is off I will get adjustables.

Where's the update Craig? Figure out your problem?

Originally posted by Alan:
Where's the update Craig? Figure out your problem? Not yet, Christmas has been busy and I have not had a chance to do anything yet. I will Saturday or Sunday and post the results.