Shudder/vibration at launch acceleration

[gvccorrado]

Just starting a new thread on a previous old topic, Launch Shudder
Just checking to see if anyone has ever found a resolution? I have the EXACT same issue with my Bonneville, same as ballstatefan05, started right after the strut replacement. I was sold Monroe Quick Struts (found out after the fact Per Monroe, these should have never been available for a 00-05 Bonneville, as the spring rate is too high, two alignment shops couldn't even come close on an alignment). After talking with a tech at Monroe, he said the only issue is with the springs. I purchased Moog springs. Car then sat noticeably lower, thankfully. Alignment shop was then able to align it, could not physically do it with the springs from Monroe. I have new control arms, new axles, new engine mount. Shudder is still there. Shop that is working on it now thinks the frame or sub-frame twisted during the strut replacement process ( I did the work myself and used jack stands, on the front only, which I was told was a no no). Reason they think this, is that if both axle nuts are off and wheels are off the ground, they can push the passenger side axle in until it stops (there is enough thread to still put the axle nut back on). When they do this procedure to the drivers side, the threads are all the way inside the steering knuckle/wheel bearing assembly. Anyway, has anyone ever found a resolution for this?

[crash93ssei]

With testing like that and coming to the conclusion of a bent subframe I would be running the other direction as fast as I could go...

Is there any difference in the shudder if you make a 90 degree turn and accelerate? If it makes a difference when turning, is one way better or worse then the other? Is it felt at all in the steering wheel?

Mine was worse when turning right and accelerating, and also I could feel it in the wheel, it felt horrible like something was literally coming apart. It got a little better when I replaced a bad tie rod and wheel bearing, but was still awful and made me feel uncomfortable. The harder I got on it, the more it would shake. Turned out the passenger side CV axle was shot. The inner joint had some play and grooves that could be felt when moving it by hand and had a clunk noise that I could hear off the car but never heard while driving.

[ThisGuy]

I think crash93ssei is on to something...the way that shop determined the subframe "is twisted" doesn’t necessarily mean the frame is twisted. did the shop measure the cv axles to make sure they had not come apart?

I worked on a 98' CRV with the same issue, i thought it was the wheel bearing. and after replacing the hub assembly, i tried to put the axle back in and it was really tight, so i pulled it and measured the "collapsed length".. it was 1 /34 in. too long. then i went to the parts store to confirm my suspicions.. i was correct the cv axle had came apart on the inside and would not collapse all the way. 1 new axle later(and hub, which i think the axle messed up) and the vibration was gone. Im not saying this is definitely your issue but its something to look into.

Also i think if the subframe was twisted that much u would have more than a vibration issue. What were your alignment specs before and after the alignment? If your subframe is bent it would be really hard if not impossible to get the alignment correct because theres not much of a factory caster adjustments on your bonneville...

[gvccorrado]

Thanks for the ideas. Shudder/vibration is more noticeable for me on a straight acceleration from stop. It goes away for the most part when you are up to speed, although it is noticeable when you get on it at highway speeds. This only started after I put these *dang* Monroe quick struts on. I noticed immediately after I picked up the car from the alignment shop. Thought for sure it was a tranny issue, so took it to the tranny shop. They had good news in that it wasn't tranny related, but both my axles were very worn and I had a broken engine mount. (this was my next project anyway, so new axles went on as well as an engine mount).They called me later that day and said "still shudders/vibrates". They agreed to work on it for free after they recommended new parts that didn't fix the issue. They have tried a different set of axles, they have checked that the engine hadn't shifted, have even loosened the entire front suspension up and basically started from scratch re-installing it (struts, springs,strut mounts, control arms, ball joints, tie rod ends, tires have been rotated). I'm confident I have it at the right shop, these guys are a small shop , seasoned ex-race car builders.They are scratching their head and the only thing they can think of is that something is off on the geometry of the car to cause this. I'm now wondering if the strut spring combo is just the wrong setup for this car. Monroe strut 71685 Moog spring 60232. I know the spring that came on the quick strut is bad, as Monroe does not offer the quick strut any longer for the Bonneville as the spring had too high of spring rate. Even with the Moog springs, the car seems like it sits to high in the front. Moog springs have been on for a month. Does anyone know what the factory spec is for ground to wheel well distance. If this is too high and the spring hasn't compressed enough, the axles would be at too much of an angle and possibly cause this vibration. That is my theory at least. I personally don't think any thing is bent. Could anyone that has not lowered their SE provide that measurement for me (ground to front wheel well)? I'd really appreciate it.

[crash93ssei]

Taller springs should not have any *real* effect as far as vibration is concerned, the angle that it would put the inner CV is not severe enough to cause damage that fast. The axles they tried, we're they new also or used? It seems like I hear stories once in a while here of people having issues with new axles. I bought a used one from a salvage yard that felt good when moving around by hand - not too tight and not loose, installed it and no vibration at all. My gut says it is a CV issue.

[gvccorrado]

Vibration existed before the new axles were put on, shop thought that was part of the cause as they were very loose. They have taken a used axle off another Bonneville that were working on and the vibration still exists. They are confident it is not a tranny issue, as besides this vibration it runs very smooth for a car with 190k. I've talked to frame/axle shop and they have agreed to take a quick look to see if they can point out anything that is bent. Here I am, all excited to replace 190k suspension parts and have a smooth riding car as well as save a huge chunk of change doing the work myself, but it has turned out to be extremely frustrating. In all fairness, if I hadn't dealt with the Monroe quick strut issue, this wouldn't have been so bad. Thanks again for your replies.

[SurfingBonnedriver]

OK folks, I have the same issue with Gabriel 57051 Quick Struts. I had them put on this weekend, and aligned. Ride height to the top of the fender wheel arch is 29 5/8". Gabriel tech assistance indicates it should be around 28. I also have shudder on acceleration, worse cornering, worst on left handers when applying power from the apex off. Feedback is coming through the steering wheel like the caster is off (wobbling shopping cart wheel syndrome). Right side, Timken bearing and CV shaft approx 6k-8k miles back, left side bearing, Timken, with the struts. (Oh, I did discover that when the ABS wire is not flully clipped to the bracket, it will chew a hole in the outer CV boot quickly, and the check tire pressure light comes on) :-( Oh well, new passenger CV axle coming up. Gabriels tech suggested that CV joints will "seat or wear in" within the normal range of suspension travel. OK, that makes sense, so the vibration could be caused by the jacked up front end changing the "normal" angles for CV axles and changing the ball/retainer engagement area. Therefore I am establishing a new wear pattern on the CV assembly. But, the CV also flexes with steering angle, so how is it that the existing CV's would have that narrow a wear pattern. We'll see when the new left side shaft goes in.

I jacked up the car, both front wheels a week before the job was sublet in an attempt to change the bearing. Suffice it to say, I do not believe a Harbor Freight impact wrench generates 250 ft-lb of torque as advertised, especially when the bolt for the bearing is spec'd at 70 ft-lb. I supported the jackstands on the front subframe right at the rear attachment bolt. Note, I drove the car for a week with old struts and one bearing with play, no shudder. New struts and bearing, shudder. I have to believe that jacking the car up that much in the front is screwing around with the effective caster setting. I don't buy that having both front wheels off the ground for work should affect the cradle. Every time I go to the dealership, I see front end work occurring with all four wheels off the ground. From a physics perspective, I do not see a way that the load path changes between two and four wheels off the ground.

[crash93ssei]

Everything you just described is exactly how I would describe when my passenger side axle was shot, except it was worse on right hand turns.

It is the inner cv axle that is the cause in my case and I still hold that believe for these issues you guys are having. With the suspension lifted up like a monster truck with quick struts it actually extends the axle out and the tripod bearings in the inner cv joint don't ride where they normally do, that is why it would seem worse turning one direction then the other. In my case, weight transfer while turning right extended the axle even more outside of the normal range, while turning left compressed it some which seemed to lessen the effects.