MAJOR vibrations when braking from high speeds

[laner]

Hi,

I have a 99 GA SE (3400, 126,000 kms) and when I brake from high speeds (120kph+) I get a MAJOR vibration coming through the car, enough to wake up my passengers with my watch rattling. I thought at first it was my rotors. Completely new front rotors and pads were installed a few weeks ago and I'm still getting this shaking.

My Brother-in-law took it in to his shop and he thought it was the cv joints. As it turns out, it seems to be a problem with the ETS system (or so he figures). When he unplugs it from the tranny there is absolutely no shaking or vibrating at all. The only problem is that when that's unplugged, both the odometer and the speedometer don't work.

He has tried turning the ETS off from the dash but that doesn't change a thing.

Is there a way to disable the ETS without disablng the gauges?

Funny thing as well, on the way in to the shop the power steering pump went....I got rid of a 95 Olds Cutlass Conv. to get this cause it was causing me problems....I'm starting to regret it now.

Anybody have any suggestions??

Laner

[HeyDace]

Your brother in law is a mechanic? Dude, Have him check the rear bushings on the front control arms. They blow out of the control arms, very common problem and the symptoms are exactly that, shaking at high speed brake. You probably feel the steering wheel shake also. Going over bumps they may rattle or bang too.

[laner]

Thanks for the suggestion, but why would it stop when disconnecting the sensor from the transmission??? Could it be from a problem with my ABS (same sensor as ETS)???

[laner]

Sorry, I was mistaken, the ABS sensor is separate from the ETS....

[HeyDace]

Its a possibility that the ETS would have an effect on the root problem. But you need to find the root problem. I think it may be in the C-arm bushings, the symptoms you described are very much like that of the front bushings. I work on a lot of GA's and this is a common malady.

[Gimli]

No, the ABS sensors ARE the same as ETS, and have nothing to do with the transmission. The sensor on the transmission is the vehicle speed sensor, which is why when you disconnect it you lose the gauges.

I personally would take it to someone who knows about GAs for diagnostic...

[rixGAphx]

Originally posted by laner
Thanks for the suggestion, but why would it stop when disconnecting the sensor from the transmission?

It's quite possibly a coincidence rather than cause-and effect.
Bad bushings are often a good/bad condition, in that *sometimes* they happen to seat just right and everything's peachy.
Then you go over a bump or take a hard turn and the bushing shifts out of position, resulting in squirrelly handling or shaking.

Perhaps when the b-i-l was disconnecting the cable, he leaned heavily on the vehicle or had the vehicle in the air, thusly 'resetting' the suspension so it operated properly (for a while).

Don't just go throwing money at possible parts.
It's most probably a suspension item, so whomever looks at it should be familiar with GA's and suspensions.

BTW, bad CV joints don't generally rear their heads as shaking. The first signs are leaking grease from the boots, followed by soft 'clunkin' sounds at tight low speed turns (parking lot manuvering).

Finally, 120kph = ~ 75mph.
As you decelerate hard from this speed, you pass thru the 40-60mph 'zone' where *most* tire imbalance occurs.
With this, and any, shaking, make certain the tires are balanced and the ailignment is proper before proceeding to more exotic/$$$ scenarios.
After all, the owner's manuals tell us to EXPECT the tires to become unbalanced as they wear, and the alignment to need occasional adjustment.

Good luck.
-Rick