Skip to main content ↑ ↓
Topic: At Wit's End...This Cat SHUDDERS on Bumps (Read 6619 times) previous topic - next topic

At Wit's End...This Cat SHUDDERS on Bumps

Ok...Lowdown First...got this 1987 XR7 for free in August 2005. Around $9400 has gone into it - I've managed to overpay for just about everything on it (I'm not complaining - I obviously like the car). This car has 162,000 miles on it  (I'm the second owner I've put on 4000 miles on it in one year). This car SHUDDERS over rough and not-so-rough roads. Both the front and rear of the car act like an old lady wearing loose underwear. This makes no sense - I had a 1987 LS V6 which rode MUCH smoother - This car should ride like a baby Mark VII. JUST ON THE SUSPENSION - I've changed the following over the past 13 months:
Replaced Rear Horizontal Shocks
Replaced L/S & R/S Stabilizer Bars
Replaced L/S & R/S Tie Rod Ends
Front End Alignment
Replaced Rack & Pinion Assembly
Front Struts
Front Brakes
Front Rotors
Rear Shocks
Rear Brakes
Rear Drums
L/S Wheel Cylinder
R/S Wheel Cylinder

Can anyone suggest something I may be missing? I am giving this car to both of my sons in January 2007 and the two mechanics I use can't seem to  think of anything else.

At Wit's End...This Cat SHUDDERS on Bumps

Reply #1 –
Maybe the tires? I have seen and driven cars that shuddered cause of the tires. Even brand new tires once in a while will have problems. I would find a shop that has a tire balancing machine that can simulate road force on them or replace them.

At Wit's End...This Cat SHUDDERS on Bumps

Reply #2 –
does it do it at any perticular speeds? if your wheels are out of balance it will shake at certain speeds (ie. 45-55 mph)

i agree with it might be the tires, new ones can have defects, and old ones can get flat spots it they have sat...a quick easy way to check for severe distortion, is to jack the car up and spin each wheel, if its bad, u can see where it is somewhat oval.
1988 Thunderbird sport
2004 Ford F150 Lariat
2008  Chevrolet Cobalt Sport
2007 Suzuki DR-Z400S dual sport/Supermoto
1988 Thunderbird LX - sold
1988 Mercury Cougar XR-7 with GST kit - gone

Still around square #1 - But Thank You Both So Far!

Reply #3 –
I am sure the tires DO need a speed-balancing. At speeds over 60 the steering wheel DOES vibrate. But when I wiite that the car shudders, I mean it hits a bump and bottoms out so bad the entire car shudders, at any speed. It's like the car has 20 year old shoocks and struts on it. The tires look Ok - they are about 40% used.

I am primarily looking to you guys for suggestions at to perhaps other suspension parts I should replace (You know something obvious like "Hey you forgot to change the Johnson Rod" - stuff like that". As far as car suspensions goes, believe me even your WIVES know more about this than I do.

At Wit's End...This Cat SHUDDERS on Bumps

Reply #4 –
balljoints,Strut mounts etc need to be checked
[SIGPIC][/SIGPIC]
1974 maverick lsx powered turbo car SOLD
1973 maverick Tijuana Taxi Tribute
1957 chevy LSX Turbo project (race car)
Owner of Joe Dirt Fabrication

At Wit's End...This Cat SHUDDERS on Bumps

Reply #5 –
I'm thinking possibly the bushings...either the stock ones are completely worn out, or the replacements are urethane which transmit much more vibration. What kind of shocks/struts did you put in?

My old '88 XR7, and '88 T-Bird Sport, both rode like a truck. Wait, I take that back...my current Mountaineer rides better than both of those cars ever did. The sport V8 suspension is just naturally harsher vs. the base V8/V6 suspension. I attribute that to the springs...they had a more aggressive rate. What you could do is have the springs inspected, make sure all the isolators are in place (front and rear), and that none of the springs are broken. If everything checks out...change them. In this case a downgrade will give a much better ride but should still handle fine. I think that's probably the only way you'd be satisfied with the ride quality. Trust me, those thoughts went through my mind many, many times (like, wintertime).

At Wit's End...This Cat SHUDDERS on Bumps

Reply #6 –
Quote from: 87CougarDude;110657
You know something obvious like "Hey you forgot to change the Johnson Rod"


Best price on Johnson rods i've seen.
1980 birds X 3, 1982 bird, 1984 XR7, 1988 TC

At Wit's End...This Cat SHUDDERS on Bumps

Reply #7 –
Ball joints, strut mounts and control arm bushings.....
Long live the 4-eyes!  - '83 Tbird Turbo - '85 Marquis LTS - '86 LTD Wagon

At Wit's End...This Cat SHUDDERS on Bumps

Reply #8 –
So did it do the shuddering thing before you started swapping parts out?

It sounds like you want a soft, compliant ride.  Find a set of V6 springs, make sure the rubber isolators are on them, and install them.  I hope you used all the rubber bushings in the shock and strut installations.

Also, check your control arm bushings.

And most importantly, go get the tires balanced and inspected by someone that knows what they're looking at.  You can't spend too much money on the four parts of your car that actually contact the pavement.  They're the most critical part of your car's behavior in handling and ride.
.
1984 Thunderbird V8

At Wit's End...This Cat SHUDDERS on Bumps

Reply #9 –
I rated this car as a P.O.S. when I first got it - it was barely road-worthy. I poured more than $1700 (1300 Parts & 400 Labor) into it the first month I had it. It's ride was  the first day I got it, and it hasn't NEARLY improved enough since then, not for that kind of money.

Of Course, I DO want a soft and compliant ride - I'm 46 years old and my days of riding on a skateboard (or it's synonym, A Camaro) are long past. Beside that, and more importantly, I want that car to handle the ed road, not skitter all over the road every time it hits a rough patch - My KIDS are getting this thing and I want it stable, solid and sound.

, Guys....I THOUGHT Ball Joints and no one took me seriously. And since I have the skill set of Paula Abdul when it comes to automotive suspension systems, I need to always defer to these mechanics, who seem to know less than I do.  Here's the laundry list between now and 1Q 2007:

Tire Balancing [Being done today - but this is a separate issue entirely]
Ball Joints - I want them replaced.
[Examine] Strut Mounts
[Examine] Control Arm Bushings
[Examine] Front and Rear Springs - Will will probably replace these anyway, regardless of what they find.

Looks like another $1200 worth of work - Minimum.

Anyone Else - PLEASE Chime in. This is my last fling with this particular money-hungry hooker.

At Wit's End...This Cat SHUDDERS on Bumps

Reply #10 –
I wish you were closer - I'd fix all that for half the price.  lol..

Perhaps one of our compadres can get you fixed up in the NYC area...
.
1984 Thunderbird V8

At Wit's End...This Cat SHUDDERS on Bumps

Reply #11 –
Quote from: tbirdscott;110668
Best price on Johnson rods i've seen.
Better get the kneutsen valve to go with that or it will wear out your power bands causing the engine oil bypass to clog. And you DEFINATELY don't want that.

At Wit's End...This Cat SHUDDERS on Bumps

Reply #13 –
Eric:
I went back and re-read your post (Much Appreciated BTW). My question: Do the Springs, Bushings, Struts and Shocks all swap properly between the LS and XR7? If so I may order LS parts for the suspension....My mother had a 1972 Maverick with a MUCH better ride than this thing....when I say this is by far the worst riding car I've ever owned, I'm not exaggerating.

At Wit's End...This Cat SHUDDERS on Bumps

Reply #14 –
Do they swap over? Yes. No modifications are necessary. Now for the springs you should think about V8 LS springs only (for the non-sport V8). The V6 springs will drop the front end a few inches and while that looks cool, handling will suffer. The only real differences between a V8 LS and an XR7, as far as suspension, is the sway bars and the springs. Since your XR7 already has the bigger sway bars, cornering will still be fine. Your real focus should therefore be on the springs.

Now shocks/struts: I don't know what you have now, but that could also be another part of the problem. A softer strut will allow better absorption of road imperfections (which, seeing as you're from Da Bronx, you could probably write novels about). Shocks *should* match the struts but don't have to. Let us know what you've got in there now and we can help you fine-tune the ride quality with some suggestions.

In the summertime the sport V8 suspension is wonderful. Soon as temperatures drop below freezing, though, pretty much every road imperfection gets transmitted through the suspension. And I've tried softer struts/shocks with a sport suspension before...still gave a downright punishing ride. The key is definitely in the springs. Once they've spent 6 months below freezing they're just like having rocks in there. Get them above 40-50 degrees F and they get snappy again. After my old '88 XR7 and '88 Sport T-Bird, I swore I'd never have a Fox car with a sport suspension in wintertime again. Now I had to drive my old '88 Blue Max V8 in colder weather a few times and it handled fine over bumps, railroad tracks and potholes, even when it was below freezing. It stayed softer and more compliant than the sport suspension cars ever did. That car had the thicker XR7-spec front and rear sway bars too. Only thing not different? The springs. So...there you go. I think once you resolve the spring issue then you'll be much, much happier.