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So now that my powertrain is running great, it's time to focus on the suspension. I would like to start with the front. 89 IROC convertible, 120,000 miles, old set of Doral 245/50/16 tires
Known issues:
Steering is very vague/floaty on center, the car "hunts" and the suspension seems less than precise.
What appears to be an inside camber issue (excessive wear on the inside tire treadline, both sides)
Occasionally pull to the left when braking hard. Not always repeatable.
I've already changed/done:
Steering box rebuild and flex joint
struts/shocks (KYB Excel-G)
strut mounts
sway bar bushings (end links and main)
added subframe connectors (Spohn)
Brakes/calipers/rotors/pistons/drums changed front and back. All new stock AC Delco.
Pretty sure (I bought the car two years ago):
original LCA's
original springs
Thinking of starting with:
What's a good way to check LCA bushings and ball joints?
Checking Steering linkages?
Also, is this AC Delco kit correct for camber adjustment for this car?ACDelco 45K18014 Professional Camber Adjuster Bolt Kit with Hardware
1: ball joints - connects control arms to spindles
2: center link - connects inner tie rods to idler and pitman arms
3: control arms (A-arms) - supports springs, houses endlinks, ball joints, and control arm bushings
4: control arm bushings - connects control arms to frame
5: endlinks - connects control arms to sway bar
6: idler arm - connects center link to frame
7: pitman arm - connects center link to steering box
8: spindles - connects control arms to wheels and struts
9: sway bar - controls body sway
10: sway bar bushings - connects sway bar to frame
11: tie rods, outer - controls alignment and steering, connects to spindles. Outer tie rods have the grease fitting on the bottom of the pivot.
12: tie rods, inner - controls alignment and steering, connects to center link. Inner tie rods have the grease fitting on the side of the pivot.
13: tie rod sleeves - adjusts alignment, connects inner and outer tie rods
With 120k miles of unknown origin; bushings, tie rods, bj's, and center link should be replaced.
You need new tires - they have a life of 5 years!
What brand of strut mount did you use for replacement?
Application, application, application. Advice is dependent upon it.
I'm looking for OEM quality ride and handling. If there are improvements to be had, I'm not a purist and would be interested.
That being said, while I do seek the stock ride, dropping the car 1" would look great, or maybe even 1.5". Since the springs are coming out do do the LCA's, I might consider dropping the car a little.
Replace all the steering linkages, but be wary of the idler arm, a lot of the aftermarket ones have the wrong drop angle. Make sure it matches the pitman arm's drop angle. Also the A-arm bushings.
Also who did your steering box, I've found the adjustment to be off on many. There is a adjuster screw on it. If its wrong then center will be either loose (1970/80's dukes of hazard style steering wheel motion to keep it centered) or tight and feel like you are trying to keep a ball balanced on top of an arch (IE you can't quite find center)
There's some really cheap kits out there and then there's Spohn and PST. This is fun, low miler car, not a racer. Should I avoid certain low end or are steering linkages basically at least all pretty good?
I've had luck with the part store parts, most don't like them. Though make sure the inner tie rod ends have the grease fitting on the end not the back side or it will hit. Read through this https://www.thirdgen.org/forums/susp...dler-arms.html
Sadly a lot of these parts are made by a few places and re branded these days.
Just get Moog for replacement - Rock Auto. Going forward, regularly check the center link for excessive play - it's a regular maintenance item for our cars with 16" or larger tires.
Everyone has their preferences on bushings - I like Global West (Del-A-Lum). They also carry an upgraded rubber selection if you want those for particular pieces on the car (don't go rubber on the arms). No one company has all the best components. Some have good this - and not so good that. Pick and choose - read/search/etc.
Since you'll take out the a-arms to press in bushings and the ball joints, might as well blast and paint them. Replace springs at same time. UMI has a good handle on most things so see what springs they have. An inch drop shouldn't cause too many problems for your application. Ride height and roll center discussions aren't necessary, here. You can always read up and educate yourself at a later point. An extended ball joint would be a good idea even if you don't know why (1/2"). You can always ask UMI when you talk springs. All will try to sell you (get the sale), and a few will also educate you. Spend your money with people who take the time to educate their customers.
Don't like your choice of strut mounts - rubber stock-like mounts. They will not control the strut even when new and will degrade fast. I like Spohn's spherical bearing mounts and they are secured better than others (UMI/Founders/etc. : Detroit Speed are the best and cost the most). If you can afford to, change them while you have everything apart. You need to control the strut and the tire patch. Dampahs and rubbahs, again. Buying used is not advisable for suspension parts, but I would even suggest trying (if money is a concern) to get used Spohn mounts before putting everything back together; OR, call them and ask if they have any visual seconds/flawed/imperfects they would sell (still perform well). Next to struts and tires, this is the most critical control piece in the suspension and the slop gets magnified from mount surface to tire surface distance.
No need for a super tire (aren't any in 245-50-16) with an average strut. Don't think I'm knocking you, I'm just trying to match my advice to where you are at. A new decent tire in your size: https://www.thirdgen.org/forums/whee...5-50-16-a.html
This will bring your car alive and bring back the fun quotient. Nothing, Nothing brings back the fun (not even HP) like a good handling car. Pics if you got 'em.
Although it is a noisy Vert, I am wary of anything but rubber bushings for street cars. I've tried poly in other cars and they can be harsh. Those DetroitSpeed mounts are gorgeous.
If I may, what would you go with where budget wants to be kept down, but not necessarily a limiting factor, for setting up a fun, tolerant, and still comfortable street car?
Front coilovers are not a good idea. You're placing shock load and spring load all on the fender/strut mount area - this is sheet metal. They try to re-enforce this area with a plate. I used their plate from this kit to re-enforce the mount area, anyway. You can see that in this pic, and you can see the spherical bearing inside the Spohn strut mount. Rear coilovers are a good idea and new shock tech is showing up in the coilover arena more than any shock for our cars. A plate is welded in the back and it works well. But any discussion goes beyond what your application is - you can always search and read up if you want to.
Del-A-Lum is a great bushing for the a-arms - they are not just a hunk of poly. You're only looking for movement in one plane. No worries here - especially with a very compliant strut, KYB; and, if you go with a package spring kit you will also be very compliant. Your concerns have some merit on the rear suspension, but that's not the topic of this thread.
KYB is not bad, just that is a compliant damper. It will work well with a softer/packaged spring set. There will be more up and down movement of the wheel assembly (less constant tire patch). You'll need a wonder bar/steering brace if you don't already: http://www.top-downsolutions.com/ste...or-firebird-(a
By the time you replace the normal parts and bushings, get new mounts, get new tires mount & balanced, get alignment, you'll be close to $2k. Then it will be time to sort out the rear. Stay within your build philosophy (application, application, application), don't deviate, and keep the car on the road for enjoyment. Keep downtime to a minimum. This morning, I woke up to -20 degrees, but there's no traffic on the roads
Just get Moog for replacement...Everyone has their preferences on bushings - I like Global West (Del-A-Lum).
On both of my cars, I bought Moog steering components (with the exception of a Baer bumpsteer kit in lieu of the outer tie rod and sleeve on my GTA because it is lowered). Moog has the centerlink, both inner & outer tie rods, tie rod sleeves (although I found a set of Hotchkis sleeves for my T/A instead), and idler arm that are quality pieces. Doing all of the linkage at once also makes dissassembly a lot easier. All you have to do is disconnect the outer tie rod from the spindle, the idler arm from the car, and the nut that holds the centerlink to the pitman arm. Then the whole thing drops out in one piece. For my T/A, I used it as a template to get the new pieces close to the original length so I could drive the car to the alignment shop.
If you are so inclinced, and the budget permits, it would be a good time to take the gearbox out and have it rebuilt. I just had the gearbox in my GTA rebuilt by Marty at www.powersteering.com. He did pretty good work. I had him do my gearbox and pump. He turned it around and had it back to me in less than a week. Since I've had it back in my car, the steering feels so much better. No more wandering in the steering wheel.
I also agree on the Del-A-lum a-arm bushings, but they are pricey. That's why I only have them on my GTA and not my T/A at this point. Maybe one day.
Are the OEM springs in the IROC variable or fixed rate? If I lower, looks like 1-1/4" is kinda the sweet spot. Leaning towards fixed rate but want the ride not to clobber me.
Instead of lowering springs I suppose I could go with longer ball joints. Where do I get those extended ball joints? Howe? Would a 1" lower the car 3/4"?
Last edited by Tootie Pang; 01-30-2019 at 05:21 PM.
OEM is fixed rate or even rate throughout operating range.
Variable would have one spring rate at ride height and another rate at say 2" compression. Not many will attempt to use these (STG used them in the rear). Forgettabout'em.
Ok here's what I've decided to do. Looks like a couple grand but it will go a long way
1. Replace all steering linkages with a kit. Price is nuts. I'll check it all when it arrives. If it's subpar, it's going back.
2. Replace LCA bushings (Moog) and go with 1/2" extended ball joints from UMC
3. Replace old coils with UMI fixed rate springs- 1-1/4" drop about
4. New set of BF Goodrich Sport Comp-2 tires. These are almost a full 2" wider than the General G-Max for the same size.
5. Refinish original rims
Already done: sway bar, struts/shocks (KYB), mounts, steering box and flex joint
This will be fun. I'll update as I go...
I will get to the rear links a little later.
Last edited by Tootie Pang; 01-31-2019 at 09:29 PM.
Trying to keep budget reigned in. So a bumpsteer kit brings the outer "tie rod to knuckle" geometry matched with the extended ball joint? I want to do this but only if it really will make spirited driving noticeably better. I have no plans to track this car.
Last edited by Tootie Pang; 02-01-2019 at 11:40 AM.
01-29-2019, 11:00 AM
