Has anyone purchased the Arraut rear control arms for bump steer correction for pre 88 Fiero? The website says that it is necessary to remove some material from the stock spindles to suit the new control arm. Does anyone have the details as to how much material and where exactly it must be removed?

I installed a set of these control arms for a local club member, several years ago. The mods to the knuckles are irreversible, and render them unable to be used with a stock suspension. You may want to grab a spare set of knuckles, if you think you might want to revert to the stock suspension.

I should also add that the Arraut bumpsteer kits adds several pounds of unsprung weight to the suspension. The adapter piece that mounts the stock knuckle to the custom control arm is a hefty piece, made from a solid piece of steel.

Personally, I think you'd be better off using '88 Fiero knuckles with either an '88 Fiero cradle and suspension, or a custom control arm similar to the Arraut one, so you can keep your pre-'88 cradle. And a side benefit of using the '88 knuckles is that you get to use the '88 vented rear brakes. Just a thought.

[This message has been edited by Blacktree (edited 03-05-2014).]

See my Cave, Bump Steer before you order parts.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Bump steer issues are HIGHLY exaggerated.

Have you rebuilt the suspension on your 25-30 year old car?

I used to be one of those people who dismissed the difference between the pre-'88 and '88 rear suspension as a bunch of exaggeration. But after doing the '88 cradle swap in my '87 Fiero, I have seen the light!

Keep in mind that I had completely refurbished the suspension in my '87, along with several upgrades. It got new ball-joints, new tie rods, new wheel bearings, KYB dampers, Eibach springs, urethane control arm bushings, aluminum cradle bushings, front & rear Addco sway bars, and the 4-wheel Grand Am brake swap. The car handled like a go-kart, and cornered very well. But the rear end would still feel a little fidgety sometimes. Swapping in the '88 rear suspension eliminated that.

The funny thing was, I swapped in the '88 rear suspension because I wanted rod-end suspension links, and wanted to delete the toe links. The '88 cradle swap gave me that, with very little fabrication work. The handling improvements due to the improved suspension geometry were actually unintentional. But they are welcome.

[This message has been edited by Blacktree (edited 03-05-2014).]

Thanks for the input and suggestions regarding suspension modifications. To clarify, I am doing a complete suspension upgrade ( for an F355 project) front and back with a wide track system including coilovers and 13" brakes. I'm sticking with my mint 85 chassis and engine cradle, hence the Arraut suspension upgrades. I don't have a particular concern regarding bump steer, however, the Arraut rear control arm comes with the adaptation so I will make the necessary modification to the spindle to accommodate it. At this time I am looking for info regarding the actual spindle changes that other PFF members may have completed on their projects.

For the money, swap in an 88 cradle. Lots of benefits over the different control arms, bumpsteer issues aside.

quote Originally posted by Yarmouth Fiero: At this time I am looking for info regarding the actual spindle changes that other PFF members may have completed on their projects.

OK, gotcha. The mods involve drilling out the hole in the knuckle for the toe link. The hole is slightly conical, to positively seat the tie rod end into the knuckle. You have to drill that out (to make a straight hole), so the bolt from the adapter can be used there. You'll also have to chop off a piece of the knuckle that sticks out below the tie rod end, because it interferes with the adapter bracket.

Edit to add: and since you're installing 13" brakes, you'll also need to chop off a piece of the knuckle that sticks out near the bottom. When you try to fit the pieces together, it'll become pretty obvious where the knuckle needs to be chopped.

[This message has been edited by Blacktree (edited 03-05-2014).]

Like Blacktree said , the mods are pretty easy .i have the bumpsteer kit on my car and it works well , there is no twitchiness in the rear suspension any more .It is nice and smooth on the highway . As far as roadholding i find there to be no difference from my old RCC tubular arm and coilover strut setup.I am using the same spring/strut combo as before .What I dont like :
1 .
It is a lot heavier than my old setup
2.
It is noisy going over bumps at slow speeds .There is some banging going on back there that I have not been able to figure out .Only happens at less than 35KM/hr but it is just plain annoying .Driving around older areas of Toronto is almost unbearable .On good roads there is no banging , potholes cause it .
So eventually I am going to remove this setup and put back on my old RCC lower arm and build an upper A arm so i can mount QA-1 coilovers in the back like I have on my front suspension .I started to do this a while back but when it came time to start cutting frame parts I backed out of the job .But with all the ideas i have gotten from Bloozeberry's thread and the suspension redesign thread , i feel confident that i can make a good job of it now .I traded my GT rear wing for 2 sets of rear knuckles with stock brakes so I have most of the parts I need .There are lots of pics of my suspension mods on my build thread "ecotec swap " now on page 2 of the construction zone .

quote Originally posted by wftb: It is noisy going over bumps at slow speeds .There is some banging going on back there that I have not been able to figure out.

I'm willing to bet the clevis pins on the toe adjusters are getting loose. Those clevis pins are literally a weak link in the system. I'm not sure why they didn't use rod ends instead.

could be , but every month i get under there and crank it up tight .no change but my car is heavily modified , could be something else .I am not putting down this product , just giving it fair revue .And I have had it on for 2 years now and until i figure out something better it is staying on the car .

I have no complaints about my HELD rear-bump-steer kit since I shaved .3" off the face of the spindle. Prior to that I'd wear out axle ends because the splines wouldn't go all the way thru the hub. I've also gone thru a number of bearings but my bearings are the 5x4.75" conversion ones.

This is on the car that I oval track race with and it definitely out handles my 88 formula, but then again my Formula is running stock tires...

My next mod is going to be the strut tower adapters that move the top of the spings inboard since on extreme corners, my tires will rub the spring, but I'm using deeper Camaro wheels...

Thanks for all the feed back everyone. I'll probably proceed as planned with this suspension upgrade.

Has anyone ever tried to modify a pre 88 cradle by removing the control arms and adding a links type suspension?

quote Originally posted by Blacktree: I'm willing to bet the clevis pins on the toe adjusters are getting loose. Those clevis pins are literally a weak link in the system. I'm not sure why they didn't use rod ends instead.

I noticed the same thing when I installed the setup on my 86 GT this winter - not a good idea. The instructions were not clear how tight the clevis bolt needed to be, the toe would change several degrees if the bolt was not really tight due to the clevis bolt holes being slightly bigger than the 3/8 bolt, but it looked like the clevis needed to rotate with the suspension travel. I emailed them a couple times but didn't get an answer so I changed it to a rod end & necessary longer tie rod sleeve from Speedway, no chance of any play or getting loose now.

quote Originally posted by Boostdreamer: Has anyone ever tried to modify a pre 88 cradle by removing the control arms and adding a links type suspension?

I was actually going to do that. The plan was to get some '88 rear knuckles, and make suspension links to match. But the '88 knuckles that I found came with a cradle and suspension attached, so I just swapped it all in.

quote Originally posted by olejoedad: For the money, swap in an 88 cradle. Lots of benefits over the different control arms, bumpsteer issues aside.

Let me beat this horse for a minute...

Benefits of 88 rear rear cradle swap....

Better ride quality
Better suspension geometry
No design issues - proven and strong
Easily upgraded for larger brakes
Cost effective
Lower unsprung weight
No safety (failure) issues

You are building a Lambo rebody - why would you install a bandaid fix with documented design issues that 'fixes' an insignificant 'problem', when you can significantly improve the entire rear design?

Well, it's not like you can just go the store down the road and order up a full 88 cradle, suspension and braking system...

They are available.
There is one in the Mall right now.

[This message has been edited by olejoedad (edited 03-07-2014).]

quote Originally posted by olejoedad: They are available. There is one in the Mall right now.

There was a guy in the mall who was fabricating aluminum versions of the cradle...but aren't the knuckles impossible to find?

Wouldn't "impossible" be an exaggeration if the parts are for sale right now in the Mall?

quote Originally posted by lou_dias: There was a guy in the mall who was fabricating aluminum versions of the cradle...but aren't the knuckles impossible to find?

All he did was talk about making an aluminum version. He was a crook who has been previously banned under a different user ID for taking people's $$$ and not delivering products.
https://www.fiero.nl/forum/Forum2/HTML/125210.html

The 88 crables and suspension parts are not too hard to find, you just have to be patient. But they will cost more than the 84-87 parts.

As long as they would be fabricating stuff, why limit it to just the 88 Fiero suspension? Surely there are other knuckles and links that could work.

quote Originally posted by AL68: I noticed the same thing when I installed the setup on my 86 GT this winter - not a good idea. The instructions were not clear how tight the clevis bolt needed to be, the toe would change several degrees if the bolt was not really tight due to the clevis bolt holes being slightly bigger than the 3/8 bolt, but it looked like the clevis needed to rotate with the suspension travel. I emailed them a couple times but didn't get an answer so I changed it to a rod end & necessary longer tie rod sleeve from Speedway, no chance of any play or getting loose now.

can you post a picture of this mod , sounds like something i would like to try .thanks

While my original question regarding Arraut rear suspensions certainly generated some interesting discussions regarding pre 88' vs 88' rear suspension, I would like to add a note that Richard at Arraut Motorsports sent me a detailed description of the process involved in spindle preparation and installation / setup of their rear control arm with bumpsteer correction. Thanks to everyone who added their comments on this topic and thanks to Richard for supplying the detailed write-up. Since I have yet to purchase my parts from Arraut I don't feel it is appropriate for me to post their documentation. However, I think Richard would supply the document to current and future clients if they contacted him directly.

Regards

Graham

quote Originally posted by olejoedad: For the money, swap in an 88 cradle. Lots of benefits over the different control arms, bumpsteer issues aside.

I am in agreement on this. Pontiac had a major investment in redesigning the suspension. With unlimited resources don't you think they designed a better system than what was previously on the car?

quote Originally posted by wftb: can you post a picture of this mod , sounds like something i would like to try .thanks

I didn't take any pics, it was really easy to do.

The rod end was Speedway #1750116, I had to make a spacer to reduce the 1/2" rod end hole to 3/8 for the bolt.

The rod end has shorter threads than the clevis so I made a longer tie rod sleeve.

I used Speedway tie rod sleeve #91099065GS (8" long x 5/8 thread, couldn't find a 5" one), tapped the RH threads deeper & cut to 5" long.

I assembled it the same way as the clevis, put a thick 3/8 washer on the bolt where it goes through the rod end. The rod end bolts to the front (towards front of car)
side of the lower control arm tab.

thanks for the part #s and write up i will definitely look in to this .