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Excessive brake dive by masospaghetti
Started on: 06-28-2015 06:22 PM
Replies: 11 (206 views)
Last post by: masospaghetti on 06-30-2015 12:30 PM
masospaghetti
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Report this Post06-28-2015 06:22 PM Click Here to See the Profile for masospaghettiClick Here to Email masospaghettiSend a Private Message to masospaghettiEdit/Delete MessageReply w/QuoteDirect Link to This Post
Compared to my DD, a 93 Honda Accord, the Fiero dives much more severely under braking. To me it seems excessive. Both cars have stock suspension. The Fiero has Sensatrac dampers.

What could cause this? Or besides stiffer springs and dampers, is there any way to reduce it?

It's a 86 GT.
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olejoedad
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Report this Post06-28-2015 06:41 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
How old are the shocks?
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Gall757
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Report this Post06-28-2015 06:46 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
comparing your 93 Honda to a pre-88 Fiero is a tough comparison. I have read that the brake-dive issue was a design problem, and not easily fixed, but the 88 is not so bad...perhaps some more exotic shocks would help.
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theogre
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Report this Post06-28-2015 07:37 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by olejoedad:
How old are the shocks?

yes... because old shocks/struts will affect braking.
Even more so w/ lowered cars because many have damage shocks and/or struts. Damage on low cars can happen very fast.

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masospaghetti
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Report this Post06-28-2015 11:27 PM Click Here to See the Profile for masospaghettiClick Here to Email masospaghettiSend a Private Message to masospaghettiEdit/Delete MessageReply w/QuoteDirect Link to This Post
I replaced them a couple years ago. I realize they are the comfy shocks, not performance ones.
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thesameguy
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Report this Post06-29-2015 02:37 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
On most older cars, the only thing responsible for brake drive is the springs & shocks. Newer cars typically employ anti-dive techniques - which is a function of the relationship of the front control arms - that cause the actual control arms to resist dive. I believe Mercedes pioneered this on passenger cars in the late '80s, so I think it's unlikely the Fiero has any of that technology - you're going to be relying entirely on springs & shocks. FWIW, my '87 on Koni Specials set to the hardest setting and slightly cut front springs exhibits no dive of which to speak, and I've got a fair amount of brake to play with (C6 brakes). If yours is worse than your Honda's, I would assume you've got something not working properly. "Stiffly sprung" is not a value I'd have attributed to my '94 Accord.

[This message has been edited by thesameguy (edited 06-29-2015).]

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masospaghetti
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Report this Post06-29-2015 06:02 PM Click Here to See the Profile for masospaghettiClick Here to Email masospaghettiSend a Private Message to masospaghettiEdit/Delete MessageReply w/QuoteDirect Link to This Post
That's interesting. I wonder if the Accord has such technology? It does employ a radius arm in addition to the control arm. For a pedestrian vehicle, the setup and geometry is actually quite good (double wishbones).

But yeah its definitely a comfort oriented suspension. Maybe I should change my shocks and see how that does.
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thesameguy
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Report this Post06-29-2015 06:32 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Honda was definitely building a better car back then, it would not surprise me to find out they were doing good things with their front suspensions.
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olejoedad
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Report this Post06-29-2015 06:52 PM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
The dive you are experiencing is partially due to the rear suspension lifting the rear of the car as well; front suspension geometry on the rear doesn't work all that well.
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masospaghetti
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Report this Post06-29-2015 10:12 PM Click Here to See the Profile for masospaghettiClick Here to Email masospaghettiSend a Private Message to masospaghettiEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm starting to understand why people say the 84-87 suspension isn't the greatest....
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wftb
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Report this Post06-30-2015 12:12 AM Click Here to See the Profile for wftbClick Here to Email wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
Anti dive geometry has been around and used in most production cars since the 60's , maybe earlier I don't really know .But basically the upper control arm when viewed from the side with the wheel removed will have a tilt to it at the inboard mounting points .If you drew a line through the upper arm mounting bushings , you would find that the line slopes upward to the front of the car .Generally the shallower the angle the less anti dive .84 - 87 fieros do have anti dive , but it was designed around 13" wheels and tires , low power and fairly light weight .Then later models got the v6 , bigger wheels , heavier body and more options and the anti dive was not enough for a lot of people .But higher spring rates and better shocks will cure most of that .Comfortable ride shocks will make it worse for sure .
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masospaghetti
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Report this Post06-30-2015 12:30 PM Click Here to See the Profile for masospaghettiClick Here to Email masospaghettiSend a Private Message to masospaghettiEdit/Delete MessageReply w/QuoteDirect Link to This Post
Interesting. Would putting KYB's on the front only help or is this a bad idea?

The rear Gas-A-Just struts are harder to find and fairly expensive, about $200 for the pair. The fronts are super cheap though.
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