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87/87 vs 88 suspension by Edmonchuck
Started on: 02-15-2013 11:24 PM
Replies: 10 (3082 views)
Last post by: Patrick on 09-27-2013 06:26 PM
Edmonchuck
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Report this Post02-15-2013 11:24 PM Click Here to See the Profile for EdmonchuckClick Here to visit Edmonchuck's HomePageSend a Private Message to EdmonchuckEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hey all!

I am well on my way to getting the first Fiero to play with in many years. However, I am looking for the real differences in the GT suspension in the 86/87 v 88 cars. I am familiar with bump steer and the other fun issues with the time in the Corvair (unsafe at any speed, maybe, but a HELL of a lot of fun), but

a) is there a truly noticable difference in the handling and geometry,
b) does doing the converstions/builds from the kits I see make a noticable difference,
and
c) is it worth giving a darn?

I've been searching on a few forums and come up with "just buy an 88 car", but there are very few that I like that I would do much too...the ones on the market are just too pristine...
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IIKool
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Report this Post02-16-2013 06:50 AM Click Here to See the Profile for IIKoolClick Here to Email IIKoolSend a Private Message to IIKoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
I was told along time ago, that the best of both worlds where, a 87 front end and a 88 rear end.
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Bloozberry
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Report this Post02-16-2013 07:13 AM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
The Fiero is nothing at all like the Corvair when it comes to handling.

As for the difference between the earlier cars and the 88's, in everyday driving I doubt anybody would know the difference except that the '88's are sprung softer. The whole bumpsteer issue was blown way out of proportion by the media back in the day and it carries on in discussions even today because of it, in my opinion. I've had ample opportunity to drive fully restored versions of both cars. Only when the car is pushed to the limits (say in autocrossing or slalom) that the '88 shows it's superior design.
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Old Lar
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Report this Post02-16-2013 08:26 AM Click Here to See the Profile for Old LarSend a Private Message to Old LarEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have an 87 GT and an 88 GT. The 88 GT does seem to drive "better", but any more, I'm in to cruising rather than road racing.
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fieroguru
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Report this Post02-16-2013 08:26 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Most racer types shy away from the 88's fronts in the past due to the wheel bearings, but with the tapered rollers that are now available, that issue is probably resolved.

The 88's have a lower scrub radius in front so it is easier to turn the wheels in parking lot maneuvers. This also reduces kickback in the steering wheel when one wheel hits a bump, so the 88 didn't need the steering stabilizer that the 84-87's had. The 88 upper a-arm is fully adjustable for Caster/Camber whereas the 84-87 is limited to the fixed adjustments of flipping the ball joint 180 degrees and moving the washers on the pivot bolt front from the front/rear... both of these adjustments are "you get what you get" and very difficult to dial in precision from side to side. The 88's came with vented rotors, so brake upgrades on them are quite simple and relatively inexpensive without the need to machine down the stock hubs. From an engineering perspective, all current 88 brake upgrades bolt the caliper bracket to the machined side of the mounting surface on the upright/spindle, whereas the 84-87 front brake kits bolt to the as cast side of the upgight, which greatly reduces the parallel precision between the caliper pads and the rotor. The 84-87 front lower a-arm does not have the bushings co-axial so cycling the suspension up/down induces bushing deflection. Not so much of an issue with rubber bushings, but when you replace both of them with poly, this misalignment starts increasing the binding of the suspension due to less available bushing deflection. One redeeming aspect of the 84-87 front suspension, is the lower a-arm is of the offset design with the front bushing setup to take the vast majority of the lateral loads and the rear bushing acting more for braking/acceleration/road harshness. So you would run poly in the front bushing placement and keep rubber in the rear to firm up lateral control while minimizing road harshness (and allow the rear bushing to easily deflect to accommodate the bushing misalignment)... but I have never seen anyone do this.

The 88 rear is the tri-link design that separates the lateral (turning) loads from the acceleration/braking/road bumps. This allows you to run rod ends in the lateral links while keeping rubber bushings in the trailing link for great precision in toe control and zero bushing deflection under lateral loads, while the rubber bushings in the trailing link keep road harshness very close to stock. Since the 84-87's use a lower a-arm, its two bushings play double duty and stiffing the bushings for improved lateral control, also results in increased road harshness under daily driver situations. Then you have the solid mounted cradle (which the 84-87 can be solid mounted with aluminum bushings, or welded in sleeves), but at additional cost/work. Most brake upgrades on the 88's that use the stock 88 fiero calipers and retain the stock parking brake setup. The 84-87 rear brake upgrades need non-stock calipers and often require additional parts/work to retain the parking brake function. Lastly the 88 rear cradle has a factory rear sway bar, so it fits without any impact to ground clearance and was dialed in by the GM engineers for improved "safe handling", while it isn't optimized for optimal handling with an experienced driver, it provides benefit while keeping the car safe for normal drivers to drive.

For the vast majority of daily drivers you will not notice many of these items, besides the difference in cost of brake upgrades, but the more work you put into the car and the more you ask of it from a performance perspective, then the differences start to show up.
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Raydar
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Report this Post02-16-2013 10:32 AM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
I sold an 85 GT - the first new car I had ever bought - solely based on the steering kickback.
The limited alignment capability of the front suspension was the icing on the cake. I hated driving that car.

I would drive my 88 - or most any 88, for that matter - anywhere.

------------------
Raydar
88 Formula IMSA Fastback. 4.9, NVG T550

Praise the Lowered!

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Edmonchuck
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Report this Post02-16-2013 11:39 PM Click Here to See the Profile for EdmonchuckClick Here to visit Edmonchuck's HomePageSend a Private Message to EdmonchuckEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks everyone! fieroguru, thank you for the detailed explanation.

I appreciate the input.

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BillS
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Report this Post02-17-2013 12:08 PM Click Here to See the Profile for BillSClick Here to Email BillSSend a Private Message to BillSEdit/Delete MessageReply w/QuoteDirect Link to This Post
I am a long time road racer (i.e. SCCA style track racing). I have owned and driven an 87 GT at the same time as I owned and drove an 88 GT and so have a basis for comparison. T

The 88 is a far better starting point in terms of cornering ability, feel, and adjustability. If you want modified Chevette front suspension, by all means go for it. But I wouldn't. The fact that I still own the 88 speaks for itself.
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Larry Nakamura
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Report this Post02-18-2013 01:28 AM Click Here to See the Profile for Larry NakamuraClick Here to Email Larry NakamuraSend a Private Message to Larry NakamuraEdit/Delete MessageReply w/QuoteDirect Link to This Post
I had an 86SE and test drove an 88GT when it was announced that the
car was to be discontinued. I traded in the 86 and ordered an 88GT. I
thought the difference was that substaintial. I've heard you can do alot of
upgrades to pre-88 cars to make them preform good. Thus the saying, just
go with an 88. I remember that GM spent 30 million dollars developing the
88 suspension.

Here is a description of the changes from Automotive Engineering Oct 1987.

* Elimination of the steering damper assembly
* 30% shorter spindle length (90 vs 64 mm)
* 30% shorter scrub radius (49 to 35 mm)
* 20% reduction in king pin angle (7.5 to 6 degrees)
* 20% longer upper control arm length (177 to 214.2 mm)
* 25% longer lower control arm length (280 to 350 mm)
* Larger stabilizer bar (22mm to 28mm)
* 12% shorter turning radius (11.4 to 10.2 m)

Rear Suspension:
* Revised chasis cradle design for suspension attachments
* New tri-link design allowing for specific tuning of each component
* Increased rearward rear wheel motion with jounce for reduced impact harshness
* Lower spring rates (44 to 25 N/mm)
* Inclusion of 22 mm stabilizer bar with the WS6 suspension package
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Edmonchuck
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Report this Post09-27-2013 05:44 PM Click Here to See the Profile for EdmonchuckClick Here to visit Edmonchuck's HomePageSend a Private Message to EdmonchuckEdit/Delete MessageReply w/QuoteDirect Link to This Post
I know, old thread bump, but it looks like I am one phone call away from having an 88 in my garage.

T-Tops and all.

It looks fairly clean, but time will tell if I made the right choice.

Thanks again for the advice!
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Patrick
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Report this Post09-27-2013 06:26 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

I've been autocrossing my '84 duke for the last three years. I've lowered it and added a rear sway bar.

I recently acquired an '88 Formula. The car's in great shape, rides like a Cadillac compared to the the '84.

However...

The '84 will run circles around the '88 (stock suspension with new shocks/struts/ball joints). No comparison at all.

I'm looking forward to dropping/stiffening the suspension in the '88, and then trying that Fiero at the track.
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