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Whats so special about 88 cradles? by kawana
Started on: 08-17-2013 12:25 AM
Replies: 15 (691 views)
Last post by: Lou6t4gto on 08-18-2013 12:48 PM
kawana
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Report this Post08-17-2013 12:25 AM Click Here to See the Profile for kawanaClick Here to visit kawana's HomePageClick Here to Email kawanaSend a Private Message to kawanaEdit/Delete MessageReply w/QuoteDirect Link to This Post
So ive been out of the fiero world for 4 years now, but im gunna try and pick up a project car to swap an L67 into. Every build thread I read through has an 88 cradle getting swapped in it seems. Is there any reason why I couldn't just use the stock cradle in the 85-87 fiero I buy? What is so amazing about upgrading to an 88 cradle?
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mrfiero
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Report this Post08-17-2013 12:35 AM Click Here to See the Profile for mrfieroClick Here to Email mrfieroSend a Private Message to mrfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
Solid mount to frame (no rubber bushings), 3-link rear suspension (instead of a lower A-arm), rear sway bar (GT & Formula only) and vented brakes (versus solid) are the main reasons.
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NoMoreRicers
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Report this Post08-17-2013 12:58 AM Click Here to See the Profile for NoMoreRicersClick Here to Email NoMoreRicersSend a Private Message to NoMoreRicersEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here's a good explanation.

ETA: Fixed drunk spelling.

[This message has been edited by NoMoreRicers (edited 08-17-2013).]

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jb1
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Report this Post08-17-2013 01:19 AM Click Here to See the Profile for jb1Click Here to Email jb1Send a Private Message to jb1Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by mrfiero:

Solid mount to frame (no rubber bushings), 3-link rear suspension (instead of a lower A-arm), rear sway bar (GT & Formula only) and vented brakes (versus solid) are the main reasons.


all can be changed with the exception of the 3 link on the 85-87, you pulling cradle anyways so order Rodneys aluminum bushings, add the rear sway bar and brake upgrades ( take your pick)

------------------


87 GT
series 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a
My Build

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kawana
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Report this Post08-17-2013 02:06 AM Click Here to See the Profile for kawanaClick Here to visit kawana's HomePageClick Here to Email kawanaSend a Private Message to kawanaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jb1:


all can be changed with the exception of the 3 link on the 85-87, you pulling cradle anyways so order Rodneys aluminum bushings, add the rear sway bar and brake upgrades ( take your pick)




Thanks for your input, that sounds like a more viable option for my build, with how rare and expensive 88 cradles seem to be around here.
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jb1
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Report this Post08-17-2013 02:27 AM Click Here to See the Profile for jb1Click Here to Email jb1Send a Private Message to jb1Edit/Delete MessageReply w/QuoteDirect Link to This Post
I will be honest I have thought about using an 88 cradle but really end up asking myself why?? replace your control arm bushings and tie rod ends and struts etc and should handle great, I am in the middle of it now , I have all poly suspension and cradle mounts doing all new shocks struts tie rod ends ball joints , hope it is worth the effort.. and upgrading brakes..

------------------


87 GT
series 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a
My Build

[This message has been edited by jb1 (edited 08-17-2013).]

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fieroguru
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Report this Post08-17-2013 07:34 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by mrfiero:

Solid mount to frame (no rubber bushings), 3-link rear suspension (instead of a lower A-arm), rear sway bar (GT & Formula only) and vented brakes (versus solid) are the main reasons.


To elaborate further on the points above...

The 3 link design uses separate links to control the lateral loads and accel/decel loads. This allows you to stiffen the bushings or go rod end joints in the lateral links for zero bushing deflection and precise toe control while keeping the trailing link soft (keep the rubber bushings) so ride harshness remains at near stock levels. On the 84-87 the lower a-arm plays double duty with all the loads being handled by the 2 bushings. So if you want to stiffen the bushings for better lateral control, you also stiffen them for the accel/decel and will see an increase in ride harshness... Most people who complain about poly suspension upgrade have an 84-87 or added poly to the trailing link on the 88.

The 84-87 rear suspension has pro-squat built into it. So its designed to squat down under accel loads. The 88 rear suspension (at stock ride height) uses the geometry of the trailing link to help resist this squat under acceleration.

The 84-87 rear suspension has poor toe control that causes significant toe changes as the suspension is cycled. To reduce this you have to alter the placement of the rear tierod or stiffen up the rear springs to limit suspension travel (which impacts ride harshness). The 88 has much better toe control stock and you can upgrade to rod ends in the lateral links to eliminate bushing deflection with minimal impact on ride harshness.

The 88 rear suspension has the top of the strut 1" further inboard which increases the camber gain through suspension cycling to help keep the tires flat to the pavement. While the 88 rear still needs more camber gain (via changing the lateral link geometry, relocating the top of the strut inboard another 1", or both), it is still better than the 84-87. This means the 88 can run less static negative camber (and improve tire wear) than the 84-87, or run the same and have even more available lateral grip by using more the tire contact patch.
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kawana
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Report this Post08-17-2013 09:25 AM Click Here to See the Profile for kawanaClick Here to visit kawana's HomePageClick Here to Email kawanaSend a Private Message to kawanaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:


To elaborate further on the points above...

The 3 link design uses separate links to control the lateral loads and accel/decel loads. This allows you to stiffen the bushings or go rod end joints in the lateral links for zero bushing deflection and precise toe control while keeping the trailing link soft (keep the rubber bushings) so ride harshness remains at near stock levels. On the 84-87 the lower a-arm plays double duty with all the loads being handled by the 2 bushings. So if you want to stiffen the bushings for better lateral control, you also stiffen them for the accel/decel and will see an increase in ride harshness... Most people who complain about poly suspension upgrade have an 84-87 or added poly to the trailing link on the 88.

The 84-87 rear suspension has pro-squat built into it. So its designed to squat down under accel loads. The 88 rear suspension (at stock ride height) uses the geometry of the trailing link to help resist this squat under acceleration.

The 84-87 rear suspension has poor toe control that causes significant toe changes as the suspension is cycled. To reduce this you have to alter the placement of the rear tierod or stiffen up the rear springs to limit suspension travel (which impacts ride harshness). The 88 has much better toe control stock and you can upgrade to rod ends in the lateral links to eliminate bushing deflection with minimal impact on ride harshness.

The 88 rear suspension has the top of the strut 1" further inboard which increases the camber gain through suspension cycling to help keep the tires flat to the pavement. While the 88 rear still needs more camber gain (via changing the lateral link geometry, relocating the top of the strut inboard another 1", or both), it is still better than the 84-87. This means the 88 can run less static negative camber (and improve tire wear) than the 84-87, or run the same and have even more available lateral grip by using more the tire contact patch.


Mhmm I see. Yup... I know some of these words.

Seriously though, I think I get some idea of what you're saying.
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92wastheyear
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Report this Post08-17-2013 11:10 AM Click Here to See the Profile for 92wastheyearClick Here to Email 92wastheyearSend a Private Message to 92wastheyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by kawana:


Mhmm I see. Yup... I know some of these words.



Haha....that is what I was thinking reading that
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Lou6t4gto
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Report this Post08-17-2013 01:36 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
so at the end of the Day, the '88 is "superior", But, it costs More to Get, & to Rebuild. The question is: Is it Worth it TO YOU ?
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lou_dias
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Report this Post08-17-2013 01:51 PM Click Here to See the Profile for lou_diasClick Here to Email lou_diasSend a Private Message to lou_diasEdit/Delete MessageReply w/QuoteDirect Link to This Post
All in all, you can put coil-overs on the pre-88 and use adapters to mount the top inboard 2" as well as use the RCC or HELD/WestShore/AurratFabricators/FieroStore rear bumpsteer correction kit and handle as good as an 88 on the track.

As an owner of 3 Fieros, one an 88 Formula, one a 87 GT with the RCC kit and one an 87GT with the Held kit, all I can say is - they work.

If you do a search, I believe there is a member here who has re-created the 88 cradle in aluminum...if you really need one. I think it will be hard to find the rest of the components to replace it with unless you happen to find a totaled 88 in a junk yard...

[This message has been edited by lou_dias (edited 08-17-2013).]

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Report this Post08-17-2013 02:45 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
 
quote
Originally posted by fieroguru:


To elaborate further on the points above...

The 3 link design uses separate links to control the lateral loads and accel/decel loads. This allows you to stiffen the bushings or go rod end joints in the lateral links for zero bushing deflection and precise toe control while keeping the trailing link soft (keep the rubber bushings) so ride harshness remains at near stock levels. On the 84-87 the lower a-arm plays double duty with all the loads being handled by the 2 bushings. So if you want to stiffen the bushings for better lateral control, you also stiffen them for the accel/decel and will see an increase in ride harshness... Most people who complain about poly suspension upgrade have an 84-87 or added poly to the trailing link on the 88.

The 84-87 rear suspension has pro-squat built into it. So its designed to squat down under accel loads. The 88 rear suspension (at stock ride height) uses the geometry of the trailing link to help resist this squat under acceleration.

The 84-87 rear suspension has poor toe control that causes significant toe changes as the suspension is cycled. To reduce this you have to alter the placement of the rear tierod or stiffen up the rear springs to limit suspension travel (which impacts ride harshness). The 88 has much better toe control stock and you can upgrade to rod ends in the lateral links to eliminate bushing deflection with minimal impact on ride harshness.

The 88 rear suspension has the top of the strut 1" further inboard which increases the camber gain through suspension cycling to help keep the tires flat to the pavement. While the 88 rear still needs more camber gain (via changing the lateral link geometry, relocating the top of the strut inboard another 1", or both), it is still better than the 84-87. This means the 88 can run less static negative camber (and improve tire wear) than the 84-87, or run the same and have even more available lateral grip by using more the tire contact patch.


Nice write-up, guru. A + for your effort.

There is NO comparison between the ride quality of the two designs, the 88 is FAR superior.
As to handling, the early design can be made to handle nearly as well, but at the cost of ride quality, and it is not inexpensive. The "fixes" to the early design are really bandaids instead of cures.
I have had to repair some of the "fixes" on the market, after seeing some of the design flaws and maintenance needs, I want nothing to do with them.

My fully modded 86 SE will be getting an 88 cradle when the V-8 goes in, in my opinion its more than worth it.

[This message has been edited by olejoedad (edited 08-17-2013).]

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Lou6t4gto
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Report this Post08-17-2013 07:31 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
not to sound like a wise ass, But when you say "There is NO comparison between the ride quality of the two designs, the 88 is FAR superior.
As to handling, the early design can be made to handle nearly as well, but at the cost of ride quality" . If it's Not the "handling", What do you "Mean" ?
A" softer ride" ? I am all in favor of the car "Riding" like a bigger car (Comfort), is That what you mean ??
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fieroguru
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Report this Post08-17-2013 09:15 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

not to sound like a wise ass, But when you say "There is NO comparison between the ride quality of the two designs, the 88 is FAR superior.
As to handling, the early design can be made to handle nearly as well, but at the cost of ride quality" . If it's Not the "handling", What do you "Mean" ?
A" softer ride" ? I am all in favor of the car "Riding" like a bigger car (Comfort), is That what you mean ??


Ride harshness is how much the small bumps or pavement seams are transmitted through the chassis. Take a bone stock 88 and a bone stock 84-87 and run over the same normal roads with some irregularities and most will say the 88 rides smoother. So even with the 84-87 cradle mounted with rubber bushings, they can't overcome the benefits of the solid mounted 88 cradle with the tri-link design.

When trying to get more precise/confident handling, the first mod is to replace the 84-87 cradle bushings with poly or aluminum. This upgrade reduces cradle to chassis movement and deflection, but you start to lose ride comfort and start to feel even more of the road irregularities. If the cradle bushings weren't enough for you, the next normal step is to replace the rubber bushings in the lower a-arm with poly. Again this stiffens up the bushings and reduces compliance for better lateral control, but once again you start to feel even more bumps on the same road. Now with minimal bushing compliance, you still notice the bump steer... You can add one of the available bump steer correction kits to reduce it. At this point you now have something much closer to the stock 88 suspension, but 2 of the mods have negatively impacted ride harshness. So the 84-87 started out with a rougher ride than the stock 88 and you made it worse while trying to match the 88 performance but still haven't addressed the pro squat built into the suspension (it was anti-dive built into the design for FWD application, but it became pro-squat when it was moved to the rear).

So now lets look at the 88. If stock isn't good enough for you, first upgrade is normally poly bushings in the lateral links or going with rod ends. Since the road irregularities will try to push the wheel rearward, nearly 100% of the force is controlled via the trailing link. So if you leave this with rubber bushings, you can pretty much do anything you want to the lateral link bushings to reduce bushing compliance without seeing a significant increase in road harshness... simply because the try-link design separates the fore/aft loads that are key to ride/road harshness from the lateral loads while cornering.

Both years suffer from poor camber gain in the rear, but the 88 starts out with a better curve (as long as you don't lower it). For people seeking optimal on track performance, they have to run significant static camber so while cornering the tire stays as close to perpendicular to the road as possible. This excessive static camber doesn't have a significant impact on road harshness, but it does have a significant impact on tire wear. So a stock 88 will have to run less static camber and will see less irregular tire wear. The 88's also have the option of performing a lateral link relocation either by raising the inboard attachment points on the cradle cutting/welding required) or by using the brackets I designed to relocate the outboard attachment point. Either method increases the camber gain and reduces the static camber needed for the same cornering capability. The 84-87 currently does not have any option of changing the camber curve via the lower-arm without extensive cutting/welding.

Relocating the top of the struts further inboard also helps increase camber gain, but doing it on either chassis requires cutting/welding. However, since the 88 strut towers physically protrude further into the engine compartment, there is more room for the 88's to pull the top of the struts inboard. The further they go in, the more the camber curve increases. The only available strut relocation kits are for the 84-87 and they only relocate the strut to the stock 88 position. On my 88, I have relocated them 1" further inboard, but this isn't a product I normally sell due to the amount of work needed for the installation.

So hopefully after reading all this you can see that the 88 starts out with a better ride than the 84-87, and the 84-87 must give up its ride quality as it tries to match the handling of the stock 88. However, the 88 can be upgraded to improve handling and rear geometry without having a significant change in its ride quality (as long as you keep the trailing link rubber bushings).
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olejoedad
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Report this Post08-18-2013 12:10 AM 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
Very succint analysis.
I applaude you.
Bravo!

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Lou6t4gto
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Report this Post08-18-2013 12:48 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
GREAT Explanation ! Thank You :-)
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