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88 Rear Strut Relocation - 1" further inboard by fieroguru
Started on: 02-24-2012 06:51 PM
Replies: 22
Last post by: Will on 03-02-2012 03:14 PM
fieroguru
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Report this Post02-24-2012 06:51 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
In my quest for some really wide wheels under a stock fiero body https://www.fiero.nl/forum/Forum2/HTML/120740.html
I pulled the whole upright inboard about 1 5/8" and needed to move the top of the strut so I could set the rear camber at zero. This mod requires conversion to coil overs as the stock springs will no longer fit.

I am reusing the stock 88 spring hats, but needed to shift the bolt pattern 1" to relocate the strut. So some 1/8" steel was welded to one side. The single bolt didn't have enough room to be moved 1", so I moved it 1/2" and will drill a new hole in the strut tower. Here is the modified spring hat:


To keep everything looking clean and tidy, I fabbed up a beauty panel for the top side (this is a 16ga template, the final one will most likely be 1/4" aluminum, or 1/8" steel):


Here is an early mockup showing where the strut will end up:


The top panel needs the strut tower surface to be flat, and I needed to enlarge the hole, so this part got some work:



Test fitting the top panel shows that more material needs to be trimmed away:


As I looked at where the new hole needed to be drilled in the strut tower, it was very close to the larger original hole, so I clamped a piece of aluminum to the bottom side and welded the old hole closed:


Then it was time for another test fit and to review how this mod will look - notice the hat is flipped from stock to gain an additional 1" of strut travel to help compensate for the lower stance:




Here is a stock one:


I think this will look pretty decent once everything is finished and painted. I may reduce the radii around the bolt holes so the inboard end stays flat to the strut tower.

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Alex4mula
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Report this Post02-25-2012 02:29 PM Click Here to See the Profile for Alex4mulaSend a Private Message to Alex4mulaDirect Link to This Post
So now you are going to make us a kit to fit 11" wheels? Super! Will start saving for this one
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mattwa
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Report this Post02-25-2012 02:41 PM Click Here to See the Profile for mattwaSend a Private Message to mattwaDirect Link to This Post
To the untrained eye or a passing glance, it looks stock! Nice work.
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fieroguru
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Report this Post02-25-2012 06:41 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
 
quote
Originally posted by Alex4mula:

So now you are going to make us a kit to fit 11" wheels? Super! Will start saving for this one


Maybe... The 2 upper parts, my rod end lateral link setup (with swaged tubes) and new trailing links would probably be the included components.

The challenge would be the needed shorter axles. For a stock manual fiero (stock transmission, in stock location), I think the axles will be off the shelf parts, but when you get to all the various autos, F40's and various engine placements, then the # of different axles needed (and some would have to be custom) becomes a significant issue.
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Report this Post02-26-2012 04:18 PM Click Here to See the Profile for Alex4mulaSend a Private Message to Alex4mulaDirect Link to This Post
 
quote
Originally posted by fieroguru:


Maybe... The 2 upper parts, my rod end lateral link setup (with swaged tubes) and new trailing links would probably be the included components.

The challenge would be the needed shorter axles. For a stock manual fiero (stock transmission, in stock location), I think the axles will be off the shelf parts, but when you get to all the various autos, F40's and various engine placements, then the # of different axles needed (and some would have to be custom) becomes a significant issue.


You are right. Didn't think about the axles. Not in the mood to change those. Ok. I can still dream about it
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fieroguru
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Report this Post02-26-2012 06:55 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
The passenger side strut tower had the lip ground smooth, but then I realized the dogbone bracket interferes with the top plates. Not an issue, as the dogbone bracket will be getting removed, but it was a delay none the less. I finished up modifying the lower hat for the other side:


Then made the aluminum top plates and welded nuts to the bottom side:



The new look:



For the coil over spring, I am planning to weld some 3 1/2" exhaust pipe to the stock 88 bump stop ring:




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joesfiero
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Report this Post02-26-2012 10:00 PM Click Here to See the Profile for joesfieroSend a Private Message to joesfieroDirect Link to This Post
Very nice work. Too many people dont appreciate the skills of a good fabricator. As I have been teaching myself fabrication (with some help from experienced fabricators) for a few years, its very enlightening to see things like this and really makes me happy that people with your skills are into our little cars.

The ONLY suggestion I have, and this coming from an amateur so take it with a grain of salt, is that instead of cutting down the radii around the inboard hole of your beauty plate, maybe give it a curve down just to follow the curve of the tower. Of course that depends on the thickness of the final material you plan to use, too thick would be difficult to curve.

-Joe
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Report this Post02-27-2012 12:21 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
 
quote
Originally posted by joesfiero:

Very nice work. Too many people dont appreciate the skills of a good fabricator. As I have been teaching myself fabrication (with some help from experienced fabricators) for a few years, its very enlightening to see things like this and really makes me happy that people with your skills are into our little cars.

The ONLY suggestion I have, and this coming from an amateur so take it with a grain of salt, is that instead of cutting down the radii around the inboard hole of your beauty plate, maybe give it a curve down just to follow the curve of the tower. Of course that depends on the thickness of the final material you plan to use, too thick would be difficult to curve.

-Joe


Yes, skills and good tools are very benefitical to an automotive or fabrication based hobby. I like to build stuff and take my time to ensure it looks decent in the end.

I am still torn about the end radius, so I made the aluminum ones the same as the original template. I might give the hanging over end a love tap or two to bend it to match the strut tower. If I do not like it, then I can reduce the radius some. I can't reduce the raduis on all 3 due or it would espose the hole underneath... just one of my many design/aesthetic challanges.
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Report this Post02-29-2012 08:11 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
Finished up welding the 3 1/2" exhaust pipe to the OEM bump stop washer:




You can ignore the cheapo honda springs, I will be getting some 10" 300 ones:

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Report this Post02-29-2012 09:59 PM Click Here to See the Profile for qwikgtaSend a Private Message to qwikgtaDirect Link to This Post
Guru,
From our last conversation about rear struts, I saw that QA1 makes an adjustable rear coilover strut for the 3rd Gen F body

http://www.qa1.net/qa1_moto...uble-adjustable.html

but at almost $950 they are a little steep to still need some fab.

Rob
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Report this Post02-29-2012 10:05 PM Click Here to See the Profile for Tha DriverClick Here to visit Tha Driver's HomePageSend a Private Message to Tha DriverDirect Link to This Post
In img 9915 it looks like you're putting the weight of the car on the rubber bushing. You can't do that (it will ruin the bushing). I like to use a smaller tube inside the spring & I weld it to the upper plate.
~ Paul
aka "Tha Driver"

Custom Fiberglass Parts

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Report this Post03-01-2012 12:19 AM Click Here to See the Profile for KurtAKXSend a Private Message to KurtAKXDirect Link to This Post
Have you figured what effect this will have on the 'wheel rate'? Are you anticipating needing stiffer springs?
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fieroguru
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Report this Post03-01-2012 06:36 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
 
quote
Originally posted by Tha Driver:

In img 9915 it looks like you're putting the weight of the car on the rubber bushing. You can't do that (it will ruin the bushing). I like to use a smaller tube inside the spring & I weld it to the upper plate.
~ Paul
aka "Tha Driver"

Custom Fiberglass Parts


After about 1/8" of compression, the contour of the washer makes contact with the contour of the metal base plate which will then transfer the load from the springs to the base plate directly.
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Report this Post03-01-2012 06:49 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post

fieroguru

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quote
Originally posted by KurtAKX:

Have you figured what effect this will have on the 'wheel rate'? Are you anticipating needing stiffer springs?


The rear spring rate is very close to 100% at the wheel according the the suspension analyzer. The spring rate with my old SBC swap was in the 225 range and with the car lowered I would still bottom out the struts on rough pavement (this was after flipping the spring hat to maximize available travel). The LS4/F40 swap will be less than 100 lbs lighter which is only about a 9% change in rear weight, but I am also adding heavier rotors and wheels. 300 lbs will firm the ride up some more, but still be decent from a ride harshness.
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Report this Post03-01-2012 07:00 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post

fieroguru

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quote
Originally posted by qwikgta:

Guru,
From our last conversation about rear struts, I saw that QA1 makes an adjustable rear coilover strut for the 3rd Gen F body

http://www.qa1.net/qa1_moto...uble-adjustable.html

but at almost $950 they are a little steep to still need some fab.

Rob


I checked out the front struts on the thirdgen and their threaded top attachment is too short to use the stock upper fiero mount and the strut body is 1" longer. Welding on the needed lower flange could fix the length issue (shift the strut down), but on my car with the struts moved inboard, it will have even less clearance between the strut and frame rail. I will probably use the current struts and see how bad the dampening is, then figure out if it is worth the effort to make the thirdgen struts fit.

I would prefer to use lower cost stock replacement struts that were designed around a higher spring rate then spend 2-400 per strut for aftermarket performance... especially if they are going to need lots of rework to make them fit. It is all about balancing cost, performance and ease of application. The lower the initial price, the more willing I am to spend 2-3 hrs per strut making them work. Unless I happen to come across a great combo of parts that would make a conversion financially viable, I probably will not offer a strut upgrade for the stiffer springs.
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Report this Post03-01-2012 12:11 PM Click Here to See the Profile for WillSend a Private Message to WillDirect Link to This Post
 
quote
Originally posted by fieroguru:


After about 1/8" of compression, the contour of the washer makes contact with the contour of the metal base plate which will then transfer the load from the springs to the base plate directly.


Don't think that's such a good idea... that's a very high point load that neither component was designed for... Remember that the dished washers above and below the stock strut hat are only there to capture the end of the strut if the bushing fails.

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Report this Post03-01-2012 12:14 PM Click Here to See the Profile for WillSend a Private Message to WillDirect Link to This Post

Will

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quote
Originally posted by fieroguru:

I would prefer to use lower cost stock replacement struts that were designed around a higher spring rate then spend 2-400 per strut for aftermarket performance... especially if they are going to need lots of rework to make them fit. It is all about balancing cost, performance and ease of application. The lower the initial price, the more willing I am to spend 2-3 hrs per strut making them work. Unless I happen to come across a great combo of parts that would make a conversion financially viable, I probably will not offer a strut upgrade for the stiffer springs.


The Koni struts are designed for stock spring rates. If upping the spring rates, the Konis should be revalved. It's actually not very expensive. FYI.
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Report this Post03-01-2012 01:17 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
 
quote
Originally posted by Will:


Don't think that's such a good idea... that's a very high point load that neither component was designed for... Remember that the dished washers above and below the stock strut hat are only there to capture the end of the strut if the bushing fails.


It is 1/8" thick steel ring pushing on 1/8" steel ring, supported by a 1/8" steel strut tower.
I could reduce the diameter of the inner washer and allow the spring to just rest entirely on the spring hat, but the end result would be very close to the same.
If I see any bending of the washer, I can always weld on an outer extension to the cup portion so it will make contact with the hat around its OD as well as making contact around the center portion.
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Report this Post03-01-2012 01:19 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post

fieroguru

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quote
Originally posted by Will:


The Koni struts are designed for stock spring rates. If upping the spring rates, the Konis should be revalved. It's actually not very expensive. FYI.


I have zero interest in running Koni's
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Report this Post03-01-2012 02:29 PM Click Here to See the Profile for L67Send a Private Message to L67Direct Link to This Post
 
quote
Originally posted by fieroguru:
I have zero interest in running Koni's


Just curious... why?
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Report this Post03-01-2012 06:26 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruDirect Link to This Post
 
quote
Originally posted by L67:
Just curious... why?


Out of the budget and/or not a good fit for the build theme of the car... take your pick.
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Report this Post03-01-2012 07:28 PM Click Here to See the Profile for gtxbulletSend a Private Message to gtxbulletDirect Link to This Post
GURUUUUUUUUUU!!!!!!!!!
Why must you make all these cool add ons!?!?!



tell you what, if I win the lottery, I'll buy one of everything you make

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Report this Post03-02-2012 03:14 PM Click Here to See the Profile for WillSend a Private Message to WillDirect Link to This Post
 
quote
Originally posted by fieroguru:

Out of the budget and/or not a good fit for the build theme of the car... take your pick.


What's the "build theme of the car"?

As *performance* dampers go, the reds that Koni has for the Fiero are actually really cheap.
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