Rear shock absorber install - by VisualKei

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VisualKei
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Re: What did you do to your Fiat lately ?

Post by VisualKei » Thu May 30, 2019 3:00 pm

I just installed a set of Vogtland springs today, Energy poly bumpstops, Energy poly spring isolators (one set, installed at the top. Reused OEM rubber one on bottom of spring), and Bilstein B8's.

People have been doing the budget KYB Gas-A-Just KG5564 rear shock install for a while now. The original application is for the 1984-1987 Corvette without the Z51 suspension package (lowered sport suspension). The KYBs about 3/8" shorter than the stock Abarth shock absorber. For $25 each on Amazon Prime, it's a bargain to improve the factory shocks. It's not going to approach purpose-specific high end street/strip shocks, but it's an improvement over OEM.

Bilstein B8's are the same as their B6 line in design principle--improved sport handling shocks over OEM (Bilstein B4 are OEM direct replacements), but the B8 is slightly shorter and revalved to deal with lowering springs to allow proper spring pretension on the vehicle, while the B6 is meant for installation with OEM-height springs. It's not going to approach Bilstein's higher-end B12/B14/B16/Clubsport stuff by any stretch of the imagination, but it's an improvement over OEM. They aren't much more expensive than the KYB at $50 each on Amazon.

The caveat of this install is one needs to use reducer bushings (a number of them) to shim the eyelet holes down. The bottom eyelets on the shocks require two 16mm OD x 12mm ID x 20mm long oilite bronze or oiless steel, two each (for a total of four). The commonly used one cited for this job is available on Amazon, Dayton 3FJU sleeve bearings. The top eyelets require 12mm OD x 10mm ID x 10mm long bushings in oilite bronze or oiless steel, four each (for a total of eight). Amazon sells these as well. The 16mm shock eyelet should be a gentle press-fit but the 12.1mm eyelet is slightly oversized, so make sure you don't lose your smaller bushings when you're moving stuff around during the install.

By way of comparison, the following are measured Abarth shock lengths:
OEM (used): 14.75" eye-to-eye
KYB Gas-A-Just KG5564 14.375" eye-to-eye
Bilstein B8 24-184588 13.75" eye-to-eye
The Bilstein B8 is a full inch shorter than the OEM Abarth, and mildly shorter than the KYB shock meant for a stock corvette without the Z51.

The ground-to-fender-arch of the car, for those concerned about lowering aesthetics:
front: 24.5"
rear: 25.5" (before)
rear: 24.375" (after)
Difference: 1.125" drop in rear (Vogtlands advertised as 1.4" rear drop)

Energy poly spring isolators are about 1/8" thinner than the OEM rubber, though I have a feeling when you drop the car down, the squish of the OEM rubber puts them at the same height as the thinner-but-stiffer poly units, so I don't think these played any role in changing ride height. If I planned better, I would have ordered two sets and gotten rid of the second set of rubber isolators, but I am not sophisticated enough to tell if these even make any difference.

Energy poly bumpstops are simple to install. OEM bump stops on top just pop out. Energy units install on the bottom of the spring cup. The 8mm (roughly 5/16") hole on the bottom of the spring cup needs to be drilled out to 3/8".

Ride quality: I haven't done a bunch of twisties to see how it compares, but the rear feels more settled, with less roll during jerks or sweepy turns. I was executing emergency braking to break in my rotors/pads last week and the rear end would get squirrely in a straight line from the weight transfer. It still does it with the new suspension components in the rear, but it's less pronounced and doesn't feel like it nose dives as rapidly. The rear feels mildly stiffer and settles quicker when I do an informal push or jumping test on the rear of the car with the hatch open

I haven't remotely had the chance to experience threshold braking while approaching a turn or play with trail braking dyanamics. I also don't have enough skill to allow me to to get into these situations, or the experience to judge the dynamics of the vehicle in such situations. I guess ultimately, I changed some parts and it "feels better" but in a way I can't quantify. It's possibly some part placebo and some part real.

Easy to do. 15mm socket at 52lbft for the top shock mount, E18 socket at 74lbft for the bottom shock mount (I don't know the 12pt socket workaround size, I have an E-torx set laying around). Plenty of room. Minor drilling or enlargening of an existing hole. It took longer to lift the vehicle and dismount/mount the wheels than the actual shock/spring and bumpstop install. Used a jack on the rear beam to get the right height to get the bottom shock eyelet lined up.

This was a relatively cheap experiment, all things considered. $100 for rear shocks, $150 for springs (coupon code), and $25 for bumpstops and spring isolators, so just under $275. I haven't installed the front springs yet, not sure if I want to do it because of the hassle of removing struts and compressing springs, and I don't know if I feel the need to lower the front. I just wanted the rear to feel more confident and I wasn't ready to commit to something like the Bilstein B14 coilover set.
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Mangavideo
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Re: Rear shock absorber install - by VisualKei

Post by Mangavideo » Tue Jul 02, 2019 7:16 am

Great article here
"Initially, it was a search for practicality. Ultimately, it was a decision of Passion"

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MadFiat
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Re: Rear shock absorber install - by VisualKei

Post by MadFiat » Tue Jul 02, 2019 2:27 pm

Awesome writeup.
2015 Rosso Abarth 5MT - MAD FIAT - EC Phase 2 + Supporting Mods
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Rael Nema
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Re: Rear shock absorber install - by VisualKei

Post by Rael Nema » Tue Jul 02, 2019 6:50 pm

Kinda wishing I went for 205/45, now, lol.

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Re: Rear shock absorber install - by VisualKei

Post by RobSmith » Fri Dec 27, 2019 2:33 pm

Thanks for the writeup!
Did you check to see how much clearance you had between the bumpstop and the frame(After you set the wheels back on the ground?)? Did you get a pic by chance?

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MadFiat
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Re: Rear shock absorber install - by VisualKei

Post by MadFiat » Thu Feb 20, 2020 9:12 pm

I have the KYBs on my 500 Turbo.. they're squishy. Wondering if the Bilsteins will get me where I want...

edit:
Just found a set of two for $186 shipped.... sold.
2015 Rosso Abarth 5MT - MAD FIAT - EC Phase 2 + Supporting Mods
2015 Granito Lucente 500T 6AT - Projecto Estupido
2017 Fiat 124 Spider 6MT - Another one???

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Re: Rear shock absorber install - by VisualKei

Post by MadFiat » Sun Mar 15, 2020 11:15 pm

Update: Just swapped from the KYB to the Bilstein on the rear. Swapped the front from stock to Koni. Still on vogtland springs.

World of difference! I would recommend the Bilstein hands down over the KYB. Thanks for the tip.
2015 Rosso Abarth 5MT - MAD FIAT - EC Phase 2 + Supporting Mods
2015 Granito Lucente 500T 6AT - Projecto Estupido
2017 Fiat 124 Spider 6MT - Another one???

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Re: Rear shock absorber install - by VisualKei

Post by texanbrit » Mon Mar 16, 2020 11:07 am

MadFiat wrote: Sun Mar 15, 2020 11:15 pm Update: Just swapped from the KYB to the Bilstein on the rear. Swapped the front from stock to Koni. Still on vogtland springs.

World of difference! I would recommend the Bilstein hands down over the KYB. Thanks for the tip.
Probably should have done the rear shocks on their own, for science. I'm not sure how much influence the front struts have on the rear setup. Glad that you got an overall improvement though.
2013 Abarth 500c (NGen Turbo'd) - Isabella
2012 500 Pop (broken, engine rebuild on hold) - Popabella
2014 500L (Daily workhorse) - The Hulk
2013 Abarth 500 (broken engine, current project) - Abby

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Re: Rear shock absorber install - by VisualKei

Post by MadFiat » Mon Mar 16, 2020 5:19 pm

texanbrit wrote: Mon Mar 16, 2020 11:07 am
MadFiat wrote: Sun Mar 15, 2020 11:15 pm Update: Just swapped from the KYB to the Bilstein on the rear. Swapped the front from stock to Koni. Still on vogtland springs.

World of difference! I would recommend the Bilstein hands down over the KYB. Thanks for the tip.
Probably should have done the rear shocks on their own, for science. I'm not sure how much influence the front struts have on the rear setup. Glad that you got an overall improvement though.
True, but I know that with the KYB's I got a lot of "dip" in the rear that I'm not feeling now.

I think the longer KYB shocks were not letting the lowering springs settle to their natural position honestly. Holding it up just a little bit farther thus the spring compressed more easily. Once it started compressing intertia took over and it would just bottom out.

Whatever the cause, the rear has settled down as much as the front. Though I might try a notch softer on the front Konis, as I you certainly feel the difference in various body parts now.
2015 Rosso Abarth 5MT - MAD FIAT - EC Phase 2 + Supporting Mods
2015 Granito Lucente 500T 6AT - Projecto Estupido
2017 Fiat 124 Spider 6MT - Another one???

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Re: Rear shock absorber install - by VisualKei

Post by texanbrit » Tue Mar 17, 2020 10:05 am

MadFiat wrote: Mon Mar 16, 2020 5:19 pm
texanbrit wrote: Mon Mar 16, 2020 11:07 am
MadFiat wrote: Sun Mar 15, 2020 11:15 pm Update: Just swapped from the KYB to the Bilstein on the rear. Swapped the front from stock to Koni. Still on vogtland springs.

World of difference! I would recommend the Bilstein hands down over the KYB. Thanks for the tip.
Probably should have done the rear shocks on their own, for science. I'm not sure how much influence the front struts have on the rear setup. Glad that you got an overall improvement though.
True, but I know that with the KYB's I got a lot of "dip" in the rear that I'm not feeling now.

I think the longer KYB shocks were not letting the lowering springs settle to their natural position honestly. Holding it up just a little bit farther thus the spring compressed more easily. Once it started compressing intertia took over and it would just bottom out.

Whatever the cause, the rear has settled down as much as the front. Though I might try a notch softer on the front Konis, as I you certainly feel the difference in various body parts now.
My front end is set very soft, seems to keep rubber on the road better that way especially on the uneven road surfaces we sometimes encounter in the hill country.
2013 Abarth 500c (NGen Turbo'd) - Isabella
2012 500 Pop (broken, engine rebuild on hold) - Popabella
2014 500L (Daily workhorse) - The Hulk
2013 Abarth 500 (broken engine, current project) - Abby

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