Rear Sway Bar Question

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RRoller123
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Rear Sway Bar Question

Postby RRoller123 » Tue Jul 11, 2017 11:20 am

I am thinking of adding a rear sway bar.

For those of you who have added a rear sway bar, obviously they keep the car flatter, but I am curious if they cause the ride to deteriorate noticeably, i.e. harsher in the rear? More pounding, worse on potholes, etc? Any noticeable difference, or is it all good?

Pete
'80 FI Spider 2000 (rolling "resto")
'74 X1/9 (many years ago)
'79 X1/9 (fewer years ago)
'86 Jaguar XJ6 (2nd Hobby Car)
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/SB
2015 Keystone Montana High Country 343RL

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AndyVAS
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Your car is a: 1980 Fiat 124 Spider
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Re: Rear Sway Bar Question

Postby AndyVAS » Tue Jul 11, 2017 11:57 am

I've not felt any difference in ride quality.
Andy Phillips
Vick Auto - Technician, Performance Engine Builder & PFI Developer (with ITBs)
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RRoller123
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Re: Rear Sway Bar Question

Postby RRoller123 » Tue Jul 11, 2017 12:19 pm

Thanks, that is good to hear! This is on my upgrade list fer sher.

Pete
'80 FI Spider 2000 (rolling "resto")
'74 X1/9 (many years ago)
'79 X1/9 (fewer years ago)
'86 Jaguar XJ6 (2nd Hobby Car)
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/SB
2015 Keystone Montana High Country 343RL

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chrisg
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Re: Rear Sway Bar Question

Postby chrisg » Tue Jul 11, 2017 1:27 pm

I'd put the rear bar in with lowering the CG of the car as a bit of a must. My '71 does not have a rear bar & once I re-acquaint myself with it's slinky handling, it handles well...clearly, these cars were designed to handle with body roll. Otherwise, I always use rear anti-sway bars in my 124s. I have never noticed that this particular change causes the ride to be harsh, but on the other hand a cushy ride in a 124 sounds like my own concept of a room in hell! There is probably much debate to be made on a larger front bar & you have to remember ride height, springs/shocks & tire width (and aspect) all factor in, but for a rather normal Fiat 124 street machine, I think the rear bar is a must.
Chris Granju
Knoxville, TN
'71 FIAT 124BS (stock, pretty), '72 FIAT 124BC,'76 FIAT 128 Wagon (rat rod), '85 Bertone X 1/9 (FI, efficiency machine) '70 124BC (project,project), 79 X1/9 (hot rod in rehab), '73 124BS (2L, mean), '74 124 Special TC

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RRoller123
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Re: Rear Sway Bar Question

Postby RRoller123 » Tue Jul 11, 2017 2:07 pm

I am running Sumitomo 195/60-14 all around, and the track has been widened both front and rear by ~2.5" (30mm at every wheel, with Serpent Motor Sports' spacers/converted to studs). It sticks really well to the ground with this setup and the stock front bar, so I am not likely to put a larger front sway bar on, but I am interested in reducing the rear inside wheel lift and what that may do for the ride overall.

Obviously it should improve the overall flatness and handling, but the ride is pretty harsh already, even with the front tires down below 30psi. If there were a significant decrease in ride quality, I would probably not do the rear bar. I don't race this car, or even drive it overly hard, but if a rear bar would keep it a little flatter without a lot of consequence, I would be likely to do it.
'80 FI Spider 2000 (rolling "resto")
'74 X1/9 (many years ago)
'79 X1/9 (fewer years ago)
'86 Jaguar XJ6 (2nd Hobby Car)
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/SB
2015 Keystone Montana High Country 343RL

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toplessexpat
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Your car is a: 1976 Spider 1800
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Re: Rear Sway Bar Question

Postby toplessexpat » Tue Jul 11, 2017 10:32 pm

I found doubling up the rear long arms inboard a nice approach that didn't change the ride in a straight line, but tightened up nicely around corners.

One spider runs a thick rear seat, and it's considerably tighter all round.
---
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RRoller123
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Re: Rear Sway Bar Question

Postby RRoller123 » Wed Jul 12, 2017 5:50 am

Do you mean welding in new mounts and adding a second set of trailing arms in back? I am not sure I understand what you are saying.
'80 FI Spider 2000 (rolling "resto")
'74 X1/9 (many years ago)
'79 X1/9 (fewer years ago)
'86 Jaguar XJ6 (2nd Hobby Car)
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/SB
2015 Keystone Montana High Country 343RL

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toplessexpat
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Your car is a: 1976 Spider 1800
Location: Houston, TX

Re: Rear Sway Bar Question

Postby toplessexpat » Mon Jul 31, 2017 9:24 pm

No - put an extra set of arms inside of the existing ones using the same brackets. Add a fender washer to retain the bushing on the very inside (not sure it's essential, but I did anyway), and use longer bolts (ACE sells them)
---
Many classic Fiats - it's a disease!
forum.mirafiori.com

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Odoyle
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Your car is a: 1983 Pinafarina Spider

Re: Rear Sway Bar Question

Postby Odoyle » Tue Aug 01, 2017 12:03 am

I installed an Adco rear sway bar on my 83, of which I think offers some pros and cons. The pros being noticeably better turn in control at all speeds. The behavior of the back end feels more predictable and stable. Cons are the holes you have to drill into the rear frame rails for the u-bolts. Also, the back end seemed to be bucking a little when I let off the gas, and the bar was hitting the lower part of the diff sometimes. Solved the issue by having some spacers made so the bar wouldn't contact the differential. In retrospect, this issue may have been attributed to the US spec rear springs, which throw off the geometry of the car. Also, be careful that you don't put your rear metal brake lines at risk of being crimped when routing the U-bolts over the differential. I saw a post where someone else had done it like that and did the same only to find that the brake line got crimped and had to replace the rear hard lines. And sometimes the the u-shape locating bracket (above metal spacers) shifts away from the u-clamp requiring it to be readjusted. Contacted Adco at one point with some questions/feedback and essential dismissed my assesments. Over all, it a decent addition, considering it's installed correctly.

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johndemar
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Your car is a: 1976 Fiat 124 Spider
Location: Phoenix

Re: Rear Sway Bar Question

Postby johndemar » Tue Aug 01, 2017 8:28 am

My experience is that the ride itself, and far as harshness is concerned hasn't changed at all.
What is apparent is the improved cornering ability, with the rear tires staying flatter with the pavement.
76 Fiat 124 Spider
One owner since July 20, 1976
Amadio Motor, Jeannette, PA

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azruss
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Re: Rear Sway Bar Question

Postby azruss » Tue Aug 01, 2017 2:26 pm

I installed an Addco rear bar 4 years ago. Left the front sway bar stock. Running stock 71 springs in an 80FI. 195/55x15s. I run 29 psi in front 28 psi in back. The ride is harsh due to the tires, not the sway bar. It did take the push out of the car in the corners. (my main objective). It also makes the inside rear tire lift in a hard corner. I solved that by installing a LSD

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RRoller123
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Re: Rear Sway Bar Question

Postby RRoller123 » Tue Aug 01, 2017 2:43 pm

Thanks all for those inputs, that is very helpful. :)
'80 FI Spider 2000 (rolling "resto")
'74 X1/9 (many years ago)
'79 X1/9 (fewer years ago)
'86 Jaguar XJ6 (2nd Hobby Car)
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/SB
2015 Keystone Montana High Country 343RL


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