Coilovers

Suspension related stuff goes in here.
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PMcG

Coilovers

Post by PMcG »

As part of a possible track car build, I've been assessing the viability of coilovers with an adjustable upper control arm for the spider to facilitate ride height, weight balancing, camber and castor adjustments. This is the coilover part - the adjustable UCA is trickier and will come later. Replacement parts for the coilover are all from QA1 - US304 (shock), SS110SDM (stud mount conversion), and 8MB375 (spring). Here's what it looks like on my mule. Total cost $273 from Summit for one side.

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Extended shock - 326mm
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Compressed shock - 239mm. The shock doesn't compress fully because of the bump stop.
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Coilover installed on mule.
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The bottom of the coilover assembly is a bit of a tight fit on the LCA but there is still enough room to adjust the shock. The lower shock mount bolt supplied, is a little big for the mounting hole in the LCA - this will require a bush in the lower mounting shock with the existing bolt or enlarging the hole and using the bolt supplied. There isn't a lot of meat around the hole in the LCA so the bush is probably better. The coilover ring is close to the bottom of the threads here because there is little or no weight on the spring with the engine out. when there is weight on the spring, the coilover ring will be higher up the threads giving more adjustability.
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The spring is a 8" Mustang II coilover spring with 2.5" on the bottom increasing to 3.5" at the top. The existing top mount for the existing spring is a good fit for the Mustang coilover spring. I selected a 375lb which is soft for the track but they are available up to 700lb. I don't know the spring rate for the stock spring.
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The top mount for the shock in the stock location.

Not a perfect solution but I will use this setup when I get to that stage, if I proceed, which is still dependant on coming up with an acceptable adjustable UCA. Would welcome any comments on the coilover or the adjustable UCA.
User avatar
FiatMac
Posts: 290
Joined: Sat Aug 01, 2009 1:14 pm
Your car is a: 1982 2000 Spider
Location: Salisbury, North Carolina

Re: Coilovers

Post by FiatMac »

Stan McConnell
Retired Mechanical Engineer
Salisbury, North Carolina
82 2000 Spider (driving)
78 124 Spider on the rotisserie
76 124 Spider parts car or possible Lemons racer
83 parts car
PMcG

Re: Coilovers

Post by PMcG »

Thank you FiatMac. I have not seen that before. I searched before I started but didn't find that post. Could have saved me a lot of time. Looks like great stuff.
vandor
Posts: 3996
Joined: Sat May 23, 2009 1:23 pm
Your car is a: 1971 124 Spider
Location: Texas, USA

Re: Coilovers

Post by vandor »

I assume you know that neither the upper or lower shock mounts are strong enough to double as spring perches.
The upper mounts would get broken out just from some stiff shocks.
Csaba
'71 124 Spider, much modified
'17 124 Abarth, silver
http://italiancarclub.com/csaba/
Co-owner of the best dang Fiat parts place in town
PMcG

Re: Coilovers

Post by PMcG »

Very good point Vandor. I hadn't considered that sufficiently. The upper spring perch and the upper shock mount are in the stock locations. Would increased shock loads on the upper shock mount be sufficient to separate the mount from the frame? The lower mounting is a much bigger issue as the spring load and the shock load are both going through the lower shock mount, which is already not very solid looking.

Part of this project includes an adjustable UCA which I was hoping to mount in the stock location. Looks like I will have to add a new or modified LCA to the design as well. Hmm.
vandor
Posts: 3996
Joined: Sat May 23, 2009 1:23 pm
Your car is a: 1971 124 Spider
Location: Texas, USA

Re: Coilovers

Post by vandor »

I see now that the upper end of the spring rests on the spring perch, so that should be fine. The shock mount should be ok as long as the shock is not super stiff.
You could easily reinforce the stock lower a-arm so the load is transferred from the shock mount to the spring perch areas.
Csaba
'71 124 Spider, much modified
'17 124 Abarth, silver
http://italiancarclub.com/csaba/
Co-owner of the best dang Fiat parts place in town
Spyderbyte
Posts: 1
Joined: Mon Sep 28, 2015 4:55 pm
Your car is a: Fiat 124 Spider 1978

Re: Coilovers

Post by Spyderbyte »

Hi all, this is my first post and I must say there is some fantastic info on this forum.
Now down to business - has anyone tried or investigated using an early MX5 (Miata) coilover kit on their Fiat Spider?
I have read the details on the QA1 system with great interest, but they are not available here in Germany and I am looking for a local solution.
Cheers, Paul
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v6spider
Posts: 1035
Joined: Tue Feb 28, 2006 6:57 pm
Your car is a: 4.3L V6 Powered 1972 124 FIAT Spider
Location: Mount Vernon WA

Re: Coilovers

Post by v6spider »

That would be me I did the mustang II coil-overs from qa-1.

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The coil-overs are awesome 12 way adjustable dampening and rebuildable. Plus the amount of fab work was minimul as they use the original upper spring buckets. The work to be done is a fab up of the perch on the lower control arm.

Cheers!
Rob
http://www.v6spider.com
4.3L V6 Powered 1972 124 FIAT Spider
User avatar
v6spider
Posts: 1035
Joined: Tue Feb 28, 2006 6:57 pm
Your car is a: 4.3L V6 Powered 1972 124 FIAT Spider
Location: Mount Vernon WA

Re: Coilovers

Post by v6spider »

FiatMac wrote:Have you seen this post?
http://www.fiatspider.com/f08/viewtopic ... ver#p47837
Here the correct link:
http://www.fiatspider.com/f15/viewtopic ... ver#p47837

Looks like I'm not the only one that did this mod..

Cheers!
Rob
http://www.v6spider.com
4.3L V6 Powered 1972 124 FIAT Spider
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