Lowering the Spider

Suspension related stuff goes in here.
Jrscobra
Posts: 64
Joined: Sun Mar 05, 2017 1:14 pm
Your car is a: 1972 Fiat Spider 124

Lowering the Spider

Postby Jrscobra » Mon Jun 26, 2017 10:21 am

I want to lower the spider when it gets on the road.
Ive ordered Competizione 15x7's and 195 50 15's for the car.

Anyone running this set up? Anyone with pics of before and after?

Best Springs for lowering?

narfire
Posts: 3943
Joined: Sat Dec 27, 2008 2:14 am
Your car is a: 1980 124 spider
Location: Naramata B.C.

Re: Lowering the Spider

Postby narfire » Mon Jun 26, 2017 12:07 pm

I have 205/50-15's on mine and I believe the overall diameter is close to the original 13 inch wheels. Where I got the lowering was switching out the KYB's to Koni yellows and I have un-altered IAP reds for springs. Some chop springs to lower, tried that, didn't like the ride and fit. I believe the vendors here offer a progressive spring. But as mentioned the Koni's made the difference in lowering the stance. With the 1" front sway bar as well the handling is terrific ...for a 37 year old car.
80 FI spider
72 work in progress
1978 Toyota forklift
1978 GMC 3/4 PU
2017 Golf R

Jimb
Posts: 662
Joined: Mon May 05, 2008 1:03 am
Your car is a: 1985.5 Volumex

Re: Lowering the Spider

Postby Jimb » Mon Jun 26, 2017 5:08 pm

195/50 15 are stock tire size for my car.

Image
Jim

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azruss
Posts: 3612
Joined: Sun May 30, 2010 12:24 pm
Your car is a: 80 Fiat 2000 FI

Re: Lowering the Spider

Postby azruss » Mon Jun 26, 2017 9:02 pm

195/55/15 will match the original tire OD the best. This will minimize speedo error.

Jimb
Posts: 662
Joined: Mon May 05, 2008 1:03 am
Your car is a: 1985.5 Volumex

Re: Lowering the Spider

Postby Jimb » Mon Jun 26, 2017 9:46 pm

azruss wrote:195/55/15 will match the original tire OD the best. This will minimize speedo error.


But I believe that still depends on the brand. Tires can be all the same size but have significantly different rolling circumferences.
Jim

PhillySpider
Posts: 284
Joined: Tue Apr 26, 2016 6:51 pm
Your car is a: 1980 Spider 2000
Location: New Hope, PA

Re: Lowering the Spider

Postby PhillySpider » Tue Jun 27, 2017 9:14 am

Jimb wrote:
azruss wrote:195/55/15 will match the original tire OD the best. This will minimize speedo error.


But I believe that still depends on the brand. Tires can be all the same size but have significantly different rolling circumferences.
Jim


I don't believe that's the case...the #'s are the #'s. In the example above, 195mm is the width, 55% of the width of the sidewall height, 15" hole diameter (specifies rim size).

Here's a great tool that lets you put in two tire sizes and shows you visual comparisons of size. You enter your stock size (OEM) and the tire you're looking at and it'll give you actual speed comps at 10, 20, 30 etc up to 90 mph. Your 195/55/15 is almost identical to the stock 165/80/13's. Speeds up to 90mph are spot on, though in one mile the stock tire will make 886 revolutions and the 15" tire will make 888. 2 revolutions per mile...the odomoeter will be just about dead on at 1 milliion miles :)

Here's the link to my favorite tool:
https://tiresize.com/calculator/

Jimb
Posts: 662
Joined: Mon May 05, 2008 1:03 am
Your car is a: 1985.5 Volumex

Re: Lowering the Spider

Postby Jimb » Tue Jun 27, 2017 11:05 am

It's my understanding that tires vary in their Treadmill, Traction, and Temperature ratings....and these affect the rolling circumference, which in turn affects the speedometer.
Difference tires react differently to heat and cold...in some cases quite substantially. For example my Tacoma pickup has new tires that are the exact same size as original spec but different manufacturer. The speedometer now shows I'm going about 4 klm/hour faster at 90 than with original tires.
Jim

Jrscobra
Posts: 64
Joined: Sun Mar 05, 2017 1:14 pm
Your car is a: 1972 Fiat Spider 124

Re: Lowering the Spider

Postby Jrscobra » Tue Jun 27, 2017 4:02 pm

Jimb wrote:It's my understanding that tires vary in their Treadmill, Traction, and Temperature ratings....and these affect the rolling circumference, which in turn affects the speedometer.
Difference tires react differently to heat and cold...in some cases quite substantially. For example my Tacoma pickup has new tires that are the exact same size as original spec but different manufacturer. The speedometer now shows I'm going about 4 klm/hour faster at 90 than with original tires.
Jim


I THINK Jimb is right. My 35's on my jeep are more like 34's, but the Tires before measured 35's on the dot. I guess it wont matter any way, I ordered 195 50's and theres no looking back!
Jimb, your car has a great stance! Cant wait to show mine off!

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azruss
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Your car is a: 80 Fiat 2000 FI

Re: Lowering the Spider

Postby azruss » Sat Jul 01, 2017 3:10 pm

Tires do vary. They also change diameter depending on wear, speed, etc. If you go the the tirerack webpage, the give information on tire diameter of various brands and sizes. I used this to calculate what size i needed for 195s. I decided to not go with 205s because I didn't want to give the car a heavier feel than I was already giving it. The 195s definitely give the car a rougher ride than stock. I actually dropped by tire pressure a couple of pounds to help compensate. Running 30 psi in front and 28 in back. Last time i checked the tires it had gone down to 28 in front and 26 in back and still drove great.


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