Front spring comparison

Topic: Front spring comparison (Read 5707 times) previous topic - next topic

Front spring comparison

December 03, 2014, 07:12:45 PM

I debating between running one of these two front springs on my Thunderbird. It has a 5.0 with aluminum heads and the smog pump/Thermactor system removed. It does still have functioning A/C. With the stock Thunderbird LX springs front springs and 225/55/16 tires the car has about 3 inches of clearance between the top of the tire and the fender lip. I would like to drop that about 1.5 inches or so. I'm stuck between the MOOG 8598 spring (87-93 5.0 Mustang replacement) or the MOOG 8594 spring (99-04 Mustang GT replacement).

MOOG 8598: http://www.oreillyauto.com/site/c/detail/MOO0/8598/03360.oap?year=1981&make=Ford&model=Mustang&vi=1133446&ck=Search_03360_1133446_-1&pt=03360&ppt=C0361
MOOG 8594: http://www.oreillyauto.com/site/c/detail/MOO0/8594/03360.oap?year=1999&make=Ford&model=Mustang&vi=1354744&ck=Search_03360_1354744_-1&pt=03360&ppt=C0361

Both springs have virtually identical free and installed heights but the 8598 springs have a slightly higher load rating and In/lbs rate. I'm thinking that the 8598 is the way to go but I'd like some thoughts first.

BTW I did use the search function for both of these springs. I couldn't get a concrete answer either way.

Front spring comparison

Reply #1 – December 03, 2014, 11:09:03 PM

Those kind of look basically like stock replacements to me, but with lousy (low) spring rates. It's been a minute since I've had a stock spring in front of me to compare those specs to, but neither would get the green light from me. Those rates look like base/V6 range stuff.

The only upside is that they're linear rate, so if you do go with the heavier of the two, and the car sat a bit high, you could trim the springs a bit (from the bottom) to get the ride height where you like it.

Front spring comparison

Reply #2 – December 04, 2014, 12:01:31 AM

I know V8Demon is running the 8598 spring in the front of his car (5.0 aluminum heads) which is why I've been leaning towards them. Do you have a better suggestion? I'm fine with the stock rear springs but ever since I swapped on the aluminum heads my Thunderbird has sat about .75-1 inch higher in the front.

Front spring comparison

Reply #3 – December 04, 2014, 01:11:00 AM

They're V8 rates. If you're worried about the height on the 8598 you could check out the 8600.

Front spring comparison

Reply #4 – December 04, 2014, 01:17:22 AM

http://rs280.pbsrc.com/albums/kk191/V8Demon/Car%20Tech/MoogSpringsspecsheet-1.png

http://rs280.pbsrc.com/albums/kk191/V8Demon/Car%20Tech/MoogSpringsspecsheet-2.png

I don't know if the links will work as I'm posting from a mobile device.... Lemme know and I'll fix if need be.

Also, from when I did my initial research: http://www.foxtbirdcougarforums.com/showthread.php?19115-TC-springs

Front spring comparison

Reply #5 – December 04, 2014, 11:25:47 AM

Looking through your thread Kitz ran the MOOG 8600 springs with an aluminum headed 5.0. Didn't lower the car much at all (maybe 3/8"). It looks like I'm going to be picking up a set of 8598s. It looks like they should drop the front of my Thunderbird about 1.5 inches, which would be perfect. The 8594 springs look like they would drop the nose way too much. When I swapped on the aluminum heads the nose of the car went up about an inch from the weight reduction. I'm just trying to get it back to where it was with iron heads.

Front spring comparison

Reply #6 – December 04, 2014, 12:27:02 PM

I think you may be happy with Vinnie's setup. His stance is really nice. I don't remember specifics, but I think he had a recent thread on it.

Front spring comparison

Reply #7 – December 04, 2014, 04:21:14 PM

Comparing the replacement springs for an 88 Thunderbird LX:
MOOG 8658: http://www.oreillyauto.com/site/c/detail/MOO0/8658/03360.oap?year=1988&make=Ford&model=Thunderbird&vi=1140310&ck=Search_03360_1140310_3405&pt=03360&ppt=C0361

With the replacement spring for the 87-93 5.0 Mustang (spring V8Demon runs):
MOOG 8598: http://www.oreillyauto.com/site/c/detail/MOO0/8598/03360.oap?year=1981&make=Ford&model=Mustang&vi=1133446&ck=Search_03360_1133446_-1&pt=03360&ppt=C0361

The 8598 springs have the same spring rate and only a 35lb less load rating. Plus the installed height is .75 inch shorter. That should be enough to drop the nose of my Thunderbird down 1-1.5 inches. Exactly what I'm looking for. I think I'm going with the 8598 spring unless someone has a better idea.

Front spring comparison

Reply #8 – December 04, 2014, 06:55:39 PM

Couldnt you just trim a little of the current springs you have?????

= free

Front spring comparison

Reply #9 – December 06, 2014, 11:07:00 AM

Quote from: mcb82gt;441314

Couldnt you just trim a little of the current springs you have?????

= free

From what I've read that screws with the spring rate. Plus new parts are cool

Front spring comparison

Reply #10 – December 06, 2014, 11:29:21 AM

That is only if the springs are progressive rate. If they are a linear rate spring then chop away.

Darren

Front spring comparison

Reply #11 – December 06, 2014, 11:42:05 AM

Quote from: Aerocoupe;441355

That is only if the springs are progressive rate. If they are a linear rate spring then chop away.

Darren

Ah that's how it goes. I'm still going to get the 8598 springs though. With basically the same load rating and rate and being .75" shorter they should do exactly what I want them to.

Front spring comparison

Reply #12 – December 07, 2014, 07:31:07 PM

There are so many different spring rates.from the factory depending on option packages one would have to consult there door tag and get a hold of some info on stock spring rates and part numbers direct from Ford. AFAIK, this has not been done for our particular cars. Closest thing I can find is that Moog chart I posted.

Example: The 2005 Mustang had SEVEN different front springs that it could possibly have come with depending on engine, transmission, and other options. The end goal was to make height as close as possible across the line for all of the different combinations.

Front spring comparison

Reply #13 – December 07, 2014, 10:06:55 PM

That's the thing I'm not sure exactly what springs are in my car. All I know is that the MOOG replacement ones are close to the 8598 springs but the 8598 springs are about .75 inches shorter. Hopefully that lowers the front 1-1.5 inches (lowering the gap between the top of the tire and fender from 3 inches to 1.5-2 inches, matching the rear).

Front spring comparison

Reply #14 – December 27, 2014, 08:58:22 PM

Just for comparison purposes: MOOG 8598 springs on the left, 88 Thunderbird Turbo Coupe with automatic springs on the right.

They are almost the same height.