Need help with rear suspension MK 1

[BLUE KNIGHT]

Hi, I bought my roadster back in 95 (?) from someone else ..... I've had it stored for years and now want to up-date it .... # 2972K ... I'm on a serious budget ( I'm 74 ) .... I want a more comfortable ride , and think I can achieve that with softer rear springs .... Has anyone only changed out the OEM Mustang springs ( mine are from a 93 Mustang coupe ) for some with less strength (? ) ..... Does anyone know what the OEM rear springs were RATED at ..... Thanks much in advance ..... I have a few other questions, and will ask those separately as I progress ...... Mike :)

[austinsnake]

A quick search revealed this article which seems to summarize Fox stock spring rates (scroll down a bit in the article) and many alternatives/options.

https://theinfamousproject.com/mustang-oe-aftermarket-spring-rates-comparison-chart-everything-you-need-to-know/

I would guess that coilovers would be a better option that modified springs, but I'm still not on the road with my 3.1 coilover build, so can't say for sure.

Good luck!

Brian

[CraigS]

I would figure out what shocks you have first- brand and model number hopefully stamped on them somewhere. McAffee kept me from looking at the link above so I don't know what it includes. A few things I remember from long ago. When you use OE springs in an FFR you need to cut some off of the top coil. I don't remember how much but there is a chance your springs were cut too much so are stiffer than they need to be. In general, I'd look for shocks and or springs for a 4 cylinder automatic Mustang because I think they will be the softest. If you get to where you want to try shocks, buy the least expensive one you can find. Monroe or similar usually have a couple of shock lines and my experience is the cheapest are usually the softest. Hopefully someone will have the old FFR instructions for cutting the springs they can post.

[PG_Cobra]

If you are suing stock Fox Mustang GT rear springs they are 125-180 lb/in which gives a very soft ride. If your ride is too hard with these springs binding control arm bushes may be your problem if you have control arms with urethane bushes. First step re-grease or replace the urethane bushes. Best of luck

[BLUE KNIGHT]

If you are suing stock Fox Mustang GT rear springs they are 125-180 lb/in which gives a very soft ride. If your ride is too hard with these springs binding control arm bushes may be your problem if you have control arms with urethane bushes. First step re-grease or replace the urethane bushes. Best of luck

Thanks .... in the article ( LINK ) in post #2 .... He mostly refers to " Lowering springs " ..... at the end He lists what the OEM 79-93 spring was ....ie. Rear 185 lb / in rate. with a spring length of 13.5 inches..... I'll look to see if the ones I have, have been cut ...... From what I see the FFR set-up using an OEM spring, the rear height adjustment ( of the car body ) was accomplished by turning the entire spring on the mounting tube attached to the frame. ....I'll investigate further ...... thanks again..... Mike :)

[BLUE KNIGHT]

I would figure out what shocks you have first- brand and model number hopefully stamped on them somewhere. McAffee kept me from looking at the link above so I don't know what it includes. A few things I remember from long ago. When you use OE springs in an FFR you need to cut some off of the top coil. I don't remember how much but there is a chance your springs were cut too much so are stiffer than they need to be. In general, I'd look for shocks and or springs for a 4 cylinder automatic Mustang because I think they will be the softest. If you get to where you want to try shocks, buy the least expensive one you can find. Monroe or similar usually have a couple of shock lines and my experience is the cheapest are usually the softest. Hopefully someone will have the old FFR instructions for cutting the springs they can post.

thanks .... I went to ROCK Auto to see what they had for spring rates ... the 4 cyl. rears were listed at 650 Lbs. ( not in lb/in ) and the 8 cyl. were 580 Lbs. ( not in lb/in ) these measurements were for AC Delco brand .... the other brands didn't state that info ...... I think my shocks are " Monroe-matics, I'll have to check that ..... thanks .....Mike :)

[BLUE KNIGHT]

A quick search revealed this article which seems to summarize Fox stock spring rates (scroll down a bit in the article) and many alternatives/options.

https://theinfamousproject.com/mustang-oe-aftermarket-spring-rates-comparison-chart-everything-you-need-to-know/

I would guess that coilovers would be a better option that modified springs, but I'm still not on the road with my 3.1 coilover build, so can't say for sure.

Good luck!

Brian

I agree " coil-overs " would be better as would an " IRS " set-up .... but money is an issue ..... to be continued ...... thanks .... Mike :)

[ptstew]

Here’s a picture of the page from the FFR assembly manual regarding donor rear springs.
152806

[BLUE KNIGHT]

Here’s a picture of the page from the FFR assembly manual regarding donor rear springs.
152806

Thanks .....all info helps ......... Mike :)