Reccomendations for new rear leaf springs?

65ShelbyClone · Nov 17, 2006

I looked around and found some threads similar to what I want I want, but not exact. I don't want to hijack any old threads, so I have a question here. I am looking to do a Trans-Am style weekend fun car that will see some street miles. I already have KYB Gas-A-Just shocks and a 1.125" front swaybar installed. Sitting on my shelf are 620lb front springs and very soon I will do at least a 1" A-arm drop with Granada discs.

What type of conventional(not mono) leaf spring would you all reccomend for my car? It won't be a daily driver, but I don't want the springs to be tooth-rattling either. Stiff is alright, but not harsh. I see a lot of mention on the 4.5 leaf mid-eyes. What about a 5-leaf mid-eye? All opinions are welcome.

19stang66 · Nov 18, 2006

I have the exact same suspension setup you have, I went with the 5 leaf mid-eye leafs and I love the ride and the handling is amazing, but my rear sits a little high.

65ShelbyClone · Nov 18, 2006

One of the biggest handling improvements I've ever experienced is from the big front swaybar. I had the same 1.125" on my old '65 notch and it made up for a lot of shortcomings in the suspension.

The tough call is that lots of people may have the same rear springs on their cars, but all of them sit differently(same with the fronts). I'd rather not resort to lowering blocks.

C0V3R · Nov 19, 2006

For something unusual (although mono) I'd recommend flex-a-forms on my experience so far

Rapid · Nov 19, 2006

19stang66 said:
I have the exact same suspension setup you have, I went with the 5 leaf mid-eye leafs and I love the ride and the handling is amazing, but my rear sits a little high.

I am set up about the same way and am running a rear bar as well. I am very pleased with the result. I am renting a 2006 while my 65 is at the body shop and the handeling to ride ratio is better on my 65. I will be adding sub frame connectors over Christmas so that may stiffen it up more.

Red Barchetta · Nov 19, 2006

C0V3R said:
For something unusual (although mono) I'd recommend flex-a-forms on my experience so far

There's a gent who lives in Australia on another forum I frequent who has a '66 fastback with the flex-a-forms and swears by them. I'm interested in hearing more about your experience to compare to his.

How exactly do you have your rear suspension setup? Are you using anything to locate the axle laterally other than the leafs? Are you using standard shackles? What spring rate are you running? Do you have a rear bar? Essentially, I want to know it all!

I too have a '68 coupe and I'm trying to figure out what I'm going to do with the rear. I plan on open tracking the car so I already have an EvM Watts link waiting to be installed, but I need to sort out exactly what I'm going to do before I start just slapping things on.

65ShelbyClone · Nov 19, 2006

Red Barchetta said:
How exactly do you have your rear suspension setup? Are you using anything to locate the axle laterally other than the leafs? Are you using standard shackles? What spring rate are you running? Do you have a rear bar? Essentially, I want to know it all!

I too have a '68 coupe and I'm trying to figure out what I'm going to do with the rear. I plan on open tracking the car so I already have an EvM Watts link waiting to be installed, but I need to sort out exactly what I'm going to do before I start just slapping things on.

Are you asking me or C0VR3R?

1965-Mustang · Nov 19, 2006

I have Maeir Racing 4.5 low rear leaf springs with KYB shocks. I live in the North East which means pot holes and the ride is fairly harsh when you hit them but the handling is a lot better than the original equipment. I would recommend them.

Red Barchetta · Nov 19, 2006

65ShelbyClone said:
Are you asking me or C0VR3R?

Sorry if I wasn't clear. I was asking COVR3R as I'm interested in the glass leafs.

washMO66 · Nov 19, 2006

I have the five leaf reverse eye and the rear stance is right and the car handles pretty well with the 620's up front, sway bars, TCP uppers (shelby drop) and rack & pinion steering. The ride is pretty stiff in the rear but for a weekender not overly harsh.

palerider94 · Nov 19, 2006

Based on previous post I did I went with 4 1/2 leaf with Grabatrack shocks. I wanted a good balance between comfort and handling. I heard that the kyb makes the ride a little too harsh. I will use 620s with kyb and bearing roller perches up front. Plan on putting on this week - I'll post results.

C0V3R · Nov 20, 2006

Red Barchetta said:
There's a gent who lives in Australia on another forum I frequent who has a '66 fastback with the flex-a-forms and swears by them. I'm interested in hearing more about your experience to compare to his.

I assume you mean booboofoo. I took the punt based on his feedback.

Red Barchetta said:
1) How exactly do you have your rear suspension setup?
2) Are you using anything to locate the axle laterally other than the leafs?
3) Are you using standard shackles?
4) What spring rate are you running?
5) Do you have a rear bar?
Essentially, I want to know it all!

1) FAF's lowered 1.5in from stock. Koni red adjustables somewhere close to the softest setting. One or two off IIRC. KMAC Rear swaybar (not fully tightend up yet). 17x8x225 wheel/tyre combo
2) No
3) Yes
4) 225 I think, I didn't specify when I ordered. The springs have the numbers 225 and "Mustang" written on them.
5) Yes. I put it on after the FAF's. Not sure if it has added to or detracted from the ride yet. Its not fully tightened up as far as it can go.

Red Barchetta said:
I plan on open tracking the car so I already have an EvM Watts link waiting to be installed, but I need to sort out exactly what I'm going to do before I start just slapping things on.

I took the car to a track day before with the old shot springs. I'll be going again on dec 14 with the new setup.

Summary - bad road surface feels way way better than before with less banging/etc - my passengers noticed the difference. Seems to be alot more responsive. Is well balanced with my RRS coilover front end. If I did them again I might go a touch softer, but I havent played with my shocks yet.

SoCalCruising · Nov 20, 2006

65ShelbyClone: If you go to a 5-leaf rear spring, use a soft-valved shock to get a decent ride. I use Global West 1" de-arched 5-leaves (and 1" lowering block) and CureRide shocks (sold by GW). Nice combination. Reverse eyes are great, so long as your tire size isn't too large (tire rub could be a problem). Good luck.

65ShelbyClone · Nov 20, 2006

SoCalCruising said:
65ShelbyClone: If you go to a 5-leaf rear spring, use a soft-valved shock to get a decent ride. I use Global West 1" de-arched 5-leaves (and 1" lowering block) and CureRide shocks (sold by GW). Nice combination. Reverse eyes are great, so long as your tire size isn't too large (tire rub could be a problem). Good luck.

Are the KYBs "soft?" The only other shocks I've ever had on an early Mustang were regular old Monroes, so I haven't done much first-hand comparing. My KYBs are brand new, so I'll probably use them anyway.

As for tire size, I don't forsee using anything bigger than a 15" wheel and 9" wide tires. I have 225/60/R15s F/R right now which are 8" at the tread and 9" total section width. I don't know what too large is, but I do know I' d like to avoid flares.

SoCalCruising · Nov 20, 2006

I think those tires are fine. I run 225/50-16s and these have a wider tread and are okay. KYBs are harsh when teamed with a stiff spring. The GR2 would be a better choice, IMHO. If you use the KYB (Gas Adjust) and the ride is too harsh, don't blame the springs, change the shocks. The GW aprings are the beefiest 5-leafs I've seen and they are fine with a soft valved shock. Of course, Koni adjustables are a great way to go, but $$$.

Red Barchetta · Nov 22, 2006

C0V3R said:
I assume you mean booboofoo. I took the punt based on his feedback.

Yes, I read about Ive's setup over on C-C.com. As credible as he is , I'm just trying to get as much feedback as possible.

C0V3R said:
1) FAF's lowered 1.5in from stock. Koni red adjustables somewhere close to the softest setting. One or two off IIRC. KMAC Rear swaybar (not fully tightend up yet). 17x8x225 wheel/tyre combo
2) No
3) Yes
4) 225 I think, I didn't specify when I ordered. The springs have the numbers 225 and "Mustang" written on them.
5) Yes. I put it on after the FAF's. Not sure if it has added to or detracted from the ride yet. Its not fully tightened up as far as it can go.

I took the car to a track day before with the old shot springs. I'll be going again on dec 14 with the new setup.

Summary - bad road surface feels way way better than before with less banging/etc - my passengers noticed the difference. Seems to be alot more responsive. Is well balanced with my RRS coilover front end. If I did them again I might go a touch softer, but I havent played with my shocks yet.

Thanks for the feedback. One thing people don't take into consideration about leaf springs is spring rate. All they talk about is 4 leaf vs 4 1/2 leaf, vs 5 leaf, but never about spring rate. Do they even list the spring rate for most leafs? The only company I know that lists spring rates is Maier Racing. I've seen 160's, 165's and 200 lb springs.

225 sounds on the high side, but I've also heard that a 225 glass spring is like a 160 steel spring. Though I wonder if going with slider shackles would help, especially compared to delrin or urathane bushings. I'm of the "soft spring, tune with sta-bar" school of thought on suspension setup so I'm trying to get an idea what spring rate people are running with glass springs.

Cheers!

Sebastien

palerider94 · Nov 22, 2006

Just swapped out leaf spring yesterday - 4 1/2 leafs, standard eye with Grabatrack shocks. Grabatrack are made by monroe and are supposely softer than KYBs. Got recommendation from Opentracker who frequents this site. Right on the money - ride is firm but not too harsh. Took over a rough road and it handled well did not bounce around and was not teeth rattling - good ride.

66HertzClone · Nov 22, 2006

I used a set of four leaf 138# springs bought from NPD. These are 1" drop and my 225/50 x 16 tires are close but do not rub. I used the KYB gas a just shocks and do not find the ride harsh. I installed the G/West del a lum bushing kit in these springs, according to G/West these take the place of a rear sway bar.

Red Barchetta · Nov 22, 2006

66HertzClone said:
...I installed the G/West del a lum bushing kit in these springs, according to G/West these take the place of a rear sway bar.

Really? That's reason enough right there not to buy anything from G/West as by the sound of it, that person doesn't really know what they're talking about. Bushings do not take the place of a rear bar, nor does a rear bar take the place of bushings.

What's really happening is you're changing the overall spring rate of your suspension by switching to del-a-lum bushings. It's a compromise since the del-a-lums help with lateral location, but at the trade off of increase spring rate. It would be interesting to hear your feedback if you were to switch to slider shackles or normal rubber bushings.

65ShelbyClone · Nov 22, 2006

SoCalCruising said:
KYBs are harsh when teamed with a stiff spring. The GR2 would be a better choice, IMHO. If you use the KYB (Gas Adjust) and the ride is too harsh, don't blame the springs, change the shocks. The GW aprings are the beefiest 5-leafs I've seen and they are fine with a soft valved shock. Of course, Koni adjustables are a great way to go, but $$$.

I figured the Gas-A-Justs would be. Even on sacked-out stock springs they really stiffened things up. Do you have a nice side and/or profile shot of your car's rear height? I'll probably bite the bullet and get 5-leaf mid or reverse eye rears anyway, but I'd like to get the rear height as close to right as I can without blocks.

Reccomendations for new rear leaf springs?

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