shock absorber selection

68er · Nov 29, 2009

lets see if you guys can steer me in the right direction, i am in the process of rounding up parts for a suspension upgrade on my 68 convertible & trying to decide which brand of shocks to buy.

the brands i am considering are:
kyb gas-adjust
koni
edelbrock

a little background on my setup:

the car is mostly driven on the street, and occassionally drag raced/driven hard enough to drift a corner when the situation allows it. i already did a 4 wheel disc conversion, with a set of 17/9" wheels. it has a 9" posi w/under rider traction bars, export brace, montycarlo bar, new ball joints, tie rods, and idler arm, etc....

the plan is to lower the upper control arms 1 inch and probaby just cut the coils a little ('70 boss handling guide says 1 coil) i also will install a 5 leaf/1" drop springs in the back with a sway bar. as well as all the free welding reinforcments in the '70 boss guide, along with a set of subframe connectors and new shocks.
so far i have everything except the sub frames and shocks.

any tips/advice?

Helmantel · Nov 30, 2009

I don't have personal experience with KYB's but many say that they're really harsh. I use Konis myself, which I like, but other than a pair of worn out Midas replacements, I don't really have anything to compare them with.

IIRC, the cutting of one coil, as mentioned in the Boss book, applies to the recommended spring. I believe that is a standard Ford spring for some other application that, when one coil is cut, results in a 600 lb/in lowering spring for the Boss/Mustang. Cutting your stock springs may not give the same result.

Also, the five leaf rears may be a little stiff, especially if you plan just to cut the stock fronts. If you are going to use them, I would try it without a rear sway bar first. The extra leaf already reduce the roll in the rear and making things extra stiff may result in more oversteer than you like. Oversteer is fun when predictable, but not so fun in a fast corner when you didn't expect it

tx65coupe · Nov 30, 2009

I have KYB gas adjust on mine and am happy with them. They are a good performance shock for the price. The KYB GR2 is softer so its less stiff.

I hear many people like the Koni shocks, but they are more expensive.

I don't know about the Edelbrock shocks for our application, but I have heard good things about them in general.

2+2GT · Nov 30, 2009

the brands i am considering are:
kyb gas-adjust
koni

Having used both, I can tell you the Koni is MUCH stiffer than the Kayaba Gas-A-Just, I moved to PA from FL, where I had Konis for years. I couldn't stand the harshness on the bad roads here, yanked the Konis, and sold them

edelbrock

If you mean the IAS, I've never used them on a Mustang, but I hear good things

a little background on my setup:

the car is mostly driven on the street, and occassionally drag raced/driven hard enough to drift a corner when the situation allows it. i already did a 4 wheel disc conversion, with a set of 17/9" wheels. it has a 9" posi w/under rider traction bars, export brace, MonteCarlo bar, new ball joints, tie rods, and idler arm, etc....

the plan is to lower the upper control arms 1 inch and probaby just cut the coils a little ('70 boss handling guide says 1 coil) i also will install a 5 leaf/1" drop springs in the back with a sway bar. as well as all the free welding reinforcments in the '70 boss guide, along with a set of subframe connectors and new shocks.
so far i have everything except the sub frames and shocks.

I'd do the upper arms alone, and see if you like the results first. Then, if you want to go lower and stiffer, do the 5-leaf and coil cut. It's gonna get harsh. I'd probably like it, but it's not for everybody.

rbohm · Nov 30, 2009

in regards to the shocks, the konis are the best, though expensive. they are fully adjustable and are designed to be set at full soft initially and adjusted as they wear. they are also rebuildable.

the KYB's are very good shocks, some have complained that they are too stiff, but i havent found that to be true.

the edelbrocks i have heard good things about, but never used them.

coolblue65 · Nov 30, 2009

you may also want to consider Bilsteins, I just switched from KYB's to them and I am happy with the change. Still very stiff, but not quite as bouncy as the KYB's.

2+2GT · Nov 30, 2009

rbohm said:
the KYB's are very good shocks, some have complained that they are too stiff, but i havent found that to be true.

Location: tucson,az/luray,va

You haven't driven the roads around here, I'm guessing. I used the Konis for over 5 years in FL, but 6 months in PA and I was done.

bocksta · Nov 30, 2009

I just installed Bilsteins in my 66 convertible. Only did the rear shocks as i have coil overs up front . I'm very happy with them. I live in New England an the roads are bad , very bad. They ride great.

RGS0907 · Nov 30, 2009

tx65coupe said:
I have KYB gas adjust on mine and am happy with them. They are a good performance shock for the price. The KYB GR2 is softer so its less stiff.

I hear many people like the Koni shocks, but they are more expensive.

I don't know about the Edelbrock shocks for our application, but I have heard good things about them in general.

I put new KYBs in this year & they feel pretty good to me as well.

65ShelbyClone · Nov 30, 2009

I have Kayaba Gas-A-Justs in my '68 with sacked-out 41-year-old springs. They seem a little harsh only on sharp, fast bumps like potholes. I also have a 1.125" front swaybar and that adds a little harshness, but together they are not uncomfortable. I have heard numerous times that the KYBs are better with performance springs. I guess that's good because I have Grab-A-Track 620 coils ready to go in and five leaf mid- or reverse-eye leafs planned.

jcp123 · Nov 30, 2009

5-leafs will be pretty stiff, I run the 620's up front with 4.5 mid eyes out back and KYB's all around. I found the ride to be pretty well on the stiff side, though not uncomfortable by any means. The handling is pretty good. Smaller bumps seem to get absorbed much more gracefully, as 65Shelby alluded to. There's still a tad bit of wallow on sudden steering inputs though. This setup shines on the highway, it loves the 60-75mph range. Overall I think it strikes a good balance if the car's a driver at all. IMHO the 5-leafs will be too much unless you're planning to make a road racer or autocrosser out of the car.

I had some air shocks in the back of my '68 Hardtop (brand unknown, had the KYB's up front) and they seemed to do pretty well, rode a little better but didn't help the wallow. They're more useful if you're loading your car up for vacations all the time though.

rebel65 · Nov 30, 2009

I got the full Grab-A-Track thing, i already had a better/bigger Front sway bar so i didn't install that, but:
i got the 750 Big Block Springs ( accidentally ) chopped a bit to get the car from looking like it has no engine in it to about level with the 4.5 Leaf Mid eye's. and now it's sitting about....as high as my car did before! prolly 1/2" lower but that would also be due to a different tire/wheel selection, PO did the 'shelby drop' the normal stuff. it has the KYB's and i concur that they are nice and stiff but sometime bouncy. so if you are looking for lower than what your car looks now go for the reverse eye, i recommend the 4.5 leafs they are pretty crazy stiff : ). really ties up the rear very well.

68er · Dec 1, 2009

jcp123 said:
5-leafs will be pretty stiff, I run the 620's up front with 4.5 mid eyes out back and KYB's all around. I found the ride to be pretty well on the stiff side, though not uncomfortable by any means. The handling is pretty good. Smaller bumps seem to get absorbed much more gracefully, as 65Shelby alluded to. There's still a tad bit of wallow on sudden steering inputs though. This setup shines on the highway, it loves the 60-75mph range. Overall I think it strikes a good balance if the car's a driver at all. IMHO the 5-leafs will be too much unless you're planning to make a road racer or autocrosser out of the car.

I had some air shocks in the back of my '68 Hardtop (brand unknown, had the KYB's up front) and they seemed to do pretty well, rode a little better but didn't help the wallow. They're more useful if you're loading your car up for vacations all the time though.

sound like a consensus for the most part...

i'm a little confused now about my leaf springs now....they are definitly a mid-eye type, but what do you mean by 4.5? ... i got'em off craigslist in like-new condition - mostly because the old ones are so worn out that it looks live i have a trunkload of dead bodies in there.

i wonder how it would be if i took the little leaf out?

68er · Dec 1, 2009

2+2GT said:
I'd do the upper arms alone, and see if you like the results first. Then, if you want to go lower and stiffer, do the 5-leaf and coil cut. It's gonna get harsh. I'd probably like it, but it's not for everybody.

i suspect you are right...

i'm going to put the leafs on 1st, then set the weight back on it, and try to determine how much coil spring to remove if any. i've read that a 1" uca drop nets @ 5/8" lower stance. that may be ok...a slight rake looks pretty cool.

Bocksta's '66 looks badass! if mine winds up sitting like that, i'll be pretty happy.

tx65coupe · Dec 1, 2009

jcp123 said:
5-leafs will be pretty stiff, I run the 620's up front with 4.5 mid eyes out back and KYB's all around. I found the ride to be pretty well on the stiff side, though not uncomfortable by any means. The handling is pretty good. Smaller bumps seem to get absorbed much more gracefully, as 65Shelby alluded to. There's still a tad bit of wallow on sudden steering inputs though. This setup shines on the highway, it loves the 60-75mph range. Overall I think it strikes a good balance if the car's a driver at all. IMHO the 5-leafs will be too much unless you're planning to make a road racer or autocrosser out of the car.

I had some air shocks in the back of my '68 Hardtop (brand unknown, had the KYB's up front) and they seemed to do pretty well, rode a little better but didn't help the wallow. They're more useful if you're loading your car up for vacations all the time though.

I just wanted to say do not ever run air shocks. The shock mounts are not designed to support weight and the air shocks can break through the mount into the trunk.

bocksta · Dec 1, 2009

for the rears

If your thinking about racing the car you may want to checkout the rancho's @ Calvert Racing - The Leader in Leaf Spring Innovation . They look adjustable and you could setup you car how you want when you want.
I did alot of looking at the different shocks available before i bought the Bilstiens .If i thought i would have raced it more i would have gone with the Rancho's for the rear shocks.They are more for racing an not for the street handling comfort from what i read.
Thanks for the comments

66forfun · Dec 1, 2009

2+2gt
I am curious if you adjusted the konis before throwing in the towel on them. I run them with the 4.5 mid eyes and the 620 1" drop front coils in PA and love them, they needed dialed in though.

S-Car-Go · Dec 1, 2009

I had the eddys on my car and switched to Bilstiens. Loved the improvement. Currently I wouldn't use any other shock. I've used kybs and konis on other cars. If you go gas-adjust, go with a softer shock in the back like GR2.

I didn't like the underrider bars in the corners and pulled them off. I'm using Maeir leafs, but Cobra Automtive makes a shock/spring that replaces the bar so it doesn't bind. Looks interesting.

I have GW sub frame connectors and they are ok. Miaer didn't make any for convertibles at the time. Their SFC have more attachment points and they now make them for convertibles. I'd go that route if I were to do over.

Last, be careful with "620" springs. Some are 620 lb per inch of crush, others are more like 525 and called 620. Find out the crush rate before making the final decision. I'm using some 525 lb/in and love them (I think Mustangs Plus sells 620 that are really rated at 525 or 540). The real thing can be considerably stiffer depending on shock.

65ShelbyClone · Dec 1, 2009

Shortening the coil will also increase the rate.

jcp123 · Dec 1, 2009

tx65coupe said:
I just wanted to say do not ever run air shocks. The shock mounts are not designed to support weight and the air shocks can break through the mount into the trunk.

Hmm, didn't know that. Mine were on the car when I bought it, so I just stuck with those. Only shock mount trouble I had was up front...all that Portland rain where the car used to live finally caught up to it when I bounced over a railroad track

68er said:
sound like a consensus for the most part...

i'm a little confused now about my leaf springs now....they are definitly a mid-eye type, but what do you mean by 4.5? ... i got'em off craigslist in like-new condition - mostly because the old ones are so worn out that it looks live i have a trunkload of dead bodies in there.

i wonder how it would be if i took the little leaf out?

The 4,5 leaf spring actually isn't much softer than the full 5-leaf. IIRC, the four leaf is about a 160# spring rate, the 4,5 is 180#, and the 5-leaf is 195#. On a 4,5 leaf, you'll have four regular leafs and then a small one at the bottom that only goes through one of the three clips that hold the leafs together. It actually looks a lot like a 5-leaf. Take the half leaf out and I presume it'd be just like a 4-leaf, probably a pretty comfortable ride.

shock absorber selection

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