SLA VS Mcpherson

[Mr Joshua]

Searching for this type of thread is near impossible. Too many people use acronyms, thus most VBB sites not supporting that, or anyone tagging the results i'm after has resulted in the creation of this thread. Which might be the first of many on this particular subject. So...

I can only find two companies that carry an SLA package. Agent 47 being one
http://www.agentfortyseven.com/Fox/Fox_suspension.html
and
http://www.griggsracing.com/index.ph...4359_2015_3260
Both offer similar support.. But what i'm after is the differences between the SLA and the McPherson.. A well thought out SLA setup VS Mcpherson with Coil overs, tubular A-Arms 96+ spindles, tubular K-member (pushing the wheels further forward) etc.. I'd be more swayed by the griggs setup, but i'm offput by their lack of an updated website and rumors of horrendous tech support.
So school me in the reasons for or against SLA and Mcpherson.

[wraithracing]

I will say that the Agent 47 unit is an excellent unit and has set track records at most of the tracks in NASA where they run for their class of either American Iron or American Iron Extreme. So in a competition environment it can be worth it.

The biggest downfall for Macpherson Strut (MS) is that it was originally designed for small lightweight vehicles and intended in most cases for FWD. With that said, you can make a MS suspension handle very well. The problem with the Fox MS is that it is a modified setup. Normally the spring is on the strut (coil over). The Fox setup has friction issues because of the lower control arm location and how the spring sits in the lower control arm. The wheel rate on a stock Fox is @ 25% of the spring rate where a CO is @ 90% and similiar rates apply for a SLA. If you look at the difference in spring rates between a racing fox with regular springs and one that switches to CO the difference is huge. Many road racers use up to a 800 lb springs with stock spring locations, but that relates to @ 200lb wheel rate. But switching to CO allows the spring rates to drop to 350 lbs that equals a 315lb wheel rate. This is due to the fact that with a CO you get a more direct spring rate where the stock setup loses alot of wheel rate due to the motion of the spring. So with a CO you can get better handling using lighter springs and a better ride. The same holds true for the SLA. You get better spring and wheel rates. In addition the camber curve is usually more adjustable. The other advantage to the SLA is the deletion of the shock towers too.

Keep in mind that a SLA is a Short Long Arm suspension where the upper A arm is shorter than the lower A arm. This again is to improve the camber curve and handling of the suspension.

Is it worth spending the money to convert a Fox to a SLA. "How Fast do you want to go?" If you are a road racer and the very edge of the capabilites of your current setup, then yes! You will go faster with a well sorted out SLA than a modified Fox MS. Although in most cases the difference is a couple of tenths to a couple of seconds for someone that can drive the wheels off a good RR Mustang. Are those precious seconds worth the @ 5K price tag? Only you can answer that.

You can make an excellent handling and riding Mustang/Fox by installing the full compliment of Griggs or Maximum Motorsports equipment on the MS setup. The Coil overs make the largest improvement IMHO as to ride quality. Add all the other parts such as CC plates, tubular arms, tubular K, bump steer kit, better spindles, and brakes now you have one bad ass Mustang! The nice thing about MM is that you can piece a system together as funds and time allow. The support is excellent, the parts are high quality and proven, and price wise they are as good or better than either Griggs or Agent 47 IMHO.

Trey

[Mr Joshua]

problem with the agent 47 unit is i run into posts like these.
http://www.moddedmustangs.com/forums...uspension.html

[onebad93LX]

I have an SLA front suspension and Watts Link rear. Handles likes rails, horrible ride on bumpy roads.

Mine was originally built by Corey Shaw and was called the Contex Control Suspension..

http://www.mustang50magazine.com/how...tem/index.html

i believe Maximum Motorsports bought the rights..

[Mr Joshua]

That is amazing. I love the way they designed the rear setup. But the front has me intrigued. The mounting to the spindle by using the old strut mounts is nifty. Using a body that looks like an old strut w/ a ball joint mount at the top. I'm not sure i like the design of the ball joint receptacle. But it's thinking outside the box.
I'm still not liking any one design. I like MM's beefy K member, but they don't offer an SLA setup. Both the Griggs and Agent 47 use A frames on top of the mounting bolts for the K-member to the top of the sub frame. I just wish there were more options.

[mustanghammer]

A properly desinged SLA will have a better camber curve, better scrub radius and will support a lower ride height while maintaining proper geometry. Ask the manufacturers how they compare to an optimized strut front end.

From what I have seen these are bolt in kits that have to work within the space provided by the factory strut tower, frame rails and k-member. This may compromise the location and length of the control arms. So, despite the superior design they may not work as well as they could.

Where are you racing and what class are you looking at? I may know someone you can talk to.

I ran a pretty serious strut front end on my C Prepared solo mustang. It had 2.5" drop spindles that I made using Baer modified Fox A Sedan spindles. This allowed me to lower the car a significant amount while keeping the front end in perfect geometry. The suspension had near perfect bump steer and even had a little camber gain but nothing like a good SLA.

Regarding spring rates on OE mustang strut front end. We calculated the ratio to be closer to 50% - spring rate vs wheel rate. You can get more than enough spring on strut mustang in the stock location as there is plenty of room and high rate 5" coil springs are easy to get. To make my mustang work with 12" wide racing tires I ran 1650lb springs on the front in the stock location. The stiff springs worked as long as they were matched to good struts and the proper rear spring rate. A really stiff chassis is also necessary - my car had 26 point roll cage.

[RichV]

I think Global West has some options as well. I remember seeing some stuff on display at SEMA.

This/these type of suspension modification(s) is/are for track cars IMO. It will not ride well on the street. Like Trey stated, is it worth $5K for those seconds on the track? possibly. But you will definitely not improve ride on the street.

[85GT-79FJ40]

Another thing to consider is the availability of replacement parts 5-10-20 years from now. This could be way more inconvenient than something like a now-discontinued wheel if you ever had an accident sometime in the future.

[Mr Joshua]

A properly designed SLA will have a better camber curve, better scrub radius and will support a lower ride height while maintaining proper geometry. Ask the manufacturers how they compare to an optimized strut front end.
From what I have seen these are bolt in kits that have to work within the space provided by the factory strut tower, frame rails and k-member. This may compromise the location and length of the control arms. So, despite the superior design they may not work as well as they could.
Where are you racing and what class are you looking at? I may know someone you can talk to.
I ran a pretty serious strut front end on my C Prepared solo mustang. It had 2.5" drop spindles that I made using Baer modified Fox A Sedan spindles. This allowed me to lower the car a significant amount while keeping the front end in perfect geometry. The suspension had near perfect bump steer and even had a little camber gain but nothing like a good SLA.
Regarding spring rates on OE mustang strut front end. We calculated the ratio to be closer to 50% - spring rate vs wheel rate. You can get more than enough spring on strut mustang in the stock location as there is plenty of room and high rate 5" coil springs are easy to get. To make my mustang work with 12" wide racing tires I ran 1650lb springs on the front in the stock location. The stiff springs worked as long as they were matched to good struts and the proper rear spring rate. A really stiff chassis is also necessary - my car had 26 point roll cage.

Much like the IRS I’m currently in the process of installing, it’s constrained by it’s factory packaging. Sad to say but it will never be as good as a purpose built setup from scratch. My goal is to get it as close to perfect as I can while working within the confines of those restrictions. Bending those restrictions as much as I can, while still retaining a street legal vehicle.
I’ve mainly been looking to AI/AIX but haven’t flipped through the rule book as I’m not sure I want to actually compete. More like create a car capable of running with or above cars in those particular classes using existing cars as a general template of what area’s to pursue.
I haven’t ruled out a Mcpherson strut system, however I’d much prefer using SLA. If it came down to It I’d like to use a MM K-member with the Griggs SLA, possibly customizing the upper shock mounting point. The adjustability of a well thought out SLA system to me outweighs what the Mcpherson system offers.
Subframe connectors and a well thought out cage is certainly in my future to tie all the points together, once I get things sorted out.

I think Global West has some options as well. I remember seeing some stuff on display at SEMA.
This/these type of suspension modification(s) is/are for track cars IMO. It will not ride well on the street. Like Trey stated, is it worth $5K for those seconds on the track? Possibly. But you will definitely not improve ride on the street.

GW seems to be more interested in the earlier mustangs 64-1/2-72 and doesn’t appear to have anything that would fit a foxbody. Being “worth it” is all in the eye of the beholder. I’m well aware of what rides well on the street, if comfy was my main concern I would have a plush interior in the car instead of bare steel. As it stands now I’m still contemplating interior choices. Some of which are not comfy in the slightest. The time my car spends actually on the street has been extremely limited so far. And well cost, yea, if anyone that’s reading this hasn’t followed the $ I’ve spent so far. $5k is like pocket change.
I wouldn’t make a statement like that. As there is always a possibility of anything happening, full of surprises and such. I’ve certainly experienced fresh pavement on a well banked on/off ramp. Was I at my skill’s peak, or the cars limit? I’d sooner say that I was at my wife’s Honda’s limit, than my own. My actual racing experience is limited to F1 Boston. I wouldn’t consider multi lapping my friends an accurate assessment of my talent/skill, but a general purview of things to come.

Another thing to consider is the availability of replacement parts 5-10-20 years from now. This could be way more inconvenient than something like a now-discontinued wheel if you ever had an accident sometime in the future.

I’m also not real concerned with replacement parts persay, however Griggs is still going strong after more than a few bumps and twists in their financial future. If they happened to go out of business after a few more years and I was left holding the bag on certain parts. I’d have to either find acceptable replacements or switch to something else that’s close or fabricate something on my own.

[wraithracing]

Much like the IRS I’m currently in the process of installing, it’s constrained by it’s factory packaging. Sad to say but it will never be as good as a purpose built setup from scratch. My goal is to get it as close to perfect as I can while working within the confines of those restrictions. Bending those restrictions as much as I can, while still retaining a street legal vehicle.
I’ve mainly been looking to AI/AIX but haven’t flipped through the rule book as I’m not sure I want to actually compete. More like create a car capable of running with or above cars in those particular classes using existing cars as a general template of what area’s to pursue.

I don't know what your budget is and I am sure that if you are a skilled fabricator and do most of your own work and installations you can lower the overall costs. But I will tell you that if your bench mark is to run with the top AI or AIX guys, just bring a wheelbarrow full of cash! Most of the top AI guys have at least $25-30K into their cars. I believe Chris Grizwold has over $75K into his SN95 AX championship car and it uses most of the MM catalog of parts. I will also say that although any of the cars could be driven on the street, the odds are you wouldn't enjoy the ride IMHO.

Good Luck!

Trey

[Mr Joshua]

I think i'm close to $50k so far, and climbing. That cover my wheelbarrow? Too bad a chunk of that was spent on body work, and not more on go fast, handling goodies.
With my idea's i think I've got another solid $50k+ to invest, before i get close to slowing down.
Just a tad crazy..

[Mr Joshua]

ah-hurrrr!?!?!
=

[Mr Joshua]

Is this for real or just eye candy?

[mustangxtreme]

That's mighty purty.

[Mr Joshua]

That's what worries me, it's pretty. That and i don't see much information about it, if any, on any of the hardcore forums..

[85GT-79FJ40]

That's what worries me, it's pretty. That and i don't see much information about it, if any, on any of the hardcore forums..

Probably because it's so expensive nobody can afford to put it in their race car. But it sure is pretty. Makes the rear IRS look old school.

[Mr Joshua]

There's no price on the website for a reason.

[wraithracing]

I think i'm close to $50k so far, and climbing. That cover my wheelbarrow? Too bad a chunk of that was spent on body work, and not more on go fast, handling goodies.
With my idea's i think I've got another solid $50k+ to invest, before i get close to slowing down.
Just a tad crazy..

Then Yes! You are close to a wheelbarrow full! If you have the money and are willing to spend it, then I would personally would throw the Agent 47 SLA up front if you are doing the Cobra IRS setup in the back. Have you looked at Full Tilt Boogie's IRS offerings. http://www.fulltiltboogieracing.com/ This is one of times that I buy suspension parts from someone other than MM myself. Great guy to deal with and alot of real experience with the IRS and it's idiosyncrasies.

As for the bling bling suspension above, that is designed and manufactured by JME Enterprises. Here is the link http://jmeenterprises.com/index.htm The last time I saw any pricing on the front suspension it was @$5K, the only issue is, I believe the design is only for the early Mustangs. I know their 70 Model show car has one in it, but I believe they make it for 64-70 IIRC. Suposedly designed by a mechanical engineer and is a functional as it is good looking, but I have no real proof of that either.

Trey

[Mr Joshua]

Then Yes! You are close to a wheelbarrow full! If you have the money and are willing to spend it, then I would personally would throw the Agent 47 SLA up front if you are doing the Cobra IRS setup in the back. Have you looked at Full Tilt Boogie's IRS offerings? http://www.fulltiltboogieracing.com/ This is one of times that I buy suspension parts from someone other than MM myself. Great guy to deal with and alot of real experience with the IRS and it's idiosyncrasies.

As for the bling bling suspension above, that is designed and manufactured by JME Enterprises. Here is the link http://jmeenterprises.com/index.htm The last time I saw any pricing on the front suspension it was @$5K, the only issue is, I believe the design is only for the early Mustangs. I know their 70 Model show car has one in it, but I believe they make it for 64-70 IIRC. Suposedly designed by a mechanical engineer and is a functional as it is good looking, but I have no real proof of that either.

Trey

I thought so, but need constant clarification, as it’s a giant hole that consumes money voraciously. I’ve got some more research to do on the Agent 47 piece, the earlier link that I had posted about a supposed failure. I haven’t been able to locate any other discrepancies, but I’m sure like all companies, they have their issues and are constantly working to refine their product. One of the problems I’m finding or not finding with the Agent 47 setup is, pictures of it installed. It seems that it’s run through a variety of revisions. The pictures on their site leave much to be desired. Only one small itsy bitsy picture on their fox section.
I have certainly had in depth conversations with Bruce about the direction of the IRS in my car. He’s certainly one of the best to talk with about the potential of the IRS. A pair of his rebuilt knuckles should be arriving sometime next week. After those arrive I’ll be talking with him again about upgrading the rest of the IRS before installing it into the car. I believe it will be getting a full complement of the products he offers.
I’m certainly interested in the JME piece as this car will most likely be relegated to minimal time at the track. It appears to be a fairly stout piece when compared against agent 47 and Griggs. I would tend to put Griggs in between the JME piece and Agent 47 as far as looking sturdy. However I ran into one person that had called and asked about the fox platform and he got quoted a price of $8500
I found a picture of the other style they offer.

I’m thinking that both style will fit the fox based platform, obviously with modifications.
Contacting them along with Agent 47 and Griggs will be something I have to do before pursuing any of the three setups.
Finding someone that’s installed each of the three into a foxbody would be nice. Hopefully at least one or two will feel the need to chime in here. As after searching C-C.com I’m coming up a little short on installation pictures of any of the setups. Both Griggs and agent 47 have their followers for sure, more so with Griggs. I’d wager that’s due to them being around forever, which is one more positive on their side. Hopefully I’ll be able to find more in depth information about installations on all three.

[wraithracing]

The problem with the Fox is that most of the top racers in AI, AIX, and AS are moving to either the SN95 or the S197 chassis. The newer chassis' are so much stronger to start with and the aftermarket has really embraced them with tons of support.

I don't think you can go wrong with any of the setups if you do your homework and set it up correctly. My personal opinion on Griggs is that they make awesome products and really helped to start the aftemarket suspension business (road racing wise that is) for the Fox Mustang way back in the late 80's/90's. Unfortunately Bruce Griggs tends to run his business like most engineers that I have come in contact with. His products are generally top notch, but customer service, timely shipping, delivery, etc are not something they focus on. Therefore it hurts their business model. Their opinion always struck me as "we make the best stuff out there, so you should be willing to wait for it, no matter how long it takes." Again that is my honest opinion and others will vary and some have had great experiences with Griggs, I am just not one of them. In their defense, most of my experiece was in the late 90's/early 2000's, but from what I have seen on c-c.com things have not gotten any better.

Good Luck!

Trey

[Mr Joshua]

I would certainly agree with you on that, even the 05+'s are getting alot of support put behind them, leaving our dear old fox platform in the dust.

Again i'd have to agree. With griggs i think that i'd be more inclined to talk to one of their distributors, same w/ Agent 47 and see what pops up.

Spot on, at least as far as all the internet banter surrounding Griggs is concerned. I'll probably end up seeing for myself.
I have a feeling i'm going to get a chilly reception, as i'm not a "Racer" so to speak. I'm hesitant to post anything on C-C, i prefer to use that "Search" function.
thanks for all the tips

[mustangxtreme]

Looking at JME's site, here is what they say about their product.

.Our NEW, patent pending PRO-Series™ suspension system, here are some key bullet points:

· SLA (Short & Long Arm) / Double wishbone design replaces inferior strut suspension on 1979 and newer Mustangs

· CAD/ CAM Designed and modeled using SolidWorks 2007

· Design F.E.A. (Finite Element Analysis) Confirmed using COSMOSWorks 2007

· CNC Machined out of 6061 T6 Billet Aluminum

· All geometry optimized for unsurpassed handling and performance

· Zero Bump steer

· Tested and proven on the race track

· Modular construction

· Center section of K-member removable for access to remove oil pan without need to remove engine or k-member

· Wheel track and width adjustable for race application

· 3/8” drive adjusters on control arms make alignment adjustments easy

· Spindles incorporate a 2 inch drop in ride height to maintain proper suspension geometry

· Spindles have caster already built in for better stability

· Available in traditional upright shock or cantilever pushrod design as an option for ease of tuning on track

· 3 position Adjustable anti-roll bar provides a wide range of adjustability

· Self Lubricating spherical bearings require no maintenance

· Can accommodate any caliper combination

· Uses off the shelf Fox or SN95 Mustang rack-n-pinion steering rack

· Wide range of shocks available to suit customer’s needs

[Mr Joshua]

Looking at JME's site, here is what they say about their product.

I've looked over their site quite a bit and I'm looking for a bit more. Someone that's installed the kit, someone who's driven with a kit installed, track time comparisons, etc..
A manufactures claims are all well and good, but real world testing is the key. Some things look awesome on paper, and yet in the real world they sometimes fall far short of their original expectations.
There are plenty of people with Griggs kits installed, a few less with Agent 47, and i haven't found one person running this kit, yet.

[mustangxtreme]

I understand that. I was looking more at the 79 and newer Mustang portion of that.

[4idfox]

I run in AI here on the west coast. Not in 2011 but will be back in the car in 2012. I am running a strut front end but plan on an sla someday. JME's stuff seems to be bling to me. There fox body car that was covered in 5.0 magazine a few years ago was not a serious race car just bling. ( my opinion )

I am leaning toward agent47 as they are racing there stuff and supporting the racing here on the west coast. No better way find a products flaws than to test it over and over. Cory is doing that.

The Griggs stuff has been proven to be very good for a long time.

I believe a member here has built his own sla. Horsewidower on this board. I spoke with him at thunderhill a few years ago and if I am remembering correctly he had built his own sla. This is somthing I will look into also when I decide to make the change. There is lot's of software to design with out there.

Troy