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Newbie Mustang suspension questions


David Algozine

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I will getting my comp lisence this April to run in the IN/OH region. I bought a Bondurant 95 GT that I am tuning for this season. I'm looking for advice on a decent set up. I'm planning on installing Koni DA's and either Race or Super Race H&R springs. Any input ?

 

Also, installing 96+ spindles, X2ball joint, bumpsteer kit, caster/camber plates, MM rear lower control arms. The car already has a panhard bar.

 

Do the rules allow aftermarket front "A" arms with off set bushings?

I would like to use MM "A" arms w/ Delrin bushings.

 

Any advice on sway bar changes from stock?

 

I was hoping to get some good information from some of you experienced west coast drivers. Keep in mind I'm on the other side of the country.

 

Any info or advice would be appreciated,

Dave

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David -

 

The MM front control arms wouldn't be legal on a Mustang - when you use them, you must convert to a front coilover setup. That isn't legal for CMC.

 

Also, regarding the sway bar - section 8.36.12 is pretty clear on this. You can update/backdate, but you must use stock sway bars.

 

Unfortunately, I can't help much with the setup on a CMC car, as I'm learning this myself right now on a Fox3 car.

 

Very cool that you bought one of the Bondurant cars. What number car did you buy? I wonder if it's the one my son and I drove a few years ago.....

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Dave,

Get a hold of Tim Laplante ,he is the director for the Indiana /Ohio region and lives near you.

Tim and I built his SN 95 from the ground up and he can tell you every little trick.

The Bondo cars make very good CMC cars!

Good luck,

Tony

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Adam,

Thanks for the input. I bought #29 and my friend bought #27. They are in excellent mechanical condition. I feel with a few suspension modifications they should be a good and economical CMC car.

 

Tony,

I been in contact with Tim. We met last year while I was in the HPDE ranks. He has been very helpful thus far. But, I didn't want to become a pest, so I thought I would contact more of you experienced west coast guys for some info. Any thoughts on the spring and shock combo. Based on Tim's comments I was resolved to using the Koni DA's, but I'm not sure about the springs.

 

The H&R Super Race

front 950-1050

rear 260-300

 

H&R Race

front 750-850

rear 260-280

 

Thanks for you interest

Dave

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I run 900lbs on the front and 200lbs on the rears.

Make sure the springs are linear rate.

I get them at www.tcracecars.com , or 1 800-296-3760 and ask for the SSS springs at $39 each.

They work great.

Sway bars I run the stock front, and no rear bar at all.

Shocks Koni D/A are nice,but you can get away with the Tokicos 5 ways if you want to save money.

That is what I have on my car and I'm real happy with them.

Tony

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Dave-the H&R "race" springs are too soft in my opinion. I ran them my first season in my '86. They allow too much movement. Linear/specific rate is the way to go. The rates Tony mentioned are good. I run stock sway bars as well. Just get the car out on the track and start having fun!

 

Good luck.

 

Greg Robinson

robinsonmotorsport.com

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Tony,

I went to tcracers site, but I was overwhelmed by the number of SSS springs listed. Any part/code numbers or specific info would help. They have several listings for front 900 lbs and rear 200 lbs.

I assume these springs are not Mustang specific, so what do these do for the ride hieght?

 

Greg,

Great web site.

"Just get the car out on the track and start having fun! "

Not trying to set the world on fire, but I hate to have to redo something.

 

 

Looking forward to getting back on the track.

Thanks

Dave

email - [email protected]

 

P.S. - Now do you understand the statement "not wanting to be a pest"

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Dave - you can call me every day - I'm happy to answer any and all questions..

 

here are the part numbers you need - though I only run the 800's up front and 250s in the rear... so the last number of the part number will change to what ever rate you want ...

 

SSS 12 250PT Spring 12"X 5 1/2-250 pigtail

SSS P12-5-0800 Spring Stock Length UNPNTD

 

I cut about 1 coil off all springs to get the ride height I wanted

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Hey David,

 

Sounds like the crew here has gotcha squared away.

 

My son and I drove #23 -

 

number23.jpg

 

The Bondurant cars rock - full cage, great suspension setup, and working AC!

 

Good luck getting the car ready to go. I am so psych'd for our first race, I'm about to explode!

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The Bondurant Mustangs have some modifications done to them that aren't readily apparent, yet may or may not be legal under the CMC rules. I am not talking of the toreque arm which is obviously not legal.

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Interesting.

I have a Bondurant car,and I have not found anything that is not legal yet..except the 13" rotors and 17" wheels,my car does not have the torque arm,and is running the 4 link with a panhard.

The bondo cars were created in different stages since they had over 300 of them,so there may be several different builds out there.

Dont worry we will catch anything that may not be legal out there while at the track.

So bring it out and run anything you have and enjoy.

Cosmo.. are you trying to make waves...just buy a Camaro, so I can beat you in my Mustang!!

Tony

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The main thing I noticed on Gary's car was the strut towers. I know that the rules say you can have CC plates, and you can also slot the towers for more adjustment. It doesn't mention sectioning the tower and moving the adjustment holes rearward 1". As other modifications of that type are legal, this may be a case of semantics. I don't mean to cause waves, but I think this should be in the open especially since you have one and are the director.

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I had a feeling thats what you were talking about. I personlly don't see any advantage. Its the same as adjusting with the CC plates, but I'm sure it will need to be discussed. I wonder why Roush went to the trouble of cutting the strut towers instead of using CC plates.

If required, I'll just cut them up again, and put them back in the stock location.

 

Dave

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Hey, I didnt say I was racing that car..yet.

We will look at this next week,and I really don't see a problem with this, since the adjustment is open with C/C plates anyway.

Hang tight and I will bring it up with the other directors and show them my " other" car.

thanks,

Tony

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Tony, I didn't really think it was an issue as long as it's in the open. Even if something may be legal in the spirit, "if it isn't written here, it's illegal." There are many easier ways to accomplish what has been done to these cars.

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The prevailing opinion is to use linear spirngs over variable rates. Can someone give me the specific reasons for this?

My thinking (keep in mind newbie) is that a variable rate would be more versatile, especially for a CMC car. Rather than changing springs for different tracks, wouldn't a variable rate allow the car to better compensate for slower bumpy tracks and still provide a higher rate for faster, smoother tracks?

Looking for opinions and experiences.

 

Dave

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Dave, the variable rate springs I used (H&R "Race" springs from MM) were fine my first year but I didn't care for the amount body movement I was getting. Brake dive was pretty pronounced and body roll was always a factor. This would probably be good in the rain, however. I have seen others run the "Super Race" springs without complaint. It really boils down to what you feel comfortable with in the car. The variable rate will allow body movement before the handling really firms up and in my opinion makes the car unpredictable. Again, I ran the "race" springs for a season and did just fine. I am happy with the linear rate springs I have now.

 

If you would like to give the "race" springs a go I have a set that are yours for $50.

 

Good Luck,

 

Greg Robinson

#12/55 Mustang

Team Hi Line Motorsports

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Thanks for the response.

Last year I had a different 95 GT that I used to run HPDE. I put an 01 IRS in and I used the H&R "Race spring" and Bilsteins. Obviously it was a great improvement over stock, but thats all I have to compare it against.

If I dicided to use the variable spring I would use the "Super race", because I felt the same body movement you described. However, that could be a function of the initial spring rate and not the fact that they are variable.

The other related issue is that both the Race and Super Race rear spring rates are higher than what other experienced drivers recommend for the nearly stock suspension. I'm assumming that the recommendation for low rear spring rates is based on compensating for the 4 link bind.

Any comments?

 

Dave

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Dave

 

I'm no Mustang expert by any means, but here's some potentially useless advice:

 

Take other driver's advice with a grain of salt. Seriously, a lot of times people make apples to oranges comparisons without knowing. A CMC car and a street legal car that sees regular track time are probably bad cars to compare. They weight different amounts, have different weight balance, likely run different tires, and the owner probably has completely different standards with regard to comfort, NVH, etc. This could have a big impact on spring choice.

 

Springs work in concert front and rear, and vary widely with other choices in suspension pieces (torque arms, panhard bars, etc). Plus, a lot of Mustang guys run coilovers, which have very different spring rates though they might have essentially the same wheel rate.

 

Just some thoughts...if the spring rates that Tony and Greg are talking about are substantially different than what other drivers have mentioned, it may have something to do with different application.

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just another voice...listen to Al, all his points are valid....the most important one is that by listening to many sources you may very well end up with the wrong setup for your car....if you can find a series champion or someone that regularly wins races in your class or make of car, in this case a CMC Mustang, then see if they will help you with your setup....are you interested in every Tom, Richard or Harry that has an opinion?...I don't think so...go for someone that can give you the straight scoop that works for them...in this case you are incredibly fortunate to have the CMC Director willing to open his build book and give you the exact parts on his winning Mustang...why would you even consider talking to anyone except Tony?....Everyone has opinions but I've always listened to those who back them up with wins...have fun.

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Good advise, but just to clarifiy. My question is, what are others' opinion/experience on using linear vs variable springs, assuming they have very similiar rates?

 

The other quetion is, why are most, inlcuding this forum, recommending rear springs with very low rates? I assumed it was to off set the increase in the rear wheel rates due to the 4 link suspension bind that is associated with the stock rear set up, but I wasn't sure. If thats not the case than I would wonder why the car doesn't push even worse with such low rear spring rates?

 

It is much easier for me to buy name brand, off the shelf springs rather than make modifications (cutting to length, even though they are only minor mods). I see myself cutting and re-cutting, only to end up unsatisfied with the end result (Keep in mind, newbie). Also, nearly all the name brand springs are progressive rate, even those listed as race/competition springs.

 

I really appriciate everyones input, and I am more than willing to take advantage of the information that has been given. However, I am also trying to learn the reasons behind the choices, so I can better understand how it all works. Believe me, I am thrilled that Tony, Tim and others have been so forthcoming with information. And I also believe that certain informaiton needs to be learned through experience, which I am looking forward to achieving. I guess I'm more intersted in the theory behind the set up, rather than ask everyone what they are using. The fact that the rules limit the suspension mods, makes the CMC unique from many classes, including open track guys. The information and products are plentifull if you're going to drastically modify the suspension, and most of the street products don't apply either.

 

 

Thanks

Dave

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My $0.02...

 

Linear and variable spring can't have similar rates - two different animals. But if you mean a 'variable spring with a 300/500# rate' vs. a 'linear 500# rate', read on...

 

Linear rate springs are best for racing since they're predictable. Variable rates are better for the street as far as the early part of the spring travel smooths bumps, while the stronger late travel handles the big stuff.

 

Now, when does the big stuff happen? Hard braking for one. So, on track with a variable rate spring, at maximum braking, you blow through the 'soft rate' almost immediately, and then only have (let's say) half of the available suspension travel to support the car. Now the car is pointed down 2" further than if you had a linear spring. What if there's a big dip right before the turn? The guy that has high rate linear springs will still have 2" of travel left, while the variable rate guy is hitting the bump stops. BAD for control.

 

Rear springs with low rates? Well, 1) because there's no weight in the rear, once all the extra stuff is removed, and 2) because these cars are so light in the rear (relatively), you want all the weight to move back there for acceleration out of corners.

 

As for advice, listen to the CMC Mustang guys on spring choices -not only rate, but SIZE. If you go buy a 900# spring at stock length, you're gonna look like a 4x4. So you cut it down and check again, and again, and again. Remeber, every time you cut a spring, the rate rises, so now your 900# spring is about 1050#/inch. Ugly, if you ask me.

 

Also, try to buy the springs and shocks from the same place as a package. With the high spring rates most people like to run (except me), the regular valving on shocks may not be enough. Most off the shelf shocks are valved to work with stock rates. Another bad combo. OR, if you already have shocks, get them revalved to match your springs. That's a HUGE difference.

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