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Suspension issues

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Suspension issues

Post by DrJ on Fri Dec 26, 2014 9:17 am

Now that the drivetrain is all but complete I want to begin to address two suspension related issues. The first involves my MX's nose dive when breaking hard. One of our members was good enough to describe the aft angled upper A-arm originally incorporated into the Mustang II front end. Ours are apparently parallel and therefore do not benefit from this. As I try to learn about front end mechanics I wonder if everyone has this problem. If so then it is likely an engineering issue that could possibly be solved. If few of you have this issue then I would suspect it is a wear issue on some of my existing components.

The second concern is the lack of the steering (manual rack) to return to neutral coming out of a turn. Again do all experience this?? If not it could be an alignment issue or a worn rack etc.

Any feedback would be great. Hope all had a safe and happy holiday.

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Re: Suspension issues

Post by Terry Crist on Fri Dec 26, 2014 12:29 pm

You can purchase anti-dive brackets that can take care of that.

As far as the steering not going back to center on its own, that is probably an alignment issue. Caster or camber I can never remember which.
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Re: Suspension issues

Post by Hotrod on Fri Dec 26, 2014 4:12 pm

Increasing positive caster angle will help with return to center, but will increase steering effort. It will also help the car to track better with a "center pull" on the highway, but will feel heavier in curves.  It's a compromise as with most engineering.

The upside is that the Sebring uses standard width Mustang II steering racks.  You could always convert to the power rack and run as much caster as you want (within reason).  The later Fox body Mustang power racks can be installed with offset rack bushings and are supposed to give a better ratio and feel. As well as being easily adapted to the GM pumps if you're running a Chevy engine.

Mike
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Re: Suspension issues

Post by Jimboquick on Fri Dec 26, 2014 7:37 pm

I'm considering the removal of my '90- built, "MX's" {'Mustang II' ?} manual rack and replacing it with just a power rack {but no p/s pump, at least initially. The current [4+ turns, lock to lock] is just way too slow for a 2,400# car. Which year "later-Fox body" is recommended with offset rack bushings ?
Jimbo

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Re: Suspension issues

Post by Hotrod on Fri Dec 26, 2014 9:54 pm

The info I looked at says 85-93 V8 power racks were 15 to 1 and are the quickest.  Earlier Fox power racks are listed as 20 to 1.  The manual racks are 25 to 1.  I don't know how that translates to turns lock to lock.  That would depend on the actual rack travel and if it has any internal stops.  Some applications apparently did.  I have a Fox power rack hanging in the shop.  I can check it out, but it'll be next week.  

Also, I think the Fox racks are variable ratio.  I've read that they are slower at the center and quicker at the extremes of travel.  Don't quote me on that though.  

The offset bushing sets actually only have one offset bushing.  One of the holes in the Fox rack is in the right location for a Mustang II.
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Re: Suspension issues

Post by Jimboquick on Fri Dec 26, 2014 10:26 pm

Thank you for that info. My experience with the current manual steering rack gives credibility to the 25:1. My front suspension is FoMoCo stamped upper and lowers with unknown shocks and the stock { I believe} front sway-bar ass'y. Don't remember any 'brake-dive', but the alignment is set up for street use and doesn't show any unusual wear.
Regards,
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Suspension

Post by DrJ on Sun Dec 28, 2014 10:11 am

Thanks for the feedback.
Terry, would you know where these anti dive brackets can be found? The usual search brings up a host of things but have not found Mustang II specific parts (other than substituting a new tubular front end for her.
Paul

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Re: Suspension issues

Post by Terry Crist on Sun Dec 28, 2014 2:10 pm

Paul,

They are mostly used in racing. I can send you a blueprint and even a flat pattern DXF file if you want. I drew some up for The C-427. The only thing is that they rotate the shaft 90° and you would have to bolt it up differently. You would use shims like a Chevy would for alignment.

Believe me though, your alignment guy will be much happier with you.

I will have to search this site to see where to upload the prints for anyone to use.

David, is there a place on this site where you can actually attach files that can be downloaded by others?
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Suspension

Post by DrJ on Mon Dec 29, 2014 8:33 am

Thanks Terry that would be great. If posting it is an issue you can e-mail me at:

[You must be registered and logged in to see this link.]


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Re: Suspension issues

Post by David V. on Mon Dec 29, 2014 4:52 pm

Hey Terry, you can just e-mail them to [You must be registered and logged in to see this link.] and i'll post them up in the database section. PDF if best if possible, I have no idea if DXF files will work but i'll give it a shot

Cheers!
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Re: Suspension issues

Post by Terry Crist on Mon Dec 29, 2014 8:28 pm

David,

Sent you an e-mail.
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Re: Suspension issues

Post by David V. on Tue Dec 30, 2014 1:21 am

Thanks Terry, I'm on it...

...Update: I have uploaded your diagrams in the Database section, here is a link to the topic: [You must be registered and logged in to see this link.]

Let me know if there's any problems

Cheers guys Very Happy
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More Suspension Candy

Post by DrJ on Thu Jan 01, 2015 9:52 pm

So many of us have admitted that the ride quality of our MX's is a bit uh stiff. I as many of you know by nowI know little about reengineering my car yet I insist on doing so. My last post on anti dive has yielded a wealth of information from our members and I believe it to be an issue I can now correct. During this process I have stumbled upon the topic of substituting fully adjustable air units that replace both the shocks and springs front and back. (see ridetech.com for lot's of information) I am intreged as it's marketing insuates that I could generate a gently plesent drive for day to day while dialing in a firmer ride for "spirited driving" (you guy's do do that right?). Yeh it is a little pricey but if one factors in fully adjustable shocks, maybe a buck fifty each corner and new springs for an additional cost (assuming we get the spring rate right) you get close to the cost of the more basic version of this admittedly unorthodox approach.

What U Guy's Think??

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Re: Suspension issues

Post by Hotrod on Thu Jan 01, 2015 11:31 pm

It could work.  I have air suspension on the rear of my T bucket (way OT car for this forum)just to improve the ride quality.  That type of car usually weighs less than 2000 lbs and are difficult to get sprung for a good ride.  Mine weighs 1700 lbs and rides decent.  I am planning on adding air assist to the rear of my Sebring during the rebuild, mainly because I anticipate varying loads.  I want the body stance and suspension travel to stay the same all the time.

A couple of things to consider.  Adding or releasing air to an air spring will alter it's load capacity, but will also change the ride height.  If you make the springs stiffer with more air, your car will sit higher.  One of the air suspension companies may be able to recommend a bag size that minimizes this.

Also, if you make the springs softer for a good ride, the roll stiffness of your suspension will be less.  You may want to look into stiffer antiroll bars with the air bags.  Air Ride Technologies used to have a lot of good design tech on their website, but I think they removed it all when they started selling the Shockwave setups.  The need for more roll stiffness in the bars was one of the things I seem to remember being explained.

Mike
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Re: Suspension issues

Post by David V. on Fri Jan 02, 2015 1:54 am

Hmm, interesting that you guys mention this, I have springs + Air-shocks on the back of mine, the spring rate always stays the same and is quite stiff, but I can adjust the shock by adding or removing air by way of a valve in the trunk. This does change the ride height and if I inflate the shocks to the max it puts a lot of load on the shock mounting points (Have broken one on a pothole once). I usually keep it about mid-range. The rear feels quite cosy when there's air in it but one of the things that makes the ride quite hard in general is the front springs and all the scuttle shake I get. If I could figure out a better setup I would be very happy but for now it does the job. Was considering a switch to adjustable coilovers in the future, maybe those fancy KW ones with external reservoir and damper/bump adjustments.

Food for thought...
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Re: Suspension issues

Post by Jimboquick on Fri Jan 02, 2015 11:23 am

The broken lower shock mount mirrors my experience exactly as my experience last year, excepting that I don't have air-assisted shock absorbers on the back. I'm quite happy with the rear coil springs that I installed a couple of years ago ... they are # MC1127 from / recommended by The Eaton Detroit Spring Co. The rear shocks are currently KYB 'for a '79 Mustang, six cylinder car.
On my 'MX' there are two sets of mounting holes on the frame for the upper shock mounts ... don't use the lower holes unless you enjoy 'bottoming out' ! The ride height works out perfectly with 275/60x15 rear tires. There may be better rear shock choices yet to be discovered. I'm still wrestling with universal joint issues / adjustments, however ... I suspect that an error was made by the car' original builder regarding welding the rear suspension mounts to the 8" FoMoCo rear end ass'y. This spring , I'll again load the seats of the car with 9 bags of water softener salt {which we use up over the following months in our house} after putting the car onto the alignment rack of our local Goodyear Select
facility ... then try to accurately, repeatably measure the u-joint relationships between the TH350 and the 8" rear, road-ride height vs. extreme "jounce / rebound' positions. Never an easy thing to nail down. just getting tired of pinion seal leaks and premature u-joint wear.
My front suspension needs improvement ... does the same as you've described {'scuttle shake"} using stock, stamped FoMoCo upper / lower arms, OEM front anti-sway-bar, unknown front shocks {supposed to be for M2 /Pinto/ Maverick?} that are questionable road-ride height perhaps 3/4" too high on 215/65x15 tires. tires are all at 25 psig.
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Suispension

Post by DrJ on Fri Jan 02, 2015 4:20 pm

Well Mike and Jim bring up good information. First to Mikes point that varying air pressure changes ride height. The impression I got from Ridetech's site was that if provided with the proper measurements and weights they could send out this Shock Wave unit that would place one at the proper height. That adjusting the air pressure from that datum would have minimal negative effect due to height/cg issues. Could all be marketing.
Their 104 series claims to be appropriate for independent front suspensions weighing between 1,200 and 2,000 lbs per axle. Their 7000 series to be utilized for live axles weighing less than 1,500 lbs. Both would seem to be within our cars specifications.

Now Jims reply was interesting. You found springs at Eaton Detroit, a facility I too found online and believed to be a good source for a solution. So you are saying that your MX with the springs and shocks you specified generated a compliant, comfortable daily ride??

Would certainly prefer to use the correct conventional parts and technology to achieve desired results than to take a shot with something unconventional.

Paul

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Re: Suspension issues

Post by Jimboquick on Fri Jan 02, 2015 4:26 pm

I'd sent information to 'Mike' @ Eaton Detroit Springs and he recommended the pieces that I then purchased for the rear. The KYB rear shocks were pieces that I acquired here in Georgetown, ON. {there may be much better pieces out there ... just passing along my experiences to-date.
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suspension

Post by DrJ on Fri Jan 02, 2015 4:34 pm

But Jim, your impression is that with your set up the rear is not harsh when driving along irregular surfaces? I understand that the front end is another matter.
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Re: Suspension issues

Post by Jimboquick on Fri Jan 02, 2015 4:52 pm

In my ignorance, I'd initially mounted the top of the rear shocks into the lower of the two sets of frame mounting holes. The ride was prone to bottoming out on the shocks ... until I broke the right rear lower shock mount right off the axle ass'y. on a nasty pot-hole ! The ride now is not nearly as harsh {in the rear} as it had been. The front, needless to say, needs further refinement .
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Suspension

Post by DrJ on Fri Jan 02, 2015 7:05 pm

OK Jim now I have something to work with aft end wise. Where are you at Jim Country/State/Territory wise??
Paul

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Re: Suspension issues

Post by Jimboquick on Fri Jan 02, 2015 10:48 pm

Georgetown is part of Halton Hills, Ontario, Canada. NNW of Oakville, West of Brampton and east of Guelph.
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Suspension

Post by DrJ on Sat Jan 03, 2015 10:35 am

Well Jim I am just across Lake Ontario between Buffalo and Rochester. When the weather improves, perhaps in the spring, I would love to journey out and take a ride in yours. Figure it is better to com[pare the relative ride quality before I pull the trigger on rear end suspension parts.

Paul

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Re: Suspension issues

Post by Jimboquick on Sat Jan 03, 2015 1:17 pm

That would be a great idea for May / June ... as I've struggled with 'improved reliability' [cooling, electrical, suspension, fuel expansion / tank, suspension, brakes and u-joints] issues, meeting in the Niagara Falls area could be a great day's cruise...
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Re: Suspension issues

Post by David V. on Sat Jan 03, 2015 8:23 pm

I'm going to be near the Kingston area for the summer, why don't we do a little local Sebring cruise along with anyone else that wants to join? Would be nice to compare the cars Smile
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