1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Front Suspension/Steering Geometry Issues and Solutions.

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Old 12-05-10, 10:44 AM
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Front Suspension/Steering Geometry Issues and Solutions.

Alright, as to direct the rear end thread back on course, here we can discuss problems and solutions for Ackerman, bumpsteer, turn radius and things of that ilk.... And go.
Old 12-05-10, 02:28 PM
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going to move some of the posts from that thread here...

Originally Posted by Hyper4mance2k
How? He's not the first to do coilovers, or a sway bar, or a strut tower brace, or a rack and pinnion. Jim Susko PWNS all on front suspension setup. His are the only "turn in spacers" that actually add ackerman. His are offset to correct the geometry, noone else does that, just spacers like the ISC ones in my car. Jim is the only person who offers a real bolt in double adjustable solution and the only person who sells shocks able to deal with spring rates above 300lbs. Mind you Jim probably has 30 years on Billy.

Mind you I do love RE-Speed and I run their coilovers on my car. They make fantastic parts, some of the best, but they have hardly solved the front end's problems.

Originally Posted by GSLSE-YA
7's only sell ackerman arms which will increase ackerman over stock, especially when combined with turn in spacers. I run 2" turn in spacers from sevensonly. I also run their large diameter upright with big bearing spindles and big brakes.

The geometry problem I'm working on now is bump steer. We're getting 1/8-1/4" toe in for every inch of up suspension travel. We have adapted a kit that raises the steering nuckle 1/2" onto the ackerman arm. Seems to have almost eliminated bump steer.

Most people with first gens probably don't realize they have bump steer, mainly because it is toe in bump steer, it feels stable but it still causes a certain amount of unwanted scrub. It's probably the least important 1st gen suspension geometry problem.
The gforce bolt in at the strut and at the arm at different angles. If you just use a big spacer it adds toe that you have to align out. Gforce actually add ackerman the more steering angle.
Originally Posted by mustanghammer
Good question!

Actually I'm pretty pleased with the front end on the RX7. It can be lowered and with strut spacers it is possible to maintain geometry. As strut front ends go I think this one works pretty good. There are improvements that can be made, however.

On my racecar, every pickup point has a spherical bearing - including the strut rods. As far as spacers are concerned I have used both the Susko ackerman spacers and the straight - non ackerrman spacers. I like the ackerman spacers for Solo/Autocross use because they make the car turn in better and work better in transition. For clubracing I perfer the npn-ackerman spacers because I don't like twitchy cars on a race track.

The big strut tube conversion is important if heavy rate springs are going to be used. We made the ones on my car.

For my STU project I will be lowering the car another inch. To compensate I will add a 2" spacer to the strut and raise the top of the strut tower. I'm also going change the sway bar to an adjustable Speedway design.

Here are some shots of the strut tower mods. I'll shoot some shots of the struts, sway bar design over the next week of so.







Cool! Thanks for the information regarding the front end. I am pretty well versed on suspension dynamics, and I am failing to see where the spacers change the Ackerman, as they do not change the angle of the steering arm, or the tangent of the strut mount and the lower ball joint. Or the intersection to the rear axle centerline.

I see that it does do the roll center mod to the good side, but that's about it.

Can someone illuminate this relationship?

GD

Originally Posted by rwatson5651
In my view the issues with the 1st gen front suspension are:

1. camber adjustment

2. Roll center adjustment

3. Ride height adjustment

4. Better steering than the antiquated recirculating ball setup

5. Maintaining desirable ackerman geometry

Maybe there are others I am not considering????

For me the ReSpeed setup accomplishes all the above except #5 and since I have the Racing Beat Strut tops I can use turn in spacers that give the ability to adjust/change Ackerman. It is the perfect solution as far as I am concerned. It also gives the option to adjust the steering ratio. ( I have tried both 20-1 and 15-1)

I guess I should have said that Billy had the best solution for me, IDK about everyone else.....I have no experience with the Gforce products so I cannot comment on them except to say that you do have a point about the turn in spacers, with Billys setup you do need to address the Ackerman issue somehow.

Maybe he has not been around as long as some others but I am happy with my setup. As far as I can see there are no shortcomings to it other than price.
There was a place in Seattle that told me they could rebuild my box. I wish I remembered the name of the place. All they did was rebuild RB boxes.

p.s. found it. i never researched price or exactly what they'd do, but the guy told be he could rebuild them right before I moved to Cali.
http://www.redheadsteeringgears.com/
Originally Posted by rwatson5651
You are correct, you do lose a little turning radius, (not a lot), but it is not because of the rack, it is because the inside of the tire strikes the sway bar, which in the respeed setup is thicker than stock. I am running 205-50-15s, not sure of the exact offset,(its close to stock). If you have more narrow tires / different offset you would have a sharper turning radius.
Originally Posted by Gen1onr
I lost a **** TON of steering radius when I installed the respeed rack and pinion.
Its the ackerman that really kills it.

If it wasnt so tight and awesome at speeds I would really dislike the conversion. I find it much harder to get out of a tight driveway now

Come spring I plan to explore some modifications to restore proper ackerman geometry... Does'nt seem like an easy task with the stock tie rod ends though.
Maybe some turn in spacers put on the opposite sides from a stock setup?
Longer control arms?
Anyone else try to remedy that issue with the respeed setup??

I would absolutely love it if I could restore the turning radius.




Edit: Sorry to derail the rear suspension thread.. someone start a front end thread!!! haha
I'll start by saying that I have a huge amount of respect for Billy since he's the only guy out there developing new products for our cars. He also happens to be one of the nicest guys I've dealt with!
However I'm surprised no one else has posted about the issues with the turning radius on the respeed setup. I have the rack and pinion kit on both my FB's and while I absolutly love the feel of the steering while driving, any kind of parking lot/driveway etc is very annoying, to say the least.
I have spoken to Billy about this a few times and basically the fix is to make a new knuckle arm that angles outward (away from the car) this of course requires a bigger wheel as it would hit the stock sized wheels... Apparently taking the stock arms and simply switching them around though will angle it out too much so some modifications would be needed. I've been toying with the idea of experimenting with this, however I haven't gotton around to it.
Anyone else do anything with it?
Also sorry to have gotton off topic
My understanding is that the fix is possible (correcting ackerman with the R&P kit),
but would cost some money.

I think that if enough people were interested in a correction, and were willing
to pay the costs, then Billy would provide a solution.
I dont care how much it costs! Im in for a solution!! Thats the only bothersome thing about the respeed kit.

No disrespects to Billy!!! Great guy, awesome products! Just a minor issue...




IIRC the tie rod clearance issue is with the brake rotor, and not necessarily the wheel.
I was thinking about looking into a combination of roll center blocks and custom outward angled steering knuckles?
Just not sure about clearances until I get under the car again.

I run 17" wheels so Im sure I can get away with the wheel clearance, just not exactly sure what kinda fabwork its gonna take.. Either way Im determined to remedy this issue!

If someone doesnt beat me to a front suspension thread, Ill make one when Im ready to experiment with the R+P kit.

Cheers!
I checked some references to see if I was messed up. I was correct in my assumption that those spacers cannot add steering angle unless it changes the
angle of the steering arm in relation to the spindle. It does alter the roll center giving the effect that it turns in better. Take a read on this page as it does explain it well.

http://www.smithees-racetech.com.au/ackerman.html

For quicker turn in, you cound move the outer tie rod closer to the spindle. But it would most likely be along he same vector and still not adding or changing the Ackerman angle.

Good discussion!

GD
I think a slight modification to the design of the steering knuckle the comes with the kit to angle the steering knuckles outward would increase ackerman and shorten the turning radius. All it would take would be for the two holes for the bolts to moved slightly.
It would move the tip of the knuckle out. Wouldnt that help? I have considered asking Billy to sell me two knuckles without the mounting holes so that I can drill them myself.

Originally Posted by gawdodirt
Ok, bear with me here and use your imagination. The Ackerman as it stands has the steering arms angled inward. Correct? So if you want to tighten the Ackerman, heat and bend the steering arms inward and then weld a gusset to maintain the dimension. Now you have more Ackerman. It should turn in faster. Check the bump steer as it will accentuate this. The rack, or relay rod will either have to be moved up or down to remove any bumpsteer,. Or the outer tierod.

Angle the arm outward only will decrease the Ackerman angle.

GD .
Yeah, that would make sense for the stock front end, however the respeed kit is front steer.
To get proper ackerman they would have to angle outwards and in that case the brake rotor appears to be in the way
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Originally Posted by Hyper4mance2k
I already said it changes the angle that the steering arm mounts to the strut tube & LCA therefore the spindle...
You can kinda tell on the pic on his site
These are the new ones

It's much more clear on his older ones.
Originally Posted by 82transam
Agreed, its really the only downside to the kit. As for clearance you're right the rotor is what keeps it from going out too far, but I also believe there could be issues with the bottom of the tie rod rubbing on the wheel as thats already an issue if you are using certain brands of tie rods and the 13" wheels. OEM Mazda tie rods are nice and compact and fit fine, but aftermarket ones tend to rub. I think moving the tie rod further out would increase the possibility. Not really an issue if you are running bigger wheels like I usually do, but I like the option of going back to the stockers sometimes.
Maybe Billy can chime in as I'm sure he can explain it a whole lot better than I can
HOPE THIS HELPS KEEP THE DISCUSSION GOING

Last edited by elmerxfudd; 12-05-10 at 02:30 PM.
Old 12-05-10, 02:42 PM
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Thanks for the dedicated front suspension thread. I'm looking forward to some new ideas in this area.
Old 12-05-10, 03:08 PM
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LOL! You could've just PM'd a mod and they can pull the posts out of the rear thread and post them in here.
Old 12-05-10, 04:47 PM
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If I was going to do it again, I'd section the crossmember to move the subframe an inch higher.

Possibly sectioning the body would be easier. Either way, the body would have to be cut for tie-rod clearance.
Old 12-05-10, 05:01 PM
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Originally Posted by peejay
[IMG]h[/IMG]

If I was going to do it again, I'd section the crossmember to move the subframe an inch higher.

Possibly sectioning the body would be easier. Either way, the body would have to be cut for tie-rod clearance.
one of the big differences in the FD and Rx8 chassis, is that the frame rails ARE moved up an inch or two.

IE lower car and keep stock geometry...

the lower control arms need to point slightly down, from pivot point to pivot point. so once you've got the biggest roll center spacer/corrector the inner pivot needs to move, and mazda actually left some room....

camber curve, or lack of, is the second problem.
Old 12-05-10, 07:10 PM
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Okay, here is a question.....why swap in an FC front suspension into an FB?

I personally don't see the advantage to this swap and I was racing in a class that allowed me to make that big of a change I would fabricate a double A-arm front end.

So educate me!
Old 12-05-10, 07:11 PM
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im curious to see what mods anyone have done to the factory fb suspension to gain more steering angle.
Old 12-05-10, 07:59 PM
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Originally Posted by mustanghammer
Okay, here is a question.....why swap in an FC front suspension into an FB?

I personally don't see the advantage to this swap and I was racing in a class that allowed me to make that big of a change I would fabricate a double A-arm front end.

So educate me!

I think it is perceived to be a easy upgrade, and it is been done enough that there are lots of info to follow to do it. Im with you, when I upgrade I will get a rack and make my own a-arms might even go to a double wishbone. with inboard shock/springs, if I feel like really upgrading. till then I just want to make the steering a bit quicker which is easy enough.
Old 12-05-10, 08:33 PM
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Why?

The short version is, my P/S box was worn out (drove on the street okay but did scary things under load), and I used up my last set of FB spindles. Even the "big bearing" FB spindles are pretty weak and bend very easily. Fortunately, I never suffered a catastrophic failure, just noticed a gradual increase in negative camber that would coincide with an inability to keep the wheel bearings in adjustment.

FC spindles are much stronger. FC racks are also a lot easier to find.

That's all.

The suspension may be lighter, too. The 2'x2'x1/4" steel plate on the front of the car protecting the oil cooler and radiator kinda negate any weight savings though!
Old 12-05-10, 08:36 PM
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Originally Posted by mustanghammer
Okay, here is a question.....why swap in an FC front suspension into an FB?

I personally don't see the advantage to this swap and I was racing in a class that allowed me to make that big of a change I would fabricate a double A-arm front end.

So educate me!
you get rack and pinion steering, bigger brakes, more off the shelf suspension parts, and it kind of bolts in. i agree for the work, you might was well find a spindle and do a double wishbone setup
Old 12-05-10, 08:46 PM
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Basically for me, the FC front end was:

1) Rack and Pinion (power or not)
2) Ease of Install of 13B and all its variants
3) Easy use of TII/GXL/Vert brakes
4) Larger aftermarket for shocks, bushings, swaybars, Brakes etc etc
5) Use of larger bearings
6) Easy swap to 5lug hubs
7) Stronger LCA's

I could continue but the main thing in my eyes was to dispose of the pitman arm steering. I really detest that style of setup. I've seen brand new parts fail catastrophically at the track specifically due to their design. I wasn't going to take that chance.

Another reason i think people do it, is it makes the car perform 100% better for very little effort and in most cases, very little money.

The car drives noticeably different (better) when you hop from one setup to the other.
Old 12-05-10, 09:01 PM
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That's one thing I definitely noticed. Between the front end change (more caster, more direct steering, no more floppy bearings) and the rear end change (3-link/Panhard) my car simply does not drive like an FB anymore.

Both of my FBs had nasty wandering problems no matter what I did with alignment, even when all front end components were in excellent condition. Tramlining and following ruts meant you really had to be on your toes when driving it.

Now, you just point the car in a direction and it goes there without any ideas of its own, whether driving at .5/10ths or 10/10ths.

The real eye opener, oddly enough, came the first time I drove it to work. (It was several months after the conversion before I ever brought the car home) On one of the roads I travel, there's an intersection at a maybe 10 degree right kink in the road. Because of the way the road was rutted, I needed to steer firmly to the right to drive straight, then quickly apply left lock while approaching the intersection (as the road went right!) to keep from smashing into the curb. It was instinctual to do this. It was like the office workers in the scene in Men in Black where the intergalactic superball was flying around. With the new suspension, I just pointed the car where I wanted it to go, and I didn't have to correct for road texture *at all*. The other people on the road must have thought I was nuts when I started laughing manaically while driving

I must note in the interests of full disclosure that my SA also drove this way. But then, I have never driven any 1st-gen that EVER drove as well as that SA did. Odd.
Old 12-05-10, 09:15 PM
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Sweet, I want an FC front end.
Old 12-05-10, 11:13 PM
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Originally Posted by wankel=awesome
Sweet, I want an FC front end.
ya there kinda even thinking about it.
Old 12-06-10, 02:15 PM
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One way to get more steering angle is to cut off the stops on the LCA's and remove the stopper screws from the knuckle arms.

I wish I had the money to get a set of the gforce turn-in spacers. I run the 1.5" ISC racing ones that re just straight spacers. I will say they made a huge difference with turn in and stability through a curve.
Old 12-06-10, 03:32 PM
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In response to the Ackerman specifically to the Re-speed rack kit, the outer pickup for the tie rod can be moved outboard. We had modeled this in the beginning and it simply meant the steering arms would be handed. Meaning there would be a left hand and right hand version.

There were a number of things we decided not to pursue for the base kit in order to maintain a decent cost. There were so many things we wanted to fix on the front geometry we had to pick the best ones to incorporate. The Ackerman loss was not deemed as important since it really only effects heavy steering situations like parking lots and driveways. I had always envisioned adding additional parts configurations to take the kit one step further but with all the other projects the time had not come yet.

There are a few variables to work around when deciding how far you can move the tie rod pivot, tie rod size and brake package are the two most prevalent. Some have used the stock arms with extra fabrication work, others have modified the supplied aluminum arms. The object is going to be to move the hole location as far outboard as possible. Stopping 1/32" shy of the tie rod making contact with the brake rotor or backing plate.

We will be happy to look into this option if enough are interested. Simply put, out of over 100 kits this has only been mentioned a few times. Most customers do not see it as an issue.

-billy
Old 12-06-10, 06:48 PM
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Billy, I am experimenting with a couple different solutions for this issue,

Would it be possible to purchase a couple of steering arms that come with the kit, without the two mounting holes (the two that bolt to the bottom of the strut)?
Old 12-06-10, 09:06 PM
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Thanks for the explanation regarding the FC front end.

I agree with is the weakness of the spindle - they do fail sometimes. But in all honesty the FC spindle isn't that much biiger and the outside bearing is the same between the FC and the big bearing FB spindle. I have my spindles magnafluxed every other year and I check the included angle when aligning the car. As long as it is 12 degrees the spindle isn't failing.

As I have mentioned before, my racing class doesn't allow an FC front swap so we have learned how to make the FB work. It helps to have access to a lathe and tig welder. So, I'll run the ReSpeed big brake kit and enjoy that the fact that I can lower my car and maintain proper suspension geometry using spacers.

I'll post up what we built in a few days.
Old 12-07-10, 01:31 PM
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Time to show my ignorance I can't seem to wrap my head around why the arms need to angle outward on a front steer setup to achieve the correct ackerman angle. The arms on the FC front end angle inward, this is whats causing the confusion I think.... Hopefully you guys can set me straight...

Mustanghammer: I've really enjoyed the pics you posted in the rear suspension thread, looking forward to more pics of the front end of your car!
Old 12-07-10, 01:33 PM
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Wait a minute.... There's a problem with the front end geometry on RX7s?




.
Old 12-07-10, 01:41 PM
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I'm going to post this in both thread because I thinks it has some good info.

http://www.gtcars.ca/online/car-care...need-know.html

I know its not FB related but still.
Old 12-07-10, 05:32 PM
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Originally Posted by mustanghammer
Thanks for the explanation regarding the FC front end.

I agree with is the weakness of the spindle - they do fail sometimes. But in all honesty the FC spindle isn't that much biiger and the outside bearing is the same between the FC and the big bearing FB spindle.
The outside isn't where they seem to be bending, though. At least, it wasn't obvious. But it would get to the point where I could torque the spindle nut with a ratchet and still have play in the bearings. (Of course I'd never drive the car with them cranked down like that!) Looking at the spindle, the wear patterns on the spindle would be uneven.

The strut tubes themselves are pretty fragile, too. Never was much of a problem when using modified wet struts, but I have a set of housings with Konis in them that I can't remove. I'd try a slide hammer but I'm afraid that I'd just damage the strut.

I do know that the FC spindles also have a reputation for snapping off but it's a lot less common to occur.
Old 12-07-10, 06:30 PM
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Originally Posted by peejay
I do know that the FC spindles also have a reputation for snapping off but it's a lot less common to occur.
I've only heard of this once and that was because of improper maintenance of the bearings.

Good grease and regular packing should have decent results.
Old 12-07-10, 07:10 PM
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Originally Posted by nofords
I've only heard of this once and that was because of improper maintenance of the bearings.

Good grease and regular packing should have decent results.
You probably don't hit many waterbars while doing circuit racing or autocross

I don't stage rally either, just rallycross, which in theory doesn't have any areas where you can get air or have speeds above 60. Crap happens though and I've been told that I can get air over just about anything, Duke Boys style Given that ruts are the fast way through a corner, I end up taking a lot of side hits. Proper suspension tuning helps keep from bottoming out, which I suspect was a lot of why I was trashing so many spindles.


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