Camber change after 1.5" drop?

[mtnickel]

I did search on this but couldn't find anything, so excuse me if this has been covered.

 

Does anyone know how the s30's camber changes after a 1-1.5" drop (73 240z). I looked for anyones alignment results with either stock or any sort of drop and came up with nothing.

 

I know some cars take to lowering better than others depending on the geometry of the arms. My hondas for instance, have always been very close after mild/sport drops.

 

Also, I know camber plates are popular, but is it not possible to just slot the stock bolt holes to get some camber change? From a few measurements it looks as though there is at least 5/16" of clearance to go inward. The strut top hat material is also pretty thin and can be massaged if a little more is needed.

This would be for a street car of course. I know the racers typically go the plate route to run much more aggressive camber.

 

Basically I'm building a car that is 95% street driven and will be doing a mild (1-1.75" drop) and am wondering what similar people have done for camber and alignment changes.

 

Regards,
Mark

[RebekahsZ]

If car is on street and only dropping it that little I would just blow off the camber changes and not worry about bit. The squatted rear is kinda "in" and you will just go thru tires a little faster. Just go for it.

[JMortensen]

Lowering a bit on your typical Z gets you too much neg camber in back and still not enough in front. Simple solution is an adjustable front control arm for the front and camber bushings for the rear. Be careful not to try and get too much neg camber in front as you quickly run out of tie rod adjustment.

[mtnickel]

Is there any particular reason I couldn't sketch out a template and just elongate the stock strut mount points by maybe 1/4" in the direction they need to go (1/4" out in the rear and 1/4" in on the front). I realize it could get close to the edges of the metal tabs up there, but I could reinforce those as well.

Mathematically that would give about .75* of camber change. Now maybe this isn't enough to justify it, but thought it was worth a thought.

 

My predicament is that it's just a street car where I want to keep the stock top hats for less noise, yet I also am trying to do as much fab work myself to save on parts (thus eliminating camber plates and expensive adjustable arms). I could perhaps do the lower control arm pivot relocation as well, but that seems like guess work trying to get the camber correct.

Regards,
Mark

Edited March 3, 2014 by mtnickel

[JMortensen]

If you have the capability to do all of that, then you might consider making a set of front control arms. It's not that hard to do, a bunch of people have made arms and posted about it here (240hoke and bjhines come to mind, there have been many others). I had a machinist make mine in the attached pic, they're about as simple as you could ask for. Just a stock arm that was cut, a tube welded into the cut end, and the threaded tube end welded into that. I would make it so that with the rod end all the way adjusted down, they are stock length. 

 

If you made your own front arms and bought rear camber bushings, I'd guess you'd be into it less than $200. $75 for the rear camber bushings, and a little bit of tubing, some threaded tube ends and some rod ends and jam nuts for the front. 

 

EDIT--Looks like I saw the price on the front camber bushings. Rears are more expensive. Still should be able to get out of it for $300ish.

Edited March 3, 2014 by JMortensen

[clarkspeed]

Measure it on the car. Straight edge and cheap digital angle gauge from Harbor freight or phone app level. I've driven some fast cars without any adjustment.

[RebekahsZ]

You are worrying too much about it for a street car. It doesn't matter that much. Yes, you can elongate the holes. If you autocross, you will get tired of the car pushing, but you can always add camber plates after pushing for a couple of years. These modifications can definitely be staged if you are just a hobbiest like me. The only adjustment that will make your car totally suck is toe-in; if it is way off it will make the car pull and eat up a set of tires. Otherwise, you can adjust your speed to the way your car drives. Camber has no real effect on a car driving in a straight line. If it pushes when you enter a corner, slow the heck down before turning. If the rear gets loose when you add a bunch of throttle, don't do that! If you want to go as fast as you can on the track, then try to get to johnc's alignment specs per the FAQs forum then adjust from there. I started with some used sectioned struts to make the car look cool (I was about 26 years old). Then after a couple years I tried offset bushings but they were so terribly noisy (just the rears-the fronts were fine since they aren't right behind your arse). After a couple years, I got tired of having to almost stop at autocross before entering a turn, so I added front camber plates. That helped the pushing, but when I added a V8 i couldn't keep the arse under me, so I added rear camber plates. Wanted to try adding caster the following year, so I went to TTT front LCAs for the spherical bushing. Then the next year I went to large tires, so I needed Modern Motorsport rear LCAs to narrow the rear track. Now I'm flaring the rear fenders, so the narrowed track isn't needed anymore. Having trouble with rear traction drag racing, so I went to adjustable Konis this winter, and I'll see if that helps. I've had the car more than 20 years now and still enjoy it. Would it have been cheaper to do all my mods at the beginning? Sure. But, neither TTT, nor Modern Motorsport existed when I started (actually Modern Motorsport has come and gone). Would I have won more national championships if the car were better prepared, surely not.

Edited March 3, 2014 by RebekahsZ

[mtnickel]

You are worrying too much about it for a street car. It doesn't matter that much. Yes, you can elongate the holes. If you autocross, you will get tired of the car pushing, but you can always add camber plates after pushing for a couple of years. These modifications can be staged.

 

Thanks for the input guys. So long as the alignment won't be off to the point of really bad tire wear, it's probably fine for now. I think pushing in the corners is probably better for me to start as this is my first RWD car and most powerful. I was only asking now as the engine bay is going to be painted this week and I wanted to finish off any additional metal work before it goes to paint. I can always do bolt in plates or LCA later.

 

Mark

[JMortensen]

If you drive like a grandma, your rear tires will wear the insides first. If you drive hard, the front tires will wear the outsides first. Either way, if you rotate them a lot you should do OK.

[RebekahsZ]

I think Jon just called me a grandma....

 

Hey Jon, send me a link to some photos of your latest work on your car-last I heard you were working on the fenders. I'd like to catch up... BTW-I'm still on the first set of your awesome axles. Your looking for truck tires is a good sign!

[mtnickel]

If you have the capability to do all of that, then you might consider making a set of front control arms. It's not that hard to do, a bunch of people have made arms and posted about it here (240hoke and bjhines come to mind, there have been many others). I had a machinist make mine in the attached pic, they're about as simple as you could ask for. Just a stock arm that was cut, a tube welded into the cut end, and the threaded tube end welded into that. I would make it so that with the rod end all the way adjusted down, they are stock length. 

 

If you made your own front arms and bought rear camber bushings, I'd guess you'd be into it less than $200. $75 for the rear camber bushings, and a little bit of tubing, some threaded tube ends and some rod ends and jam nuts for the front. 

 

EDIT--Looks like I saw the price on the front camber bushings. Rears are more expensive. Still should be able to get out of it for $300ish.

John,

Do you have a link to where this hardware can still be purchased? I think I even have a spare set of arms that can be used while I'm doing the fab work.

Sadly, I'm just now finally getting to my suspension work. Sectioned struts, 175/200 springs on adjustable sleeves. Front RCA.

 

I did slot the stock strut holes for fun. Using the stock insulators, the front can only go in about 1/4" which is maybe 1/2-3/4* of camber. Every bit helps, but will make the rest of the change in the lower arm. The rear however can move a solid 5/8" inward leaving plenty of camber adjustment there. I will get some pics up.

Though mainly street, I'm really looking at getting into some auto crossing. After some pro karting sessions and lots of seat time on my pseudo racing simulator (assetto corsa), I need to get out in the Z as well.

 

Now just need to decide on sway bars. Will start with stock front/no rear and see how the roll balance is.

Edited July 19, 2016 by mtnickel

[Chickenman]

I've been Autocrossing in BC since the mid 70's. We have a very Healthy Autocross scene here with many Test Sessions and driver training courses. Velocity by VCMC for example.

 

Personally I think a 175 front 200 rear spring combo is too soft in the front for our events and tracks. I'd go with at least a 250 frt  200 rr combo. The hot setup for VERY fast street and Autocross 510's is a 300 lb front spring on ZX struts. The 510 is much lighter than a Z up front, yet the ride isn't too bad. Surpringly smooth as a matter of fact.

 

You're going to get different theories on spring and bar combo's, but the current PNW Coast Autocross " Hot " setup on 510's and Z's seems to favor a " moderately "  stiff spring with the softest front bar you can get away with. This gives good initial turn-in due to the soft front bar, yet still supports the outer corner. And it prevents nose dive.

 

A big consideration is that we run a lot in the wet. Big front bars just make the car under-steer in the rain.

 

I'll give you a PM with some contact info. I'm a BC Z Registry member. We may have already met at some of of the Club's meets???

 

Richard

[JMortensen]

John,

Do you have a link to where this hardware can still be purchased?

Google "race car threaded tube ends"

http://www.colemanracing.com/Tube-End-Threaded-P3952.aspx

http://www.swracecars.com/store/Threaded-Tube-Ends-OSCAR_83.aspx

https://www.summitracing.com/search/product-line/meziere-threaded-tube-ends?SortBy=Default&SortOrder=Ascending&tw=threaded%20tube&sw=Meziere%20Threaded%20Tube%20Ends

 

The problem with the Z control arms is that the hole is fairly small. IIRC a 1" diameter tube fits inside the stock arm when you chop it, probably want to cut one and double check that... The problem is that the tube ends have different ODs. That Coleman piece is a 1" OD, so if you put a .083" wall tube on it it's now a little shy of 1 3/16" and won't fit in the arm. BJhines fixed that by cutting the arm lengthwise and then welding it all back together. The guy who made my arms turned the tube ends down to fit in a 1" OD tube IIRC. Either way works, obviously having a lathe helps if you're trying to use the right size tubing so that the arm doesn't need to be modified.

[mtnickel]

Google "race car threaded tube ends"

http://www.colemanracing.com/Tube-End-Threaded-P3952.aspx

http://www.swracecars.com/store/Threaded-Tube-Ends-OSCAR_83.aspx

https://www.summitracing.com/search/product-line/meziere-threaded-tube-ends?SortBy=Default&SortOrder=Ascending&tw=threaded%20tube&sw=Meziere%20Threaded%20Tube%20Ends

 

The problem with the Z control arms is that the hole is fairly small. IIRC a 1" diameter tube fits inside the stock arm when you chop it, probably want to cut one and double check that... The problem is that the tube ends have different ODs. That Coleman piece is a 1" OD, so if you put a .083" wall tube on it it's now a little shy of 1 3/16" and won't fit in the arm. BJhines fixed that by cutting the arm lengthwise and then welding it all back together. The guy who made my arms turned the tube ends down to fit in a 1" OD tube IIRC. Either way works, obviously having a lathe helps if you're trying to use the right size tubing so that the arm doesn't need to be modified.

 

What's wrong with welding the threaded insert directly in without a tube?

[JMortensen]

What's wrong with welding the threaded insert directly in without a tube?

Less area to weld on the control arm? Mine plugged into the arm 3 or 4 inches, and the guy plug welded the tube to the arm in a bunch of spots, migged the end of the arm to the tube, then tigged around the end of the tube and the threaded insert.

 

It might work without tubing. Never tried that or seen it done, but if it's welded well and the connection is solid, maybe that's enough. Maybe get someone better at fabrication to throw out an opinion. This would have been a perfect question for John Coffey.

[mtnickel]

Your way certainly would be stronger but more work. I figured perhaps most of the force is Tension/compression with minimal torqueing/bending. I would to the same as BJhines and do maybe an 1/8" notch along the top and tig weld. along with tig welding the end and 2 plug welds on each side.
 How much NVH is added from these solid mounts? Really not many options for maintaining quiet but having adjustibility (especially if I want to add caster down the road).

 

Best I could think of would be to taper the ends of the poly bushings a little, and then slot the rearward inner pivot point. Could then loosen the pivot bolt while adjusting caster to change it's rotational axis, and tighten back up. Then Control arm fab would have to be double sided with a type of turnbuckle.

 

Less area to weld on the control arm? Mine plugged into the arm 3 or 4 inches, and the guy plug welded the tube to the arm in a bunch of spots, migged the end of the arm to the tube, then tigged around the end of the tube and the threaded insert.

 

It might work without tubing. Never tried that or seen it done, but if it's welded well and the connection is solid, maybe that's enough. Maybe get someone better at fabrication to throw out an opinion. This would have been a perfect question for John Coffey.

[Chickenman]

These are what I ended up getting. Not as much adjustment as some, but you don't have to cut out the strut towers.

 

http://www.ebay.com/itm/MK1-PillowBall-Bearing-Strut-Upper-Mount-For-Coilover-Kit-Mounts-Plates-240Z-/381703716541?hash=item58df507ebd:g:CwUAAOxygPtS3Kbw&vxp=mtr

 

 

[JMortensen]

NVH wasn't a problem for me when I was driving my Z daily. I had rod ends on the TC rods too, never minded it at all.

[mtnickel]

NVH wasn't a problem for me when I was driving my Z daily. I had rod ends on the TC rods too, never minded it at all.

many thanks. I would think the solid top hat on the strut would contribute a lot more than the control arm bushing. As always many thanks Jon. Hope to meet you someday soon being in the Northwest (Vancouver, BC).

[Chickenman]

If you get the spring and bar rates correct, you shouldn't really have to run much Castor. Stock castor settings are more than enough for Autocross from my experiences ( and my setups ) . Any extra, really just makes them a bear to steer with wider sticky tires. I've seen way too many guys crank in a bunch of Castor because of articles they've read on extra Castor inducing Negative Camber on Mac struts. It's not needed in my experiences and you can do far more with balanced Spring rates, reasonable bar settings,  Camber settings.and .... proper rear Brake Bias ( the last one is very important )

 

Extra Castor increases steering effort a lot and it also adds weight jacking to the outside tire, which can be detrimental. I always like to keep Castor settings and steering effort reasonable for Autocross.

 

My Autocross cars ( Datsun 510's, Datsun 1200's, 240Z's, Big HP  2nd and 3rd Gen Camaro's and Audi A4 Quattro's ) have all had great turn-in, and are very much on the nose.  Quick directional change,  crisp Turn-in  with no under-steer is very important in Autocross. The AWD Audi A4 is well known to be an under-steering pig, but with a few setup changes to springs and bars, even those can be tamed. I hate under-steer with a passion....

 

Personally, I have never been had to use " Toe-out " or any other Tricks to get the nose to Turn-in on any car I've ever competed in. Autocross, Road Race or Hillclimb.  Those who do have to use Toe-out to get crisp Turn-in usually have their springs rates out of balance or have some underlying geometry problems that need to be corrected. Toe-out is a bitch on a daily driver, especially in the rain. Not that we get much of that here...right?

 

One thing that will definitely help the front end bite is a Strut Tower brace. A strut bar that is triangulated to the firewall is the best of course, but even a strut bar just between the two towers makes a noticeable difference. .

 

Triangulating the steering rack mounts to the frame horns also adds rigidity. If you plan to compete on a regular basis, check your local  rules to see if you are allowed to do this. BC Region runs SCCA rules now...