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Check my thoughts. Car Pushes.


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My 280Z has Illuminas and Tokico springs 1" lower. I run "bump" spacers and ST 1-1/8" and 7/8" swaybars. I run 225-50/16 tires. I run near 0 toe. Urethane bushings all around. I also use front and rear tower bars. All other (camber/caster) settings fall wherever the factory parts let it fall.

 

The car pushes a bit just after turn-in and both outside tire edges are wearing fast. It has seen a couple of track days and lots of aggressive windy roads.

 

It's mainly a country, weekend, road car.

 

Before I go and get a thinner front swaybar and adjustable everything:

1)How far can I push the stock T/C arms forward with washers (if any).

2)How much neg. camber can I get by just slotting the strut towers?

3)Am I way off the mark?

 

"Flame Suit On"

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...(camber/caster) settings fall wherever the factory parts let it fall.

The car pushes a bit just after turn-in and both outside tire edges are wearing fast...

2)How much neg. camber can I get by just slotting the strut towers?

cygnusx1: The Tokico springs you have are stock diameter? There really is not a lot of room up in the spring towers for the stock springs to move. I doubt you'll be able to get much added camber by slotting the towers without changing springs.

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Yep. You might get .5 degree out of a slotted strut tower (SWAG). About the same for shimming the TC rod I would bet. Adjustability is nice, might consider some camber bushings as a cheap way to get it, if you're getting serious camber plates are a better option. Adjustable TC rods will give you the caster adjustability.

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I added aluminum/delrin offset bushings front and rear... TC ball sockets... slotted upper tower holes(inward only)... added 1" B/S spacers...swaybars front and rear(I'll have to get dimensions later)... Tokico blues and someone's(MSA) blue springs(stock fitment).

 

Adjusted ~1/8" toe out in front... -1.5* camber each front...

Adjusted ~3/16" Toe in in rear... -1.5* camber each rear....

cant remember caster... I adjusted one side with washers to bring to spec with other side.

 

In addition... I removed bumpers... relocated battery... added custom roll bar with chassis/floor reinforcement... NOT BOLTED TO WHEELWELLS. I added custom strut tower braces as well...

 

The car handles great... no excessive push/understeer... no problems with the tail being loose/oversteer... I am able to rotate the car under trail braking without upsets or scares... I still need more camber in the front to reduce edge wear... I can get on the power in the turn without any problems... You need to remember to unwind the wheel to find grip in some cases... but this is normal for any car.

 

Another great benefit from this is that the car is much more stable under hard braking at high speeds... The suspension does not move around under the car anymore with the offset bushings and chassis reinforcement...

I can nail the brakes at the limit of trction going 115MPH and it stays straight with a neutral feeling steering wheel.. until you lock a front wheel, then you better be holding on tight.

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BJ's setup is pretty much exactly what I ran when I put my car together. Works well as a compromise street/track setup. I used to have 2 marks on my tie rod. One was 1/8" toe in and the other was 1/8" toe out. You can adjust that little bit on one side only. Running toe out on the street will tear up your front tires, but it only takes loosening one jam nut and about 1/4 turn of the turnbuckle to change the toe at the track.

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That's what I was afraid of. It's either a tiny bit of adjustment or an expensive can of worms to go all out. I do have stock diameter springs. With all the reading I've been doing, I understood that more caster, in effect, gives more camber (dynamically). I was hoping that someone would tell me that just adding a degree? or so of caster with washers and half a degree? neg. camber by slotting the towers inwards, would be enough for the street and occasional track days. I was also hoping that it would make life a bit easier for my tire edges. I know it's not the ultimate hightech answer but BJ's setup seems alot better than nothing and not too costly either.

 

You see, I hate to undo what I have already done. ie. Springs and struts and I really don't want to get into welding camber plates on the car. Although I may end up going all fully adjustable suspension someday, my next big expense is going to be either a)EFI Programmable or b)an engine rebuild.

 

Thanks.

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Lose the bump steer spacers. Unless the car is really REALLY low, they take away negative camber. I didn't miss them any when I got rid of mine.

Slotting the shock towers got me .5 deg negative. Definitely worthwhile for the price (if you don't mind a little butchery!).

Eccentric Al/delrin bushings might get you another .5 deg, some anyway.

Stock front sway bar, maybe?

 

Ultimately I lengthened my front control arms 9/16" to get more negative up front. With that and slotted towers (and polyurethane bushings) I'm ~2.25 deg. up front. ~1.8deg. in back. Minimal toe-out up front, ~1/16 toe-in in back (Al/delrin bushings). With this setup I had to get rid of the rear sway bar to make it neutral. All is not ideal, as it picks up the inside front outta low-speed corners, but it is pretty fun and reasonably fast:)

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I hesitate to remove the B/S spacers because I am pretty sure that the front control arms are pretty close to horizontal already. I will check it again though it's a good point. I may also try to round up a used 1" 240Z front swaybar instead of my 1-1/8".

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In the good ole days a good alignment shop used to be able to put a rig on your strut and bend the bottom of it up to a degree. Have to watch your tire clearance on the inside against the strut, but otherwise a pretty dang cheap way to get another degree of negative camber. Dunno if they still do that sort of thing, its been a few years. For a track car on radials you really need prodigious amounts of front camber.

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I hesitate to remove the B/S spacers because I am pretty sure that the front control arms are pretty close to horizontal already. I will check it again though it's a good point. I may also try to round up a used 1" 240Z front swaybar instead of my 1-1/8".

 

Camber is maximized when the control arm is perpendicular to the strut, not when it is horizontal. Lose the spacers and I *promise* you more negative camber:)

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In the good ole days a good alignment shop used to be able to put a rig on your strut and bend the bottom of it up to a degree. Have to watch your tire clearance on the inside against the strut, but otherwise a pretty dang cheap way to get another degree of negative camber. Dunno if they still do that sort of thing, its been a few years. For a track car on radials you really need prodigious amounts of front camber.

 

Yeah, I used to do that to BMWs all the time back in my alignment days. Used a bracket that bolted to the hub, then basically a big 'C' clamp around the strut and a porta-power between that and the hub bracket and pump away to 'bend' the camber negative. I have never seen any shop in this country doing it.....

Tim

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I've heard of shops doing that. In fact I seem to remember a friend saying that a shop did that to her Z about 10 years ago because it was way off. I never knew what they were bending. For some reason I had imagined them bending the strut right up at the top.

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When you are presented with the need to get more negative camber on the front end of the car... slotting the strut towers will not get you much... But if you get real happy with a cutoff wheel.. you can remove the innermost portion of the upper insulator housing... there is another half inch of inward motion that can be attained that way...

If you are mashing it against the inside of the strut tower... then the rubber will still be supported on all sides... the spring contacting the tower will be your limit on how much you can cut..

 

Another easy free camber/geometry upgrade is relocating the holes in the lower crossmember to locate the control arms upward and outward... Many people who do this have to move the upper mounts OUTWARD to reduce negative camber... especially if you are running 10" wide tires...

 

Jmortenson has been working on ideas for relocating the TC bucket to match this alteration of the control arm mounting location. another fix for the TC bucket location is to add a spacer between the lower X-member and the chassis... this would place the raised control arm mounts and the TC buckets in the same plane...

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More caster will make turning harder. I am around 4.5* and will be taking a little out. You could run offest bushing on the LCA's instead of slotting your top strut mount to gain a little more camber. You would need to space the TC rod out to keep the caster the same. You could run a softer front bar. I have a 1" bar I would swap if you wanted.:mrgreen: I would try adding or lower front tire pressure first though as it would cost nothing.

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Lots of great ideas here! I am going to study all the options and experiment within a week or so. I like the idea of relocating the inner control arm holes. I never liked the idea of eccentric bushings because they also move the inner LCA up and down when you adjust for in and out.

 

Thinking out loud:

Relocating the LCA holes (very carefully) could give me a nice amount of neg. camber. but no adjustment. I would also need to make the tie rods longer somehow which is not unsurmountable. Slotting the towers in conjuction could give me +/- 1/2 degree or so. Then I could add some washers to the T/C rods to make some more caster or at least match the two sides up. Then I could experiment later with a softer swaybar and tire pressures to fine tune. Yikes. If I change too many things at once...I could bury myself and end up throwing in the towels and buying everything ajdustable! Break time.

 

Clifton, I would trade swaybars with you but I am not sure what I need yet.

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Clifton, I would trade swaybars with you but I am not sure what I need yet.

 

 

If you decide you want it let me know.

 

There is enough length of the tie rod ends to run eccentric bushings offset all the way out. I run them on my 71'. I have AZC control arm on my 73' and lengthend them 10mm over stock so I know there is atleast an extra 10mm in them if you go that route. If you can weld a few people have cut off the lca ends and welded a tube and used rod ends there. I think 240hoke did it too and had pics.

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don't forget that offset bushings have another desirable effect... They are made of aluminum... and they rotate in thin hard plastic sleeves... they keep the suspension parts from twisting or shifting under loads...

 

The same effect is gained through the use of Heim joints/Johnny joints/spherical bushings... they provide a hard location for the suspension parts...

 

The main drawback to the Aluminum+delrin bushings is that they tend to wear fast and they will bind if they are forced out of their plane of rotation... like adding a lot of caster by pushing the wheels forward...

You can account for this when you redrill your crossmember mounting holes... the crossmember is thin and flexible.. it will conform to the slightly angled holes when you tighten it up... you can also "flex" the crossmember's sides to align the sides of the sheetmetal crossmember with the faces of the offset bushings.

You will also need to provide a grease nipple to the inner control arm mounting hole. This will allow you to grease the sliding parts of the bushings...

 

When you get to the part where you need to drill the new holes in the front crossmember...

 

1. drill the front holes in their new location

 

2. get the suspension together(except springs)... try to have everything set as close to how you want it when the car is on the road... caster, camber using the bolt placed partially though the front hole only...

 

3.then I used a large drill bit that closely matched the mounting bolt size to spot drill the hole location on the back side of the crossmember... pull everything apart and complete the drilling process, deburr and weld the new washers to the inside of the crossmember in the new holes locations.

 

4. bend the sides of the crossmember to closely match the slightly angled faces of the offset bushings.

 

This will allow you to push the wheels forward without binding the offset bushings... they will rotate in the correct plane with the movement of the control arms.

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"..they will rotate in the correct plane with the movement of the control arms"

 

Not exactly. The old Kontrolle style offset aluminum/delrin bushing will always bind up because of the connection of the LCA to the T/C rod. The application really requires a heim.

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