Custom LCA pictures

[peej410]

here are some pictures of the control arms i made last week. if anyones interested in having me make some get in touch with me. i made a nice sturdy fixture to make them so remaking them will be easy

 

 

 

 

 

 

 

 

they get 3/4 heims that are rated for 10,000+ static radial load.

[240hoke]

Nice work.

 

I made some exactly like that a while ago. The consensus was that it is much much better to go head and put in a tunbuckle to that they are on car adjustable. They will be a pain to set and reset designed like that. ALso is the heim all screwed into at normal camber settings or halfway in between, i guess what im saying is are hte arms to increase negitive camber or for both positive and negitive?

 

For this reason I will be making a new set on car adjustable, there is alot of information in the archives about this and what parts to use.

 

Anyway for those of you that want to do it yourself i did a little write up here:

http://www.geocities.com/projectzt/LCA.html

adjustable t/c rods:

http://www.geocities.com/projectzt/tcrod.html

 

Heres a pic of the complete assembly with adjustable t/c's too:

 

_Austin

[BWRex]

I agree.I had mine made like Austin's and they turned out awesome.Still having trouble finding materials for the T/C rods though.Welds look tough,unit looks super beefy.

[peej410]

well the fixture that i made will accomodate either method. i made these partially to fix a few other problems i had. i made sure that i could use the fixture for many other designs, it will also accomodate caster changes and the like. i designed them to the length that puts the end of the arm half way down the heim joint thus making them adjustable in both directions. it would have been nice to adjust them with a tierod but this will be a street car so ill pretty much set it and forget it your care looks like its coming along well!

 

i do like the adjustable TC rod too, but if i was going to make those for other people id need a stock Z to work off of, because my rear pickup points are relocated. so my TC's need to be longer to get the right amount of caster.

[JMortensen]

You almost never need to make the control arm shorter IME. Making it longer means more neg camber which almost anyone who wants a set of these is going to be after. Mine were made with the rod end all the way in at the stock length. Mine were also made with 5/8 rod ends so there isn't as much adjustment as there would be in the 3/4 end, so I may be splitting hairs a bit.

[peej410]

You almost never need to make the control arm shorter IME. Making it longer means more neg camber which almost anyone who wants a set of these is going to be after. Mine were made with the rod end all the way in at the stock length. Mine were also made with 5/8 rod ends so there isn't as much adjustment as there would be in the 3/4 end, so I may be splitting hairs a bit.

 

 

with as low as my car currently sits i have just a taste too much camber, so being able to go in and out will help

[Mikelly]

I'd not do an adjustable arm without the TC ROd. It is an integral part of the whole package. Something to keep in mind is if you get more positive static caster, you will be much better off with less static negative camber. I'd like to be able to fabricate a Tie Rod that is longer for the Z, that would allow even more adjustment of the TC and control arm...

 

Side note: Most of the current higher end sports cars are pushing much higher numbers for positive caster, and require less negative caster to get the maximum performance out of current technology tires. One example is the C5/C6 corvette. When equipped with V710 tires from Kumho, a C5 with 7 degrees positive caster and 1.5 degrees negative caster will perform as well or better as a similarly equipped C5 with Hoosiers on it. Hoosiers require more negative camber to work well, and therefore aren't as "street/track" friendly... The hoosier is simply more of a track tire and requires a more aggressive setting to make it work to optimal setting. kumho designed their V700 series tires with this in mind... most guys would like to just slap on a second set of wheels and tires for the weekend and not have to get the car re-aligned before a track weekend. Hence their performance with lower negative camber required.

 

Mike

[peej410]

what i was looking into doing was making a pillow ball mount (read spherical bearing) that bolted to the stock tc rod mount. ihavent figured it all out yet because i havent had the time but it seems that most of the approaches so far actually shorten the TC rod. i would think that this would change the geometry of the front suspension quite a bit. it moves the pivot point of the TC rod in towards the strut pretty far.

 

does the suspension geometry in the corvette scenario come into play ? the guys race car i work on is an ex-shock tech for ohlins, he said hes not sure what is ideal for a Z but he runs 7 positive caster on his porsche 914-6 and he got 2nd place at the runoffs this year in EP (i was crew chief) can anyone suggest a suspension book that encompasses different suspension designs?

[tube80z]

Side note: Most of the current higher end sports cars are pushing much higher numbers for positive caster' date=' and require less negative caster to get the maximum performance out of current technology tires. One example is the C5/C6 corvette. When equipped with V710 tires from Kumho, a C5 with 7 degrees positive caster and 1.5 degrees negative caster will perform as well or better as a similarly equipped C5 with Hoosiers on it. Hoosiers require more negative camber to work well, and therefore aren't as "street/track" friendly... The hoosier is simply more of a track tire and requires a more aggressive setting to make it work to optimal setting. kumho designed their V700 series tires with this in mind

Mike[/quote']

 

As Mike points out caster is very tire dependent and generally related to lateral tire stiffness. As you go up in caster you need to think about caster trail. That's the difference from where the steering axis hits the ground to the contact patch. The lever arm that is created from this point to the contact patch will lead to increased steering effort as it gets longer. To counter this the hub must be moved forward to reduce the distance.

 

A good starting point is one half the steering axis inclination for caster. So on a Z that's going to be around 6 to 7 degrees. Caster trail will generally need to fall in .5 to .75 inches. That will give you a point to test from to see if more or less works better.

 

A Swift 014 FA car has 7.3 degrees SIA and usually runs 6.8 degrees caster. Scrub radius is 1.72 inches. Caster trail is .63 inches. Just in case you're curious.

 

Cary

[tube80z]

does the suspension geometry in the corvette scenario come into play?

Yes' date=' kinematic changes (suspension geometry) will have more influence to the handling than what you can get with spring/bar/shock changes. If you're looking to really increase performance this is an area to focus on.

 

can anyone suggest a suspension book that encompasses different suspension designs?

 

A good DIY book is Race and Rally car sourcebook by Staniforth. For more of an engineering approach, Milliken's Race Car Vehicle Dynamics. And an even better option would be to invest in Claude Rouelle's seminars in data acquisistion. He spends a couple of days talking about vehicle dynamics. It's like having a book you can ask questions of and get answers (http://www.optimumg.com). And if you're really fortunate the seminars by ICP (Richard Pare and Steve Lathrop), which are aimed at club racers and have a ton of good info on them.

 

Cary

[dj paul]

does anyone have any pictures of how these would be used? i saw the one by 240hoke and that helps a little, how much would i have to modify my suspension bracket? if i got these from you?

[Mikelly]

With adjustable control arms, there is no modification to the suspension "brackets"... Not even sure what you're refering to there, but bottom line is worst case scenario is you drill out the holes in the crossmember to 3/4inch hole for the bolts or burn out the steel sleeve in the existing control arm and reuse that and the factory Nissan inboard control arm bolt/ nut.

 

As to the other comments and questions, I can give a direct answer to the correlation between the double A arm setup of the Vette compared to the single upright lower I arm of the Zcar... We comped a set of our arms to Steve and Ian and they set their Zcar up with them using 7+ degrees of caster or more. The end result was less negative camber, more contact patch on the ground at static load, and much less problems with the car on smooth autoX surfaces. That car rules most circuits and won most events they entered, and is still very successful. The only issues they encountered was making sure the car settings didn't change over events. They had two drivers, and beat on the car, which had hard bushings (some were aluminum I think) in post pickup points and ran on very sticky slicks on a very stiff suspension. This is harder on a car, and this car was a specific track only car, gutted and weighing about 2000#. Positive Caster directly aids making the car steer better, and in my opinion is more important than negative camber because we often forget about the natural dynamic camber loading of the suspension, plus the bumpsteer/ Ackerman relationship. If you can get the most contact patch at all times (very difficult in the best of circumstances) then you have more traction to work with at all corners...

 

Mike

[peej410]

i havent installed the bushings yet because of my TC rod issue, which is why id want an original Z to make these for first before selling them to the public. id also like to thoroughly test them on my own car. if you just want a set of control arms just like mine, and you intend to make your spacers and figure everything else out yourself let me know.

 

 

 

[dj paul]

thanks for the pictures and info guys, id like a set of those, but dont need them for a little bit. if you need time testing and stuff i can wait. but also could get them now.

[blueovalz]

Side note: Most of the current higher end sports cars are pushing much higher numbers for positive caster, and require less negative caster to get the maximum performance out of current technology tires. One example is the C5/C6 corvette. When equipped with V710 tires from Kumho, a C5 with 7 degrees positive caster and 1.5 degrees negative caster will perform as well or better as a similarly equipped C5 with Hoosiers on it.

 

When I started on my Z, and after investigating this whole mess with caster/camber relationships, I lengthened my TC rod, moved the crossmember forward, and of course, did the usual "adjustable" control arm modifications (and being the body was built around the chassis, I had no problems with the wheel openings from the increased wheel base dimension) The end result was 7º of caster. Braking was much improved with the decreased camber (ran about 1º or less) as a result. The backside of it was, once I put the car on the street, my perception was that it "hunted" (pulled side to side) more than before on uneven road surfaces. Smooth surfaces did not do this. My current challenge is to reduce this "hunting". I experimented with reducing the toe to zero, but the results were mixed and not definitive. Any help from you guys would be appreciated.

[Mikelly]

Terry, This is a common issue with the C5's as well. What those guys are doing is setting front toe out to 1/16 or Zero and setting the rear toe in to about 1/16th to 1/8th with better stability for street driving. Also, Newer technology low profile tire designs are incorporating better tread patterns and altered sidewalls to combat this "hunting" on uneven road surfaces!

 

Might be worth investigating for the Zcar suspension setup!

Mike

[peej410]

im not sure what you guys would think of it, but my Z would tramline a little bit before too. so i took the top rack mounts (the things that almost look like straps) and welded in pieces that i shaped to fit the contours of the rack. then carefully filed them so they fit in the rack after welding them to the "straps" this made the car steer awesome. it also only took a few hours of fitting to get them right. i had the poly steering rack mounts in but with the car sitting flat not moving when you turned the wheel the rack would still move in the body, now. no movement.

[JMortensen]

It's not the caster that causes the front end to wander. It's the camber and toe. In fact lots of Mercedes run 11º of caster, which is why when you see one parked with the wheels cranked they look broken. More caster makes it harder to steer and when you come out of a turn it makes the wheel return faster. Harder for you to turn = harder for bumps in the road to turn.

 

For a street car reducing negative camber and running 1/8" toe in will all but cure the wandering front end. Not the most racey setup, but that's what works for the street. I used to have two lines painted on my tie rod for 1/8" toe in and 1/8" toe out. I'd go to the autox and jack the front end up and move that one tie rod. Should have been using more toe out than that, but that's what I was doing.

[johnc]

Way back, when I still drove my 240Z on the street in its BSP configuration I would only reduce the toe out. I drove with 6.5 degrees of postive caster, 3.2 degrees negative camber front and 2.8 degrees negative camber rear. It was "lively" and I prided myself on being able to bounce the passenger's head off the side window any time I wanted.

[peej410]

In fact lots of Mercedes run 11º of caster' date=' which is why when you see one parked with the wheels cranked they look broken.

[/quote']

 

haha i had a hunch thats why my dads SL always looked so funny parked at full lock.

 

whats the proper way to measure caster? is it just the direction of the suspension travel? or is it something more complex? feel free to use actual suspension talk jargon, id like to be more specific when i ask questions in the future.