I have an ‘84 z28 and I’m freshening up the suspension all around while I wait to get my sfcs welded in. I’ve found both the j@m poly ball LCA and the extreme joint LCA and was wondering is anybody here has had any experience with the extreme joint LCA they offer. I was planning to get the poly ball as I’ve heard great things but wanna see if the extreme joint LCA is worth the extra $30. Also would the adjustable LCAs and Panhard bar be of any benefit vs the non adjustable components I’m planning to order? My car is primarily street driven (sometimes rather enthusiastically) and I plan to keep the suspension at stock height due to the wonderful roads of MA. I also have 26”x12”wide tires in the rear. Here’s a link to the extreme joint LCA.
https://hotpart.com/product/camarofirebird-82-02-lower-rear-control-arm-black-extreme-joint-street-race-jm-products-made-in-the-usa/

 

Save your money and buy this

https://www.umiperformance.com/home/...-control-arms/

With said extra money buy this

https://www.foundersperformance.com/...v=f24485ae434a

 

LCARBS are something I haven’t really considered putting on my car since I plan to keep the suspension at stock height. Do the LCARBS have any benefit on a stock height car or did you recommend them to fix the LCA angle that my bigger rear tires cause? I’m assuming that they would need to be welded in if I really plan to beat on the car?

 

You can google it and get a really good explanation, but they really improve traction, even on stock ride height vehicles. I often study the geometry of all these parts as I'm building my suspension on my 88 right now, but I don't quite feel like I'm knowledgeable enough to really start explaining the ins and outs of it all. Just google lower control arm relocation and there are plenty of diagrams and explanations.

 

In a nutshell, when accelerating the forces applied to the LCA's go in two vectors, Up and Down (Y) and front and back (X). When you lower the mount of the LCA via a relocation bracket, it changes the ratio of which force goes where. Relocated LCA's transfer more force in the Y direction and less in the X, directly loading the tire more.

 

Since the first response mentioning LCARBS I’ve been doing a lot of reading and it seems I should install my new springs and shocks to see if I truly need LCARBS. It seems the ideal geometry is to have the LCAs level to the ground or slightly lower on the axle side. If replacing my sagging springs and putting in new shocks in the rear makes my control arms level or slightly lower on the axle side it seems I shouldn’t need LCARBS. Somebody correct me if I’m wrong.

 

I am no suspension expert but there is truth to this. Lowering changes the instant center of the car and ultimately weight transfer to the tires. It's a dance that all components need to play nice in for the best results. Tires also play a huge part, as well as power. A weak 305 won't expose this relationship as much as a higher power mill.

 

Yah since I swapped out the 305 for a 400 hp 355 I’ve definitely felt the need to upgrade my suspension which has led me here.

 

LCARBS should be used when the car is lowered to maintain the factory geometry. Thats why they exist.

Same reason extended balljoints exist. Lower the front end, it changes the A-Arm geometry, so the extended ball joint restores the correct geometry. Course everything else needs to be adjusted then too. Domino effect.

That said, stock factory stamped arms are wet noodles. I remember a video from a 4th gen I think, showing the stamped LCA's bowing like made, you could see the relation between the LCA flex and the wheel hop. Other parts play a roll too, TA flexes a lot. More traction you have at the tire, the more force acts on the links. More power you have, the more force too.

I don't get wheel hop AT ALL on my car. It either grips and goes, to breaks traction and smoothly spins. I have the UMI double adjustable Roto-joints.

 

The fact is that if you're getting wheel hop on your third gen (or 4th gen) it's not a question of LCARB's or ride height, but what is broken, loose or worn out. I say that all the time, people argue with me and I've never seen a car that I wasn't able to find something wrong with it when looking it over.

Optimum geometry for all-around use is with the LCA's level at ride height or as close as you can get. Arguably you might get slightly better handling (more consistent turn in...) with them level or _slightly_ up in the back and slightly better dragstrip "hook" with them slightly down in the back. If you need them more than slightly down in the back to hook you're either making no power and on crap tires or something else is wrong. If you have them more than slightly down in the back and you're making OK power and on decent tires, you'll find that you'll get too much anti-squat and the suspension will push down on the tires too hard (too much reaction) and you'll find that you will hook hard on the line and then the tires will literally bounce (sometimes you can see the sidewalls compress and I've even seen the rims leave marks on the track) and you'll lose traction a few feet out. A friend shooting video on the line is pretty valuable for dragstrip suspension tuning.