I have a 1990 Camaro with 34mm sway bar infront and a 18mm I'm back. I feel like the 18mm is a pretty weak sway bar and alot of people say that the 24mm is the best for the rear. Other say to keep your rear as small as possible. Any input? I originally wanted to do a 34/24 combo but not sure now. What would be a good rear size for a front 34?

 

Your setup right now is understeer safe.
How is your tolerance for off throttle oversteer?

 

For what it's worth, that was the original combo on my 85 IROC.

JamesC

 

I believe my 91 has 34/23 and with global west springs and adjustable shocks, it handles very well and has mostly understeer, but can throttle into oversteer.

I think a 22-24 works ok with 34-36 fronts

 

Combo works well
Higher rated rear springs can help vs sway bar change also

In general you can stiffen either or or both to tune the in or out oversteer

 

Wrong: You want to install the biggest rear sway bar you can under your Thirdgen possible. Using Poly bushings ( not end links ) rather than factory stock rubber will also be 'like' adding another mm or 2 to the bar. Poly End links help too - don't get me wrong - but not nearly as much as Poly Bushings around the bar itself.

The largest bar you will probably find is a 24mm. There was a 25mm rear bar, but I've only confirmed it's existence in the 85 Trans Am - ONLY. Most early/mid Z28's have a 23 bar stock, IROC's have the 24. Later Camaros tended to have larger bars than early cars.

Zack also hit on a good point; Springs. Make a note of the Spring code on the tags taped to the original springs so you know where you started the adjustments. Springs and bars were "matched" at the factory,... meaning that if you install Z28 sway bars in a Coupe and both are using he same tire/wheels, it will still not handle like a Z28.

While bigger is not better in every car,...( I tried a 24mm in the rear of my 95 Z and had to reduce it back to a 22mm - Stock was 18 IIRC ) bigger IS better when it comes to Thirdgen Rear Sway bars !!

 

My 86 came with 34/23mm and the 92 came with 30/18mm. I put on 36/24mm on the 86 and moved the 34/23mm over to the 92. lol.

 

Adjustable rear is also option

 

Sway bars tend to be the most confusing suspension part. Which is ironic, because they have the most basic function. Trying to determine a good front/rear combination by numbers alone won't work. We need to know if the car is a V6 or a V8. Also if it has subframe connectors or not.

General rule of thumb is that if the car is a V6, the 34 front bar works well. If it's a V8, the 36 front bar is the one to get.

But what to get on the back? If it's a V8, the 36/24 (front/back) combo is a nice stock setup that works well (this came on my GTA). If the same car has subframe connectors (SFC), drop the rear bar down a number. Something like a 36/22 combo.

With a V6 and a 34 bar up front. I'd aim for a 20-22 rear bar. 22 without SFC...... 20-21 with SFC.


Why the smaller rear bar with SFC? Adding SFC does tighten the car front to back (which is good)......But adding SFC also increases the lean in the back of the car (which is bad). The car naturally wants to lean more in the front due to weight. Adding the SFC means that the front rolling over will now pull the rear of the car rolling over too. Because of this, you want to lower the rear sway bar by about 2 mm when you add SFC. The net result is that the rear inside tire will stay planted on the road, instead of wanting to lift and transfer the weight to the front outside tire.

I witness the above on my drive home from work. I drive west along the highway, then it sweeps to the right until it's heading north. That corner is banked the wrong way. At 60 mph, no big deal. The car simply corners like any other corner. At 75 mph, the rear feels "OK" but it doesn't feel like it's as connected as it could be. The front outside tire on the other hand feels like it's getting more loaded, despite me being on the gas pedal the whole time.

I do have del-sphere LCA and del-sphere PHB. So there is no axle hop due to the PHB. And everything rotates as it should with the LCA. This keeps the rear predictable. But the SFC + 24 mm sway bar is still working against me.

Dropping my swaybars from 36/24 to 36/22 should solve this issue. That would keep my rear inside tire more planted to the ground and simultaneously transition less movement towards the front outside tire.