24mm front torsion bars???

cay-ahe · 10-15-2007, 02:30 PM

I have an 82SC race car with the 22/30 set up custom valved Bilsteins. The car was built like this about 5 years ago. I spent the year learning numerous new tracks and getting used to the car(It's new to me).

I am going to work on the suspension to stiffen things up further. I see many are now going with 23/33. The 33 rear sounds good to me but to keep things in relative balance to my current set up I think a hypothetical 24 front would be closer to my current front rear ratio. 22=210lb to 30=294lb or .71 24=296lb to 33=427lb or .69 Maybe that does not matter.

Does anyone run with 24mm up front? If not why not? Has anyone tried them and gone back to 23mm up front?

Shawn 357 · 10-15-2007, 02:56 PM

What sway bars do you have? Do you know your weights per wheel from the last time you corner balanced your car? What size tires do you run? What brand/model tires do you run.
My Dad's carrera has 23/33 and it feels well balanced but that doesn't mean anything if your car has any big differences in weight etc.

Depending on your sway bars you will probably be able to adjust out any difference and more with them.

89911 · 10-15-2007, 03:10 PM

I spoke to the owner of SmartRacing years ago about what would be the stiffest torsion bar he would recommend for the traditional suspension 911 and he said he would not go higher then 22mm. Above that, you are actually pushing the maximum limits of the front suspension limits and you would incur flexing and failure of the assembly itself. It just wasn't designed to have that much resistance. Better to go with coil overs if you need more.

cay-ahe · 10-15-2007, 05:53 PM

I have Smart Racing sways and am running 245 or 235/17 and 275/17's. I have no problem with car balance I just want a stiffer set up. I just want to reduce body roll at this point. Regarding tires I have tried Toyo RA1's, MPSC, and Hoosiers. I don't know the corner weights, sorry.

Jack Olsen · 10-15-2007, 09:49 PM

What vendor has 24mm front torsion bars?

Jeff Alton · 10-15-2007, 09:56 PM

Elephant Racing does.

Cheers

cay-ahe · 10-16-2007, 03:57 AM

Like Jeff said Elephant has them listed and I would guess others have them.

89911, the car has a six point welded in cage. I have a basic strut brace now but the 935 style brace that Elephant Racing has now looks very interesting too. No doubt in any racing you are pushing the limits of parts and pieces but that kind of goes with the territory.

jaydubya · 10-16-2007, 04:03 AM

I was looking at 24s for the front for the same reason that you are considering them when I was getting ready to upgrade from 22/29. I was told that they were primarily for turbo cars since they have a slightly longer moment arm up front (perhaps because of the wheels/spacers?) and thus need a little bigger bar to get the same wheel rate.

I wound up going with 23/33 and couldn't be happier.

cay-ahe · 10-16-2007, 04:17 AM

Jaydubya, do you think 24mm would be too stiff?

jaydubya · 10-16-2007, 04:29 AM

I don't think they would be "too stiff" like your car is going to fall apart because of the additional stiffness, but I think that 23 mm is plenty for the front of our cars and that a bigger front bar is going to introduce additional understeer and additional inside front wheel lift that you don't want.

If you want a true expert's opinion on this stuff, contact Steve Weiner at Rennsport Systems. He's incredibly knowledgable regarding the suspension setup for 911s and a great guy to boot, but be warned, talking to him may cause you to spend money

Cheers,

Jeff

cay-ahe · 10-16-2007, 04:43 AM

Gotcha and thank you for the insight. I hear you on the $$$ thing.

It's really the rear of the car that I am trying to increase the spring rate while keeping the overall balance that I currently have. Right now I still have alot of adjustment on both sways to dial in the handling as needed. I just am driving the rear wheels way up in the wheel wells and still have a little more side to side suspension transition at high speed than I would like.

jaydubya · 10-16-2007, 04:59 AM

For what it's worth, I don't have to run much sway bar on either end with the 23/33 mm bars. I can adjust the balance with very small changes in swaybar position. With 22/29 I ran a lot of sway bar on both ends, especially on the rear, and still had too much body roll on the rear and too much inside front wheel lift. Plus running a lot of sway bar on both ends made the car twitchy. Now it is perfect

Don't forget to revalve your Bilsteins (or get adjustables if you have money to burn).

cay-ahe · 10-16-2007, 05:06 AM

Sounds good. Revalving the struts is in the budget. I'm trying to make do without going the JRZ/Moton route. I hope this is not a mistake. I have been real happy with the Bilsteins in general.

jaydubya · 10-16-2007, 05:13 AM

Quote:

Originally Posted by cay-ahe

Sounds good. Revalving the struts is in the budget. I'm trying to make do without going the JRZ/Moton route. I hope this is not a mistake. I have been real happy with the Bilsteins in general.

It's not a mistake unless your competitors happen to have the JRZ setup

It seems that not many people in PCA G class have them.

cay-ahe · 10-16-2007, 05:19 AM

Careful you can get flagged for taunting

. I may evolve in that direction one day.

barney911rs · barney911rs's Garage

Coil-over would be the best solution for stiffening the suspension beyond what T-bars can do if the rules you are running under allow that. You never mentioned if you are running PCA or what. Obviously a stock class will not allow this. Maybe it's time to consider moving to a GT class that will allow you to make more aggressive suspension modifications. For example, the NASA GTS Challenge group uses HP/Weight to class the cars, so you can go hog wild on suspension stuff, and stay away from $$$$$$$$ engine mods to compete.

cay-ahe · 10-16-2007, 12:49 PM

I will be running GTS2 with NASA. I wanted to stay within the PCA rules. I may just forget about that for now and just build with one rules group in mind. Coilovers may give superior performance for the dollar up front also. I don't know how much additional space coilover will take. Do you think I will have brake ducting issues with coilovers?

I'll stay with the t-bars on the rear though just trying to keep this as simple as possible.

barney911rs · barney911rs's Garage

Welcome to NASA, I think you will enjoy it. I had several issues that prevented me from getting the car on the track this past year, but I went to all the Mid-Ohio events to see friends and watch the racing. Not sure when I'll have time to finish it, but I just did my car to coil-over. Check with Pelicanite Clint Smith at Rebel Racing products. He has a very nice kit. The biggest issue is you need to reinforce the rear shock mounts. For brake ducting, my biggest obstacle has been the cantilever 8" slick in the front. I need to come through the inner fender well. For know I'm just running the a-arm scoops. I can talk to you later in more detail about NASA or my coil-over conversion if you want?

Superman · 10-16-2007, 03:31 PM

I have heard that the front "A-arm" is robust enough for 23's, and not robust enough for 24's. That is, with 24mm torsion bars in front, there is potential to bend the a-arm.

Chuck Moreland · 10-16-2007, 04:32 PM

Quote:

Originally Posted by Superman

I have heard that the front "A-arm" is robust enough for 23's, and not robust enough for 24's. That is, with 24mm torsion bars in front, there is potential to bend the a-arm.

Can you back that up?

I've setup probably 15-20 cars with 24mm tbars and not a single problem.

If people are truly having problems, I'm ready to learn. Otherwise let's not start another internet urban-legend.