Has anyone built their own front swaybar?

j-rho

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Seems like there are almost no pre-fabbed options out there for SRT-10 front swaybars. There appear two be two Comp Coupe bars - a simple stock-style (but stiffer) one, and the uber-expenive (was quoted $1800) blade-adjustable one.

The SRT-10 appears to have a pretty simple path for its swaybar with a perfectly straight center section. This 'should' make it easy to fabricate a bar using components from a company like Speedway (http://www.1speedway.com).

I'm looking for a good adjustable option for the front of my car, and the ability to change effective arm length as well as the wall thickness of the center section are two big advantages to the Speedway-style bars. Wondering if anyone has tried it.

Thanks! :)
 
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We have produced adjustable front bars for the Viper since 96' and can supply you with one if you provide your bar back as a core. The price is $595 and includes stiffer rear bar bushings to accent the front bar. There are 2 adjustments softer and 4 stiffer combinations available. There is a $100 core charge without your bar returned FYI.
 
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j-rho

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Hi Mark,
Thanks for the reply. This is going on a Stock-class autocross car, so I don't get to play with the rear. I think the SRT is going to need a lot of front bar with the yucky stock diff and 315/345 Hoosiers.

Is the bar you make a redrilled stock bar or ? What are the %ages of increase/decrease in stiffness at the exteme ends of adjustment for your bar?

Thanks!

--Jason Rhoades
 

rcl4668

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Hi Mark,
Thanks for the reply. This is going on a Stock-class autocross car, so I don't get to play with the rear. I think the SRT is going to need a lot of front bar with the yucky stock diff and 315/345 Hoosiers.

Is the bar you make a redrilled stock bar or ? What are the %ages of increase/decrease in stiffness at the exteme ends of adjustment for your bar?

Thanks!

--Jason Rhoades

Jason --

I am interested in using my 2008 for SCCA Solo and other autocross events. What do you mean by "the SRT is going to need a lot of front bar with the yucky stock diff and 315/345 Hoosiers." I am assuming that the new diff in the 08s is an improvement over the 03-06 diff but doesn't stiffening a front sway bar result in more understeer? I though the 2003-06s tended toward understeer. Does using the 315 size Hoosiers overcompensate and create an oversteer condition? Thanks.

/Rich
 
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j-rho

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Hi Rich,
Need a codriver in 2008 for some National events? ;)

Actually it remains to be seen if the 2008 Viper is even going to be allowed to run in Stock class. I'm going to guess that the regular '08 makes it in but the ACR gets pushed to ASP, as happened with the previous ACR. But we won't know for a little while, for your sakes I hope it does, for my sake (I have an '04), I hope it doesn't. ;) The SRT-10's presence in SS is tenuous and I think the Maxcy's almost spoiled my plans by doing quite well last year.

As for the front bar. From what I've seen thus far the Viper understeers a bit steady-state in stock form, even with a good alignment. At first glance, more front bar would seem the wrong thing, and if you only ever ran on stock tires, it would be.

As we move from 275 front and 345 rear street tires to 315 front and 345 rear race tires, we are doing two things, both of which will necessitate more front roll stiffness.

The first thing is we're increasing the size of the front tires a lot (40mm) relative to stock. This is going to increase front grip relative to rear, which is seeing no width increase. More front grip = shift towards oversteer. A little bit of oversteer is ok, especially in autocross, but we don't want it to get out of hand. A good range of adjustability is key to be able to keep the car working well on a variety of surfaces - asphalt, concrete, HPT, etc. I don't really know how much front bar is going to be the right amount; the beauty of the 1.25" Speedway-style bars is you can change the center section from a soda-can .095" wall thickness all the way up to 1.25" solid, or even larger OD centers in extreme cases. I'm going to guess the Viper will end up wanting something around a .250" wall (what I plan to start with), but I don't know much about the stock bar rates yet so it's hard to say. With a Speedway-style bar, for less than $100 you can shift your adjustment range stiffer or softer to suit. Lot better than having to buy a whole 'nother bar.

I know the stock 10" wheels aren't ideal for a 315 but a 285 really throws off the diameters, and IMO is too little tire for a car of this weight (at an autox anyway).

The second thing is these R-comps are adding a lot of lateral grip relative to stock. The result of this is the car will be transfering a lot more weight to the outside in the corners. This means the inside rear corner will have a lot less load (and available grip) mid-corner than the car had stock. The result of this increased grip means the diff is going to have a much harder job when we get on the gas, and the car is going to want to spin the inside tire a lot more than it did on the stock tires.

By increasing front roll stiffness relative to the rear with a stiffer front swaybar, we are making the front tires do more of the "work" in the corner. More scientifically, we are changing the lateral load transfer distribution such that in a corner, the front sees a higher percentage of the total lateral load transfer. Increasing load transfer % in the front means we are decreasing it in the rear (for a given lateral g), which means we will have more weight on the inside rear tire, which means the diff won't have to work as hard. Or ideally, not at all. :) The crap diff is a real weakness in this car, too bad Dodge couldn't give us a clutch-type (the Corvette unit works great) or some sort of preloaded Torsen. Oh well. Two of the three people that actually read this far are saying to themselves "why don't you just get some Motons and a better diff" but of course, these aren't allowed by the rules - in Stock class we have a very limited toolset to "fix" our cars with, so we have to do the best we can with what we have.

If everything goes well we'll have a car that turns AND puts power down out of corners without smoking the inside rear tire, which is really frustrating. I used to autocross a Stock-class Honda S2000 which has a Torsen (Quaife-like) diff and is notorious for this. Later I autocrossed with good success a slightly modified Nissan 240sx with its stock (crap) viscous diff, which has characteristics similar to the Viper diff.

I hope you choose to stick it out and run Super Stock in 2008. In my opinion it is the toughest class in all of the SCCA, part of why I chose to run there. If all this lateral load mumbo jumbo sounds interesting to you and you'd like to learn more, Herb Adams' Chassis Engineering is a nice accessible text that explains it well.
 

rcl4668

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Hi Rich,
Need a codriver in 2008 for some National events? ;)

Actually it remains to be seen if the 2008 Viper is even going to be allowed to run in Stock class. I'm going to guess that the regular '08 makes it in but the ACR gets pushed to ASP, as happened with the previous ACR. But we won't know for a little while, for your sakes I hope it does, for my sake (I have an '04), I hope it doesn't. ;) The SRT-10's presence in SS is tenuous and I think the Maxcy's almost spoiled my plans by doing quite well last year.

As for the front bar. From what I've seen thus far the Viper understeers a bit steady-state in stock form, even with a good alignment. At first glance, more front bar would seem the wrong thing, and if you only ever ran on stock tires, it would be.

As we move from 275 front and 345 rear street tires to 315 front and 345 rear race tires, we are doing two things, both of which will necessitate more front roll stiffness.

The first thing is we're increasing the size of the front tires a lot (40mm) relative to stock. This is going to increase front grip relative to rear, which is seeing no width increase. More front grip = shift towards oversteer. A little bit of oversteer is ok, especially in autocross, but we don't want it to get out of hand. A good range of adjustability is key to be able to keep the car working well on a variety of surfaces - asphalt, concrete, HPT, etc. I don't really know how much front bar is going to be the right amount; the beauty of the 1.25" Speedway-style bars is you can change the center section from a soda-can .095" wall thickness all the way up to 1.25" solid, or even larger OD centers in extreme cases. I'm going to guess the Viper will end up wanting something around a .250" wall (what I plan to start with), but I don't know much about the stock bar rates yet so it's hard to say. With a Speedway-style bar, for less than $100 you can shift your adjustment range stiffer or softer to suit. Lot better than having to buy a whole 'nother bar.

I know the stock 10" wheels aren't ideal for a 315 but a 285 really throws off the diameters, and IMO is too little tire for a car of this weight (at an autox anyway).

The second thing is these R-comps are adding a lot of lateral grip relative to stock. The result of this is the car will be transfering a lot more weight to the outside in the corners. This means the inside rear corner will have a lot less load (and available grip) mid-corner than the car had stock. The result of this increased grip means the diff is going to have a much harder job when we get on the gas, and the car is going to want to spin the inside tire a lot more than it did on the stock tires.

By increasing front roll stiffness relative to the rear with a stiffer front swaybar, we are making the front tires do more of the "work" in the corner. More scientifically, we are changing the lateral load transfer distribution such that in a corner, the front sees a higher percentage of the total lateral load transfer. Increasing load transfer % in the front means we are decreasing it in the rear (for a given lateral g), which means we will have more weight on the inside rear tire, which means the diff won't have to work as hard. Or ideally, not at all. :) The crap diff is a real weakness in this car, too bad Dodge couldn't give us a clutch-type (the Corvette unit works great) or some sort of preloaded Torsen. Oh well. Two of the three people that actually read this far are saying to themselves "why don't you just get some Motons and a better diff" but of course, these aren't allowed by the rules - in Stock class we have a very limited toolset to "fix" our cars with, so we have to do the best we can with what we have.

If everything goes well we'll have a car that turns AND puts power down out of corners without smoking the inside rear tire, which is really frustrating. I used to autocross a Stock-class Honda S2000 which has a Torsen (Quaife-like) diff and is notorious for this. Later I autocrossed with good success a slightly modified Nissan 240sx with its stock (crap) viscous diff, which has characteristics similar to the Viper diff.

I hope you choose to stick it out and run Super Stock in 2008. In my opinion it is the toughest class in all of the SCCA, part of why I chose to run there. If all this lateral load mumbo jumbo sounds interesting to you and you'd like to learn more, Herb Adams' Chassis Engineering is a nice accessible text that explains it well.

Jason -- wow, thank you for the excellent tutorial. I actually plan on buying a set of the new 2008 ACR rims and tires for use at HPDE events and autocrosses. These are the 295/30/18 front and 345/30/19 rear Michelin Pilot Sport Cup tires on the lighter weight Sidewinder rims. Just as an FYI, the ACR is equipped with a thicker front sway bar; I wonder if this bar would be what you re looking for? The added benefit is that it would be a stock, OEM component from Mopar. The big question, of course, is if and when Mopar will make this available for sale as a stand alone part.

/Rich
 
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j-rho

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Hi Rich,
The ACR bar is worth trying I suppose. The problem is we don't know its range of adjustability - it may be great on one surface, but not so good on another. While it is great to be able to buy something you know fits, swaybars are probably the easiest suspension piece to put together yourself, and in the Viper's case that's especially so since the center section has such a straight path (many cars have multiple bends to clear accessories, oil pan, etc.).

If you're looking for other Mopar ready-to-buy parts, you should be able to get either of the two comp coupe style bars from Dodge racing.

The Michelin PS Cup tires are a good choice for HPDE, but they're going to be tough to work with at autocross, especially in Oregon. Like a slick, they need some heat in them to work properly, and it'll be tough to get the requisite heat in them at an autocross. I ran them at a ProSolo event in Wendover, UT, back in 2003 not long after they had been released here, and only on the hottest day, on my last pair of runs (ProSolo has many runs back-to-back) did the tires "come in". I think you'll find autocrossing on them frustrating, as they will almost never generate very good grip up in your cold climate.
 

rcl4668

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Hi Rich,
The ACR bar is worth trying I suppose. The problem is we don't know its range of adjustability - it may be great on one surface, but not so good on another. While it is great to be able to buy something you know fits, swaybars are probably the easiest suspension piece to put together yourself, and in the Viper's case that's especially so since the center section has such a straight path (many cars have multiple bends to clear accessories, oil pan, etc.).

If you're looking for other Mopar ready-to-buy parts, you should be able to get either of the two comp coupe style bars from Dodge racing.

The Michelin PS Cup tires are a good choice for HPDE, but they're going to be tough to work with at autocross, especially in Oregon. Like a slick, they need some heat in them to work properly, and it'll be tough to get the requisite heat in them at an autocross. I ran them at a ProSolo event in Wendover, UT, back in 2003 not long after they had been released here, and only on the hottest day, on my last pair of runs (ProSolo has many runs back-to-back) did the tires "come in". I think you'll find autocrossing on them frustrating, as they will almost never generate very good grip up in your cold climate.

Jason --

Good to know about the Sport Cups and autcrossing. Are you running the Hoosier A6? I can't really justify two sets of rims (one for autox and one for track days) so I need to find a tire that will work well, if not optimally, in both settings. I suppose I could stick with the stock Michelin PS2s as they are a great tire but do not rise to the performance levels of an R-compound tire.

On another note, you seem to really know your stuff; do you mind if I pm you later regarding more specific autox questions?

/Rich
 
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Jason, Rich,

I will check on the actual numbers for our front bar for you and let you know. By the way I am working on a deal with an 06' coupe owner from Cali for a possible co-drive for the 08' season in National events and Pro Solo so I hope to "not" share all our secrets. ;-)

99ESP for now
 

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Jason, Rich,

I will check on the actual numbers for our front bar for you and let you know. By the way I am working on a deal with an 06' coupe owner from Cali for a possible co-drive for the 08' season in National events and Pro Solo so I hope to "not" share all our secrets. ;-)

99ESP for now

Thanks Mark! BTW, I am a complete autocross novice and will be doing it for fun only and not at the pro level (yeah, I know, famous last words). I therefore pose absolutely no threat to your SCCA Pro/Solo efforts. Jason, on the other hand . . .:)

/Rich
 

Alan Patterson

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I believe you will need a softer front swaybar to correct the understeer problem seen on nearly all Vipers... (Gen II and Gen III for sure)

I drive an 06 coupe fully prepared for autocross (ASP class) It has 3-way adjustable Motons, Quaife Posi, 3 inch Corsa exhaust, delrin bushed control arms, light weight flywheel, etc., etc. Also, I run A6 hoosiers: 315 18 inch tires up front (on 11 inch wide rims) and 335 18 inch on the rear (for lower gearing vs the 345's which are a little taller) (FYI: If you use Hoosiers for autocross you need at least 3 degrees negative camber on the front and about 2 degrees in the rear. They really hook-up well with these aggressive settings)

Bottom line, I still need a softer front swaybar. Currently I run 4 lbs more tire pressure up front to compensate for the oversteer condition. It works, but a softer swaybar allows beter optimization of tire pressures. I didn't realize that Woodhouse (Mark Jorgensen) would be willing to make up an adjustable swaybar for the front... I have one of them that I used successfully on my Gt-2 viper (Gen II) previously, but it won't fit on the Gen III car.

I will be contacting Mark soon to get one!!
 
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Alan, your Street Prepared car that's been lowered, running different spring rates, and a different diff, is in an entirely different circumstance than those of us campaigning the cars in Stock class. I agree that an SP car should usually run swaybars smaller and softer than stock, if only for the weight savings. You can get away with smaller/softer bars because you can create all the stiffness you need with springs; no such luck in Stock. We can't get three degrees up front either.

A smaller front bar on a Stock-class SRT-10 running big front tires is only going to exacerbate numerous problems listed above.

Rich, I plan to start with the Hoosier A6. The tire has proven itself top dog in the DOT autocross tire wars. Kumho is releasing a revised version of their V710 in a bunch of new sizes, including some Viper-fitting ones (305/30-18, 335/30-19) - when those hit the market I might give them a try. My new CCWs should be here next week.

I have tracked a bit on Hoosier autocross compound tires - they work awesome for the first few laps, but if it's warm out, they'll go off pretty quickly, especially with the power and weight of the Viper. There is a thread on this forum somewhere of a guy that uses A6's as his only tires, which I think is a bit nuts. You might try the R6, which is a great track tire, but it too, will be a bit like the Michelin PSC in its need of heat. The Michelin at full tread looks like it could move some water so it may be your best bet as an all-around tire.

You should make it down to the Atwater ProSolo event in April, lots of great competition, lots of fun, all on a great lot for the Viper!
 
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Hey Alan,
Come to think about it, I think we may have met one time, a few years back at an AAS event at Atwater. I think it was the weekend my buddy Jason Uyeda and I were up there running the Stock-class MR2 Spyder. Dunno if you remember me, but I think I remember seeing your car and talking to you.

I hope to make some more AAS events this year, they are the best autocross events anywhere, IMO.
 

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Hey Alan,
Come to think about it, I think we may have met one time, a few years back at an AAS event at Atwater. I think it was the weekend my buddy Jason Uyeda and I were up there running the Stock-class MR2 Spyder. Dunno if you remember me, but I think I remember seeing your car and talking to you.

I hope to make some more AAS events this year, they are the best autocross events anywhere, IMO.

What's AAS and do they have a website?

/Rich
 
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