Off Season Weight Reduction Options

[IROC383]

Guys,
1. Does anyone have any comments about swaping out the stock Kmember for the tubular Spohn version? I'm working on losing weight in the 3rd gen SPO car and wondered if anyone will acknoldge it is stong enough for road racing abuse.
2. Has anyone swaped over to the Rack and pinion sterring (Pinto) for weigh reduction?

3. What are the best headers for 3 gen vs. tranny combo for clutch fork clearence issues.
Currently use T56,LT1 version with Heddman standard not shortys.

Just need some quick easy responses on these topics.

Thanks

[InfernalVortex]

Guys,
1. Does anyone have any comments about swaping out the stock Kmember for the tubular Spohn version? I'm working on losing weight in the 3rd gen SPO car and wondered if anyone will acknoldge it is stong enough for road racing abuse.
2. Has anyone swaped over to the Rack and pinion sterring (Pinto) for weigh reduction?

3. What are the best headers for 3 gen vs. tranny combo for clutch fork clearence issues.
Currently use T56,LT1 version with Heddman standard not shortys.

Just need some quick easy responses on these topics.

Thanks

I am an amateur, but I don't really trust any of the tubular k-members for this kind of thing. I've heard WAY too many issues about the terrible fitment and other complications that come with the Spohn k-member. There are lots of complaints about it altering the geometry of the steering system and requiring a lot of grinding to work properly. So there's tons of people whining about it on TGO. PA Racing makes one, but it doesn't really seem geared towards road racing at all. It looks relatively flimsy compared to the others. If I were going to get one, I'd probably go with the UMI road race member. I like the way it looks, although I still don't think it's as strong as the factory one. But I like the double hoop arrangement.

http://umiperformance.com/catalog/index.ph...products_id=732

http://www.thirdgen.org/techboard/suspensi...oduct-82-a.html

Manual rack isnt really feasible unless you want a terrible turning radius. Theres a guy on TGO who's determined to find a suitable rack for our cars because the Pinto rack just isnt it. It ruins our turn radius. The steering geometry has to be completely redesigned to make it work and so far no one has pulled it off well. It's easy for a drag car, because they just have to keep it going straight.


Hedman Long Tubes work fine with the T56. The only problem Im aware of is the Hedmans don't like the T5 slave cylinder all. They try to occupy the same space. But with a T56 you can do whatever you like. I would however suggest fabricating a double-hump crossmember to keep the ground clearance reasonable.

This post has been edited by InfernalVortex: Dec 7 2013, 05:05 PM

[CrashTestDummy]

Kind of what Infernal says. With few exceptions, the aftermarket K-members are built primarily for the drag racing crowd. They do okay up and down and front-to-rear motion, but not well side-to-side. By the time you've gusseted everything and increased the structure enough to be strong enough, you're at, or above stock K-member weight. Stick with the factory K-member. Cut some lightening holes, if you must, and weld up all the seams, but that's about it.

I'd also re-use the stock lower control arms. You can cut that section out of the middle where there's places for shocks to mount, and cut some lightening holes along the leading and trailing edge (I've seen this done on some 3rd Gen C Prepared cars with success) and call it a day.

The Pinto rack is going to be too slow for you, probably. A couple of friends spent last summer fabbing up a new front suspension, including a rack-and-pinion, on their 2nd Gen Camaro CP car. After bending a couple of stock-type racks, I think they ended up buying an Appleton rack and using it. Even after a LOT of cad designing, they ended up increasing their turning radius some. Otherwise, it looks like it did well. They did start with a 2nd Gen K-member, for the same reasons as above.

http://oversteergarage.com/2013/03/10/one-...and-another-in/

[nape]

I'm not familiar with SPO rules to know what's legal, but the best weight reduction is to remove everything that's not necessary and if it has to be there, replace it with something made of AL.

Spending money is not the best way to reduce weight in these cars, spending time pays a lot more dividends. Most every manufacturer that makes something "lightweight" isn't that much lighter and a lot of composite companies list the weight of their products and it's usually way off (heavier).

Rack setups are a pipe dream in these cars unless you build custom spindles with shorter steering arms or you buy an expensive circle track rack and you have to custom fab your mount. Oil pan clearance will be a problem as well unless you cut the firewall and shove the engine way back.

Write up a little more info on what your goals are and maybe we can point you in the right direction.

[roostmeyer]

The pinto racks are much too long for bumpsteer and much too slow of ratio to be of any use for our 7" or so long steering arms. I'm not sure about the total travel, but it wouldn't surprise me that there's an issue there as well.

Speedway has sweet racks with servos for $800, but you'll need a new steering shaft as well as a mount. Pitstopusa has a hydropressed bracket that you could weld onto the k-member. Not sure if the splines would work but the fourth gen shaft looks like it would be close as well. The stock box is ~29lbs, the sweet rack/servo is 16 or so. With that you're also eliminating the centerlink, drag link, a supporting bracket or two, wonderbar, and I think you could then cutout the battery trays on both sides without hurting anything. My guess is 25+lbs off the nose of the car.

So yeah, a lot of money and fab time for 25lbs ($32+/lb). For me not having to go hand over hand in autocross would make it worth it, especially if I can find a rack/servo for ~$300 used. I think the stock ratio works out to be ~1.8" per turn, so you could more than double the factory ratio. The rack should have better feel as well if the servo and pump are matched up correctly. To be fair though a well setup box is just fine. Depending on the rack there may room for more bumpsteer adjustment on the rack (or rack spacers) to allow taller LBJ's as well.

[IROC383]

Great info.
SPO, stands for Special Production Over 3 lieters. Anything goes.
No kmember or rack steering. Thanks you for that info

Love the idea of cutting out weight in the factory kmember and AArms.

Jumping topics here.

1. How can I run 1-3/4" headers? Is there any options for this size and not hit the slave cylinder? Can't tell what the 87" Orange Iroc uses.

2. I have the option to switch from a T56 LT1 to a Jerico. Unbalanced engineering has the torque arm set up.

Any thoughts on these topics??

Thanks again for the time (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

[ReEntryRacer]

Great info.
SPO, stands for Special Production Over 3 lieters. Anything goes.
No kmember or rack steering. Thanks you for that info

Love the idea of cutting out weight in the factory kmember and AArms.

Jumping topics here.

1. How can I run 1-3/4" headers? Is there any options for this size and not hit the slave cylinder? Can't tell what the 87" Orange Iroc uses.

2. I have the option to switch from a T56 LT1 to a Jerico. Unbalanced engineering has the torque arm set up.

Any thoughts on these topics??

Thanks again for the time (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

You previously asked this:

What are the best headers for 3 gen vs. tranny combo for clutch fork clearence issues.
Currently use T56,LT1 version with Heddman standard not shortys.

Just need some quick easy responses on these topics.

I use Heddman 1 3/4" full headers with standard 3" collectors. They miss the slave cylinder (although I wrap the aluminum version I use in heat wrap) and have never had any issues there. I use a steel Hayes beelhousing that has both T5 and T10 mounting holes in it. I have used both trans in the car with these headers with no interference, currently using a TEX T101A, no issues.
The front suspension causes some creative grinding of A arms though...

[nape]

Ratio is more important then just having a dog box. A good, ultra close ratio synchro box will be faster then a factory ratio dog box.

The UE torque arm will also pay off in time shaved once you set it up to your liking. Lowering the PHB (rear roll center) is another great mod on these cars.

[Hotrodf1]

One more point for you:

I have the PA Racing K member and A arms, along with their coilover conversion kit. PA actually offers a road race version with extra gussets etc.. I'm not sure how much different it really is, but it's worked fine on my car. It was on the car when I got it, so not sure about amount of weight reduction. I actually had an a arm bolt get loose on me once, and fall out at speed. It was the front bolt, and the a arm held on with just one mount. Car didn't feel right obviously, but no damage was done. So anyway, seems like the PA stuff is ok to me.

About the rack and pinion deal - like said above, be very careful here. I had a 4th gen rack on mine (PO installed) and it resulted in about a half in of bumpsteer. It was ridiculous. I went back to the factory box setup, much happier. I think there are better places to save weight, although that is quite tempting. If you have the money for the custom rack from Sweet, you could do that. I don't know of another rack that's soooo narrow as what's needed on the third gen. I think the distance from center to center of the inner tie rods is around 17" or so. So your rack needs to be that narrow to match those pivot points. Hard to do without the custom rack.

Like TJ, I think you can spend time and get most of the weight out without spending all the money.

[CrashTestDummy]

What weight are you at, and where do you need to be, or is there a minimum?

[IROC383]

What weight are you at, and where do you need to be, or is there a minimum?

2850 is preferred, Im at 3400 -230/driver
Looks like Im down to glass change front and back, aluminum engine and lighter tranny and wheels.

[CrashTestDummy]

I'd definitely get rid of that back glass, if the rules allow it. There's a LOT of weight there. Personally, I'd keep the front glass. We have Lexan in the front of our Firebird, and if I replace it, it'll probably be with glass. It's just easier to maintain, and much nicer to look through.

The aluminum engine will help a little, but will probably do more to move the weight back in the car a bit, which isn't a bad thing. Gutting the car, removing the door bars, replacing the front fenders with aftermarket replacements and getting a fiberglass hood will all help to that end. There's also a fair amount of weight you can get out of the car with a careful choice of wheels. Our ~85 Firebird is at about 2600#, we carry about 200# to make class weight, so it's possible. We're not running a cage, but do have SFCs and a 6-point bar in the car.

[nape]

What weight are you at, and where do you need to be, or is there a minimum?

2850 is preferred, Im at 3400 -230/driver
Looks like Im down to glass change front and back, aluminum engine and lighter tranny and wheels.

There's a lot more to do to get down to 2850. Post pictures of the car, cage, interior, suspension, etc and we'll advise you where you can get your most bang for your buck.

[IROC383]

Love to add pictures.
How?

[trackbird]

Love to add pictures.
How?

Set up a photobucket (or similar) account and link them here.

[Blainefab]

The VFN pin on fiberglass hood is a pretty good bang for the buck mod if rules allow. What TJ said tho - a lot of weight will come off 1oz at a time. Also avoid putting anything back in that isn't absolutely essential.

[IROC383]

The VFN pin on fiberglass hood is a pretty good bang for the buck mod if rules allow. What TJ said tho - a lot of weight will come off 1oz at a time. Also avoid putting anything back in that isn't absolutely essential.

Kevin,
Thanks the conversation today.
Pics of car.
Go to photobucket
Search: Jrodsmith98

I'm going to add plenty more. Thanks.

[trackbird]

The VFN pin on fiberglass hood is a pretty good bang for the buck mod if rules allow. What TJ said tho - a lot of weight will come off 1oz at a time. Also avoid putting anything back in that isn't absolutely essential.

Kevin,
Thanks the conversation today.
Pics of car.
Go to photobucket
Search: Jrodsmith98

I'm going to add plenty more. Thanks.

Anytime. I hope it helped.

(I changed your username as requested but I don't see it? I'll have to go look again).