urban_cowboy

I have been reading several threads lately about improving handling. I like what Opentracker has to offer, but have a few questions. I have sent them an email, but have not gotten a response, so I though I would see what you guys/gals know.

What is the difference between their regular and racing roller spring perches?
What is the difference between their regular, racing, and drag upper control arms?
What is the difference between their regular, racing, and drag lower control arms?
What are the pros and cons of doing the 1.5" UCA drop instead of the 1"?
What are the pros and cons of installing their progressive front springs vs the 560s?

Give that I drive my car in road course situations while on the street and drag race some, it is hard to put my car in the category of road race vs. drag race. I try to not do things that are going to help one but hurt the other...if that makes sense.

boogerschnot

If you go to daze cars website, he explains most of the answers for your questions..

urban_cowboy

Ok, I got the answer to the 1.5" UCA drop question. It brings the suspension to the best possible camber curve, but a negative wedge kit is required because of the ball joint range of motion and the benefits of the 1.5" over the 1" drop are negligible for the effort.

I still have following questions though:
What is the difference between their regular and racing roller spring perches?
What is the difference between their regular, racing, and drag upper control arms?
What is the difference between their regular, racing, and drag lower control arms?
What are the pros and cons of installing their progressive front springs vs the 560s?

Scott H.

Well, "best possible camber curve" is a relative term. For a street driven car, the curve is too agressive, and will cause issues with loss of tire adheasion under braking on rough roads, with a stock length UCA. For a smooth track surface, on a car that is designed to take full advantage of the additional drop, it may be beneficial.

If you look closely at Opentracker's web site (http://www.opentrackerracingproducts.com/products/), you can see some of the differences. Like the street arms lack of roller bearings, lack of external reinforcement, and does not appear to have the "wedge cut" built in, in comparison to the "track" arms. While the drag arms appear more like the street arms, but with roller bearings. He spells out the difference in the LCAs pretty clearly, as he does with the roller perches.

So, have you completed your solo yet? I remember you went to one HPDE event last year, but hadn't heard any further on your progress. If you are still riding with an instructor, and your car is in good mechanical condition, it would be worth spending the money on seat time, and hold off until you complete your solo to start changing things around.

And just for something else to think about. If you went to a coil over LSA for the front, and a 3 or 4 link rear with a coil over, you could start off with a nice adjustable street setup, and then add competition specific assemblies as you go.
This way, instead of a permanent compromise, you can simply swap out the coil overs, and retune for track days (be it road course, or drag). Once you are organized, swapping out the coil overs, transmission, seats and harness, then retuning the suspension doesn't take more than 2 or 3 evenings. Start on Monday after work, and have the car prepped by wednesday, with two days left to fix the little things you find during the swap.
I did this for a while and it worked really well. I ended up selling the car, and I *think* the guy still runs it the same way (although by now, I hope he has newer components).

If you are thinking about getting involved in Vintage racing, then you can't do the coil overs. They aren't legal. But at that point, you will understand the importance of a "track only" car anyways.

Good luck amigo!

********edit
I forgot to mention. I'm not a fan of progressive rate springs. I've tried them, and to me they feel imprecise, and sluggish. I like a single rate spring, and shocks with adjustable low and high speed (as in shock shaft speed, not car speed) damping adjustment. I tend to like a little softer spring than most, and probably more damping in the shock.

super64

I emailed them directly and got all the information I needed overnight. They can answer all of the questions you posted twice better than anyone here can. I bought O.R.P's street ready stuff. My LCAs and spring perches are roller, while my UCAs are not roller. I did the 1.5" drop and did go with NPD's negative wedge kit. Opentracker are the most customer-friendly, honest folks out there. They will not try to over-sell you on stuff you don't actually need. Just be straight up with them as to how you will drive your car, and you'll have everything you need in a week or two.
Good Luck!

Starfury

The racing upper perches have the shock mounted on a separate set of bearings to allow the shock to rotate independently of the spring. Street benefits are negligible (as John will likely tell you), but they're noticable on the track where they help improve suspension response. One of the guys on another forum put them on his open track car and likes them.

I'm not a fan of progressive springs for performance use. They're generally used to provide a good ride without sacrificing as much handling potential, but when pushed hard they allow for too much body roll as the suspension compresses. I'm planning on going away from them on my fox body for this reason.

I have 560lb springs from Opentracker (which are actually Grab-A-Trak springs) and I like them for street use. They're firm without being too jarring and they keep the car much more stable than the old stock springs. They're not stiff enough for true open track use, but that's fine for now.

Your problem is going to be the dual strip/track purpose of the car. For the strip, you want softer springs to allow more weight transfer. For the track, you want stiffer springs to cut down on excessive body roll and weight transfer. My thinking is that you could put some 560lb springs in it and then use a big front sway bar and small rear bar for street/track use, then remove the sway bars for strip use.

cprstreetmachines

I really noticed the single roller perches on the street. But I made that change and only that one. REALLY noticed it at the strip. Front end was much easier to come up and did gain more traction at a higher psi in the tire compared to without. On the street, just didn't seem as jarring.

I've actually been talking to John the past few days. I've done the roller perches a few times, but not the lower or upper mods. The machine work is TOP notch. No sharp edges or burrs on any of the machined threads or corners. Tolerances are PERFECT.I was very impressed. He even sent me pics of specifics because he couldn't "dumb it down" enough on the ph for me. ( I was driving too, leave me alone lol.) I have dealt with companies in the past that after the experience I have refused to deal with them on principle due to rude employees, acting dumb when you encounter a problem with their product, or just being sold complete junk. It is nice to spend chunk of change and have your expectations exceeded every once in a while. His wifes a riot ta boot. I wrangled some free stamps outta her. Doesn't always answer the phone which I can totally understand. Can't move fast enough, or machinery, or ear plugs. Ask me how I know. But whether email or Ph, they always got back to me. As/if he starts to make more parts for these cars no matter what it is, I will start dropping vendors to buy from him.

urban_cowboy

Thanks so much for all the info. Scott H, you make a good point about swapping out suspension parts instead of the eternal compromise position. That is exactly where I am right now, compromise, but depending on how much of a compromise it is, I may move towards the swap out program in the future. Starfury, I have read a number of suspension books for both track and strip and I mirror your statement about springs rates. That is an issue I have right now. Lighter front springs to help my ever continueing quest for eight transfer and rearend traction vs stiffer front springs to help with my road course handling. I though the variable springs might be a good in between, but I will flush that idea based on your and John from Opentracker's opinions. I currently am running an larger than stock 1 1/8" front sway bar with a 7/8" rear sway bar...do you think the rear bar is hurting my traction at the strip? CPRstreetmachines, I am glad to hear that freeing up the frontend with the spring perches helped with weight transfer. That is one of my main goals right now.

I just got an email from John and will probably call him up to talk specifics later this week. Even without his response, based on what you guys are saying, I would probably go with the racing roller spring perches, drag upper and lower control arms, a 560 spring with a nice shock. His response appears to mirror that suggestion, but I will definitely give him a call.

My struggle is:
1. I drive this car for fun on the street (50-100miles average per week)
2. I drag race this car
3. I want to open road race this car (legally) as well as eventually doing some vintage racing
4. I want to keep the suspension and steering close to period correct to maintain the vintage street classification which is my reluctance to move to coilovers and a four link.

Some day when I find a good deal on a fastback 67-70, I will build a full out chassis car for my son and I to play with that is more customizable to the type of racing we will be doing on a given weekend and probably keep that one off the street, but until then this car has to be an all in one (street, strip, track).

Here is part of John's response from Opentracker for all those who know how to use the search feature in the future:

"Our standard upper arm is a " blueprinted " arm. We make sure they are the way the are supposed to be. In 80% - 90% of the arms I take apart, the shaft is not centered in the arm and in 100% of them, the bushings (big nuts) are too tight. We center the shafts, de-burr and pre-lube them and adjust the bushings to a torque that is not too loose or too tight and then weld the tap in place to keep them from moving. They are a good arm and work well on the street and track.

Our drag racing upper arm is our standard upper arm with a roller shaft kit. They are very smooth and work great for getting quicker weight transfer and giving a smoother ride. They work well on the street, drag strip and road course where the car has no more than the 1" upper arm drop. When you lower the mounting point of the upper arm more than 1", the ball joint angle has to be changed to stop it from binding.

Our track or road racing upper arm has the ball joint angle change built in for the 1 1/2" upper arm drop. It also has bracing on the side to stop any flex that might happen. We cut the side of the arm to change the ball joint angle and the bracing reinforces that area also. Unless the car has the 1 1/2" upper arm drop, we use our drag racing upper arm on the road course. The upper is not a weak link in the suspension. The shock tower will flex before the arm does. I have never seen a bent upper arm other than from accident damage.

The 1" drop gives a nice improvement over the stock geometry and doesn't cost much to do. The gain from the extra 1/2" drop doesn't help all that much but cost a lot to do in parts. The cost to jump from the drag racing upper arm to the track upper arm isn't worth it unless your running for points or money in my opinion and only on a road course. I like selling parts but at a point it gets into overkill.

Our track spring perches are mainly for road and drag racing. They have a separate pivot for the shock and spring. That eliminates the bind from spring-to-shock with the stock type perch body. They don't do much at all for a street car.

The progressive springs are a stock ride height spring. They can be cut go get the car lowered. They also cost twice as much as the regular springs and I'm not sure they are worth it. They don't do well on a road course. The variable rate makes shock valving an issue. In my opinion, they are a OK street spring but I wouldn't use them on a track."

Jonk67

Good indepth explaination from John, thanks for passing it on, makes it easier to wrap your head around the 'whys' for changes to the parts and how far you really need to go. I know my driving skills may never get to the level that would necessitate the need for some of his high end racing stuff but man is it tempting. I have his roller perches and am reinforcing my LCA like his so I'm aready starting down that road...
Jon

Bitter

I put a set of Opentracker perches in mine today but I did it for a reason not mentioned. I was originally going to use the cheap stock perches but they are positioned at too steep an angle. They are so tight that it's nearly impossible to reposition them before you install them. Installing them and trying to pry them into a position to accept the spring started cracking the UCA around where they mount. I was able repair it with a MIG but I chose to order the rollers rather than risk further damage. If I get a better ride out of it, it's a bonus.