| Author | Message | ||
| billy bob (Fatbillybob)
Member Username: Fatbillybob Post Number: 266 Registered: 8-2002 |
Oh by the way. I was on the track at laguna with a soupped up 360 challenge car and a 360 michelltto full race car. I was lapped by both with in 7 laps and could not hang with them past the third turn on our first lap! Damn those guys are fast. Later on the Mich blew a rod right threw the block. The sesion was red flagged until they could pick the engine parts off the track. | ||
| billy bob (Fatbillybob)
Member Username: Fatbillybob Post Number: 265 Registered: 8-2002 |
So Rexrcr, I found this old thread again and have time to get moving on this so here we go. I am sure other FC's are interested in this thread so I'll post here Vs. private e-mail until someone says I'm wasting bandwidth or your preferrence for your propriatory information. I have a 1991 stock 348 with no interior, challenge cage, one challenge seat and fire system, on Kumho Victoracers. I'm going to full slicks once the Kumhos wear out. I'am about to lower the car and go to 94 challenge spec on the suspension and see what that feels like at ButtonWillow in 3 weeks. My car I think has the old suspension pick-up points. The local FNA dealer cannot tell by looking if the updated subassembly is in there and they are not really interested in helping me find out. However, everything looks pretty stock as delivered. Basically, I'm doing club time-trials at this time and I getting smoked by fixed up BMW M3's. I have no compettition plans but I want to be fast. So assuming my ability is a 3rd grader I better have a P.H.D. suspension set-up. You wrote: "Modifying your OEM dampers is easy and affordable. Non-adjustable system is about $1900. Single adjustable is about $3400. Penske double independently adjustable is about $4900. Other than cost, there are benefits to each upgrade, mainly time savings to get the car dialed in." So what is adjustability for? Do you get the car set up once and then forget it? Do you adjust the shocks for each track and multiple times during the day like changing tire pressures? I can really feel differneces in tire pressure. Will I feel differences with adjustable shocks? You wrote:" Do you have the updated lower shock bushing upgrade (F355 style)?" No I do not. I have the 94 Challenge book with part list but the section on bushing is not intelligable. The "kit" is not available but a dizzying array of bushing and bushing sleeves are. I have no clue where to start with this. Did FNA produce a 355 bushing challenge kit that I can still go to FNA and buy for the 348? You wrote: "This modification will require alignment and corner weighting. You want the best? You must know where you're starting, otherwise we're wasting time." Agreed. I have or will have all the stuff to do this. How critical is an absolutely flat floor for corner weighting? Does a few degrees matter? If yes then how do you get or make a perfectly flat floor? You wrote: " Adjustable anti-roll bar links are always good". Do you know where to get these? Are these a universal low tech item I may be able to find through some Porshe race shop? Adjustable end links make corner weighting easier to take the bar bias out that's the only reason to have them that I know of. You wrote: "Drop gears? Makes a difference for sure." I have the ratio from the challenge cars I forget what it is 25/28 or something like that. We can cover the details here or in private emails, your choice. Best regards, Rob | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 397 Registered: 11-2002 |
Byron, consider skid plates and/or returning to factory ride height. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 396 Registered: 11-2002 |
Revalving the OEM Bilstein's is not too dificult for someone experienced in damper tuning. Trick is, many Bistein's are not field serviceable, some are. The tough part is knowing what to adjust, what to replace, why, and how. Bob, The rear suspension update starting with Speciale in '93, and all factory Challenge and all '94's have this, is lowering the upper inboard pickup point 20 mm on the rear suspension control arm. Any updated car was done with either a factory supplied jig, or most were updated by complete subframe replacement to maintain quality control. This is a world wide, not just USA update. Improves the feel of the car by lowering rear virtual roll center. Give me the history of your chassis, including last nine digits of the VIN and assembly number, any other info, too. | ||
| Byron (Bmyth)
Member Username: Bmyth Post Number: 447 Registered: 10-2002 |
I am definitely interested in hearing this... My ex 348 challenge car (now street-driven) is very low to the ground - it handles like a dream, but I've often thought about how I can save my front spoiler more by raising it by 1-1.5"... Rexrcr, any thoughts on this? Is it hard to charge the nitrogen packed dampers? Byron | ||
| billy bob (Fatbillybob)
Junior Member Username: Fatbillybob Post Number: 230 Registered: 8-2002 |
Rexrcr, I'll have to get back to you on the ?'s you asked. Specifically, is there a simple way to determine if the rear suspension had been modified? If not I need to get this car to FNA to inspect. There was some geometry point change but I am not sure exactly what it was. I am pretty sure that the modification was a silent recall where if an owner complained the car was modified. However, I do not believe that was a generalized recall campaign. I do not remember hearing of FNA changing out total subassemblys to do this modification. I think it was a cut and weld affair. I was also under the impression that the suspension mod was for high speed handling something Americans were having problem with. I did not think european's were having the same 348 handing issues they just drive faster in general and can handle it. My thinking was that this was more a perceived issue with lawyers and such cuasing FNA to do silent changes. If it was a true safetly issue there would be a general recall. FNA would not be improving handling for customers for free. So in your opinion what is the issue with the suspension modification? Did it improve track handling or was it just different handling? You know American's are safer with understeer than oversteer which does not mean you can get around a track faster. A car handling is a compromise. You need to build for the most number of situations. Anyway, I say lets do the mods on FC so people can follow the progression. I am sure it will be interesting for all. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 393 Registered: 11-2002 |
I can set you up, dude. Is your 348 an old Challenge or what? What year chassis? I can modify your own dampers as long as they're not "crimped" at the top.   This is not crimped. I can build adjustable Bilstein's, or full-on Penske's. We can go one step at a time 'till you get used to each upgrade, or start with fully adjustables, depends on your budget. Modifying your OEM dampers is easy and affordable. Non-adjustable system is about $1900. Single adjustable is about $3400. Penske double independently adjustable is about $4900. Other than cost, there are benefits to each upgrade, mainly time savings to get the car dialed in. If you just do FCA time trial or general track day stuff, modifying your shocks is the cost effective way to go. I'll be using damping curves I've developed through experience, you can buy off-the-shelf Penske's or Bilstein's, but you're on your own for damping curve development and spring rates. What tires? Slicks will work by far the best with my system, but Hoosier DOT's are okay, just less grip. Any competition plans in the future? If your car is older than '94, do you know if the subframe has been replaced or rear suspension updated to latest spec? You mention bushings, what are you running or plan to? Do you have the updated lower shock bushing upgrade (F355 style)? This modification will require alignment and corner weighting. You want the best? You must know where you're starting, otherwise we're wasting time. Track widening not necessary IMO. Adjustable anti-roll bar links are always good, no immediate need to change the bars. Camber plates are for McPherson strut suspension. You have SLA (short/long arm), much better. Drop gears? Makes a difference for sure. We can cover the details here or in private emails, your choice. Best regards, Rob | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1138 Registered: 11-2002 |
IMO handling will outrun HP far more often than people suspect. My first stop in the handling game (because of budget)was these guys: www.sherline.com/sherline Find "true" center, point the car striaght, set to specs and corner balance. | ||
| billy bob (Fatbillybob)
Junior Member Username: Fatbillybob Post Number: 229 Registered: 8-2002 |
Rexrcr, Here are the stock Challenge specs from the 94 series. Camber front -1degree 40� rear -3 degree 15�. Coil springs F/R FNA# 143390, F shock FNA# 146290, Rear shock FNA# 146291, Million dollar bushing kit 70000796. Kit not available but individual parts are at one billion dollars. Lowering no limit if chassis does not hit ground with deflated tires. Some of these modifications may not be for optimum performance but for cost minimizing compromises etc... | ||
| billy bob (Fatbillybob)
Junior Member Username: Fatbillybob Post Number: 228 Registered: 8-2002 |
RexRcr, I have been bitten by the racing bug. I started with a perfectly good 348 and now have no interior, race tires, and full roll cage and a shiny new trailer to haul the trailer queen to the local tracks. IMO horsepower is not an issue at this time. Handling is! So now I am ready to enter the black art of suspension tuning of which I have zero knowledge other than the ability to be a part replacer. With no regard for street driving what can I do for a no compromises race suspension except dollars are an object. You know its the old line...�How fast do you want to go how much money do you have? At some point it is just better to buy a better car. Anyway, I do road courses only max speed maybe in the 120mph range maybe as high as 140mph for a second. I would think you would optimizing OEM parts and add in cheap modifications such as how low to lower...until the spoiler scrapes? How wide to widen track...if 25mm in the rear is good is 30mm better? What about corner weighting? I just do not think with my experience level I can feel or appreciate adjustable camber plates, adjustable sway bars, and adjustable shocks. In fact of the adjustable shocks I have felt I really can�t say the adjustment really did any good. They may have felt a little different but really did not add to track time differences...maybe I�m that bad a driver? |