SCCA, NASA or any other road racing rear suspension???
07-16-20, 08:31 PM
#1
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Thread Starter
SCCA, NASA or any other road racing rear suspension???
What are you NASA/SCCA guys are running for rear suspension? stock geometry? equal length parallel links? 3 link? with panhard bar or watts linkage? At the moment im planing on building a parallel equal length 4 link using the factory lower rod mounts and new custom upper ones thru the floor into a custom bracket. Also plan on running a screw adjustable watts link if I can make it fit with custom coilovers in the stock shock mount locations.
P.S. I don't plan on racing any specific class... just a track day toy.
P.S. I don't plan on racing any specific class... just a track day toy.
07-17-20, 09:08 AM
#2
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its been a while, but race cars have rules so it was all stock back there, minus the sway bar. occasionally longer bolts and jamb nuts were used so the links could all be loose. i've seen people drill holes in the bushings too, more compliance in the top links just helps
Eibach used to make springs in 150/175 (and maybe more?) with dead coils so you can set the ride height, once
Eibach used to make springs in 150/175 (and maybe more?) with dead coils so you can set the ride height, once
07-17-20, 11:27 AM
#3
G-force Tri-Link with panhard bar. Bilstein "mustang" shocks. 5" diameter, 8" long springs with height adjusters on top of the springs. No rear swaybar. Simple and works well, albeit a little noisy. Also SCCA ITA legal and minimal points (or whatever they are called) in NASA.
Carl
Carl
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gracer7-rx7 (08-03-20)
07-17-20, 11:29 AM
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gracer7-rx7 (08-03-20)
07-19-20, 11:18 AM
#5
I used an equal length 3 link with a panhard bar on my race car because I have used it on other cars.....and it is cheap. It is also allowed by the rule set I am racing under - SCCA STU. I considered using a 4 link that is common in allot of SCCA E Production RX7s but given the choice faster guys went to a 3 link like the one I have because of bind. I am not an engineer but all of the 4 link cars I have seen (SCCA TransAm and GT1) have really long arms. Like 4-5 feet long.
The suspension I would investigate is the one that RIGHTBrainDesign Tuned is using. https://www.rx7club.com/build-thread...build-1096295/ We always called this a classic three link or a Lotus three link. I have seen this used in really fast Autox mustangs and it has been reported that Roush used this on the TransAm Mustangs on street courses back in the day.
Here is my build https://www.rx7club.com/build-thread...-build-992966/
The suspension I would investigate is the one that RIGHTBrainDesign Tuned is using. https://www.rx7club.com/build-thread...build-1096295/ We always called this a classic three link or a Lotus three link. I have seen this used in really fast Autox mustangs and it has been reported that Roush used this on the TransAm Mustangs on street courses back in the day.
Here is my build https://www.rx7club.com/build-thread...-build-992966/
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gracer7-rx7 (08-03-20)
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08-02-20, 01:06 PM
#10
That car is impressive.
I would recommend that before you go too wild with modifying your car that you drive it on the track. Now if you have been doing that then that’s great. If you plan to ever run TT, you will find that these mods add a lot of points and move you up to a level that is difficult to be competitive if the other entries know how to drive fast. And if you go thru that much effort, you will want to be competitive.
Good luck with the build, look forward to seeing the progress. Just remember the most important rule for a track car is getting it on the track.
Good luck with the build, look forward to seeing the progress. Just remember the most important rule for a track car is getting it on the track.
08-02-20, 01:34 PM
#11
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Thread Starter
My car is just an empty shell at the moment as I bought it like that for a few hundred bucks...... But I understand the limitations of the stock rear suspension especially after the geometry is out of whack when lowering it. I have never tracked an SA/FB.... but have driven them hard enough on the street to know the dynamics of these cars. Also I have never driven NASA or SCCA events just mostly Autocross and open track days in Puerto Rico long time ago. I am now getting back into the sport because i have the time and the money Again.
08-03-20, 11:18 AM
#12
I would recommend that before you go too wild with modifying your car that you drive it on the track. Now if you have been doing that then that’s great. If you plan to ever run TT, you will find that these mods add a lot of points and move you up to a level that is difficult to be competitive if the other entries know how to drive fast. And if you go thru that much effort, you will want to be competitive.
Good luck with the build, look forward to seeing the progress. Just remember the most important rule for a track car is getting it on the track.
Good luck with the build, look forward to seeing the progress. Just remember the most important rule for a track car is getting it on the track.
Along those lines and placing an emphasis on getting on track sooner than later, you might consider buying a turnkey race car. SCCA/NASA RX7s come up for sale all of the time and they can be purchased for pennies on the dollar. I recently saw an ad for an SCCA E Production FC convertible with a pro-built engine, racing transmission and spares for $14K. Economic times like these (like we saw in 2008-2009) can create some real opportunities if you have the cash on hand.
There are advantages to buying a log booked SCCA or NASA race car because they are typically safe (there are inspection requirements with these groups) and the car will have a value that will carry forward beyond your ownership of the car. If you like to tinker and build a ready built race car will still offer an opportunity to make the car unique and improved. My current RX7 came to me December 2002 as a well turned out SCCA ITA race car. Some quick fixes to the exhaust, some new tires and I was on the track when the season started in 2003.
08-03-20, 11:42 AM
#14
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building the car, like that moffett replica assumes you've solved a bunch of problems, when in reality you will still need to do a bunch of testing to get the setup correct. so building a complex race car is neat (i like the building part too), but it makes the amount of time that you're not competitive much longer, and just add to that if you're a new driver. if that is fine, there is nothing wrong with it at all, but the fast guys are racing because they want to be first, and like cars, but are just as happy to race you in anything and everything...
#2. is that chicken is more flammable than the car, you should have a fire extinguisher
#3. if you use a fuel cell, wash the foam, and make sure the pump can't suck itself to the bottom of the magic box
#4. unload the car with the trailer still hooked to the tuck, people get all freaked out when the trailer is rolling down the paddock by itself...
#5. trailer sway is real, and it is more frightening than anything you will do with the race car
#6. stay hydrated, its always hot at the track
#7. have fun!
what i'm saying is that its more competitive to get out on the track in a simple car, and let it evolve vs trying to build some giant killer thing, both Mustanghammer and Kurt have built killer cars, but they raced 10+ years before that in something that was more basic
Last edited by j9fd3s; 08-03-20 at 11:44 AM.
08-03-20, 01:38 PM
#15
To add to j9fd3's comments.....
I had allot of time in my car before I converted it for use in a faster class - STU. And even though it is the same car and it still drives like an RX7, the changes created a car that is completely different. It gets places on a track allot faster than it did before! Add the rust the formed when I wasn't racing, a host of drive line/suspension failure issues that I did not anticipate which kept me off the track even more.....and often I really wish I would have bought another car 7-8 years ago.
If you proceed with your build, here are some things to consider before you land on a suspension design:
I had allot of time in my car before I converted it for use in a faster class - STU. And even though it is the same car and it still drives like an RX7, the changes created a car that is completely different. It gets places on a track allot faster than it did before! Add the rust the formed when I wasn't racing, a host of drive line/suspension failure issues that I did not anticipate which kept me off the track even more.....and often I really wish I would have bought another car 7-8 years ago.
If you proceed with your build, here are some things to consider before you land on a suspension design:
- Engine Power
- A stock motor doesn't need much suspension but will let you drive more
- A stock port 12A and a header will run forever and will not be boring once you learn how to maintain momentum
- MOAR power means more suspension, brakes, tires and an expensive transmission
- A stock motor doesn't need much suspension but will let you drive more
- Tire Size and Tire Budget
- Tires are the most expensive aspect of racing on a track.
- Small tires don't tax a suspension very much
- Some 13" DOT racing tires on an IT or PRO7 suspension will let you drive rings around some really expensive cars - been there done that!
- Big tires mean a better suspension is required
- Big tires are also expensive
- Your car will need a roll cage...a good one
- Hanging a kick *** suspension on a car without a cage is waste of time
- An RX7 is pretty well made but compared to newer cars it is wet noodle
- A cage makes it easier to align and adjust a suspension consistently
08-03-20, 07:17 PM
#16
I realized I never answered your original question. I have three first-gen rx7 race cars:
White 83 NASA Pro7 with stock everything in the rear but the spec. Ground Control springs and Tokicko adjustable rear shocks. No rear sway bar. Rolls on Toyo 185's x 13.
Blue 84 SCCA ITA/ NASA PTE with basically same set up in rear except Koni single-adjustable shocks and 4.44 rear gear. No Bar. Rolls on Hoosier R7 225's x 13.
Grey 80 SCCA EP car with (not quite equal) 4-link, panhard bar and Koni double adjustable shocks. 4.88 gear. No Bar. Rolls on Goodyear Bias-Ply cantilever slicks 9.0's x 15.
I understand the DIY thing...I built two of the three cars above. But not the first one. I like fabricating and staring at my work fondly afterward(with a cocktail) as much as the next guy. That, however, does not compare to driving on the track. It pains me to see cars in the Build section that start strong with lots of enthusiasm but then slowly fade as energy, resources and time diminish and we have another aborted project car. I wasn't kidding when I said getting the car on the track is most important. So whatever you end up doing, give your self a budget and a deadline.
Do you have the stock rear assembly or did you just buy a shell? If just a shell then you'll need a parts car. Either way, I would suggest putting a stock rear-end assembly together with good springs and shocks, ditch the sway-bar, and go have fun first. You can always mod/add later. Don't sweat the rear 'bind' that everyone talks about. I have over twenty years of tracking/racing with very stock rear. It's actually a lot of fun.
If you have just a shell, then this is probably your first of many questions so feel free to ask. I would spend a lot of time reviewing mustanghammer's build thread. It is beyond comprehensive.
White 83 NASA Pro7 with stock everything in the rear but the spec. Ground Control springs and Tokicko adjustable rear shocks. No rear sway bar. Rolls on Toyo 185's x 13.
Blue 84 SCCA ITA/ NASA PTE with basically same set up in rear except Koni single-adjustable shocks and 4.44 rear gear. No Bar. Rolls on Hoosier R7 225's x 13.
Grey 80 SCCA EP car with (not quite equal) 4-link, panhard bar and Koni double adjustable shocks. 4.88 gear. No Bar. Rolls on Goodyear Bias-Ply cantilever slicks 9.0's x 15.
I understand the DIY thing...I built two of the three cars above. But not the first one. I like fabricating and staring at my work fondly afterward(with a cocktail) as much as the next guy. That, however, does not compare to driving on the track. It pains me to see cars in the Build section that start strong with lots of enthusiasm but then slowly fade as energy, resources and time diminish and we have another aborted project car. I wasn't kidding when I said getting the car on the track is most important. So whatever you end up doing, give your self a budget and a deadline.
Do you have the stock rear assembly or did you just buy a shell? If just a shell then you'll need a parts car. Either way, I would suggest putting a stock rear-end assembly together with good springs and shocks, ditch the sway-bar, and go have fun first. You can always mod/add later. Don't sweat the rear 'bind' that everyone talks about. I have over twenty years of tracking/racing with very stock rear. It's actually a lot of fun.
If you have just a shell, then this is probably your first of many questions so feel free to ask. I would spend a lot of time reviewing mustanghammer's build thread. It is beyond comprehensive.
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08-24-20, 09:48 PM
#17
Junior Member
'82 FB, running in NASA rules as ST5. Weber 48 IDA, TriLink with panhard, 15" Konig wheels, 205/580/15 Zestinos, 450 lb front springs, Koni shock in custom strut, turn in spacers, 300 lb rear springs on modified adjustable perches, NEED NEW REAR SHOCKS... what is out there that will deal with the 300 lb springs? Tried KYB AGX( Mustang shocks)... says they are good 200 lb - 400 lb. Nope!
08-25-20, 04:43 PM
#18
'82 FB, running in NASA rules as ST5. Weber 48 IDA, TriLink with panhard, 15" Konig wheels, 205/580/15 Zestinos, 450 lb front springs, Koni shock in custom strut, turn in spacers, 300 lb rear springs on modified adjustable perches, NEED NEW REAR SHOCKS... what is out there that will deal with the 300 lb springs? Tried KYB AGX( Mustang shocks)... says they are good 200 lb - 400 lb. Nope!
I have also used fixed valve circle track shocks - Welded Bearing PRO Shocks - with fabricated upper mounts that adapted the welded heim to a stud mount. Get the ones with a split value - #3 Compression and #5 Rebound with a 7" stroke. They were cheap and didn't introduce any issues.
08-25-20, 07:51 PM
#19
Junior Member
Scott, thanks. I have been looking at the Konis. Not much out there. I'll look up the specs. Used the Tokicos for ages before stiffening up the car, and they are about 2" longer than the Koni's. Not sure what the lengthdifference will do to car...
08-26-20, 01:48 PM
#20
I had Tokicos before I went to Konis. I really liked the Tokicos because of the way that allowed the car to transition through a chicane (or a slalom in an autox). Mine died and I wanted to up spring rates so had to come up with something else. But I liked them while they were alive.
It takes allot of rebound adjustment to get the single adjustable Konis to control weight transfer under heavy braking, Unfortunately, this also tightens up compression which makes the car feel numb in my opinion. Workable for club racing but not ideal at all for autox. That is why I like the double adjustable shocks. They are worth the premium in cost.
It takes allot of rebound adjustment to get the single adjustable Konis to control weight transfer under heavy braking, Unfortunately, this also tightens up compression which makes the car feel numb in my opinion. Workable for club racing but not ideal at all for autox. That is why I like the double adjustable shocks. They are worth the premium in cost.
08-26-20, 03:02 PM
#21
Junior Member
Thanks again. Agreed
As to 2tallfor7, I would highly recommend changing rear end to trilink. 7's are incredibly loose stock, and the rear suspension binds up, particularly if you mess it all up by lowering the car. The only problem I have with the trilink is that the rear end sticks so much better, I have had to change the way I drive. I can't go into corners, and rotate car with my right foot to drift it, the damn thing sticks now! Not a bad thing
I just built a car up from bare shell. Slow, careful, and think it through first. I also got rid of the rear springs perches which are for spiral-end springs, and made new flat perches for flat springs. Also found adjusters so the rear springs are now height adjustable, which makes getting cross weight right. Mine is 50.5%.
As to 2tallfor7, I would highly recommend changing rear end to trilink. 7's are incredibly loose stock, and the rear suspension binds up, particularly if you mess it all up by lowering the car. The only problem I have with the trilink is that the rear end sticks so much better, I have had to change the way I drive. I can't go into corners, and rotate car with my right foot to drift it, the damn thing sticks now! Not a bad thing
I just built a car up from bare shell. Slow, careful, and think it through first. I also got rid of the rear springs perches which are for spiral-end springs, and made new flat perches for flat springs. Also found adjusters so the rear springs are now height adjustable, which makes getting cross weight right. Mine is 50.5%.
08-27-20, 10:52 AM
#22
Full Member
mustanghammer and company have some very valid points. I thought long and hard about converting my 1992 Mazda Miata into a Spec Miata race car. Instead, I bought a used and very tired SA22C SCCA IT7 in the fall of 2018 for $2600 and spent the winter getting the car to run, taking care of maintenance issues and re-wiring the car. I attended driver's school in July of last year and raced twice last season. This year, I've raced in and finished all three races including a class win. I got the car titled, licensed and insured and I drive the car to the race track loaded with race wheels and gear (a round trip of 350 miles). To be honest, I know nothing of complex suspension setups even though I've read and re-read all four of Carroll Smith's books, most of which is way over my head anyway (LOL). Instead of re-engineering the crap out of the car, I chose to focus on learning how to drive the car. The only adjustments that I ever made to the suspension was to change tire pressures. It's amazing how much work actually goes into just maintaining a race car. Not to mention the how much it actually costs. If I had chosen to "build" my own race car, I'd probably still be "building" it and would have missed out on two great and fun seasons of racing. Just my two cents.
08-27-20, 11:53 AM
#23
Junior Member
Mikevillena, good comments. Aside from racing an FB for 20 years, I am also an instructor .You made a very important point. It's not the car, it's the driver. I drove "spec" FB for many years....stock everything .We could change spring rates . To me, that is the best way to start racing, in a simple low powered car. Learn to make a low power car go fast, then start to build up the car, after you understand what the improvement is going to do. Don't spend a lot of time, energy, money on stuff you don't understand .I have seen too many people try to start racing with fast, powerful cars, and see their frustration as I have passed them in a basically stock FB......they didn't know how to drive a race car
An original FB is an excellent way to learn car control, as they can be a serious handful . Very loose, low power "momentum" car. Have to carry momentum through corners to maintain exit speed because there is really very little torque .
Back to original poster......save some money, learn the car, then jazz it up bit by bit . I have gradually gone from stock to Street Port, then to Weber carb, then MSD direct fire ignition, to custom front struts, TriLink rear, big springs, heavy duty shocks, step by step, and the car is different after every modification.
Good luck
An original FB is an excellent way to learn car control, as they can be a serious handful . Very loose, low power "momentum" car. Have to carry momentum through corners to maintain exit speed because there is really very little torque .
Back to original poster......save some money, learn the car, then jazz it up bit by bit . I have gradually gone from stock to Street Port, then to Weber carb, then MSD direct fire ignition, to custom front struts, TriLink rear, big springs, heavy duty shocks, step by step, and the car is different after every modification.
Good luck
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08-27-20, 01:08 PM
#24
Full Member
Mikevillena, good comments. Aside from racing an FB for 20 years, I am also an instructor .You made a very important point. It's not the car, it's the driver. I drove "spec" FB for many years....stock everything .We could change spring rates . To me, that is the best way to start racing, in a simple low powered car. Learn to make a low power car go fast, then start to build up the car, after you understand what the improvement is going to do. Don't spend a lot of time, energy, money on stuff you don't understand .I have seen too many people try to start racing with fast, powerful cars, and see their frustration as I have passed them in a basically stock FB......they didn't know how to drive a race car
An original FB is an excellent way to learn car control, as they can be a serious handful . Very loose, low power "momentum" car. Have to carry momentum through corners to maintain exit speed because there is really very little torque .
Back to original poster......save some money, learn the car, then jazz it up bit by bit . I have gradually gone from stock to Street Port, then to Weber carb, then MSD direct fire ignition, to custom front struts, TriLink rear, big springs, heavy duty shocks, step by step, and the car is different after every modification.
Good luck
An original FB is an excellent way to learn car control, as they can be a serious handful . Very loose, low power "momentum" car. Have to carry momentum through corners to maintain exit speed because there is really very little torque .
Back to original poster......save some money, learn the car, then jazz it up bit by bit . I have gradually gone from stock to Street Port, then to Weber carb, then MSD direct fire ignition, to custom front struts, TriLink rear, big springs, heavy duty shocks, step by step, and the car is different after every modification.
Good luck
EDIT: By the way, I've spent a few years corner working and I've seen many a newbie driving a high powered car lose it and end up in the tire barrier. Not just during races but during HPDE's and trackdays. I'm sure a few have given up out of fear or because of the prohibitive cost of repairing their bent high powered race cars. Many a budding racing career have ended that way.
Last edited by mikevillena; 08-27-20 at 01:16 PM.