E Production 2nd Gen Racers - Rear Camber Question
01-11-10, 07:42 PM
#1
Fabrineer
Thread Starter
E Production 2nd Gen Racers - Rear Camber Question
Hello racers, I am building a 2nd gen for SCCA E Production. You can see the build here:
https://www.rx7club.com/fabrication-250/e-production-rx-7-build-875783/
I have never raced competitively before. I have a couple questions about camber in the rear of the 2nd gen.
I have some of those Mazdatrix camber adjustment links for the rear of my car, both the one that twists the subframe as well as the ones that attach to the suspension arms.
Will these parts provide sufficient camber adjustability for the rear of the vehicle? I understand that when you lower the car, it gives too much camber, and when I had it alligned, it would not adjust enough out because the link would hit the floor board, which can be modified. However, the car was previously a street prowler, and I was only running ~1deg of camber in the rear.
What do you guys run, or more importantly, what ranges of adjustability will I need to be competitive (if you're willing to share)?
I am building custom rear control arms and I need to know whether to mimick the stock geometry (not design) or to change the design to add or subtract camber that is build into the control arm itself.
https://www.rx7club.com/fabrication-250/e-production-rx-7-build-875783/
I have never raced competitively before. I have a couple questions about camber in the rear of the 2nd gen.
I have some of those Mazdatrix camber adjustment links for the rear of my car, both the one that twists the subframe as well as the ones that attach to the suspension arms.
Will these parts provide sufficient camber adjustability for the rear of the vehicle? I understand that when you lower the car, it gives too much camber, and when I had it alligned, it would not adjust enough out because the link would hit the floor board, which can be modified. However, the car was previously a street prowler, and I was only running ~1deg of camber in the rear.
What do you guys run, or more importantly, what ranges of adjustability will I need to be competitive (if you're willing to share)?
I am building custom rear control arms and I need to know whether to mimick the stock geometry (not design) or to change the design to add or subtract camber that is build into the control arm itself.
01-11-10, 10:12 PM
#2
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i'm sure you checked the camber/toe curves, and its pretty obvious that as you lower the car it adds too much negative camber and toe in.
so who cares right?
the tire does. different tires like different camber curves too. for example, we were running like 2.5 degrees of negative camber with the R888 toyos, we switch to the hankook slick, and it wanted more like -3.5, and STILL wore on the outside edge.
from what ive read on here, the slicks used in the EP classes (hoosiers, goodyears etc) want less camber than the FC suspension gives you.
if it was MY car, id run it for a season and see what the tires like.
so who cares right?
the tire does. different tires like different camber curves too. for example, we were running like 2.5 degrees of negative camber with the R888 toyos, we switch to the hankook slick, and it wanted more like -3.5, and STILL wore on the outside edge.
from what ive read on here, the slicks used in the EP classes (hoosiers, goodyears etc) want less camber than the FC suspension gives you.
if it was MY car, id run it for a season and see what the tires like.
01-12-10, 12:07 PM
#4
Fabrineer
Thread Starter
i'm sure you checked the camber/toe curves, and its pretty obvious that as you lower the car it adds too much negative camber and toe in.
so who cares right?
the tire does. different tires like different camber curves too. for example, we were running like 2.5 degrees of negative camber with the R888 toyos, we switch to the hankook slick, and it wanted more like -3.5, and STILL wore on the outside edge.
from what ive read on here, the slicks used in the EP classes (hoosiers, goodyears etc) want less camber than the FC suspension gives you.
if it was MY car, id run it for a season and see what the tires like.
so who cares right?
the tire does. different tires like different camber curves too. for example, we were running like 2.5 degrees of negative camber with the R888 toyos, we switch to the hankook slick, and it wanted more like -3.5, and STILL wore on the outside edge.
from what ive read on here, the slicks used in the EP classes (hoosiers, goodyears etc) want less camber than the FC suspension gives you.
if it was MY car, id run it for a season and see what the tires like.
01-12-10, 12:48 PM
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the car in the example is actually the integra in the link in my sig.
Trending Topics
01-14-10, 12:32 PM
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01-14-10, 12:45 PM
#9
Fabrineer
Thread Starter
Thanks for the info. I understand the best setup will occur with test and tune; however, I am interested in getting the design phase started as early as possible as that will take quite a bit of time.
It sounds like keeping as much adjustability into the part as possible is the best idea as the suspension setup is quite sensitive to the tires.
That being said, I believe the parts I already have will be sufficient for adjustability. I don't believe I am on one end of the camber spectrum yet. I will proceed with factory geometry.
It sounds like keeping as much adjustability into the part as possible is the best idea as the suspension setup is quite sensitive to the tires.
That being said, I believe the parts I already have will be sufficient for adjustability. I don't believe I am on one end of the camber spectrum yet. I will proceed with factory geometry.
01-14-10, 04:21 PM
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Thanks for the info. I understand the best setup will occur with test and tune; however, I am interested in getting the design phase started as early as possible as that will take quite a bit of time.
It sounds like keeping as much adjustability into the part as possible is the best idea as the suspension setup is quite sensitive to the tires.
That being said, I believe the parts I already have will be sufficient for adjustability. I don't believe I am on one end of the camber spectrum yet. I will proceed with factory geometry.
It sounds like keeping as much adjustability into the part as possible is the best idea as the suspension setup is quite sensitive to the tires.
That being said, I believe the parts I already have will be sufficient for adjustability. I don't believe I am on one end of the camber spectrum yet. I will proceed with factory geometry.
and the only real way to know those things is to drive the car, and start taking measurements.
its hard enough to try and figure out what the car is doing, IMO you want to try to eliminate variables.
01-14-10, 04:30 PM
#11
are you running spherical bearings in the rear control arms? (are you allowed to? I'm not familiar with E production) they'll allow you to adjust a lot more camber out of the rear with the arm adjustable type without the arms binding on the bushings. AWR and MMR both make some. (AWR is also the company that actually made the mazdatrix camber adjusters)
http://www.awrracing.com/
http://www.mmr-direct.com/
http://www.awrracing.com/
http://www.mmr-direct.com/
01-14-10, 08:55 PM
#12
Fabrineer
Thread Starter
are you running spherical bearings in the rear control arms? (are you allowed to? I'm not familiar with E production) they'll allow you to adjust a lot more camber out of the rear with the arm adjustable type without the arms binding on the bushings. AWR and MMR both make some. (AWR is also the company that actually made the mazdatrix camber adjusters)
http://www.awrracing.com/
http://www.mmr-direct.com/
http://www.awrracing.com/
http://www.mmr-direct.com/
I already own the adjustable subrame connector. Those MMR control arm bushings look very nice.
doing lighter rear arms is cool, but the suspensions job is to make the TIRE and driver happy.
and the only real way to know those things is to drive the car, and start taking measurements.
its hard enough to try and figure out what the car is doing, IMO you want to try to eliminate variables.
and the only real way to know those things is to drive the car, and start taking measurements.
its hard enough to try and figure out what the car is doing, IMO you want to try to eliminate variables.
I believe by reducing the unsprung weight you are eliminating variables, as long as stiffness and especially natural frequency are not greatly comprimised.
01-15-10, 10:26 AM
#13
AWR rear camber adjusters
AWR rear adjustable toe links
AWR rear control arm spherical bearings
MMR UHMW solid subframe bushings
Mazdaspeed differential bushings (front and rear)
Delrin DTSS eliminators
it's been too cold and rainy/snowy
01-19-10, 06:20 PM
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What's it that you want to see? I've got everything he listed above and then some but went with MMR individual camber over AWR.
Also had some delrin with stainless sleeve bushings made for the rear upper mount on the hub. No one made anything any longer that I could find and stock it's made of rubber.
Also had some delrin with stainless sleeve bushings made for the rear upper mount on the hub. No one made anything any longer that I could find and stock it's made of rubber.
01-19-10, 06:32 PM
#18
My .2
First of all I just wanna say I am glad i found this section of RX7club! Setup and custom racing fabrication has always been a passion of mine. You guys are living the dream so keep posting! I want to enjoy this hobby vicariously through you as much as possible.
Nice project!^ The CAD cage-modeling especially impressed me. Your thread has a new subscriber 
K2RD! It's so cool to be able to post in the same thread with a legitimate rotary tuner.
All I wanted to say about ^ comment is I'm not sure running an entire season is necessary just to see what tires like. A single afternoon of testing should be sufficient for that... Assuming you have alignment tools, tire pyrometers, a lap timer and maybe an on board data logger with g-sensors and such.
Obviously testing itself is a ways off for SHM's project but once its driving it isn't rocket-science to make the tires happy. (Designing parts to make it even better is another story)
Exactly... at this stage its impossible for you to know what sort of rear suspension arms to design if you have no data to work with. Once your chassis is driving in a test-mule stage collect data and play with all the adjustable parts you added until for a baseline.
Your aim is to make a better rear suspension then Mazda correct? You need to know what Mazda's suspension can do first! It's much harder to improve on something you haven't analyzed and tested right?
Camber Adjusters
Ah that's interesting. I installed those camber adjusters on my FC back when Mazdatrix was selling them as a "prototype". They did fix the camber but they were also kind of fragile. Let me explain...
The shank snapped on me at the indicated stress point as I was exiting an on-ramp on the way to sevenstock. The bushing requires regular servicing or it will wear, squeak and eventually bind. (Binding at the bushing is what probably caused the shank to snap in the first place.)
If I remember correctly I was probably daily driving on these adjusters for about six months before they failed. I can't remember if and when they started to squeak before that... In hindsight I wish I would have realized that they required removal for regular service. (The instructions from Mazdatrix said nothing about it but it should be common sense when your dealing with a solid-bushing.)
I did continue to use them after the failure but I replaced the shank with the strongest replacement I could find. (Not an easy task on a Sunday, stranded in a parking lot, without my tools using a lousy screw-jack) The stronger bolts did the trick and I did not suffer any further failures from the camber adjusters. (Although I started carrying around an extra pair in the car "just in case")
By that point, their were sings of wear on the bushing, mainly scouring, which caused them to squeak quite loudly. As a precaution I removed them for service at the first sign of squeakage (usually every few weeks) to prevent binding. I recommend a heavy duty snythetic bearing grease that's highly friction resistant. It seems to work the best and last the longest.
I don't think my limited track experience gives me better insight into the FC then you guys, but the problem with setup development like this is you will never eliminate all the variables unless you start at ground zero.
Ground Zero
Ground Zero would be literally testing a brand new bone-stock FC on slicks. Obviously they don't make brand new FC's anymore so you'd have to find one in great shape and replace ALL the bushings and suspension components with brand new OEM parts. Which would be a considerable expense to say the least lol.
Without ground zero there is no point testing a stock FC hardly at all because it is already a worn out car. It will not teach us the real limits and advantages of the original suspension design... So we skip ground zero and jump to the test mule phase, which is something very close to the final version of the race car.
Planning the Project
However the problem with building a superior version, of any part, on any chassis is you have to know certain things in advance...
1.) What are your basic limitations to development? (Do you have all the tooling you need to design and build new parts? Do you have easy access to a test track?)
2.) What is the final development deadline?
3.) Do you have a sound-financial budget for the project? (Time is money, materials cost money, everything costs money lol)
4.) Can you do it all yourself? (Usually serious development projects require a team of experts (or at least seriously patient and dedicated people) to help with whatever you don't know, can't do, or don't want to do. (If you've ever been on a pit-crew or race-development team you should know that teamwork has its own challenges.)
^That takes care of most of the how. But what about the why?
5.) Most importantly, for the whole process to be worthwhile, you need to know why you are making your own version in the first place? Is the premise for this thread (and your project) that the rear suspension of the FC is its achilles heel? If you design and build a custom rear suspension that's superior to Mazdas (and everyone else') is that your ticket to victory? Is that the advantage you are betting on?
Is there a premise to this project?
Forgive me for making assumptions, I doubt that's the case. More likely, you are looking at the car as a bunch of separate projects and problems... Hoping that if you can make even small improvements on every part of the car, it will be faster overall?
If the rear suspension is not supposed to be the focus of your project, I'm curious what your focus is? What do you think the real weaknesses of the FC are?
My .2
More to come... I have to research and examine the rear suspension a bit more before I speculate any further.
Hello racers, I am building a 2nd gen for SCCA E Production. You can see the build here:
https://www.rx7club.com/showthread.php?t=875783
I have never raced competitively before. I have a couple questions about camber in the rear of the 2nd gen.
I have some of those Mazdatrix camber adjustment links for the rear of my car, both the one that twists the subframe as well as the ones that attach to the suspension arms.
Will these parts provide sufficient camber adjustability for the rear of the vehicle? I understand that when you lower the car, it gives too much camber, and when I had it alligned, it would not adjust enough out because the link would hit the floor board, which can be modified. However, the car was previously a street prowler, and I was only running ~1deg of camber in the rear.
What do you guys run, or more importantly, what ranges of adjustability will I need to be competitive (if you're willing to share)?
I am building custom rear control arms and I need to know whether to mimick the stock geometry (not design) or to change the design to add or subtract camber that is build into the control arm itself.
https://www.rx7club.com/showthread.php?t=875783
I have never raced competitively before. I have a couple questions about camber in the rear of the 2nd gen.
I have some of those Mazdatrix camber adjustment links for the rear of my car, both the one that twists the subframe as well as the ones that attach to the suspension arms.
Will these parts provide sufficient camber adjustability for the rear of the vehicle? I understand that when you lower the car, it gives too much camber, and when I had it alligned, it would not adjust enough out because the link would hit the floor board, which can be modified. However, the car was previously a street prowler, and I was only running ~1deg of camber in the rear.
What do you guys run, or more importantly, what ranges of adjustability will I need to be competitive (if you're willing to share)?
I am building custom rear control arms and I need to know whether to mimick the stock geometry (not design) or to change the design to add or subtract camber that is build into the control arm itself.
K2RD! It's so cool to be able to post in the same thread with a legitimate rotary tuner.
All I wanted to say about ^ comment is I'm not sure running an entire season is necessary just to see what tires like. A single afternoon of testing should be sufficient for that... Assuming you have alignment tools, tire pyrometers, a lap timer and maybe an on board data logger with g-sensors and such.
Obviously testing itself is a ways off for SHM's project but once its driving it isn't rocket-science to make the tires happy. (Designing parts to make it even better is another story)
are you running spherical bearings in the rear control arms? (are you allowed to? I'm not familiar with E production) they'll allow you to adjust a lot more camber out of the rear with the arm adjustable type without the arms binding on the bushings. AWR and MMR both make some. (AWR is also the company that actually made the mazdatrix camber adjusters)
http://www.awrracing.com/
http://www.mmr-direct.com/
http://www.awrracing.com/
http://www.mmr-direct.com/
Ah that's interesting. I installed those camber adjusters on my FC back when Mazdatrix was selling them as a "prototype". They did fix the camber but they were also kind of fragile. Let me explain...
The shank snapped on me at the indicated stress point as I was exiting an on-ramp on the way to sevenstock. The bushing requires regular servicing or it will wear, squeak and eventually bind. (Binding at the bushing is what probably caused the shank to snap in the first place.)
If I remember correctly I was probably daily driving on these adjusters for about six months before they failed. I can't remember if and when they started to squeak before that... In hindsight I wish I would have realized that they required removal for regular service. (The instructions from Mazdatrix said nothing about it but it should be common sense when your dealing with a solid-bushing.)
I did continue to use them after the failure but I replaced the shank with the strongest replacement I could find. (Not an easy task on a Sunday, stranded in a parking lot, without my tools using a lousy screw-jack) The stronger bolts did the trick and I did not suffer any further failures from the camber adjusters. (Although I started carrying around an extra pair in the car "just in case")
By that point, their were sings of wear on the bushing, mainly scouring, which caused them to squeak quite loudly. As a precaution I removed them for service at the first sign of squeakage (usually every few weeks) to prevent binding. I recommend a heavy duty snythetic bearing grease that's highly friction resistant. It seems to work the best and last the longest.
doing lighter rear arms is cool, but the suspensions job is to make the TIRE and driver happy.
and the only real way to know those things is to drive the car, and start taking measurements.
its hard enough to try and figure out what the car is doing, IMO you want to try to eliminate variables.
and the only real way to know those things is to drive the car, and start taking measurements.
its hard enough to try and figure out what the car is doing, IMO you want to try to eliminate variables.
Ground Zero
Ground Zero would be literally testing a brand new bone-stock FC on slicks. Obviously they don't make brand new FC's anymore so you'd have to find one in great shape and replace ALL the bushings and suspension components with brand new OEM parts. Which would be a considerable expense to say the least lol.
Without ground zero there is no point testing a stock FC hardly at all because it is already a worn out car. It will not teach us the real limits and advantages of the original suspension design... So we skip ground zero and jump to the test mule phase, which is something very close to the final version of the race car.
Planning the Project
However the problem with building a superior version, of any part, on any chassis is you have to know certain things in advance...
1.) What are your basic limitations to development? (Do you have all the tooling you need to design and build new parts? Do you have easy access to a test track?)
2.) What is the final development deadline?
3.) Do you have a sound-financial budget for the project? (Time is money, materials cost money, everything costs money lol)
4.) Can you do it all yourself? (Usually serious development projects require a team of experts (or at least seriously patient and dedicated people) to help with whatever you don't know, can't do, or don't want to do. (If you've ever been on a pit-crew or race-development team you should know that teamwork has its own challenges.)
^That takes care of most of the how. But what about the why?
5.) Most importantly, for the whole process to be worthwhile, you need to know why you are making your own version in the first place? Is the premise for this thread (and your project) that the rear suspension of the FC is its achilles heel? If you design and build a custom rear suspension that's superior to Mazdas (and everyone else') is that your ticket to victory? Is that the advantage you are betting on?
Is there a premise to this project?
Forgive me for making assumptions, I doubt that's the case. More likely, you are looking at the car as a bunch of separate projects and problems... Hoping that if you can make even small improvements on every part of the car, it will be faster overall?
If the rear suspension is not supposed to be the focus of your project, I'm curious what your focus is? What do you think the real weaknesses of the FC are?
My .2
More to come... I have to research and examine the rear suspension a bit more before I speculate any further.
01-20-10, 11:20 AM
#19
Camber Adjusters
Ah that's interesting. I installed those camber adjusters on my FC back when Mazdatrix was selling them as a "prototype". They did fix the camber but they were also kind of fragile. Let me explain...
The shank snapped on me at the indicated stress point as I was exiting an on-ramp on the way to sevenstock. The bushing requires regular servicing or it will wear, squeak and eventually bind. (Binding at the bushing is what probably caused the shank to snap in the first place.)
If I remember correctly I was probably daily driving on these adjusters for about six months before they failed. I can't remember if and when they started to squeak before that... In hindsight I wish I would have realized that they required removal for regular service. (The instructions from Mazdatrix said nothing about it but it should be common sense when your dealing with a solid-bushing.)
I did continue to use them after the failure but I replaced the shank with the strongest replacement I could find. (Not an easy task on a Sunday, stranded in a parking lot, without my tools using a lousy screw-jack) The stronger bolts did the trick and I did not suffer any further failures from the camber adjusters. (Although I started carrying around an extra pair in the car "just in case")
By that point, their were sings of wear on the bushing, mainly scouring, which caused them to squeak quite loudly. As a precaution I removed them for service at the first sign of squeakage (usually every few weeks) to prevent binding. I recommend a heavy duty snythetic bearing grease that's highly friction resistant. It seems to work the best and last the longest.
Ah that's interesting. I installed those camber adjusters on my FC back when Mazdatrix was selling them as a "prototype". They did fix the camber but they were also kind of fragile. Let me explain...
The shank snapped on me at the indicated stress point as I was exiting an on-ramp on the way to sevenstock. The bushing requires regular servicing or it will wear, squeak and eventually bind. (Binding at the bushing is what probably caused the shank to snap in the first place.)
If I remember correctly I was probably daily driving on these adjusters for about six months before they failed. I can't remember if and when they started to squeak before that... In hindsight I wish I would have realized that they required removal for regular service. (The instructions from Mazdatrix said nothing about it but it should be common sense when your dealing with a solid-bushing.)
I did continue to use them after the failure but I replaced the shank with the strongest replacement I could find. (Not an easy task on a Sunday, stranded in a parking lot, without my tools using a lousy screw-jack) The stronger bolts did the trick and I did not suffer any further failures from the camber adjusters. (Although I started carrying around an extra pair in the car "just in case")
By that point, their were sings of wear on the bushing, mainly scouring, which caused them to squeak quite loudly. As a precaution I removed them for service at the first sign of squeakage (usually every few weeks) to prevent binding. I recommend a heavy duty snythetic bearing grease that's highly friction resistant. It seems to work the best and last the longest.
I won't be driving mine every day... but I didn't realize they were going to require so much maintenance.
01-20-10, 01:11 PM
#20
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This thread was pointed out to me by an employee --
PLEASE -- download a GCR/PCS (General Competition Rules / Production Car Specs) PDF from SCCA.com and read a lot of it.
In actuality, a 2nd gen RX7 Turbo is NOT legal in E/Production.
I have never seen a VIN check (to verify the car is NOT a Turbo) done, and when stripped down to E/P trim, I doudt anyone (including me) would care the car STARTED as a Turbo.
You can NOT use turbo side housings in the engine - they MUST be "6-port" side housings.
After SIX years of fighting, I (uppercase, bold, underlined) finally got the idiots at SCCA to approve Turbo ROTOR housings for the NA engines.
You CAN use the turbo transmission, but it is WAY heavy, ratios are not good, requires using a larger (Turbo) diameter flywheel, and hits you with a 2.5% weight penalty because it is not a STOCK non-turbo transmission.
You can NOT use the Turbo differential -- period, it is not legal.
15" Wheels only-- can not use 16"s from the Turbo.
Brakes/suspension are fine -- all the same Turbo/NA.
But remember all calipers must be OEM. Rotors must be OEM specs and NOT drilled or slotted (another battle I am currently fighting).
I use ~ zero to 1/2 degree negative rear camber, and 1/2 to 1 degree front with 23x9x15 slicks.
IDA Weber on manifold, OR stock Non-turbo manifolding and stock throttle body.
Etc. etc.
Dave Lemon, Owner, Mazdatrix
E/P #99 Convertible (build pics at: http://www.mazdatrix.com/epconv.htm)
Current E/P lap records at Cal Speedway, Willow Springs, and some at Buttonwillow
Lots of wins here and there over the years
Also 1st gen NASA PT car, and building 3-Rotor Turbo RX8 Time Attack
Member SCCA Production AdHoc Committee
(We/they make the rules for PRODUCTION cars -- but all of the bad/stupid/idiotic rules are not my fault! They were there before I was drafted!- and there are a lot of them I am fighting to change)
PLEASE -- download a GCR/PCS (General Competition Rules / Production Car Specs) PDF from SCCA.com and read a lot of it.
In actuality, a 2nd gen RX7 Turbo is NOT legal in E/Production.
I have never seen a VIN check (to verify the car is NOT a Turbo) done, and when stripped down to E/P trim, I doudt anyone (including me) would care the car STARTED as a Turbo.
You can NOT use turbo side housings in the engine - they MUST be "6-port" side housings.
After SIX years of fighting, I (uppercase, bold, underlined) finally got the idiots at SCCA to approve Turbo ROTOR housings for the NA engines.
You CAN use the turbo transmission, but it is WAY heavy, ratios are not good, requires using a larger (Turbo) diameter flywheel, and hits you with a 2.5% weight penalty because it is not a STOCK non-turbo transmission.
You can NOT use the Turbo differential -- period, it is not legal.
15" Wheels only-- can not use 16"s from the Turbo.
Brakes/suspension are fine -- all the same Turbo/NA.
But remember all calipers must be OEM. Rotors must be OEM specs and NOT drilled or slotted (another battle I am currently fighting).
I use ~ zero to 1/2 degree negative rear camber, and 1/2 to 1 degree front with 23x9x15 slicks.
IDA Weber on manifold, OR stock Non-turbo manifolding and stock throttle body.
Etc. etc.
Dave Lemon, Owner, Mazdatrix
E/P #99 Convertible (build pics at: http://www.mazdatrix.com/epconv.htm)
Current E/P lap records at Cal Speedway, Willow Springs, and some at Buttonwillow
Lots of wins here and there over the years
Also 1st gen NASA PT car, and building 3-Rotor Turbo RX8 Time Attack
Member SCCA Production AdHoc Committee
(We/they make the rules for PRODUCTION cars -- but all of the bad/stupid/idiotic rules are not my fault! They were there before I was drafted!- and there are a lot of them I am fighting to change)
01-20-10, 01:35 PM
#22
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K2RD! It's so cool to be able to post in the same thread with a legitimate rotary tuner.
All I wanted to say about ^ comment is I'm not sure running an entire season is necessary just to see what tires like. A single afternoon of testing should be sufficient for that... Assuming you have alignment tools, tire pyrometers, a lap timer and maybe an on board data logger with g-sensors and such.
5.) Most importantly, for the whole process to be worthwhile, you need to know why you are making your own version in the first place? Is the premise for this thread (and your project) that the rear suspension of the FC is its achilles heel?
All I wanted to say about ^ comment is I'm not sure running an entire season is necessary just to see what tires like. A single afternoon of testing should be sufficient for that... Assuming you have alignment tools, tire pyrometers, a lap timer and maybe an on board data logger with g-sensors and such.
5.) Most importantly, for the whole process to be worthwhile, you need to know why you are making your own version in the first place? Is the premise for this thread (and your project) that the rear suspension of the FC is its achilles heel?
tires, we also thought one weekend was enough for testing. we switched from the toyo R888 to the hankook slick. we actually had 2 weekends of testing, lap times dropped instantly.
however when we actually RAN the 25, the tires ended up with a funny wear pattern, making us have to change front tires earlier than we'd expected.
we're thinking now you almost need to go thru a set of tires to get the car setup, unless you're good or lucky. going from the Ra1 to the R888, wear was better, but the drop in lap times took suspension tuning, while going from the R888 to the hankook, it was the other way around.
5. i think that figuring out what problems you have is actually the hard part. it seems like we struggle with that, but once we figure it out the solution is really simple
01-20-10, 04:27 PM
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shm21284: Strongly suggest you join the Production discussion board.
http://prodracing.com/prodcar/
It is where you should be asking your questions, and there are quite a few Rotary production racers there.
Btw - I looked at your other thread and quality of workmanship looks REALLY good. If I get a chance I'll look at the pics closer - saw a few things. Btw, if you make that cage you were showing you will never get the car down to weight. I'm pretty sure the cell will be too low when you get the car to ride height on 15" CANTILEVER slicks.
J9FD3s and others: The difference between RA1s/R888/HankookSlicks/etc. and CANTILEVER slicks from Hoosier/Goodyear is night and day. MANY seconds per lap! Believe me as I have raced on pretty much everything since I started in 1971. (SCCA, IMSA(old one), TransAM, GrandAM, NASA, Escort Endurance, 25 Hours of Thunderhill, etc. +?) + that is why NASA has such a high PT points add-on for those slicks.
jgrewe and eage8: Yes, rules for E/P RX7 are 15x7" even though the GTUs came with 16's.
We approved the newer cars with 16"+ that never came with anything smaller. Many things there - the BMW Z3 ran with 15's instead of 16's because they would clear is brakes and there are NO cantilever slicks available above 15". There is a terrible TIRE selection at 16 and 17, so we recently (letters from racers) just approved UP TO 18" for all those cars who had 16'+ as OEM. Have to run stock calipers and OEM brake specs, so cars like the RX8 can NOT fit 15" wheels, so can not run the super stickey tires.
http://prodracing.com/prodcar/
It is where you should be asking your questions, and there are quite a few Rotary production racers there.
Btw - I looked at your other thread and quality of workmanship looks REALLY good. If I get a chance I'll look at the pics closer - saw a few things. Btw, if you make that cage you were showing you will never get the car down to weight. I'm pretty sure the cell will be too low when you get the car to ride height on 15" CANTILEVER slicks.
J9FD3s and others: The difference between RA1s/R888/HankookSlicks/etc. and CANTILEVER slicks from Hoosier/Goodyear is night and day. MANY seconds per lap! Believe me as I have raced on pretty much everything since I started in 1971. (SCCA, IMSA(old one), TransAM, GrandAM, NASA, Escort Endurance, 25 Hours of Thunderhill, etc. +?) + that is why NASA has such a high PT points add-on for those slicks.
jgrewe and eage8: Yes, rules for E/P RX7 are 15x7" even though the GTUs came with 16's.
We approved the newer cars with 16"+ that never came with anything smaller. Many things there - the BMW Z3 ran with 15's instead of 16's because they would clear is brakes and there are NO cantilever slicks available above 15". There is a terrible TIRE selection at 16 and 17, so we recently (letters from racers) just approved UP TO 18" for all those cars who had 16'+ as OEM. Have to run stock calipers and OEM brake specs, so cars like the RX8 can NOT fit 15" wheels, so can not run the super stickey tires.