Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > Race Car Tech
Reload this Page >

Had my FD corner weighed. Advise, Comments, Suggestions?

Race Car Tech Discuss anything related to road racing and auto X.

Had my FD corner weighed. Advise, Comments, Suggestions?

Old 06-03-05, 03:20 PM
  #1  
Rotary Enthusiast
10 Year Member
Thread Starter
 
John Magnuson's Avatar
 
Join Date: Dec 2002
Location: San Diego, CA
Posts: 1,147
Likes: 0
Received 0 Likes on 0 Posts
Had my FD corner weighed. Advise, Comments, Suggestions?

Had some work done at a friend's race shop and went ahead and put the FD on the scales. Here are the results with a 180lb driver in the car:

Left Front - 792 lbs
Right Front - 697 lbs
Left Rear - 732 lbs
Right Rear - 712 lbs

Or for those who like graphics:

792 | 697
------------
732 | 712

So obviously it's too heavy on the front left. I have Advance Design adjustable coilovers so I can tweak the ride height. I could raise the left rear a little bit. However the owner of the shop seemed to think that this might just mess things up since my sway bars don't have adjustable endlinks. Also my rear weights are pretty good so why mess them up.

Any advice?

Another interesting aside is that my car, a 1993 touring model with nothing removed, came in at 2753lbs once you subtract the driver. All the information I have read said that the touring model should weigh a little more than 100lb more than that. The only things I have done that reduce weight are a complete aftermarket exhaust (downpipe, HF cat, RB catback), removed the spare tire, relocated smaller battery & the AD shock are much lighter than the stock shocks. Also the car had only a half tank of gas. So do you think the half tank of gas and lighter exhaust accounts for this weight? The shop insists that their scales are state of the art and very accurate.

Thanks,

John

Last edited by John Magnuson; 06-03-05 at 03:26 PM.
John Magnuson is offline  
Old 06-03-05, 04:36 PM
  #2  
Senior Member
5 Year Member
iTrader: (4)
 
RotaryAXer's Avatar
 
Join Date: Apr 2004
Location: Dorr, Michigan
Posts: 393
Likes: 0
Received 0 Likes on 0 Posts
Well it isn't too bad actually.

The cross weight is within 1.3% of an ideal 50%. That is pretty good.

(LF+RR)/Total

A lot of people will focus on getting cross weight as close to 50% as possible. This is a good compromise on a typical street car. It will give a pretty good consistent way to get transient weight transfers to be close when turning either direction.

Other than that I would say that your 100 lbs could very easily be accounted for by the exhuast, wheels and battery.
RotaryAXer is offline  
Old 06-03-05, 05:29 PM
  #3  
~17 MPG
iTrader: (1)
 
scotty305's Avatar
 
Join Date: Jan 2004
Location: Bend, OR
Posts: 2,741
Received 18 Likes on 14 Posts
If you've got something else to use as a daily driver, you might look into removing your power steering & AC.

-s-
scotty305 is offline  
Old 06-03-05, 05:35 PM
  #4  
Rotary Enthusiast
10 Year Member
Thread Starter
 
John Magnuson's Avatar
 
Join Date: Dec 2002
Location: San Diego, CA
Posts: 1,147
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by scotty305
If you've got something else to use as a daily driver, you might look into removing your power steering & AC.

-s-
I do have other cars. I usually drive a Miata on the street although I still take the FD out at least once a week if not more. I have thought about removing the AC but I have decided not to cause once in a while I'm REALLY glad I have it. You're right that removing the AC and PS would reduce weight at the front left corner though.
John Magnuson is offline  
Old 06-03-05, 10:28 PM
  #5  
Banned. I got OWNED!!!
 
alberto_mg's Avatar
 
Join Date: Aug 2002
Location: nyc+li, ny
Posts: 2,691
Likes: 0
Received 0 Likes on 0 Posts
what height are you set to on each corner? i don't have much experiencing corner weighting other than my Rotax, but i'd say lift the driver's side front just slightly.
alberto_mg is offline  
Old 06-04-05, 01:31 PM
  #6  
Lovin The Spinnin Doritos
5 Year Member
 
Join Date: Aug 2004
Location: Huntsville, AL
Posts: 131
Likes: 0
Received 0 Likes on 0 Posts
I got rid of the ac in my FC which is my daily. It still gets some "cool" air through the vents but its basically just blowing hot air onto me, but its not too bad.
JJ01769 is offline  
Old 06-06-05, 07:02 AM
  #7  
Banned. I got OWNED!!!
iTrader: (3)
 
Join Date: Nov 2001
Location: London, Ontario
Posts: 2,483
Likes: 0
Received 0 Likes on 0 Posts
I does look OK....Could be closer. I would first get some adjustable sway bar end links. I think you will find you would be chasing your *** if you try to adjust the corner weights with the sway bars in a bind.

If you do that.....Then take some off the left front. I will move the weight to the right rear mostly but some will go to the other corners including your right front - which needs it. Your rears will get all out of whack before they get better.

-billy
Re-Speed.com is offline  
Old 06-06-05, 01:00 PM
  #8  
Rotary Enthusiast
10 Year Member
Thread Starter
 
John Magnuson's Avatar
 
Join Date: Dec 2002
Location: San Diego, CA
Posts: 1,147
Likes: 0
Received 0 Likes on 0 Posts
Thanks for the advise everyone! I suppose the next step will be adjustable endlinks and then messing with the ride height a bit. Did a track weekend with the Porsche Club of American this weekend at Buttonwillow. Great time! Played around with the rebound on the shocks a bit and found a setting that I like. Car ran very well and was competitive.

-John
John Magnuson is offline  
Old 06-06-05, 01:22 PM
  #9  
Cheap Bastard
iTrader: (2)
 
adam c's Avatar
 
Join Date: Sep 2002
Location: San Luis Obispo, Ca
Posts: 8,363
Received 37 Likes on 31 Posts
I would try raising the right front a little bit. That should take some of the weight off the left front, without messing up the rear very much. Don't move it very much
adam c is offline  
Old 06-06-05, 01:23 PM
  #10  
Do it right, do it once

iTrader: (29)
 
turbojeff's Avatar
 
Join Date: Apr 2001
Location: Eugene, OR, usa
Posts: 4,801
Likes: 0
Received 6 Likes on 4 Posts
2753lbs is pretty light for a Touring but I think it could actually be accurate.

My R1 weighed 2796lbs on SCCA scales. Full tank of gas and I had the spare in too.

1/2 tank gas = 50lbs or so.
Spare = 23lbs IIRC
Jack and tools = 5lbs?

I had a 51R battery, DP, CB to lighten the car up. 51R battery isn't the smallest you can get so you might be saving another 5-15lbs there.

Your same setup on my car would have made my R1 75-95lbs lighter or 2720-2700lbs.

I also added cruise, factory CD player and a JDM rear seat. I think those things may have added 10-15lbs.

A stock 93 Touring probably weighs 2850lbs or so. I don't think your weight is out of the ball park.

IIRC the sunroof assembly weighs about 30lbs. Do you still have the Bose?
turbojeff is offline  
Old 06-07-05, 06:27 PM
  #11  
Rotary Enthusiast
10 Year Member
Thread Starter
 
John Magnuson's Avatar
 
Join Date: Dec 2002
Location: San Diego, CA
Posts: 1,147
Likes: 0
Received 0 Likes on 0 Posts
Yes, still have the bose. The only thing I have removed is the spare since it doesn't fit over my larger brakes anyway. Still have the Jack and Tools. I have an aftermarket steering wheel too and that I know weighs at least 3 or 4 pounds less than the stock airbag/steering wheel.
John Magnuson is offline  
Old 06-07-05, 06:41 PM
  #12  
Rotary Freak
iTrader: (10)
 
Join Date: Mar 2001
Location: San Francisco, CA
Posts: 2,056
Likes: 0
Received 3 Likes on 3 Posts
Just for reference for the LS1/FD:

I had the car alignmened and recorner weighted to race specs running 18x10.5" CCW's and 285/30/18 Michelin Pilot Sport Cup tires with a full tank of gas.

2800lbs total without driver (no spare/jack/rear carpet/bins/divider)
.4993% front l690 r708
.5007% rear l712 r690

With driver in place it was within 1lb difference on the cross weights.

no a/c or p/s, touring model without Bose system, no spare, rear carpet or jack, Odessey mini battery (14lbs). Heavy 60lb dual 3" exhaust with stock rear hatch/glass and no other weight saving tricks.

Your car without a/c or p/s should be around 2700lbs which is great. Any further weight reduction and the car becomes a noisy and hot race car.

Last edited by gnx7; 06-07-05 at 06:43 PM.
gnx7 is offline  
Old 09-06-06, 01:10 PM
  #13  
~17 MPG
iTrader: (1)
 
scotty305's Avatar
 
Join Date: Jan 2004
Location: Bend, OR
Posts: 2,741
Received 18 Likes on 14 Posts
I know this is an old thread, but I'd rather add my info to this thread than create a new one. I weighed my car yesterday, and was very pleased with the results:

Empty: 2691 lbs (without driver or spare tire).
LF: 721, RF: 665 (52% front)
LR: 640, RR: 665 (48% rear)

Loaded: 2861 lbs (with 143lb driver and 27lbs of spare tire & jack).
LF: 767, RF: 672 (50% front)
LR: 709, RR: 713 (50% rear)

Touring: 3004 lbs (with 143lb driver, 143lb passenger, and 27lbs of spare tire & jack).
LF: 772, RF: 720 (50% front)
LR: 742, RR: 768 (50% rear)


Here are the mods that got me there:

Chassis:
1994 Base model, no sunroof, single oil cooler, stock stereo/cassette player and speakers (not the Bose system). The fuel tank was about 40% full, just below half a tank.

Suspension & Wheels:
Avon 245/45R16 tires. Racing Beat front swaybar, Mazdaspeed sway bar mounts, Tripint endlinks. Stock shocks, springs, wheels and rear swaybar.

Engine Bay:
Odyssey PC680 battery, Megan Racing downpipe (Jet-Hot coated). Removed Cruise Control. Everything else is stock including radiator, air pump, AC & power steering, exhaust.

Interior: all stock. Base model has cloth not leather. Autometer boost gauge might weigh 0.5 lbs. I haven't gotten around to removing the cruise control computer, but I doubt it weighs more than a pound.



For comparison, my friend's '86 Mustang LX weighed in around 3100lbs (about a 60/40 balance), and the corner scales showed my weight as being within 3 lbs of what my bathroom scale says so I trust their accuracy.
Someday I might shoot for 2600 lbs, I hope I can get there by removing the AC, PS and air pump, and installing lightweight seats.


-s-
scotty305 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
eplusz
General Rotary Tech Support
15
10-07-15 04:04 PM
Zinraf
2nd Generation Specific (1986-1992)
3
10-01-15 01:09 PM
RuffRx7
3rd Generation Specific (1993-2002)
4
10-01-15 03:08 AM
Red-Dragon_Akuma
New Member RX-7 Technical
11
09-28-15 06:09 AM


Thread Tools
Search this Thread
Quick Reply: Had my FD corner weighed. Advise, Comments, Suggestions?


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: