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

Help: FD lurches into corner when coming off throttle

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

Help: FD lurches into corner when coming off throttle

Old 02-27-03, 10:56 AM
  #1  
Re-engineering everything
10 Year Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2002
Location: Bay Area, CA
Posts: 751
Likes: 0
Received 0 Likes on 0 Posts
Help: FD lurches into corner when coming off throttle

All,

I've searched for a thread that covers this issue, but I haven't found anything--so I am putting it to the handling experts.

I have a 94 R2 with about 96k miles. Here is the issue: when I come off the throttle (say, to shift) in the middle of a corner, the car lurches towards the apex. At first I just thought I was balancing too much of my weight against the steering wheel--the power steering is so overboosted that I considered that I might be turning the car myself--but this is not the case.

It seems that the car's steering is extremely pitch sensitive. As weight transferes to the front wheels, the car wants to steer more. Now, I realize that a certain degree of this behavior is healthy, but I have owned/driven a bunch of different sports cars and I have never experienced anything like this. (911, Vette, MR2, etc.)

So, is this a common handling characteristic of the FD? Or does it sound like I have a problem? And if so, where should I start? Again, my '94 R2 has almost 100k but the suspension feels remarkably good for a car with this much mileage. The swaybar brackets are in good shape. I can't say much about the bushings, but I'll be checking them soon. The problem does not appear to be worse in right or left turns.

If anyone has experienced anything like this and can confirm that this is either normal or definetly an issue, please respond to this thread or PM me. Thanks to you all in advance,

-ch
hyperion is offline  
Old 02-27-03, 04:06 PM
  #2  
Full Member
5 Year Member
 
Join Date: Jun 2002
Location: Philly, Pa.
Posts: 243
Likes: 0
Received 0 Likes on 0 Posts
I take it this lurch is far beyond what could be explained by weight-transfer/traction shift?

(I autocross an FC, so I can't speak with experience to FD handling)

Why are you coming off throttle in the middle of a corner?!? Isn't that a ticket to an off-track excursion if you're driving near the limit?

(Or is the problem a highway cloverleaf thing, and not an on-track thing?)

I'm a little confused. Sorry to be of no help.. just trying to get things clarified..
MechE00 is offline  
Old 02-27-03, 06:02 PM
  #3  
Re-engineering everything
10 Year Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2002
Location: Bay Area, CA
Posts: 751
Likes: 0
Received 0 Likes on 0 Posts
Thanks for the response. Basically, when I run out of revs on a long corner, I have to go for a gear. I try to declutch before I go off throttle (because the transition is smoother) but as soon as the weight transfers forward, the the car turns in. A lot more than I would expect it to, and a lot more than I have experienced with any other car. It's possible that the alignment is really screwed up, but the car does not pull or track.

I checked the tyre pressures today (they were reasonable at 30-34psi) so that's not it. The car does feel a little squeamish under heavy cornering, but I chalk that up to the 205/50/R16s more than anything else. They are Toyo proxies, I believe.

(I just purchased the car, so I am getting to know it.)

I spun my friend's M3 around the block and while there is a bit of throttle steer, it's not nearly as dramatic. I am going to take it to Ivan and see what he thinks. But if anyone else has noticed this with their FD, I would appreciate even a shout to let me know whether or not it's normal.

Thanks,

-ch
hyperion is offline  
Old 02-27-03, 06:18 PM
  #4  
SEMI-PRO
iTrader: (2)
 
ZoomZoom's Avatar
 
Join Date: Feb 2001
Location: New Jersey
Posts: 2,865
Received 31 Likes on 28 Posts
I changed out my struts and springs. I thought mine were fine but once the stocks were out I realized they were dead. Pushed them against the floor in the garage and they didnt come back. After the Bilsteins and HKS springs the car is much more managable. Even so your goin to have a change of weight distribution when coming off the throttle. Just less pronounced when you upgrade and or replace worn out parts.
ZoomZoom is offline  
Old 02-27-03, 11:44 PM
  #5  
Has been.. hangin' around
10 Year Member
 
Silkworm's Avatar
 
Join Date: Mar 2001
Location: Milpitas, CA
Posts: 2,618
Likes: 0
Received 0 Likes on 0 Posts
Have you looked at the swaybar mounts? Doesn't sound quite like what you're having, but a busted front mount seems to be fairly common on FDs, and from chasing/watching one FD with a broken mount, he had all sorts of strange handling problems on turn in.
Silkworm is offline  
Old 02-28-03, 10:55 AM
  #6  
Full Member
5 Year Member
 
buttlips's Avatar
 
Join Date: Dec 2001
Location: Yep
Posts: 119
Likes: 0
Received 0 Likes on 0 Posts
Does it feel like the front end is biting more, or the rear end is losing traction?

Letting off the gas mid-turn will create trailing throttle oversteer (and loss of control if you're driving at the limit). You'd be better off starting the turn in the higher gear rather than shifting in the middleof it.
buttlips is offline  
Old 02-28-03, 11:09 AM
  #7  
Ex fd *****
10 Year Member
 
maxpesce's Avatar
 
Join Date: May 2001
Location: Ventura CA USA
Posts: 1,782
Likes: 0
Received 0 Likes on 0 Posts
Check the bushing on the TOE Control Links - They allow a slight Toe change (in) reducing oversteer, when cornering at the high lateral loads - when you let off in mid corner (bad), they relax and the toe change is reversed (toe out) Increasing oversteer. Worn toe links accentuate this effect.
maxpesce is offline  
Old 02-28-03, 12:56 PM
  #8  
I'll blow it up real good
10 Year Member
iTrader: (1)
 
RX-Heven's Avatar
 
Join Date: May 2001
Location: San Francisco, CA
Posts: 2,390
Likes: 0
Received 0 Likes on 0 Posts
Originally posted by buttlips
Does it feel like the front end is biting more, or the rear end is losing traction?

Letting off the gas mid-turn will create trailing throttle oversteer (and loss of control if you're driving at the limit). You'd be better off starting the turn in the higher gear rather than shifting in the middleof it.
Try that and then try to balance the throttle to the apex and upshift while tracking out. Compare the two by rpms/speed at a common reference point after the exit to see what works best.
RX-Heven is offline  
Old 02-28-03, 01:00 PM
  #9  
I'll blow it up real good
10 Year Member
iTrader: (1)
 
RX-Heven's Avatar
 
Join Date: May 2001
Location: San Francisco, CA
Posts: 2,390
Likes: 0
Received 0 Likes on 0 Posts
Originally posted by buttlips
You'd be better off starting the turn in the higher gear rather than shifting in the middleof it.
Try that and then try to balance the throttle to the apex and upshift while tracking out. Compare the two by rpms/speed at a common reference point after the exit to see what works best.
RX-Heven is offline  
Old 02-28-03, 02:02 PM
  #10  
es
Senior Member
10 Year Member
 
es's Avatar
 
Join Date: Mar 2001
Location: Jax, Fl.
Posts: 587
Likes: 0
Received 0 Likes on 0 Posts
Originally posted by maxpesce
Check the bushing on the TOE Control Links - They allow a slight Toe change (in) reducing oversteer, when cornering at the high lateral loads - when you let off in mid corner (bad), they relax and the toe change is reversed (toe out) Increasing oversteer. Worn toe links accentuate this effect.
This is what I'd put my money on. On throttle the rear tires tend to toe in, lift & they toe out causeing the car to rotate much easier.

My Toe links were getting bad enough to notice this at 90K miles so I upgraded to the M2 solid units.

Eric.
es is offline  
Old 03-01-03, 06:50 PM
  #11  
Re-engineering everything
10 Year Member
Thread Starter
iTrader: (2)
 
Join Date: Feb 2002
Location: Bay Area, CA
Posts: 751
Likes: 0
Received 0 Likes on 0 Posts
All,

Thanks much for the input. I think I am going to look carefully at my toe links in the rear. I'll probably just replace the toe and T/C rod with the M2 bars.

Great forum!

-ch
hyperion is offline  
Old 03-02-03, 02:06 AM
  #12  
I'm a CF and poop smith
10 Year Member
 
skunks's Avatar
 
Join Date: Aug 2001
Location: Hawaii
Posts: 3,961
Likes: 0
Received 0 Likes on 0 Posts
wait, how come your running 205/50/R16s on your rims, what rims are you running??? True you can can run as low as 205 on stock rims but I would only do so for drift and not for a gripping session. stock tire size for a FD is 225 and you can go up to 245 safely.
skunks is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
20
03-29-18 02:05 PM
CaptainKRM
2nd Generation Specific (1986-1992)
14
08-26-15 09:52 PM


Thread Tools
Search this Thread
Quick Reply: Help: FD lurches into corner when coming off throttle


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: