When the car was stock, I could run WOT around turns with perfectly neutral balance (no steering required to hold constant radius etc). At the limit, the car would 4-wheel drift.

With my slightly mdified suspension (lowered 15 mm on stock springs with Koni Sports, 25 mm rear bar, 15x7 +45 rims), the darn thing pushes sharply when I use the gas in turns. I have found that stiffer front rebound setting will help this some, but not enough (and also causes turn-in push I don't want). Rear rebound doesn't seem to have much effect on this problem. I played some with alignment (toe-out front and rear) with no luck.

Except for this problem, all other cornering phases are well balanced.

What else can I try ? Would stiffer rear springs help/hurt this condition ?

 

Are you bottoming out the front shocks?

 

No.

 

whats your camber set at(front and rear)? tire pressure(front and rear)?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itrdave &raquo;</TD></TR><TR><TD CLASS="quote">No.</TD></TR></TABLE>

Have you put zip ties on the shock shaft to make sure?

 

1) You are bottoming out the outside front. No worries though, you were doing that at stock ride height. Especially, if you had sticky tires.

2) By lowering the car all around you've gained camber. Unfortunately, you've gained more rear camber then front camber. There is your push.

As you've discovered, rear rebound will do nothing to improve a late corner understeer issue. Rear rebound will only improve early corner entry and transition phases. Adding front rebound will help late corner exit, but as you've found out, at the expense of entry push.

 

Thanks for the feedback. I'm running RT-615's and certainly not bottoming any shock - I know what that feels like (also trimmed bumpstops when I lowered it).

Have -1.5 F / -1.0 R camber (changed from -1.5 rear in order to improve lift-throttle rotation etc)

Run 37F / 29R psi for AX (again, the 29 is a bit low in order to get good lift-throttle rotation)

Does anybody know what will happen if I increase rear spring rate ?

 

Normally more rear rotation mid corner are going to be found in more rear sway bar, more rear spring and more rear rebound on the shocks. If increasing the rear rebound was not enough to make it happen, boviously it will take more than the fine tune of the adjustment. I haven't owned an ITR so I don't know where your 25mm rear bar fits in the scheme of the grand scheme of what is available for the car. More rear spring rate wil help as well but if you are using stock spring rates currently on the front, just changing rears alone might put you in an odd situation.

As mentioned above, you may already be hitting the loadside front bumpstops in mid corner so that could be your cause, showing you that a whole set of springs all around might be a good idea if you want to keep at the rough ride height that you have.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itrdave &raquo;</TD></TR><TR><TD CLASS="quote">Thanks for the feedback. I'm running RT-615's and certainly not bottoming any shock - I know what that feels like (also trimmed bumpstops when I lowered it).

Have -1.5 F / -1.0 R camber (changed from -1.5 rear in order to improve lift-throttle rotation etc)

Run 37F / 29R psi for AX (again, the 29 is a bit low in order to get good lift-throttle rotation)

Does anybody know what will happen if I increase rear spring rate ?</TD></TR></TABLE>

Honda designed the suspension on these cars to use the bump stop for added spring rate. The bumpstop is a soft, progressive bump stop. You won't feel it when you hit it. I've shortened my shocks, and removed 1" of the bump stop. That means I've increased my suspension travel by 3", which is good, since I've lowered the car three inches. In theory, I have the same suspension travel as stock. I'm using an 850lb front spring and I'm still all over the bumpstops quite often. Now, are you SURE you aren't hitting your bumpstop? Standard length shocks, stock springs, and 1/2" lower.... How much did you shorten the bump stops by?

Stiffer rear springs will make the car looser and reduce your power on understeer some.

 

I don't have measured data to show I'm not touching the bump-stops, but I have experienced the terminal understeer that occurs when you hit them hard as in disconnecting the front sway bar...

My current setup should have less bump travel in the turn than stock because I'm lowered, have significantly less roll angle and stock distance between shock body and bump-stop due to trimming stops 15 mm (same as lowering).

I went with the stiffer rear bar because the lowering and rims combined to give me horrific push in all conditions. The bar solved the turn-in and lift-throttle problems, but seemed to have little effect on the on-gas problem. So that makes me think stiffer rear springs probably wouldn't help this either...

 

How do you know you are still hitting your bumpstops ? I find it very hard to believe it is possible to hit them due to lateral acceleration alone due to fact that front wheel (for example) travels in bump about 1 in. during cornering, which means the shock is only travelling about 0.5 in. Even if you double that, it's nowhere close.

 

maybe try some more rear tire pressure? with my rs-2 tires i ran 35f 41r and adjusted to suit the course i was on when autoXIng my integra. and i had 550 600rear springs and a 19mm bar on a 90 integra.
as for checking to see if your bottoming out put zip ties on the bottom of the shaft and after your run check and see how high the tie has moved up on the shaft

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itrdave &raquo;</TD></TR><TR><TD CLASS="quote">How do you know you are still hitting your bumpstops ?</TD></TR></TABLE>

Do you know how to do the ziptie trick? That would answer your question on the matter, rather than have you just speculate and assume you're not hitting the bumpstop.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itrdave &raquo;</TD></TR><TR><TD CLASS="quote">due to fact that front wheel (for example) travels in bump about 1 in. during cornering</TD></TR></TABLE>

Are you sure about THAT? I've seen pictures of stock-suspensioned R's on track, and when driven pretty hard, it sure looks like there's more than an inch of wheel movement.

 

I did the zip tie trick once. I was autocrossing on a perfectly smooth, brand new brushed concrete pad. I shoved the zip tie so far into the bumpstop I removed it from the top of the bumpstop later that winter when I had the suspension off.

 

With 700lb fronts I hit the bumpstops with the zip tie

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Stinkycheezmonky &raquo;</TD></TR><TR><TD CLASS="quote">

Do you know how to do the ziptie trick? That would answer your question on the matter, rather than have you just speculate and assume you're not hitting the bumpstop.
</TD></TR></TABLE>

Hi,

In track racing over here, i'm also getting quite a bit of mid-corner understeer when my ITR is driven hard. When i drive quick and smooth, the car is pretty neutral and very easy to drive, but when i push the car harder during race, the car then to give mid-corner understeer too.

Have been trying out varies simple stuff but some how could not solve this too.

Now after this thread, i'm wondering if i'm hitting bump stop too. How does the zipie trick work to check on the bump stop?

Isn't the bump stop inside the monotube shock body? And do we do the test only on the front or both front and rear??

Thanks

 

The bumpstop is on the outside of the shock piston, near the top, wear the piston meets the tophat. The idea is that you slide a ziptie up between the piston and the bumpstop, such that some amount of the ziptie is sticking out (think down, toward the shock body) other than just the "head" or whatever you want to call it. After a session, examine it. If the "head" has been pushed up all the way to the edge of the bumpstop, or into it if that severely, then you're hitting the bumpstop. I wouldn't think this would really be necessary in the rear with our cars, but couldn't hurt I guess.

 

Thanks alot...

I wasn't getting that much mid-corner understeer when i was on my set of Ohlins which had longer stroke and shock body. But the ohlins are very old now, so changed to Omni full adjustables last year and added a thicker sway bar and its now more pronounced mid-corner understeer.

If they are really hitting the bump stock, can i increase my front spring rates to reduce it from hitting? But i worry it will give more turn in understeer and driving in rain during race will be a killer if too stiff. Current Front 12kg/mm and rear 8kg/mm.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chris2000 &raquo;</TD></TR><TR><TD CLASS="quote">

Current Front 12kg/mm and rear 8kg/mm.</TD></TR></TABLE>

thats a pretty heavy front bias there on teh spring rates, in my opinion. If youre springs are the same length, have you tried swapping front to rear and seeing what results you get? 8k is about 450lbs? and 12k is about 625lbs? And i'm assuming you added a bigger rear bar...
Yes you can run higher front rates to help not hit the bumpies, but raising the car 1/8"-1/4" could help as well.

 

itrDave,

Where do you get the idea that front wheel only travels 1" in bump on cornering? I have plenty of video of my stock ITR front wheels and the outside wheel seems to get buried in the wheel well to the tune of 3-4". I think you need to recognize that there is a lot of ITR suspension experience on this board. If they say you are hitting the bump stop then you are.

Regards,
Alan

 

Now that I think about it a bit more - I do see it is possible to be hitting the bump stop. I didn't think about the fact that a large portion of the bare shock travel is consumed by raising the wheel from full droop to ground position - I was thinking there was a good bit more usable shock travel than there really is...

Not sure if this phenomenon has much impact on the on-gas pushing problem. Sounds like nothing is going to eliminate this condition anyway. May just have to try stiffer rear springs for starters...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chris2000 &raquo;</TD></TR><TR><TD CLASS="quote">If they are really hitting the bump stock, can i increase my front spring rates to reduce it from hitting? But i worry it will give more turn in understeer and driving in rain during race will be a killer if too stiff. Current Front 12kg/mm and rear 8kg/mm.</TD></TR></TABLE>

Honestly, I think the problem is going to be with your shocks more than a chosen spring rate. The Omnis aren't terribly stiff to begin with. If possible, I'd suggest getting your Ohlins rebuilt. I've driven on a few different suspensions, and the Ohlins are my favorite by far.

 

There is some good info in this thread. The guys experiencing push are running stiffer front than rear with more air pressure in front etc...

The opportunity to change those characteristics are: stiffer rear springs (in addition to adjustibility if rebound), larger rear sway bar, more air pressure in back, removing front sway bar.

The ITR is much quicker when rotation can be increased by the the items above to the point where even gas in sweepers may not be enough to keep the back end from swinging around.

My current car setup is rather touchy (I like it that way):
- 12kf / 14kr springs (JIC shock/spring) & I typically adjust rear 2x whatever my front setting is per track condition
- mugen 26mm rear bar
- air pressure is typically 2-4psi higher in rear
- I do still have front sway bar attached.
- car is VERY capable of throttle steer is any long corner whether is it increasing or decreasing radius.
- azenis, RA1s, and hoosiers (all 205/50x15)have all been run with this setup successfully.

Hope this helps.

**Oh yea - come to the ITR expo so we can work on this problem together

 

I appreciate your comments. I am a bit surprised you run 'more air pressure in back'. With my setup at least, I found little/no rear end 'loosening' with rear pressure anywhere between 33 and 60 psi, that's why I went the other way - down to 29. Maybe part of this difference is R-comps vs. street tires ?I'd actually like to be able to increase the rear pressure to mid-30's by increasing rear spring/bar stiffness further.

Can you say for certain that increasing rear spring and/or bar would reduce push on the gas ?

Are you saying it's possible to have oversteer while on the gas ?

 

Increasing rear spring isnt going to make your mid-corner on the gas push any worse - because you're on the bumpstops - it might even make it worse. You gotta get the front end off the bumpstops, if its more spring, more bar, more shock travel, something.