Jump to content

Did my alignment, and now the car does this...


heywier427

Recommended Posts

When going into the first portion of a corner (any corner, sweeping or tight), the car feels like it wants to keep pulling into the corner, and I need to correct my way out of it (turn the opposite way of the corner), this leads to a very small dancing/darting/effect. I can power myself straight, but as soon as im off throttle its back. This effect is made worse if the corner has a dip in it,and the steering angles change. It really wants to pull in then.

 

Car tracks straight. Steering box is good/tight (turn the steering wheel an hair, and the wheels turn with it). I have not been able to do any high speed (65mph +) driving with it, as the driveshaft needs attention (either balancing or pinon angles)so i dont know if at speed there is any "darty" ness.

 

Alignment specs are:

 

Camber -1.25

 

Toe in .24

 

The castor Im not sure about. I do not trust my "new to me" machine. It said I was +4.xx (stock calls for 1.00)

 

I know Im pulled pretty far forward, as I have the Vintage Historics with only 2 threads showing at the adjustment (almost fully maxed inward).

 

What I did do was measure my stock tc rods from the compressed bushing face to the center of the first tc rod/control arm mounting bolt. That was 13.5". I read anywhere from 7/8" to 2" pulled forward from the stock measurement was acceptable. Obviously the more you go, the heavier the steering. I made it measure 12.75" and there is very little room to go anymore.

 

Rear camber is -1.23 on drivers side. -1.82 on pass side. (why is it different)

 

Car is not slammed, but lowered.

 

Camber plates, adj. control arms, adj. t/c rods, 1" bump steer spacer, 280z steering knucles, all bushings balljoints new. Steering techniques front swaybar 1" w/poly bushings, same in the rear, but 5/8". There is no "worn" anything. The car is pretty much "new".

 

Tokico illuminas up front, Kyb Agx in rear. Front springs 200, rear springs 175. Coilovers.

 

Ride is really good. Happy I stuck with lighter springs. I dont think they are too light. Rotary engine up front, sat pretty far back in the bay.

 

What should I try? Im newish to 510's and this is my first time driving one, so I have no references.

 

Thanks,

 

Tom.

Link to comment
  • Replies 32
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

I have the stock specs ( my new bear machine had it listed!!), but its giving me wonky castor specs.

 

I cannot accurately measure my castor, but I know Im much far forward than stock, just by looking at the wheel to fender gap.

 

I agree that this seems/feels like a castor problem.

 

Can anyone take a measurement for me? I searched, but came up empty.

 

22509770377_f653afd0bb_c.jpg

 

So if you place your tape in the t/c bushing cup, and measure back to the center of the first bolt. This would only apply to modded or adjustable T/C rods

Link to comment

So I should have re-measured stuff instead of just holding one hand on my ass, and the other out for help.

 

Needs more caster.

 

I also found 2 other issues that "could" be contributing, but the decision was made to back off the caster adjustment because the wheels "looked" to far forward.

 

510T, care to share a pic? Side shot of the front tire, wheels straight ahead. Just want to see if yours looks as forward as mine did when the t/c adjusters were almost max'd.

 

I am just shy of a 1/4" longer than the stock t/c measurement. Needs more. Will max it out and go for a ride. Just raining here now :(

 

Other contributing factors could be:

 

1. The sway bar links up front were not tight. The bolt did not have long enough threads on it, the bolt bottomed out, and didn't pull the bushings down tight. WTF.

 

2. The sway bar hits the front of the oil pan when the lca moves upward. I will shorten the center of the sway bar links, and that will push the sway bar forward and will make sure I give it an inch of clearance on the pan. That, and get shorter bolts!

 

Thanks for the suggestions. Will keep you all in the loop.

Link to comment

Just throwing this in... When I got my 620 it did the same thing. Turning into a tight corner the vehicle seemed like it wanted to turn in even more by itself. Like if I were to let go of the wheel it would turn in even tighter. Facing forward if I went across the street both front tires were pointing directly at me. This is how toed in it was. 
 
 
Maybe the machine is out of whack. Try facing the car forward and see if the front tires are lined up with the rear ones. If you can see any toe.... it's out
 
 

When going into the first portion of a corner (any corner, sweeping or tight), the car feels like it wants to keep pulling into the corner, and I need to correct my way out of it (turn the opposite way of the corner), this leads to a very small dancing/darting/effect. I can power myself straight, but as soon as im off throttle its back. This effect is made worse if the corner has a dip in it,and the steering angles change. It really wants to pull in then.

 
 
This is the very definition of trailing throttle oversteer. IRS are notorious for this although all cars do it to some small extent. Let off the gas, the car weight shifts to the front, back is lighter and lifts, inside tire toes in and steers the car. Accelerate and balance is restored. Bumps and dips make it even worse and less predictable.

 

 

 

 
 
 

Link to comment

If the issue is magnified on bumps, it's likely from an increase in king pin inclination. I don't know what struts you have, but if you're using 280zx struts you need to add negative camber, because the spindle angle is greater than the 510's. Moving the top of the strut in with the camber plats to reduce the positive camber gain also increases the king pin inclination. This is like caster except from the front view. An increase in KPI acts opposite of caster, because it adds positive camber when turning. To correct this you need to add more caster so that at a moderate steer angle you still gain a bit of negative camber. The stock amount of caster angle in the 510 is low, but for my suspension I run over 6 degs of caster with 0 deg of KPI. If my car breaks loose coming out of a corner, all the driver needs to do is back off the throttle a bit, let go of the wheel and the car will correct itself instantly. At the same time though, it needs to be manhandled around a turn, but that's the trade off.

 

175lb. springs in the rear makes for a cozy ride, but it's a bit soft if you want it to handle well. I'm running 250 on all four corners, but no one would describe that car as being "comfortable".

 

Also. be careful getting measurements from other cars, because what works the their setup may not work for yours. As soon as you change the steering arm and add bump steer spacers, you alter the whole geometry.

Best of luck Tom

  • Like 1
Link to comment

Paradime, what kind of scrub radius are you getting with a 0 degree kpi?

 

Steep enough caster (though I doubt you're anywhere near that mark) makes a car want to keep a straight line until you turn far enough that it flops over and suddenly it wants to turn itself in tighter. Think of a motorcycle with steep forks. That is caster and it works the same way, though to a lesser extreme.

 

Toe is the seemingly obvious culprit.

  • Like 1
Link to comment

510T, care to share a pic? Side shot of the front tire, wheels straight ahead. Just want to see if yours looks as forward as mine did when the t/c adjusters were almost max'd.

 

In addition to adjustable T/C rods my car has caster-added camber plates from DPR, so not all the extra caster comes from the bottom.

 

P1070435_zps6gi3gdpu.jpg

  • Like 1
Link to comment

Just to answer questions while its raining...

 

Strut housing are stock 510, just cut and lowered to accommodate the smaller shock. 1" bumpsteer spacers.

 

Tires are stretched but not by a long shot. I have driven/installed many a stretched setups, and this does not feel like tire looseness/wiggle at all. 15x7 on 195/45/15.

 

Toe is on par, but I will add more and see what it does.

 

Springs can and will go heavier if the need arises. I have 225 and 250's in stock.

 

I will set the camber plates to max caster, and then adjust the t/c castor in increments. Gonna start with full max'd adjustment, and see how it feels driving and parking lot maneuvering. Not really concerned about how hard the wheel is to turn while parking. Im strong!

 

Says its gonna rain for 2 more days!! booo...

 

510t, thanks for the pic. Mine looks about where yours is now, but my camber plates are centered at no caster.

 

Looking at pics on the web, it seems that the wheels are pulled pretty far forward on many modified cars/suspensions. So I probably had it set good when they looked "too far forward".

 

Thanks for all the responses.

 

It sounds like with the IRS system this is just how it is. It can be helped but you have to learn how to drive with it.

 

My fascination for these cars started with looks, but is hugely influenced by the masses loving the handling characteristics of them.

 

It sounds like this is never going to handle as good as the mk1 vw's we build. :(

 

My daily big turbo, automatic, a/c, 1.6 diesel, on 175/65/15's can out handle alot of much better wheel setups (i have full susp. set up really well too) But our track car on 205/40/16 just sticks to the road.

 

We'll see, Im in no way giving up, and have a track 510 waiting to be built!

 

https://www.facebook.com/media/set/?set=a.228753623838657.57881.228751380505548&type=3

 

Will make the adjustments tonight and wait for the rain to cease!

Link to comment

I don't know Mike, 12 degrees for a 280ZX, and 10 degrees for the 510. That's what SteN, 510Rob, & Troy told me.

 

See if this helps:

 

http://www.the510realm.com/viewtopic.php?t=1219

 

Paradime, what kind of scrub radius are you getting with a 0 degree kpi?
 

 

Obviously it's only zero when pointing straight ahead, and sitting at static ride hight. I haven't actually measured the scrub radius on my setup 510T, but I do know it has a slight negative scrub. I should point out though, there is almost nothing stock about my front suspension. The entire chassis was built by Troy Ermish as an B sedan race car.

 

Spherical ball joints all round

Shortened 280zx struts

Raised control arm pivot points on the cross member (like the 68 X-member)

Modified adjustable steering arms that are matched to the raised pivot points. 
Raised T/C rods,

RCAs (roll center adjusters) between the struts and the ball joints.

Lower steering box knuckle 

Willwood brakes.

 

Just like caster, steering axis inclination makes the wheels want to point straight ahead, but if you don't have the ability to adjust SAI than adding camber is the next best thing.

Link to comment

When going into the first portion of a corner (any corner, sweeping or tight), the car feels like it wants to keep pulling into the corner, and I need to correct my way out of it (turn the opposite way of the corner), this leads to a very small dancing/darting/effect. I can power myself straight, but as soon as im off throttle its back. This effect is made worse if the corner has a dip in it,and the steering angles change. It really wants to pull in then.

 

Car tracks straight. Steering box is good/tight (turn the steering wheel an hair, and the wheels turn with it). I have not been able to do any high speed (65mph +) driving with it, as the driveshaft needs attention (either balancing or pinon angles)so i dont know if at speed there is any "darty" ness.

 

Alignment specs are:

 

Camber -1.25

 

Toe in .24

 

The castor Im not sure about. I do not trust my "new to me" machine. It said I was +4.xx (stock calls for 1.00)

 

Rear camber is -1.23 on drivers side. -1.82 on pass side. (why is it different)

 

 

 

I wouldn't worry about this. It's rear camber is not adjustable without modifying the cross-member. There are many reasons why if could be different. It's an old car, things could have happened. That little bit won't hurt.

 

Positive caster is what returns wheel to center coming out of turns. I'd think +4 is okay. Spec is at least half of that though. I'd look for issues elsewhere. It doesn't appear to be with the settings you've posted at least.

 

There are more advanced angles that might help shine some light on this issue. 

Link to comment

It sounds like with the IRS system this is just how it is. It can be helped but you have to learn how to drive with it.

 

My fascination for these cars started with looks, but is hugely influenced by the masses loving the handling characteristics of them.

 

It sounds like this is never going to handle as good as the mk1 vw's we build. :(

 

It's the angle of the "semi" trailing arm that tends to F things up. Like Mike mentioned:

 

"This is the very definition of trailing throttle oversteer. IRS are notorious for this although all cars do it to some small extent. Let off the gas, the car weight shifts to the front, back is lighter and lifts, inside tire toes in and steers the car. Accelerate and balance is restored. Bumps and dips make it even worse and less predictable."

 

With a semi trailing arm IRS the outward angle in the trailing arm causes the camber and toe to shift as it travels. When the body rolls, the outside tire stays flat while pointing outward, and the inside points in literally steering the car around the corner from the rear. With your car being lowered, the fat sway bars you have, and 250lb. springs, weight transfer front and back is far less an issue than with a stock 510 suspension. That being said, you can still use trail through to your advantage. Under power, your lowered rear suspension tends to squat, and when it does, the toe shifts out. Unlike other cars, the semi-trailing arm IRS can start accelerating out of corners much earlier and harder than other more modern cars. As long as you're hooking up, the car literally feels like it's jumping off corners. Done right, this is a huge advantage on a twisty road, or track. The classic B sedan track records at Sonoma Race Way, Laguna Seca, and Willow Springs are held by Troy Ermish in his L18 510. 

Link to comment

I don't know Mike, 12 degrees for a 280ZX, and 10 degrees for the 510. That's what SteN, 510Rob, & Troy told me.

 

See if this helps:

 

http://www.the510realm.com/viewtopic.php?t=1219

 

 

 

 

 

 

Haven't seen that post. I used Byron's from '07...  http://the510realm.com/viewtopic.php?f=2&t=7213&p=79983 He's a machinist by trade.

 

 

 

Link to comment

Yep I agree with Mike and the guys.  Sounds like it's coming from the rear suspension.  Getting a set of Byron's toe/camber brackets for the rear and solid mounting the crossmember will improve the handling dramatically.  

 

One thing we've found through modeling the full front suspension on the computer is that the combination of the early crossmember (higher LCA pivots) and the Wagon steering arm and idler arm will results in very very bad bump steer.  Over the years these parts can all end up on the same car resulting in a car that handles like a pile of shit.  The early crossmember is not always an "upgrade"  

Link to comment

True that, raised control arm pivot points CAN help in lowering the car, but it's not in itself an upgrade. Everything has to be adjusted accordingly to take advantage.

 

heywier, you mentioned you have 280z "steering knuckles", Is it possible the arm is longer, or shorter than the 510? And if so would that contribute to steer diving? 

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.