Sterling

Here's the deal:
I'm short on funds for my cars, and I simply have no choice but to work with what I got. Any special parts (hub adapters, spring blocks...) I have to make on my lathe and milling machine.
So I did. Had some aluminum slots (my favorite) for the rear. 8 inch wide by 14s. The tires are Goodyear GT radials 265 50s.
The front matching slots (from a different set) are 13s, same as stock, sporting 205 60 rubber.
The rear wheels bolt pattern is 115 x 4 (I have a GS) and so I had to make camed inserts to make the bolt holes line up.
But they rubbed with only 1/2 inch clearance to the fender lip. They stick out pretty awful, but I can live with it for now.
To remedy this problem, I made aluminum spacers about two inches tall. They fit into the spring seat (upper perch) and then have a perfect recess for the spring to seat into the bottom. They work fabulously.

So my question, as I've heard so many conflicting opinions, is how is my car going to handel with 265 50 14s in the rear, 205 60 13s in the front, jacked up 2 inches in the rear, with RB springs (which had originally lowered the car about an inch)?

I left the sway bar unhooked. Should I leave it in, or yank it with this type of set-up?

I drove it tonight, but only to saftey test the riser blocks. It was too dark to put the wheels on. There seemed to be a bit more roll. I expect that will be less so when I put the wide wheels on tomorrow.

I'm really interested as to what I should do regarding the sway bar.

I've been told that this was a crappy combination before, but then read several people raving about how well their cars handeled with the wide wheels.
If it really does suck, it can all be "undone" easily enough.

REVHED

265's?

Anyway, I'm not really sure how the massive rubber will effect your handling, but, I do know that jacking the rear up so much will cause roll-centre conflict as well as increase the body-roll dramatically. Ideally, the rear end should sit 10mm lower than the front as this brings the front and rear roll centres to approximately the same height. This really improves the handling.

diabolical1

iTrader: (3)

wide wheels help your cornering grip (to a point), but not your handling, per se. if i'm understanding your description of what you've done, then it sounds like the car is pretty unbalanced. my bet is the car is going understeer severely, and then SNAP oversteer! and though you may be able to corner a little bit faster, when you lose the rear, it's going to be a handful to catch (assuming you can catch it at all) ...

peejay

EEsh. The back of the car is raised but the rear axle is "lowered" compared to stock?

That's like moving in the wrong direction! You're in effect simply raising the roll center, or worse raising the CG and then raising the roll center even higher, since the roll center is the center pivot on the middle link of the Watts linkage abd therefore moves with the rear axle.

Raising the roll center like that makes it even closer to the center of gravity. This REDUCES body roll, because the chassis has less leverage over the suspension. (When you lower the roll center with a Panhard rod, you have to put springs twice as stiff in the back just to keep both front tires on the ground! ) This is a very bad thing when the suspension moves, because suspension motion makes the roll stiffness change significantly. Ask anyone who's ever driven a '60-64 Corvair around a corner with a rise. High roll centers are SPOOKY.

This isn't going in to the fact that the 4-link binds easier the more the car is lowered. Which it will, and the effects are similar - you end up using the rearview mirror to see what you're about to hit.

I've noticed that my car handled better when the rear suspension was jacked up. Lowering is a step in the wrong direction, lowering and tall tires is doubly so.

Sterling

I had such deja vu (vous?) about this thread, so I searched, and found an old thread where I asked the same thing.
(everybody thought I was nuts in that one, too!)

So I popped the wheels on this morning, and went for a short drive.
First off, the roll is immense around corners, and I can feel the car trying to push the front. (I've only really driven three other cars besides my Rx-7, so I never experienced "push" before. It is kinda freaky!)
But really disturbing is just trying to drive in a straight line! The cars steering is dictated by the road crown (or dips & bumps), and the 1.25 inch play in my steering wheel makes its presence known.
It also seems lathargic as if the engine has to work harder to turn those big wheels. (Maybe.) The diameter is actually slightly smaller than what was on there, and I have an SE diff in it. The "lathargy" I describe could be just something percieved as such - I dunno. I need more time to play.

Of course, the steering is nowhere as nimble as it was, but I expected that from having had 205s all the way around on my other 1st.

Variables yet to test...The rear sway bar...Should I hook it up?; and perfect pressure in the tires might make a bit of difference. I'm also very interested to see what tightening the steering slop will do, as even with all that play, with skinny tires, it steered very smoothly.

There is the other factor of simply getting used to the car. I've maybe driven my wifes Z3 for a total of 12 hours all together, and I just can't get used to it. Wide wheels, power steering, ABS that have ZERO "grey area" (The brakes are either ON or OFF!), **** like that.

What I plan to do is get some 225 50 14s for the rear, and remove the riser blocks, or put different springs in.

I'm pleased with my wheel adapters, and the riser blocks I made. Unfortunately, the lift blocks make alot of noise...Well I don't know if it's them, or the sway bar that is'nt hooked up, but still bolted on. The blocks are in safely, and are'nt gonna come out by themselves.

BTW-
I also forgot to mention that I have Koni adjustables all the way around. Can I better adjust these to help compensate for the rear roll?

peejay

Woops, my bad. I didn't notice that you had spacers in there.

Yep, once again suspension theory is vindicated... move the CG up while keeping the roll center and springrates constant, and you get less roll stiffness in the rear and more understeer.

Bolt that swaybar back on! In fact go junkyard hunting for a '79-80 bar, they're 18mm and twice as stiff as the wimpy 15mm bar found on '81-85. That way you have a simple way of tuning (no bar, small bar, big bar) and since you have a nicer CG-roll center distance, you can DO tuning with that, instead of normally when the car gets lowered and the rear bar has to be removed just to get the rear suspension moving.

If you use the shocks to tune for anything, use it for transient response. (IE use the shocks to adjust the way the car reacts when you first turn in) Trying to compensate for incorrect spring rates or stabilizer bar rates will just lead to frustration.

Sterling

So stiffen the shocks up, and reattach the sway bar?

peejay

Leave the shocks alone until you put the bar back on. One step at a time. Scientific method, donchaknow.

You might find that even with the SA rear bar the car still plows like a pig. Then you either have to increase the rear spring rates (really this should be the first step, but economics usually dictate what gets done first) or soften the front.

About that softening the front. As the suspension sagged on White Trash, the car pushed more and more. It went from an oversteering bastard to a farm implement (plow, plow, plow). I kept that mongo rear bar on there. Looking back, the reason it understeered was because the front suspension was running out of travel. Picture what happens when front spring rate goes near infinity - roll stiffness also goes near infinity on that end, resulting in bigly understeer. Some more ride height would have helped.

Which reminds me, anyone know where one could find new stock springs? I already have a solution for rear springs (requires some modification, but '91-95 Escort rears are the right height and rate) but the front springs pose a problem. Probably be cheaper to convert to coilover and get some standard $29 springs of the correct rate... Oh no, a suspension that is cheap to change rates and corner weights, more ways to tune the car wrong

SilverRocket

Seems to me that as soon as go and do what you're doing, you screw up the beautiful neutral handling balance that gives the car its character and excitement. Personally I wouldn't consider running such a different set of rubber front to rear, not on a lithe little sportscar like that.

I did read that funds were the issue... if possible, what I would do is stick with the 205's, but in something sticky like the new Yoko ES110's in 205/60/14. Or DOT-R's if you really want to go nuts (more $ though).

Personally I would not mess with any of this spacer stuff.

Sorry to be pessimistic, it just seems like such a counter-productive setup. I do hope that you figure it out

peejay

After roughly 20 years of suspension sag, bushing wear, and shock deterioration, the car is rather different from where it was when it was stock. Even a little ride height change will dramatically alter how the car handles. Unfortunately it makes it even squirrelier.

SilverRocket

That's a good point. In fact, I'd say that many people would be thrilled with the result of simply restoring their suspensions with brand new factory shocks, springs, bushings and some decent tires.

Sterling

I did it cause I wanted to play. The adapters are not spacers - IE, they do not fit between the wheel and hub (therefore adding space). I made them because no matter what rubber ultimatelt ends up on the rims, I will be sporting those rims on my car! The hunt fopr them was two years long to finally get what I wanted!!!

The hellacious BF Goodrich Radial TAs were on them when they were sent by the guy on Ebay. (Previously, I thing I said they were Goodyears.)
Anyway, it was all about #1, working with what I had laying around,
#2, Using my snazzy new lathe to make the adapters and spring spacers (afterall, it's the machines I bought that is the reason I have no money for the correct tires.);
And #3, I was trying to achieve a look...Something I can't quite explain...Maybe the Mopar equivilant of "Rice"?
The Hybrid Muscle Jap car?
Anyway, I do like it, though the rear tires are still way too big.

Regarding the suspension being "nearly twenty years old", and tired; Though the bushings are still old, I do have the Konis and RB springs on there. The car did handle great! Now it's a pig, but to no suprise.

I will compromise some handeling ability to get the look I want, but only to a point...a small point!
So I'll keep on keepin on with changes untill I'm happy with the middle ground.

It's raining here in the NE for a few days. Unfortunately, it'll have to wait for the weekend when it's dry.
Car does'nt hydroplane nearly as bad as I expected it would!

peejay

Don't takr the ragging on the tire sizes seriously... I often wonder how the '85 would look wth 295/50-15's on the back (would look darn near Pro-Street) and something proportionate on the front, like say 205/60-15.

Obviously, understeer would be a problem

And a neat idea for the rear suspension... Drill out the shock tower hole, run a rod from the axle's shock mount up into the hatch area, attach that to a bellcrank, put coilovers on the other side of the bellcrank. Neat part is, 90% of the parts can be sourced from roundy-round suppliers (pick up an issue of Circle Track and peruse the ads) and circle track parts tend to be cheap, strong, and heavily adjustable. There you go, rear suspension easily adjustable for corner weighting, spring rates, shock rates, and if you make an assortment of bellcranks you can even tune the linkage to have a progressive or digressive rate.

Nothing makes me drool more than infinite tunability

What's more, if you care about that sort of thing, you can get anodized or polished chrome pieces after you pick up an issue of Street Rodder. (Another wonderful magazine full of fab-it-yourself articles and TONS of helpful ads)

Now... I have a really great idea brewing... a ahead-of-axle Mumford Link. Even better than a Watts link, it allows you to arbitratily place the roll center anywhere you want, even below ground level if you so desire.

*ding*

Well time to go and take my medication...