datsunlover Posted August 19, 2004 Share Posted August 19, 2004 Well, I have a weird problem here.. It wants to go all over the place! I just got my car on the road a month ago, and in Ontario, you have to pass a certification.. with that said, you have to assume my front end (steering, suspension) cant be all that bad. I noticed the car doing this stightly for the past few weeks, but it seams to be worse now that I have changed the rear tires.. I was running 195/60/14 all around (I know, too low and small.. but it was all I had to pass the safety check!) and since I picked up that 280zx parts car, I got two good 195/70/14 tires which I put on the rear. While this helped me with the gear ratios/cruising RPM, it seams to have had a negative effect on handling at anything over 70mph.. It is tight in the front end.. but sort of 'loose' at the same time (if you know what I mean???) It's like towing something heavy with a little truck and the front end gets really light.. I can feel the 'whale tail' actually doing it's job out back, and I figured with the huge sway bar and air dam up front, it would be stable.. but it's actually quite scarry! I literally have to hang on with both hands and be reeeeeal carefull to stay in my lane! All I can think of is maybe my alignment is WAY out.. of the rear tail is doing it's job TOO well and causing the front to lift up.. Any suggestions? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 19, 2004 Share Posted August 19, 2004 One of the big no-no's in Porsche-land is to put on a whale tail and no front air dam. Don't know if you have a front air dam or not, but that would be something to consider. Aside from that unusual whale tail thing, you ought to start with the basics. The tie rods and ball joints are usually worn, wheel bearings can be loose, steering racks can develop play. Alignment will affect the way it drives too. If you have a lot of neg camber that will cause a lot of dartiness, so if you've lowered the car some that might be a factor. Front toe setting will also affect this. You'll want a little toe in in the front to counteract the darty feeling, although a little toe out would help it turn in a bit better. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted August 19, 2004 Author Share Posted August 19, 2004 Well, it's got an air dam.. Im thinking of cutting a hole in it though (about 3" down and as wide as the grill area) to let some air in OVER it.. And the car isnt lowered (properly anyway.. read-> worn out stock suspension! ) As for the front end, I have one ball joint that is a little worn, but not a lot.. tie-rods and rack are tight.. Im gona get the alignment checked out for starters.. it's just weird that I notice it SO much after I put on the 195/70 tires on the rear.. Maybe the forward tilt has thrown off the front sespension/stearing geometry? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 20, 2004 Share Posted August 20, 2004 Bushings are most likely bad. However... it may also depend on the road you're driving on, the texture or what have you. There is this one stretch freeway near me (the 134 freeway thru burbank/glendale area for any locals) where I ALWAYS get the darting that you are talking about, in every car I've driven thru there, the car will yank left or right unexpectedly, and bad enough to put a real scare into you. The faster I"m going, the worse it happens. It is more pronounced in my Z, but not by much, and I attribute this as much to the lack of power steering, as to the worn bushings. There are a few other places where this will occur, but otherwise, even with my totally shot bushings, I really don't get any darting anywhere other than those spots... and trust me my bushings are SHOT! Quote Link to comment Share on other sites More sharing options...
Guest 305240 Posted August 20, 2004 Share Posted August 20, 2004 I got to agree with the above posts. My friend had the same problem, and he changed the rack rubber mounts to the poly ones...problem cured. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 20, 2004 Share Posted August 20, 2004 Wheel alignments are a good thing. (I just had one done today!) Actually the impressive part was that I managed to dial in my rear suspension to within 0.2* camber, and 0.05* toe with just eyeball and a tape measure. We put it on the rack and that blew me away. So with that in mind you can get pretty close with eyeball and a tape, check your alignment that way, you'll know if it's way off. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted August 20, 2004 Author Share Posted August 20, 2004 Well Im planing on doing ALL the rubber bushings this winter, as well as full suspension all around.. cause evrything is fubar in that department.. I really shouldn't be driving that fast anyway.. .. it's just weird that this problem would be SO pronounced after changing the rear tires, where as before it was only a slight issue.. And it happens wherever I drive, no matter what condition the road surface is.. I took her up to 110 mph tonite on a flat 'back road' and man it was scarry! (though it might get better over 100 or something ..nope) Like I said, I'll get the alignment checked out.. and probly try running 4 tires the same size.. I'm thinking its mostly alignment related now.. I did some HARD cornering tonite at 70+ mph and the car reacted amazinly through the twisties at that speed.. but as soon as the straightaway comes up.. hang on for dear life! I'll let you guys know what happens.. Quote Link to comment Share on other sites More sharing options...
Guest 305240 Posted August 20, 2004 Share Posted August 20, 2004 I believe by putting the larger tires on the rear, it magnafied the problem more because it put more weight towards the front. Try putting the same size back on the rears and see if it makes a difference. If it does, then you know for sure. Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted August 20, 2004 Share Posted August 20, 2004 Non stock wheel and tire combinations which move the tire contact patch outward (towards the fenders) can cause dartiness, as can excess toe out. I'll put in with the other guys here though... suspension bits moving about due to wear are the most likely culprits. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted August 20, 2004 Share Posted August 20, 2004 Well Im planing on doing ALL the rubber bushings this winter, as well as full suspension all around.. cause evrything is fubar in that department.. I really shouldn't be driving that fast anyway.. .. it's just weird that this problem would be SO pronounced after changing the rear tires, where as before it was only a slight issue.. And it happens wherever I drive, no matter what condition the road surface is.. I took her up to 110 mph tonite on a flat 'back road' and man it was scarry! (though it might get better over 100 or something ..nope) Like I said, I'll get the alignment checked out.. and probly try running 4 tires the same size.. I'm thinking its mostly alignment related now.. I did some HARD cornering tonite at 70+ mph and the car reacted amazinly through the twisties at that speed.. but as soon as the straightaway comes up.. hang on for dear life! I'll let you guys know what happens.. Larger rear tires will also make your speedometer read lower than actual. Maybe you were just going faster than you have before? I know the front end lift due to the Z's poor aerodynamics degrades really quickly past some speed. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted August 20, 2004 Author Share Posted August 20, 2004 Guess I'll clarify some things here.. Im running stock 14" Datsun 6 spokes (14X6.. right?) so I assume wheel offset can't be an issue.. and the rear tires were larger than what I HAD, but actually they're closer to the proper size required/instaled originally from the factory. I'll check the alignment by eye tomorrow I guess.. See, I have a friend who owes me some $$$, and if he gets it to me this weekend, I'll go and get 4 matching tires put on first.. If it improves it to the point where I can tolerate it again, I'll just run the rest of the summer 'as is'.. like I said, evrything is gettng replaced this winter anyway.. I just hate to get 4 14" tires when I may have a set of 15" swastikas WITH rubber comming soon.. I just don't know when that's gona work out.. Quote Link to comment Share on other sites More sharing options...
Clifton Posted August 22, 2004 Share Posted August 22, 2004 Sounds toed out. Setting toe is easy with 2 flat boards or other flat surfaces. Quote Link to comment Share on other sites More sharing options...
scorreia Posted August 28, 2004 Share Posted August 28, 2004 For a great DIY lignment guide: http://corner-carvers.com/forums/showthread.php?s=&threadid=13211&highlight=laser+alignment And if the car is getting squirrely at speed, my guess is that with the larger rear tires camber is slightly increased in the front. I am not familiar with toe changes through the range of suspension travel on the Z's, but wouldn't toe-in cause more of this problem than toe-out? You want toe-out for high speed stability, and toe-in for faster turn in response. A squirrely car would be 'turning in' when following road imperfections and such. Quote Link to comment Share on other sites More sharing options...
Clifton Posted August 28, 2004 Share Posted August 28, 2004 but wouldn't toe-in cause more of this problem than toe-out? You want toe-out for high speed stability' date=' and toe-in for faster turn in response. A squirrely car would be 'turning in' when following road imperfections and such.[/quote'] Close but you got it backword. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 29, 2004 Share Posted August 29, 2004 Alignment, alignment, alignment, alignment, alignment. Did I say alignment? Zs are very sensitive to front camber and toe at speeds over 90mph. Why? Because of the bumpsteer in the front suspension you get toe in when the suspension compresses and toe out when the suspension extends. At higher speeds, when the front ssupension lifts you get more toe in which adds to the instability. Or is ir toe out under compression and toe in under extension? I'll have to check again... Quote Link to comment Share on other sites More sharing options...
scorreia Posted August 29, 2004 Share Posted August 29, 2004 but wouldn't toe-in cause more of this problem than toe-out? You want toe-out for high speed stability' date=' and toe-in for faster turn in response. A squirrely car would be 'turning in' when following road imperfections and such.[/quote'] Close but you got it backword. Indeed I did, thanks. So to quote Mr. Wonka "strike that, reverse it." Quote Link to comment Share on other sites More sharing options...
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