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Location:
Ipswich
Registered:
July 2002
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handling problems since got fat wheel?
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Wed, 17 July 2002 09:15
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I got my ra40 lowered 2" a while ago and handling was excellent after. Was still running stock wheels. But after i got new 15" rims with 205/60 front and 245/60 rear my handling has suffered. Only noticable on the highway when speed is up around 100. The steering feels wierd and it bites a bit suddenly when cornering. Had an alignment done and no different. What could cause this problem and how do i solve it!
Thx
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 11:29
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got such big tyres cause i got them as a deal with the rims. A lower profile on the back would have been much nicer but beggars can't be choosers. Anyway it is stock for about 1 more weeks then the 1g-gte conversion will start. I don't think having bigger wheels on the back is affecting it tho. With the stock wheels i had 40 profiles on the front and 75 profile on the back. So it is essentially the same now just with wider wheels.
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Location:
c'town, NSW
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 12:31
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do u mean that the car is tramlining?
that will happen with wider wheels
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 13:23
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what is tramlining? heard the term just never found the definition. My handling problem is noticed only once i get over 80ks and more noticable on rougher roads. It is like the steering is ultra sensitive in the first 10% of movement from the centre position. This naturally causes it to kinda bite when i hit a bump that pulls the car.(like those tracks that trucks produce on highways).
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 13:36
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If you study into the physics of how a car handles you may discover that having wider tyres doesn't mean the car will handle better, first of all the suspension should be set up for a specific size of tyre, and tyre size and compund should be taken into account with the weight of the car and power the engine puts out, sure it will look nice with fat tyres but look at something that favors handling and performance more then looks, Motorsport. Now Peter Brocks monaro he entered in Targa Tasmania which has a weight of 1640kg and has a worked Gen III 5.7L V8 in it generating well over 300KW of power only has 245's on the rear now how the hell could your car need those? Personaly i would rather have a car that can handle better and corner faster then one that only looks good.
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 13:41
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I didn't say that i needed those tyres. I just said that i got them with the rims as a deal. What i did ask is what is causing this problem and how do i solve it. I realise it has something to do with the wider tyres but i wish to solve the problem with the current tyres. And i agree, i would rather have a better handling car than one that looks good too. But if i can get it to handle better while looking good then all the better for me.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 13:53
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Then try going to Pedders or Whiteline suspension and ask them as they are the real professionals and may come up with a way to correct the suspension so the car can cope with the wider tyres
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Location:
perth w.a
Registered:
June 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 14:00
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g'day helman
what you are talking about is related to bump steer - i think?
i had similar troubles with my torana years ago. the result was the wider rims moved the centre point of the tyre contact patch further from the original pivot point.
this was compounded by the 3.5" lowering job - i'll live and learn.
the end result is - hit a bump at 100kph in a corner and hang on as you change lanes - fast.
to fix it, raise it back closer to std height and find some rims with the correct offset, or change your stub axles to suit.
tyre width requirements are directly related to vehicle weight - not power. weight creates traction not width of tyre,
just my 2c worth,
hope it doesnt confuse things further,
dave
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Location:
Hobart, Tas
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 14:14
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245s on the back and 205s will promote understeer. I think this may be what is meant by the term 'tramlining', but not sure. The front tyres will loose grip first while the back ones are still sticking.... not something I would want to happen. When I got tyres I made sure they were the same all round.
I always wonder about those 'ranas and commodores with huge wheels out back. Can't be fun on the turns (but then again, neither are they....     
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 14:26
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There comes a point where you need the wider tyres on the back...you can have narrower tyres at the front because you only need SO much to do the turning, you just need the bigger ones to try to tame power oversteer situations.
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 14:26
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Oh, and they do it to give their cars more grip in a straight line!
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Location:
Hobart, Tas
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 14:30
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Who wants a lead arrow? Normally, even with wider wheels at the back, most people have a difference of 20 or 30 front/back, not 40.
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Location:
Mentone
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 14:41
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The problem is bump steer as said before. This occurs when the centre of the wheel/tyre has been changed and usually moved outwards. From the factory most cars are designed with the centre of the wheel to be at the same spot as where the kink pin inclination angle meets the ground. McPherson strust do not have king pins. Only old junkers have them but is still has the geometry built into the strut. You cannot change the kingpin angle easily so the best way to fix it is change your rims. Probably not an option or live with it. Sometines increasing the castor can help the problem but that is usually because more castor means more effort is required to move the steering.
I dont know if i make any sense but i hope i helped explain
Brad
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Location:
Tasmania
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 15:32
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Any bump steer your car has you sort of have to live with. Changing it requires cutting things, and is against the law. Check to see how many fingers you can fit between the front tyre and the strut tube. If it is 2 or more, the rims have too much offset and you have too much scrub radius. To fix that, you can only change wheels. I'm not sure how much the scrub radius will effect things though. Now that you have tried, its time to forget the factory wheel alignment specs. Get another alignment, this time with more caster. Even if this is not your problem, more caster will hide the problem and keep you going strait ahead in a more stable fashion. And make sure you have a tad of toe in. Also make sure your control arm and sway bar bushes are not worn out.
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I supported Toymods
Location:
melbourne.victoria.austra...
Registered:
June 2002
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Re: handling problems since got fat wheel?
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Wed, 17 July 2002 19:59
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my missus vn has suffered this same problem - we put 16" vt ss wheels on her calais which from memory are 245/50/16's - they replaced the std calais rims - 225/60/15's - and the car is a dog to drive - it pulls all over the place, even with the vn with its dodgy suspension setup - it has the kmac adjustable tower bearings also.
any undulation in the road pushes/pulls the car all over the place - to compensate we run a more tyre pressure up front which helps only a little.
that and the fact yokohama a539's are pretty sticky doesn't help well it sort of does if you know what i mean.
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Thu, 18 July 2002 07:16
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ok thx for the great info. I talked to my mechanic and he confirmed that this is the problem. He also sugested that a strut top camber adustment kit could fix it if i run some more negative camber. Does this sound right? This was just his sugestion as he is not too sure.
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Location:
Cabramatta, NSW
Registered:
May 2002
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 Re: handling problems since got fat wheel?
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Sat, 20 July 2002 14:33
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Tramlining is when the wheels want to follow the contours of the roads (like it's connected on the road like a tram). Different tyres are more/less succeptible to tramlining, so you could try different tyres...
Dunno about the bump steer. Have you checked how much clearance to the strut you have? How wide are these wheels? And how wide are the stockers?
I see nothing wrong with running 205s front and 245s back (says the guy with 215 front and 235 back). Not really a lead tipped arrow, you still have grip up front, and you need all the grip you can get out the back. 
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Sat, 20 July 2002 15:38
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Not much clearance to the struts at all. Bushes are a bit worn so if i lean it too hard into a corner it rubs slightly. The wheels up front are 15/205/60's. Stock was 14/185/70 i think. I will probably need the 245s at the back soon anyway as the 1G-GTE conversion starts this thursday.
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Location:
Cabramatta, NSW
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Sun, 21 July 2002 01:01
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Sorry, I meant the rims.
Do you know what offset the two sets of rims are?
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Sun, 21 July 2002 01:03
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No i don't. The stock ones are just standard steel rims. I have looked for the specs on my mags but can't find them. They are a pcw rim that is about 2-3 years old. they are 15x7 universal stud 5 spoke rims. That's about all the info i can tell ya.
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Location:
Hobart, Tas
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Sun, 21 July 2002 08:09
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| Nark wrote on Sun, 21 July 2002 12:33 AM |
I see nothing wrong with running 205s front and 245s back (says the guy with 215 front and 235 back). Not really a lead tipped arrow, you still have grip up front, and you need all the grip you can get out the back.
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Maybee, but I'm not so keen on the idea. Through a corner, the front will loose grip first a lot sooner than the back and you could understeer off it. Not nice.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Sun, 21 July 2002 09:22
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i reckon the two worst things are understeer and brake fade
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Sun, 21 July 2002 11:20
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It doesn't matter how much wider the back tyres are. The car will lose grip and understeer at the same point regardless of weather the back and front are the same size or not. With larger rear tyres tho u also reduce oversteer grip problems. Look at all the supercars. Porche, ferarri, etc. They have much greater tyres on the back than front. But this is beside the point. The greater width tyres on the back of my car are not the cause of the bump steer and this discussion has not helped me cure the bump steer. Any suggestions on how i can cure it? Will increasing camber help???
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Registered:
May 2002
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Re: handling problems since got fat wheel?
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Sun, 21 July 2002 13:30
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I always thought RA6* celicas understeered cause the engine layout puts so much weight infront of the front axle line?
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Sun, 21 July 2002 23:01
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| Helmann wrote on Sun, 21 July 2002 9:20 PM |
It doesn't matter how much wider the back tyres are. The car will lose grip and understeer at the same point regardless of weather the back and front are the same size or not. With larger rear tyres tho u also reduce oversteer grip problems. Look at all the supercars. Porche, ferarri, etc. They have much greater tyres on the back than front
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For every action there is an oppisit but equal reaction, there for if increasing the back tyre size reduces oversteer then it MUST increase understeer, of course increasing the back end grip will cause the car to understeer as this means the front end has to work much harder to try and get all that grip in the back to change direction, and as for supercars, porche, ferarri etc. they have a much better suspension set up then your car and the suspension was designed for those size tyres, your car wasn't it was designed for 185 or something around that.
and don't quote me on this but i don't think Camber will change a thing, the main use of camber is during cornering when the suspension is compressed it makes more tyre contact on the road, your having problems in trying to get the car to turn in the first place and the only ideas i can think of to try and get the front end to turn in better would be to maybe increase the toe in angle camber may help for the actual cornering but wont really play a part in getting the car to turn in the first place. try turning then ently apply a little bit of break preassure and see if the car then begins to turn easier as that will then be placing more load on the front wheels and there for reducing the back end grip.
but another thing you could try is playing around with tyre preassures try running higher preassure in the rear wheels see how that changes the cars handling then try running higher preassure in the front might find it will make a difference.
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 01:45
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Not entirely correct. If my car understeers at 80kph with 205F/205R on a given corner then it will still understeer at 80kph on the same corner with say 205F/245R. It is just that i will be able to get more grip from the rear. This is not my concern tho. I need to know how i can reduce the effects of bump steer/trameling without changing my wheels. Someone please give me an answer to THIS question. I don't care about under and over steer.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 02:05
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Then the answer is pretty bloody simple, contact an expert why don't you even try emailing Pedders suspension and tell them about your problem go into pedders or midas or some other suspension place and ask them as they are the guys who deal with suspension and car handling so they will be able to give you an answer as they have probably had many people with the same problem why just spend all your time asking us for our opinion when you can just drive down the road and ask an expert on the matter?
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 04:37
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but an expert that is selling something will sometimes not tell you the truth. I ask this question on here in the hope that there is an expert out there that is willing to help a fellow toyota driver and not try to sell me something. Besides i rang pedders and got 2 different answers. One said that there is nothing i could do and the other said that adustable strut top camber kits would fix it. No you see my dilema.
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Location:
Hobart, Tas
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 04:52
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| Helmann wrote on Mon, 22 July 2002 11:45 AM |
Not entirely correct. If my car understeers at 80kph with 205F/205R on a given corner then it will still understeer at 80kph on the same corner with say 205F/245R. It is just that i will be able to get more grip from the rear. This is not my concern tho. I need to know how i can reduce the effects of bump steer/trameling without changing my wheels. Someone please give me an answer to THIS question. I don't care about under and over steer.
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No, your car will just understeer MORE. When the front tyres approach the point where they loose some grip, the back wheels will not. The front slip angle will be greater than at the back and you will understeer. You can't really argue with physics. There is a good book on the subject written by a car engineer called 'handling and roadholding' I think - you should read it.
You SHOULD be concerned with understeer etc as it will have a big effect on what your car is like to drive. By all means put huge fat tyres on the back - I really don't think it will be as fun to drive anymore. May as well buy a fwd.
If you have a monster engine and you HAVE to have wider rear tyres, worry about it then.
BTW Porshes etc are designed like that from the factory to work with their suspension. Also, I read that the ra6x celica has a 52/48 weight distribution, which is pretty near optimum for a rear wheel drive.
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 05:10
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OK my car does not understeer any more than before. The handling is what i would call excellent. It doesn't understeer easily. I need to solve my BUMP STEER PROBLEM. Not a non-existing understeer problem. Someone who can help polease respond. IT IS A BUMP STEER PROBLEM. Am in the pocess of a 1g-gte conversion so i might need those bigger rear tyres (before anyone else says it, i probably wont need them that big). I need to cure my bump steer as with the extra power i will soon have i will encounter this problem more ( as i will undoubtedly spend more time driving over 100).
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Location:
Sydney, Australia
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 05:33
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Join the Whitelines egroup at http://www.egroups.com/list/whiteline/ and post the question there. I've found them always willing to answer questions, specially technical ones, and not just try and sell you stuff.
rgrds
sam
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Location:
Brisbane, QLD, Australia
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 06:19
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I was going to post last night, but the forums stopped responding so here goes:
If you go into negative camber, it will make it worse.
Really, the only solution is to stick with stock width. Plus raising the car back up to stock hight may help too.
I know you don't want to, so, I dunno, get used to it and learn how to handle the car now it's driving different. Be careful of cop attention too. It sounds like you can get done easy by the size of those. (They arn't legal at that size for what was originally on it, I'm pretty sure).
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Location:
Ipswich
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 08:09
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ok it is legal i have been told. Cops haven't bothered me yet either and they have pulled me over since i have had them. Rang whiteline susspension and they told me to ring fulcrum in mooroka. so i did. talked to a guy there called steve who seams like a suspension god. HE basically said that no matter what problem i have it will be curable. He also said not to bother changing wheels or suspension back as he will make it handle like it is on rails with no problems. Anyway i will take it to him to look at soon and hopefully that will be the end of my problems.
thanx for the help u guys have given
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Location:
Brisbane, QLD, Australia
Registered:
May 2002
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Re: handling problems since got fat wheel?
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Mon, 22 July 2002 08:57
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Cool, let us know what he does to fix it and how the job goes.
It's good to get to know the good suspension places.
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Registered:
July 2002
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Re: handling problems since got fat wheel?
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Thu, 15 August 2002 09:14
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could you provide us with contact numbers for the place you mentioned?? I'm driving a stock height ra40 with supra rims and i think THAT drives like a dog. I took it to pedders but they had fuck all idea, i think it drives worse now. anyways, I'd like to see if anyone can fix the tramrailing prob. mine also follows every little bump and track on the road and likes to turn hard right under brakeing.... 
but even if it drives like a dog i still can't wait to get back in it. been driving an 86 integra and a new futura and the fucken things are like driving a jumbo!!!
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Thu, 15 August 2002 09:39
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the problem you have is with wide wheels they like to train track{follow truck tracks and grooves in the road bigger brake dics{more weight} do this aswell. you can add caster to make it more stable. your toe setting will affect your turn-in aswell. if you have your settings type them up and ill tell if they can be improved on.
mick
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Registered:
July 2002
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Re: handling problems since got fat wheel?
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Thu, 15 August 2002 11:24
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18RC motor pumping 111kw????? that's over 160 hp!!!!
how the phuck?? and why the phuck??? imagine what you could have done with an RG for that sort of money!!!!
and i agree, the worst things you can have is brake fade and understeer.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Thu, 15 August 2002 11:33
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Well lets just say i paid $500 for this engine and i'm not sure if those power readings are still correct as its been a long time since it was all done but i'll get it on the dyno this monday and see what it says. and hey ok i wouldn't spend that kinda money on doing that work to the engine but at least having it means you have a engine that looks fully stock yet is bloody fast, i'm sure it will kick any other 18-RC N/A engine for sure.  but i reckon its lost a bit of power as it is getting old and had a hell of a thrash but it still has 180psi compression thats 10 over standard so it must still be in good nick and last a long time to come but again i'll see what the dyno printout says, should make a very good improvemnt on the dyno as it hasn't been tunned by anyone for over 3-4 years
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Registered:
July 2002
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Re: handling problems since got fat wheel?
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Thu, 15 August 2002 22:15
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ok, let us know because I personally don't believe the figure since a stock RC is only 90hp...
(not calling you a liar, just think you may have a dodgy reading or something)
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: handling problems since got fat wheel?
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Fri, 16 August 2002 11:02
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well i have good resources backed up by a few people and been given the name of the engine builder who did it so i can buy the specs off them if i want, but this was some time ago so i will just have to wait and see weather its still got the same power as when it was first done or how much its lost over time, if the readings i have there at the flywheel are correct i'm expecting around 70kw at the wheels but we will just have to wait and see ok mate, see if she still has what she used to have.
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