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How To - Tips => Steering / Suspension => Topic started by: 99Feeablo on November 28, 2019, 05:05:08 AM
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Question, for anyone with experience using wheel spacers on a Fiero frame Diablo Roadster. I bought some really nice wheels from Ron Dolling in Canada. Front wheels have correct (true) offset but of course my Fiero A-arms are too short requiring wheel spacers. I understand how to measure to find out how much spacer I need but wondered what everyone else was using as far as spacer depth. Seems like I’d need about 3” or so. Is 2” a common spacer used with Fiero and correct off set wheel? Thanks in advance, Steve Z.
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If I'm not mistaken, Ron Dolling also sells the proper spacers.
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No , he told me to get some off EBay, lol
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99 see if you cal locate the widetrack suspension. The spacers negatively affect the handling of the car
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99...
The proper location for the front tire axis to rotate is at a point on the centerline of the tire. The caster will point that location in front of the tire but still on the centerline. If spacers are used, the centerline of the tire moves out but the rotation axis stays because that is built-in to the suspension linkage. Moving the tire centerline out will cause the tire to travel in an arc when you turn. That also causes the front and rear of the tire to move farther front or rear when turning. The clearances of the tire to the body is very tight with these Lambo and you could have issues with the tires rubbing fenders and/or inner wheel wells.
Other things this does is it makes the steering harder AND with the tire positioned away from the rotation axis, when your tire confronts resistance, like when you hit a bump or pothole, it will transmit that impact to the steering wheel and you could have it rip the steering wheel from your hands. That might be drastic but you will feel it.
It would be best to get the wide track suspension setup.
Another thing. Spacers at the front and rear place the tires away from the wheel bearings giving them leverage on the bearings that puts extra stress on them which can shorten their life.
RT
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I have 2 - 3" spacers fiero to OEM Lamborghini bolt pattern. Used once to figure out wide track suspension.
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RT
I totally understand what your saying about the centerline and geometry and all, but here’s the thing I’m putting different wheels on the old wheels are more of a deep dish where is the new ones the actual mounting point is farther outboard, so the centerline of the actual tire never changes in the wheel well only the point at which the wheel mates to the spacer. So in it’s turning arc should be the same... I think, lol. I’m sure you’ve done more research on this than me. All I can do for now is try it and see how it goes but I agree the wide track suspension definitely makes more sense.
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99...
I see that you know what you are doing. Go for it.
What I wrote is still good info for those that are not familiar with that issue.
I hope those builders will read that and maybe have a better idea how to get it right.
RT
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Found a great image that explains how spacers affect torque and arm on wheel bearings as well as wheel offsets. Hope this helps anyone, it sure did me.
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RT
I totally understand what your saying about the centerline and geometry and all, but here’s the thing I’m putting different wheels on the old wheels are more of a deep dish where is the new ones the actual mounting point is farther outboard, so the centerline of the actual tire never changes in the wheel well only the point at which the wheel mates to the spacer. So in it’s turning arc should be the same... I think, lol. I’m sure you’ve done more research on this than me. All I can do for now is try it and see how it goes but I agree the wide track suspension definitely makes more sense.
99, Something called the scrub radius is way more important than bearing torque or anything else. A line drawn through the upper and lower ball joint and projected down to the ground and a line through the tire centerline projected to the ground determine the scrub radius, and those lines should be 3/4" apart maximum. Otherwise, even with power steering, there will be problems. The dish on your wheel will not fix it, the tire and knuckles are still in the same place. In some cases, if the wheels can be turned easy enough, taking the car out of gear and turning the wheels left to right will produce a rearward speed of about 5MPH. Without getting into the geometry details, that is the strength of the forces that you will be against.
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Wouldn't having an adapter that is the difference of the backspace of the old wheel and the new wheel be an option for feeablo? The second pic is showing the LH front suspension from the rear of an 1988 Fiero (just for reference).
01
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Guys, if any of you are going to use wheel adapter spacers Please make sure they are Hub centric and Wheel centric. That means the adapter center hole fits exactly to the rotor hub and has the lip to center the wheel straight and true.
I recommend this shop, they are the best! and can meet any spec. you need! https://www.wheeladapter.com/ (https://www.wheeladapter.com/)
This is an old pic, I have since went with bigger rotors But you get the idea...
(https://live.staticflickr.com/2553/32077721754_e8fc33e738_w.jpg) (https://flic.kr/p/QSAH7b)46 (https://flic.kr/p/QSAH7b) by Lambo Samm (https://www.flickr.com/photos/147611676@N08/), on Flickr
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Wouldn't having an adapter that is the difference of the backspace of the old wheel and the new wheel be an option for feeablo? The second pic is showing the LH front suspension from the rear of an 1988 Fiero (just for reference).
01
01, Yes it is an option, just not a good option. The new wheel does nothing to change the already bad scrub radius that the adapter had created. Notice on your drawing that the scrub is called out at 27MM, or very slightly over one inch. It is already too big without the spacer. There are two other ways to widen the track, by widening the a-arms or widening the inner a-arm mounting point. These other ways do not effect the scrub but granted they are more difficult and more expensive, and will probably require modifications to the rack and pinion in order to keep this problem solved from turning into bump steer problem presented.
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I didn't have any suspension problems on my 55 Gasser. :'( ::scratch :(
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The way I see it, scrub radius should not change at all, if the tire is physically placed in the wheel well exactly as it was with the old wheel , installing a wheel with greater offset and using a spacer to make up that area does nothing to change scrub radius. Steering wheel forces should not change at all. When the tire centerline physically moves outboard due to spacers then yes scrub is affected and also bumpsteer as well.
Sent from my iPhone using Tapatalk
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Swapping offset for a spacer, or vice versa, will keep the scrub radius status quo... but status quo may not be the best solution. You may feel that it is working fine but getting the pivot point out to as close as possible to the wheel centerline could greatly improve the handling characteristics and performance of the car. If you are happy with how it is now, then it may not be a priority... but something you should consider down the line.