[Mutt's37Buick]

I'm selecting suspension and tires for my Buick Roadmaster and I have some questions about clearances:
1) Is there a minimum clearance I should design for between the inner lip of the fender and the tire?
2) Is the minimum distance different for the front and back tires?
3) Does the tire travel straight up in the fender when the springs compress?
4) About how far will the front and tires travel up into the fender?
Thanks for your help

[35terraplane]

Originally Posted by Mutt's37Buick

I'm selecting suspension and tires for my Buick Roadmaster and I have some questions about clearances:
1) Is there a minimum clearance I should design for between the inner lip of the fender and the tire?
2) Is the minimum distance different for the front and back tires?
3) Does the tire travel straight up in the fender when the springs compress?
4) About how far will the front and tires travel up into the fender?
Thanks for your help

I don't know if I would work with minimum, you could get into trouble. On the rear a lot depends on how wide your rearend is, put one in that is too wide and you will have trouble with the fender, not wide enough you will have trouble with the frame. You can use an offset on the wheel to take care of some of that but only so much. I have seen a rearend in a car that the tire wouldn't fit between the fender and hub. I like to have about a 1/2 " between tire and fender.

The front is a different story, you want your steering wheel to go stop to stop, so you have to be able to turn all the way to right or left and not have tire hit. You have to know how low your car will sit. how wide is the front crossmember, how long are the upper and lower A-arms, distance from front of mounting plate to lip, what size tire. If your tire didn't fill the opening then you would only have to worry about travel up and down, Again then a 1/2" would work. But if it is lowered and wheel is inside opening you will have to take all this into account.

The wheels travel in a very slight arc, but they can only travel as far as the shocks let them or how stiff your springs are. That goes for how far up into the fender the wheel will go also.

Bob

[Mutt's37Buick]

Thanks for the feedback. Can you please check my thinking: One of my options for ifs my 1937 Buick Roadmaster is a 2003-2004 Crown Vic/Grand Marquis front suspension. See attached picture of one my friend just installed one on his ford truck. I measured the front fenders of my Buick by clamping 2x4s to the outside using a level to make them vertical. Measuring this distance and then subtracting the width of the lip on each fender I have 74.37 inside clearance directly in-line with the front axle.
The 03 Crown Vic front track is 63.4" and stock tires are 225/60-16 or a width of 8.8". Adding this to the track gives an outside dim of 72.26" or 1.06" clearance per side. If I use 205 (8.07") wide tires the clearance per side increases to 1.45".
1) This does not take into account the lock to lock clearance, or the camber gain. A hotrodder on a different site also said I need to consider up to 7 deg camber gain. He was talking about a Mustang II ifs and if I understand correctly, the top or the wheel moves outward at a 7 deg angle. Radius of a 205-65 R16 tire is 13.25" so by trig does this means the top moves out 1.62"? If so, then do I need at least .5+1.62=2.12" clearance on each side in the middle postion of travel?
2) The above calculation seems excessive because most modern cars have much closer clearance between the fender and top of the tire. Could it be that more modern suspensions have less camber gain than a Mustang II ifs?
3) I want to be sure an option will work before I buy a suspension. I could probably find a Crown Vic to measure clearances in center, and locked positions so I can see how turning effects clearance. I could also go to a narrower tire if needed.
Thanks for your help

[35terraplane]

Originally Posted by Mutt's37Buick

Thanks for the feedback. Can you please check my thinking: One of my options for ifs my 1937 Buick Roadmaster is a 2003-2004 Crown Vic/Grand Marquis front suspension. See attached picture of one my friend just installed one on his ford truck. I measured the front fenders of my Buick by clamping 2x4s to the outside using a level to make them vertical. Measuring this distance and then subtracting the width of the lip on each fender I have 74.37 inside clearance directly in-line with the front axle.
The 03 Crown Vic front track is 63.4" and stock tires are 225/60-16 or a width of 8.8". Adding this to the track gives an outside dim of 72.26" or 1.06" clearance per side. If I use 205 (8.07") wide tires the clearance per side increases to 1.45".
1) This does not take into account the lock to lock clearance, or the camber gain. A hotrodder on a different site also said I need to consider up to 7 deg camber gain. He was talking about a Mustang II ifs and if I understand correctly, the top or the wheel moves outward at a 7 deg angle. Radius of a 205-65 R16 tire is 13.25" so by trig does this means the top moves out 1.62"? If so, then do I need at least .5+1.62=2.12" clearance on each side in the middle postion of travel?
2) The above calculation seems excessive because most modern cars have much closer clearance between the fender and top of the tire. Could it be that more modern suspensions have less camber gain than a Mustang II ifs?
3) I want to be sure an option will work before I buy a suspension. I could probably find a Crown Vic to measure clearances in center, and locked positions so I can see how turning effects clearance. I could also go to a narrower tire if needed.
Thanks for your help

That sounds like what you would need if you could move the Max amount which you will not do, unless you run without shocks and springs. If you have almost a 1 1/2 " of clearance on each side, that should be enough, depending on how low the front end is lowered, but big cars like that most of the time are not down super low when driving. Don't forget the top of your tire is not the widest, as they go out as you go down the side.

My 33 Ford rides super low, right now with a standard offset it hit just before I hit the stop on the steering wheel. So I will have to get a wheel with an offset that brings it in a little. Now my car has a different shape of fender as yours, but the top ridge of the fender comes down to the wheel. I will send picture.

Bob

[Mutt's37Buick]

I do not plan on lowering the car more than 4 to 6 inches and a couple of that will be with smaller tires. Sounds like the Crown Vic suspension may be an option for the front. I have the advantage that my friend just installed one and he said it will be easier (and cheaper) for me to install. He has also installed a Heidts Mustang II installed. The only thing he was surprised at was the stock springs were too stiff for the ride he wanted on his '70s Ford truck. He wants it to ride like a Cadillac. The best thing about the Crown vixc suspension is it pretty much a complete assembly that just has to be mounted in correct position. I'll set it all up and have someone come in and weld the mount points. I will probably use a Lincoln Mark VIII irs (ford 8.8").
Thanks again for your help.

[35terraplane]

Originally Posted by Mutt's37Buick

I do not plan on lowering the car more than 4 to 6 inches and a couple of that will be with smaller tires. Sounds like the Crown Vic suspension may be an option for the front. I have the advantage that my friend just installed one and he said it will be easier (and cheaper) for me to install. He has also installed a Heidts Mustang II installed. The only thing he was surprised at was the stock springs were too stiff for the ride he wanted on his '70s Ford truck. He wants it to ride like a Cadillac. The best thing about the Crown vixc suspension is it pretty much a complete assembly that just has to be mounted in correct position. I'll set it all up and have someone come in and weld the mount points. I will probably use a Lincoln Mark VIII irs (ford 8.8").
Thanks again for your help.

I think it would work for you Put a Lincoln Irs in a 32 Packard once rode super.

Bob