Thread: Hub to Hub M2 kits

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Bob, the payment is in the mail errr...it's coming .

The big reason I like to ask others what works/fits is due mainly to my inexperience. I realize every car goes together different...maybe it's just nice to hear I'm on the right track after asking or maybe I'm trying to copy .

I want as wide of rear tires as I can fit, but again due to inexperience I tend to shy away from doing exactly what I want and settle for something that will be easy/cost effective for me to accomplish. Example, the 275 rear tires I have sitting around would look great on this car, but they won't fit w/o heavy modification so I settle for a narrower tire...narrowing a rear doesn't seem cost effective for me. I would tend to see what I can get and chose a wheel/tire combo to fit that. I'm not real sure how to measure for a rear width/tire/wheel backspacing either. Also, are those wheels 16"? That look and stance is more or less what I'm after...

As for the front...I will be at 56 1/2" plus 11" rotors (which I understand as well is an extra 5/8" x 2). I don't see myself not using the rotors that will come with my kit so other than gaining 2" from narrowed control arms I will likely run a tire that will fit where I'm at there. I guess the way I figure it is if others get by with that set up with narrow tires I can too...just just want to make it through this build alive and not get too crazy with this

I know I was told before the rear of the frame should be okay, but the shop reccommends partially boxing the rear as well so I want to be well imformed before I refuse. I do plan to replace the center of the X so that should help there. Did you say that was the stock rear crossmemeber...is that suffiecient for the shock mounts?

Actually I think both of you are doing fine all things considered. Indulge me my little bursts of sermonizing as I'm never sure what level of comprehension is at the other end until more back and forth occurs. So "in the beginning" I'd rather err on the side of overemphasis rather than unintentionally misleading.

As for "getting it right", I'm not sure in reality any of us hobbyists ever reaches that nirvana. There's always some way or other we outsmart ourselves. And then there's the "the more you learn, the more you learn you don't know" theorem.

You might want to double check your numbers on the amount gained from the narrowed control arms. I believe Heidt's is only 5/8" per side, not a full inch. If there is a full inch option there I'd love to learn about it.

If you were to go down the path of wider tires in back then the parallel leaves attached to stock rails isn't the optimum. That's why God invented four bars, or ladder bars, and coilovers. And that relates to the stock frame strength issue. First off, most rodders aren't exactly engineers (though we do have a few here that are), and as such will sometimes "over engineer" an application just because they THINK it's better. If you were to go the narrowed rear frame section, coilover/ladder bar, build it for high stress launches and so forth, I could see a reasonable argument in favor of additional boxing, or replacement with box or round tubing. With parallel leaves, you're basically playing to the greatest strength of the existing structure. Fairly modest torque input to the frame rails, and virtually all vertical rather than rotational (most of that type of input is disipated in spring flex). At the other end (the front), boxing is realistic because the inputs from both the engine and the control arms is more direct and rotaional.

As for questioning the strength of the stock rear crossmember, remember, with the stock transverse spring the entire sprung weight of the rear half of the car was supported by that crossmember. It's more than adequate for taking the inputs from two small shock absorbers (assuming it's not weakened by rust or damage).

Measuring wheel and tire fitment is pretty straight forward once you get the info you want/need. Your baseline for placement is the axle/rotor mounting flange. I find a long enough straight edge of some kind is useful for projecting my "midpoint". If I think I want a 26" diameter tire, then I use at least a 26" straightedge (stick if you will). If you jack the car up by the suspension that will give you the approximate mid point of travel. If you don't know, you might have to guess how much travel you'll have, particularly upward, to know where to measure for the top of tire travel. This is usually fairly critical because most wheel houses get narrower higher up. In front it's anticipating fender rub in a turn. Sometimes in the effort to fill the fenderwell nicely for visual effect, we crowd the turn interference situation. Many times it won't show on a moderate speed turn on flat surface, but on those usually rare occasions where your hitting a drive ramp at a good speed, you'll get just enough more compression to cause a hit (even worse if you've got a load of passengers with you). Your call on how big a risk that is, and if you can discipline yourself to avoid those kinds of manuevers. That orange '39 Chev was a real test for my powers of discipline!

Most tire websites have charts that give you diameter, cross section width, sidewall height data to help you figure the tire dimensions. The wheel is a little bit confusing if you don't understand a couple of variables. When a wheel is classified as six inch wide, that's the dimension BETWEEN the inner beads of the wheel outer flanges. The actual full width of the metal structure is more like seven inches, depending on how it's manufactured (cast aluminum wheels could be even wider for example). This comes into play on back space, because that's measured from the rear (hub) mounting surface to the plain of the back flange of the wheel. So our six inch wheel that has a 3" backspace, will have 4" of overall width to the front flange face (some folks think that since it's a 6" wheel the mounting flange is "centered"......not quite). So, just for discussion, let's say the tire manufacturer says a certain sized tire, mounted on a 6" rim will have an 8" cross section (the "bulge" of the sidewall at it's widest), and is 26" tall. There you have pretty much all you need to start measuring. The next thing is to keep all those other factors mentioned in mind as well as being observent aboult all the other things under there that could come in contact with the wheel/tire, e.g. brake components, tierod ends, control arms, shocks, leaf springs, and so on.

I have looked at several kits recently...some of them were 1" narrowed control arms. I don't have that specific information yet for Heidt's since it's been a few weeks and still no catelog (I talked to Fatman at the same time and they got me a catelog within a couple days along with a 35-40 specific insert ...). So you are probably right...Heidt's could be only 5/8".

I'll be using parallel leafs...so whatever tire I can fit I'll be using. No four link or anything so it sounds like the rear of the frame should hold up fine as it is.

My questioning of the rear crossmember was more about age and possible damage (visual or non visual damage). Realizing the shocks would not be adding much stress I wasn't sure if adding a new crossmember would be a good idea anyway. My crossmember seems fine, but I'll have to inspect it after blasting to make a decision.

I wasn't sure if there was a definate way to measure for a wheel/tire or not...sounds like there is still a good amount of guesswork involved especially with the upward travel. Measuring for backspacing still has me a little confused...if I were to use the stick on the hub method that will determine overall height, but how do I determine wheel/tire width and backspacing. I guess the maximum overall width is fairly straight forward, but after knowing the width how do I take that and determine the backspacing I need? Also, what is an acceptable distance for the tire from something like the leaf springs? Thanks