Thread: Hub to Hub M2 kits

Tweet

37chev, sorry, I think I got the two of you confused as we went along here, though most of what's been posted is fairly generic. I missed your question about the top hat frame. Just for general info, pictured below is a '39 Chev we had in the late '80's. That one used a stock MII/Pinto crossmember and components that we "sunk" into the front rails (can't exactly remember 3 or 4") the crossmember essentially "boxed" the notch. Also trimmed the coils, we were shooting for cartoon low. For some reason people thought we trailered the car (they're probably parents of todays rat rodders ), they seemed not to believe something with 1 5/8" clearance under the center of the grille could be street driven.

Now, 20 years of technology and learning later I'd probably do it differently, but it seemed like a good idea at the time.

You might want to read the commentary on Chassis Engineering's site about the top hat frame construction type and welding in of a front crossmember. Not sure I agree with it 100%, but it makes for interesting reading.

sorry 37Chev...somewhere along the line I went from generic questions that would benefit both of us to stealing Bob away from you in your own thread

Originally Posted by 35fordcoupe

so many questions...let me know when I start annoying you

Well..............that would be right now!!!

Just kidding................just kidding.........$1000 payment to my paypal account will take care of everything!

Here's how I earned the title "Uncle", or would that be curmudgeon? (and maybe some others not said to my online face ). You used the word "assume". There's no reason to do that, and it's a good way to waste time and money and/or end up with unsatisfactory results. It's not that hard to measure for what you want/need. I'd say one of the biggest mistakes made in car building is folks getting impatient. I sure have done it way too many times. Sometimes you get lucky, sometimes not. See my sig lines for my thoughts on luck. Mockup, mockup, mockup! Yeah, it's extra work, but it accomplishes so much in the long run it's worth every moment, and is one of the most cost effective things you'll do in a build. As an example, later I will answer your questions about what fits MY car, but don't assume it will work for you exactly the same, even though our cars are very similar in design. Build tolerances back in the day were a lot more flexible than today and sometimes the ravages of time have changed things as well.

Wheel and tire combos are one of the most abused applications out there. It drives me nuts (short trip) when someone comes on here and asks something like, "What size tire will fit my 1958 Whizbang Deluxe." There are so many unknowns about that particular car (what size wheels, what offset, what kind of brakes, has it ever had any body work done that may have left inner panels closer together, all kinds of questions like that). The guy has the car right there, measure it!!! The reason this happens is people are on unfamiliar ground. Okay, enough with the sermon so let's cover some basics.

I strongly recommend you figure out what you want to do for wheels, which will lead to tires, which will lead to your choices in components, which might lead back to your adjusting your thoughts on wheels and tires. You're building a custom fabricated car, so you control the variables. When I envisioned the '36 roadster I had an idea of stance, and I had my heart set on the wheels that are on it. Like you're doing here, I looked at similar cars. As we know, the '35 to '40 Fords use the same chassis, and the body dimensions are similar from year to year. As a GUIDE (emphasis intended) I used what was done to a buddie's '39 coupe. As an example, his was the first one I'd driven with anti-sway bars front and rear which taught me how much affect they had. Okay, one parameter set. Then I went to school on the rest of his setup, which is what we're doing here with mine. I would just want to emphasize once more, use what I tell you as a guide, not an absolute. You may have to/want to adjust to your vehicle, tastes, budget, time, experience, intended use, etc.

Okay, we've talked about the front offset and wheel size, the tire size is 195/60 in front (I like a rubber rake, and the extra width without going crazy on the aspect ratio and losing the sidewall flex for ride quality). The rear is an 8" wide wheel with 3 1/4" backspace, carrying a 255/70 tire (the 70 fills the wheel opening better than the 60 to my eye). At this point, some folks will factor in their desires based on diameter and how that effects gear ratio, I'm less concerned about that than appearance. To me, the small difference in ratio is tolerable. Speed/acceleration is low on my priority list.

Since I locked myself in on wheel/tire, that left the variable being the rear axle width, and the front track width. We set up the car, put the wheels underneath where we wanted them for spacing, and then measured. The rear axle is "easy", just take it to the shop that does narrowing and have it made to fit. Cut the housing, fab an axle or two (only need one for this application) and you're there. The front was only slightly more difficult. Typical stock MII dimensions are 56 1/2" hub flange to hub flange with stock 9" rotors. Well, I knew I wanted 11" rotors, so had to take those into consideration. The typical way most brake kits get there, and maintain a 4 1/2" bolt circle, is with a Dodge rotor. But those push the flange out 5/8" (as I recall) on each side. I was shooting for something more like 55", so that wasn't going to work. So that led to the choice of the narrowed control arms, which only got me half way there. I did a little research and learned that ECI Brakes (http://ecihotrodbrakes.com/index.html Ralph is a very helpful and knowledgable guy) made a custom hub that left the flange in the same relative position as the stock MII, so I got the 5/8" per side back right there, giving me a net 55 1/4" which worked just fine. I ended up having to shorten the rack and pinion tie rods as at the time a rack that narrow wasn't available.........at least not that I could find.

So, you can use practically any tire/wheel combo you want, you just have to adjust accordingly on whatever other variables you have. It works the other way too. If you look in my gallery, there's a maroon '32 roadster. I bought that one as a "finished", running car. It was two tone with black fenders, frame, and fuel tank, sat way too high, and had some ugly, old chrome wire wheels on it. I wanted to give it more of a traditional look, with a better stance, and didn't want to break the bank or get too deep into changing the car. In that case I carefully measured axle spacing (my fixed dimensions in that case) after lowering it and figured out what size tires would fill the wheel wells nicely, then had wheels fabbed (my most controlable variable in this case) to fit. Some color matching and painting on the black stuff, wheels and voila!!!! A fresh looking car that most people thought was built entirely to the resultant look. The "secret" was planning what I wanted and measuring how I could get there.

The CE rear springs were bolted to get the placement, and then the front and rear brackets were welded, mainly just because we were doing a frame off deal and had the welder going while it was on the rotisserie. Had I been doing a frame on deal, I would have just drilled all the holes necessary and done the bolt in method.

As for boxing, the front was done as you noted, but it's unnecessary in the rear for a street driven car. It's already a double C channel as the "tails" of the X member extend all the way to the ends of the frame within the outer rails. Since this is a roadster, I felt it needed some more frame bracing in the center of the side rails, so we added some box plate sections and some braces from the center of the X to the side rails (you can see them in the chassis rear shot). I probably wouldn't have done that on a coupe/sedan, especially if the body stayed on the frame. The center of the X member was strengthened with the CE mount that also serves to make clearance/mounting for the GM trans.

The engine is a normal SBC with a small housing MSD distributor. The trans mount actually dictates where the engine sits, although there is some room for adjustment. It sits a little tight to the radiator, and if I had it to do over again, I would move it back another 3/8" which would give me more fan options (learn something on each build).

...HEY !!!!!.....everything I am reading .....for my car or yours is just giving me more info...and in the long run....more questions.....but I like it !!!

and yes Bob.... I have read CE's opinion on using a bolt on crossmember, but that is one opinion, and I don't fully agree...but we all get to have opinions.....deep stuff, huh??

Originally Posted by Bob Parmenter

Here's a link to Heidt's site; Mustang II Crossmembers

I like that Heidt's spindle is steel rather than cast. In most of these apps the cast probably lasts as well and as long as most hot rods require. Again, it's a personal choice thing for the more durable steel, to me.

I believe you helped me too.

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

FYI: I recieved a nice e-mail from an individual up in the great northeast that has used the Jim Weimer Rod Garage M2 kits. He spoke very highly of them and said that they were"VERY nice kits".

Also, after speaking with this forum I contacted them (rod shop) and confirmed that they use steel spindles, give the option on power or manual racks, option 2" drop or std spindles, 11" chevy or ford pattern disc brakes , tubular control arms etc.....and ship for free to lower 48 states.
Many of the other kits I viewed offered these options, but at a +$$ per item.

So I have just ordered my M2 kit from them. I should have it towards the end of the week, and depending on schedules, I hope to get the install going soon. I will send out a thread just to keep anyone interrested in the progress of a rookie.

Only two reasons I could see for changing the rear crossmember; 1) it's too rusted or damaged to be trustworthy, 2) you want something less bulky and more "attractive".

For the measuring stuff here's a link that has some artwork and internal links that will save me a lot of typing, and not subject you to my incompetent attempts at drawing. http://www.rsracing.com/tech-wheel.html
And you can print it out for reference again and again.

Thanks for the link Bob...it looks as though it should be very helpful.