Torsional rigidity test: 67 coupe

mustbereel · Jan 7, 2008

Edbert said:
Don't happen to know what a stock-block 351W with aluminum heads/intake weigh do you? I know it is less than the 289 it replaced, but curious if anyone knows HOW much, probably not a lot and any gains I made are easily outweighed by the AOD (versus C4) and or 9" (versus 8").

You probably lost about 65lbs (40lbs in the heads and 25lbs for the intake - isn't that about what you said you lost over the summer?). That would put the 351 very close to the 289, maybe 10lbs under.

Edbert · Jan 7, 2008

mustbereel said:
You probably lost about 65lbs (40lbs in the heads and 25lbs for the intake - isn't that about what you said you lost over the summer?). That would put the 351 very close to the 289, maybe 10lbs under.

Thanks!

Never underestimate driver weight in your ET calculations, I wonder if driver weight affect torsional rigidity or not

Helmantel · Jan 8, 2008

mustbereel said:
420lbs sounds light but it's hard to compare without knowing exactly what is on each engine. With the Iron block my DOHC weighed 700lbs. This included AC, PS, Alt, intake with supercharger, flywheel (Al), starter, exh. manifolds, motor mounts and a few misc. hoses that were still attached. I think it included the clutch and pressure plate too. I subracted 70lbs for the Al block but haven't weighed it since reassembly.

Yeah, I thought it sounded light too. The FRPP catalog said "dressed", but that doesn't necessarily make it an apples to apples comparison.

C0V3R · Jan 10, 2008

mustbereel - did you happen to draw up plans for the rear divider plate? If you did can you please post up a copy

shelbe67 · Jan 22, 2008

I have a couple of questions, One what is the wieght of the dohc motor compared to a 460? and in my web searching I saw a kit from mustangs plus have you thought about doing similar mods? do you think that that kit would actually work like intended?

mustbereel · Jan 22, 2008

shelbe67 said:
I have a couple of questions, One what is the wieght of the dohc motor compared to a 460? and in my web searching I saw a kit from mustangs plus have you thought about doing similar mods? do you think that that kit would actually work like intended?

After a quick search I found the estimated weight of an all iron 460 to be 720lbs. The iron block DOHC (with supercharger) was 700lbs. This means with aluminum heads and intake the 460 would lighter and narrower. Probably very close to the DOHC with aluminum block. Maybe I'll put a 514 in my next project.

I like the Mustangs Plus chassis reinforcement kit and have considered it more than once. The only thing it has that I haven't done (in one way or another) are the inner rocker plates. I think the kit is best for the 65/66 cars that don't have front torque boxes. It's not too expensive and would certainly help. However, The best bang for the buck is still the rear seat divider and export brace.

Edbert · Jan 23, 2008

mustbereel said:
After a quick search I found the estimated weight of an all iron 460 to be 720lbs. The iron block DOHC (with supercharger) was 700lbs. This means with aluminum heads and intake the 460 would lighter and narrower. Probably very close to the DOHC with aluminum block. Maybe I'll put a 514 in my next project.

That never ceases to amaze me!

I had the all aluminum DOHC in my Cobra, great motor. Have the 3V in my current DD, love that motor too. But man on man did FoMoCo ever make a fat pig outta their new design, I'm talking weight and girth...PIG I SAY!

70vert · Jun 8, 2008

Modification to Reenmachine-style front subframe tube reinforcement that goes over shock tower - integrate it into the TCP upper spring mount ring, if you have TCP! Basically, where Reen has it straight through his shock tower elimination, you would curve around the TCP coilover but run stringers or an entire ring around the curve that tied into the upper spring mount/reinforcement. Remove the bolt-in coil spring cover and spring, remake the ring over the TCP coilover or just weld it into a ring that attaches to the front subframe reinforcement. In my case the next step would be to try to counter the folding action the stiffened front subframe will do where it attaches to the floor, with no roof to keep it from folding, but that's another story.

bnickel · Jun 9, 2008

mounting that ring to the down bar probably wouldn't be such a good idea, if you were to get in a wreck the impact would more than likely shear the bolt on that ring....not a good thing. now if you wre to build a cage/outer spring cover similar to the Global West unit used on their 65-66 kit, that would work a little better but even then you'd still be looking at the possibility of shearing some bolts, though less likely since you'd be spreading the loads over a wider area and more bolts.

01ragtop · Jun 9, 2008

Are you thinking of tying it into the shock towers like in this link?

If so Bnickel's idea of using the GW or making your own would work, as long as you leave clearance for maintenance to the shock/springs.

mustbereel · Jun 9, 2008

I like the idea of connecting to the outer shock tower/spring cover. SN65 has done that on their new projects:

http://www.sn65.com/images/Fire & Ice Images/06-10-09 027.jpg

70vert · Jun 9, 2008

great suggestions, all

bnickel, you always have astute observations and great suggestions, thanks. I think you might be right about that ring. I could see how it could pull away from the bolts and shear them off. I think you can see what I was trying to do, though - get something in there to work with the shock tower at the same time as the force hit the shock tower. Shock tower load is minimized and distributed at the source, but with the disadvantage you described.

01ragtop, not exactly like that. More like Reen has done, but imagine that the coil spring cover has a hole cut in it that Reen's tube goes through and is welded to. I know, I should draw this, just too busy right now. Then that cover gets bolted to the regular shock tower just like before. You could even use a heavier cover for this application. This tube would help the shock tower stay stiff from the outside.

mustbereel, I'm 100% with you on SN's work, but adding Reen's tube that extends forward on the frame rail to it but keeping all of SN's work tying it to the cowl and firewall. For a convertible, SN's work would be even MORE beneficial, strengthening that "hinge" area where front frame box meets the floor and there is no roof to help out, but I like the fact that Reen's tube goes all the way forward to the forward frame rail. It's not that you need to stiffen the area forward of the shock tower, but that front frame rail could sure help lend some support to the shock tower rather than just being pulled around by it in a big hit.

Obviously, I'm a little more obsessive about front end rigidity and cowl rigidity since I have a cowl-shakey convertible.

bnickel · Jun 10, 2008

the only i don't like about Reen's brace is that thin piece of squared sheetmetal it sit on, it just seems to me that in a front impact the welds on that would break leaving the tubes hanging out in the breeze. there is an early competition car trick where you weld an extra outer frame rail over the existing one, i think if you did that in combination with some of SN-65's bracing, some of the tricks from the Boss 302 chassis guige like skipwelding around the towers, strut rod housings and adding that lower shock tower to frame rail brace in conjunction with the tubular strut welded to the outer shock cover like 01 ragtop posted would be the best combination of strengthening things you could do. don't forget that you do still need a little crush are in the front of the car, that or wear a 5 point harness and a helmet everytime you go to the grocery store.

all the stuff we posted above will stiffen the shake-n-bake cowl of the vert substantially without stiffening it so much that it becomes unsafe for the driver on city streets or the highway.

01ragtop · Jun 10, 2008

bnickel said:
, that or wear a 5 point harness and a helmet everytime you go to the grocery store.

For some reason that one caught me off guard!

Seriously though,

Bnickel, I know you are not a fan of the MII setup, and I have read why in several different posts, but I was wondering your opinion of the Griggs GR350. Comparing it to the MII may be apples to oranges in terms of performance, but doesn't it fall victim to the same pitfalls in terms of front end stability. It looks to me like the MII cross-member might even be a little more heavy duty than the Girggs K member. It is possible to leave the shock towers in place with the Griggs, and I suppose you could connect that mini tower to the stock shock mounting point in order to transfer load IAW the original design, or maybe I am missing something To my untrained eye the Griggs seems like it would introduce an element of twisting to the frame rail as well. I know smarter people than me have given the Griggs the golden pass, and Griggs spent some time and money in R&D, what am I missing?

Has anyone drove a Griggs car? What were your impressions?

bnickel · Jun 10, 2008

i believe griggs recommends adding a down bar as well if you remove the towers.

SadbutTrue · Jun 10, 2008

Really cool thread that I'm astonished I've managed to ignore so far. Looks like it got going before I came back from school so I've probably always just glazed over it. I went through the first 6 pages and had some questions, and I figured I'd ask them before I re-read those pages and the rest of the thread in more detail.

1) Has anyone done any comparison studies between this Mustang and other cars (1st gen Camaros, S197/Fox/SN95 Mustangs, new BMW 3 series...) just to see how good/bad the cars are stock and can be with modifications? Could be interesting

2) I noticed that a lot of people said that some modifications, like the monte carlo bar and apparently subframes, don't impact torsional regidity much but obviously impact the overall stiffness of the car in other areas. Could someone define (a picture with arrows showing the force/deflection would be incredible, but if no one wants to put that kind of time in a paragprah will suffice) each of these? Are there any ways to measure the impact these parts have?

Very interesting thread though, one of stangnets finest.

SadbutTrue · Jun 10, 2008

Edbert said:
That never ceases to amaze me!

I had the all aluminum DOHC in my Cobra, great motor. Have the 3V in my current DD, love that motor too. But man on man did FoMoCo ever make a fat pig outta their new design, I'm talking weight and girth...PIG I SAY!

Really hurts when you see what GM has done with their semi-SBF-inspired LSx designs (in some ways, anyway). The LSx engines are arguably the best all-around gasoline powerplant around these days. Inexpensive enough to put in $25k cars, good gas mileage, great power, lightweight/compact design, meets smog... sigh

bnickel · Jun 10, 2008

some of your questions have been answered in the thread so a re-read is a good idea.

i agree, unfortunately, about the LSx motors, ford really dropped the ball on going with the OHC motors rather than just evolving the time proven pushrod engine, though i understand why they went the direction they did, in my opinion it was a giant flop. when they have to supercharge an extremely heavy 5.4 liter to make as much as power as a new naturally aspirated vette it's just sad, sure they do it with less cubic inches but that engine weighs close to twice the vette motor does.....

i know the 4.6 has a large following and if your into high tech motors then the 4.6 is for you but i prefer low tech pushrod motors with lots of cubes that weigh less, make power and are just generally more efficient. that doesn't mean i'm going to rush out and buy an LSx motor to stuff into my cougar though...waiting for the right deal on a 70 el camino for that actually i'll probably pull the drivetrain from my 86 towncar and swap it into a 68/69 ranchero to make me a new daily driver. i may update it to HO specs before i drop it in or may not, it's got 76,000 miles and runs great so more than likely i'll just drop it in as is and go, should make a nice daily driver pickup that gets decent mileage

70vert · Jun 11, 2008

5 point harness grocery getter

bnickel said:
don't forget that you do still need a little crush area in the front of the car, that or wear a 5 point harness and a helmet everytime you go to the grocery store.

all the stuff we posted above will stiffen the shake-n-bake cowl of the vert substantially without stiffening it so much that it becomes unsafe for the driver on city streets or the highway.

that was a good one. I'm not advocating taking anything away from the front structure, just adding to it. The crush zone shouldn't really be affected at all, or would be strengthened. I guess there is a slight worry about having a metal tube enter the cabin of the car, but the front end impact would hit the engine block first. A sideways front end impact or front 1/4 impact would push that tube against the engine compartment sideways. It is true, though, that an impact that just hit the fender/inner fenderwall and not the engine could push that bar back, though. Hmm.

I'm curious about the idea of the front end being so stiff that it is unsafe. I assume you mean "with unsafe components that could enter the passenger compartment" I could see your point once I start putting a metal tube straight from radiator support to the firewall at about chest height.

I'm glad you introduced the subject, though - it is worth mentioning that none of the modifications we are talking about should allow a piece to enter the passenger compartment. I would think that most of these efforts, including ESPECIALLY SN65's reinforcing of that corner between the firewall and the door/cowl area, would help in a front/side 1/4 impact.

mustbereel · Jun 11, 2008

The main problem with a structure that is "too" stiff is that instead of the energy of the collision being absorbed by the crush zone it is passed on to the occupants. This means there is more energy for the secondary collision - you and the steering wheel or shoulder belts, etc...

To this end SN65 hasn't extended anythinig past the shock tower.
Reem made his strut so that it will bend in a frontal collision.
My strut ends just forward of the front suspension.

A strut that reaches all the way to the front of the frame would be stronger but it also eliminates the "crush zone" although I don't think it was engineered as such in 1964.

The idea is to survive the collison, not save the car.

Torsional rigidity test: 67 coupe

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