Safety question about Mustang II conversion

I saw another forum that mentioned either having strut rods or not having them as part of this conversion.
My 1950 F1 has the Fatman Mustang II shock towers and crossmember, a 74-76 power rack and pinion and tubular steel control arms with 1/2 inch grade 5 bolts. It has 9.25 rotors and I am assuming calipers as well, I will be upgrading these to 11 inch.

The engine is a SBC 406 with TH350.

After going with 11 inch rotors is this a safe setup for this truck?
Currently there are no strut rods installed.

Thanks

 

your tubular control arms are designed in an A shape, the factory lower control arm for M2 is just straight, so they added the strut arm which makes it more like an A, this gives it stability so the arm doesn't move back and forth. so, if you already have tubular A-arms there is no need for a stut arm

 

i have put several mustang 2 kits in cars with and without the strut rods .on cars which are not as heavy of course if you have a full tubular control arm you dont need the strut arm . thats whats under my 40 ford . i am also doing a 48 f1 and im using tubular control arms with the strut arms , i feel alittle safer with all the weight on the truck using the struts . are the lower struts a full a/shape that your using ? do they have mounting holes for struts? happy to talk on phone if you want rich

 

The 36 I selling has a hiedts mustang II kit. I chose to upgrade the kit to the 11 inch brakes. Everything worked fine. I'm wondering about the use of the strut rod and the tube A arms. Would you not have a binding issue. Just a thought.

 

My '48 Chevy pickup had a MII front with tubular-style lower control arms. I upgraded to 11" Camaro discs and they never failed to stop the truck. In fact, it stopped better than my modern daily driver.

 

I dont even have struts installed on this truck. Truck was bought as is and was a project started by someone else. What I do have is Fatmanfab Mustang II coil over shock towers, crossmember with power rack and pinion attached, and upper and lower tube control arms. No struts though? I dont think there are any holes for the struts. I am not that familiar with this setup and still edumacatin myself.

JD

 

Do yourself a favor and add a little tab at the rear of the A-arm to the frame. This will add a support at the rear of the bolt that runs thru the crossmember. I have seen other crossmembers break at the hole that the bolt runs thru.


jerry

 

Boyd Who, can I ask where you bought your kit from?

 

Jerry would you happen to have a picture?
Thanks

 

My kit was made by Allan Rod & Custom in Calgary Alberta.
If your kit has tubular "A-frame" lower control arms you wouldn't need strut rods. Jerry's comment about adding a tab or gusset, is a good one.

 

I've seen some pretty scary looking MII tubular lower control arms. Narrow inner end, long tube sticking out of the crossmember with no gusset, threaded rod holding the control arm in place. They look like something that would fold back under the car if you hit a chuck hole under braking.

The strut rods may not look as tidy, but they put much greater distance between the inner pivots, making for a much bigger, stiffer triangle. Strut rods transfer braking loads into the frame better. Have also seen guys bend the strut rods outboard to line up conveniently with a bracket under the frame rail. That really screws up front end geometry.

 

An older thread from El Polacko, but a good read about the MII. http://www.jalopyjournal.com/forum/showthread.php?t=115209

 

Here's the tab mentioned earlier in the thread:


The photo is from the installation of my Fat Man stage III suspension. The threaded rods on the top was just to ensure correct distance between the upper a-arm fastening plates.

Some builders claims that the strut rod eliminator is a very bad idea. Just in case they have a point, I have bought a longer & stronger pivot bolt for the lower A arm (grade 8 instead of the original grade 5) and will beef up the lower A arm area like this:


The Fat Man crossmember don't wrap around the inside of the frame rails like most other M II kits do. It's just welded to the underside of frame rail. To compensate for that I've added some gussets on the outside to stiff up the area between the crossmember and the shock towers.
Original design:



Improved:

 

If your lower arm has a bushing on the outside front and outside rar of the lower crossmember, you don't need struts. If there is one bushing located inside the end of the crossmember, you need a strut.

You can't upgrade those dinky 9" brakes soon enough.

 

Slide, the exact setup I have is the one you have labeled OLD FATMAN. Thanks very much for clarifying that. That would then mean I do not need struts.

Is it grade 5 bolts for suspension or grade 8 bolts? FATMAN says grade 5.
Their reasoning was that the tensile strength in the grade 8 would cause the bolt to snap rather than bend and then snap like a grade 5 in theory.

 

Staleg,
Thanks for the pictures. The difference I noticed in your pictures is that my frame was not boxed in. There is a short section where the motor mounts are located about a foot wide that is boxed but thats it and the rest is open.

 

Boxing is neccessary.
Fat Man has 11" brakes and grade 5 bolts as standard.

The Grade 8 bolt will snap app at the same time as the grade 5 yes.

But the main point with my planned modifications is to make the forces pounding on the rear part of the lower A-arm bolt double sheer . Then the grade 8 bolt will be better then the grade 5 bolt.

From what I've heard bent a arms are on heavy rides and with way too stiff coils. Then too much of the forces are transmitted directly to the a arms. I'm not saying that tubular a arms are just as good as the stamped ones.

 

have to agree with blasted. lots of ways for the tubular to have problems. not the least of is after all the welding trying to find a bolt straight enough to go through it all. the only problem i ever see with strut rods is the rear mount can be a weak spot if not built strong enough. its hard to improve on factory engneering. most street/hot rod stuff is done for apearance.

 

Oohfff, a little tough to understand although I belive I understand your statement.

Drawing on my experience with Mustang II front suspensions, I belive your thoughts on tubular control arms to be inadequate and a bit missleading. A properly designed tubular control arm should not fail just because your spring rate is high. I went around with H****'s front control arms on a 50 Olds years ago and they handed me the same BS. I cut the arms apart and found they were made from low grade 7/8" X 0.909" wall welded steel tube! Clearly the reason they failed was because someone cut corners and didn't understand the loads associated with a street driven suspension. Any control arm should be built to resist repeated bottoming out, adverse conditions and general wear and tear.

Just for giggles and grins, here is how I handle the situation. I build tubular control arms from 1.25" X 0.125 wall DOM high carbon steel tubing.




This particular car is a 52 Chevy Sedan Delivery and because the customer wanted it low I turned the control arms around for better clearance.

Here is annother example doing the same trick but in both sets of these pictures you can see my control arms.

 

I can personally attest to the strength of those A-arms. I'm still running the same set that were on my truck when it got crashed 2 year ago. They just went to Austin and back aain.

Thank you Steve for building such Quality pieces and trying to educate the uninformed.


jery