Front Crossmember - Ford Weakness?

[PeterC]

I started this thread as did not want to Hijack current thread re misalignment of crank hole to to cross member repair -

The question - was the Ford front cross member "under-engineered" with frequent cracks the norm? Yes I know they are 75 years old + but they failed way back.

PeteVS previously said:

"The front cross members in early Fords took a beating. I have a '32 front crossmember that had a couple of repairs (poorly made) prior to the early '50's. It had a piece of 3/8 bar welded in just like yours has. I also have a Model A crossmember with several cracks in that area. And, someone posted a picture awhile ago of another '32 crossmember that was being repaired. Most of them fail right over the spring, where yours is patched. I would have to imagine that they were often repaired in place in the frame, likely with the engine still sitting in place and welded up by repairmen who didn't have a lot of grasp on the situation"

[Bruce Lancaster]

My take is that crossmember failure is caused by loose spring to frame U-bolts allowing movement in the center area. Failed spring center bolt, spring clamps, and leaves cracked across middle hole also related in here.
A different factor, though, on cars before '33 X member is that front and rear crossmembers get a lot of twisting load in hard use. On hotrods '28-32, at least, cutting away rear area of front member to clear engine swaps reduces the crossmember from two c-section channels to one, probably removing an equivalent amount from its torsional stiffness.

[PeterC]

So Bruce - 1935 and up was different? My 35 had a crack in the front crossmember with no previous modifications - just stock as stock coud be

Originally Posted by Bruce Lancaster

My take is that crossmember failure is caused by loose spring to frame U-bolts allowing movement in the center area. Failed spring center bolt, spring clamps, and leaves cracked across middle hole also related in here.
A different factor, though, on cars before '33 X member is that front and rear crossmembers get a lot of twisting load in hard use. On hotrods '28-32, at least, cutting away rear area of front member to clear engine swaps reduces the crossmember from two c-section channels to one, probably removing an equivalent amount from its torsional stiffness.

[Bruce Lancaster]

A '35 would I think get less chassis twist up there due to having a stout X center member, but it would be just as vulnerable as the earlier ones to destruction from loose U bolts.

[rheltzel]

I always heard it was due to loose u-bolts. Can happen on both front and back, but of course the front cross member probably takes the most stress.

[Kube]

Sponsored Links (Register now to hide all advertisements)

It was my understanding that after (during?) 1934, the cross-members were redesigned (strengthened) and the problem of cracking was, for the most part, eliminated. I have yet to experience a cracked cross-member in a 38 through 48 Ford.
I'd like Dave Rehor to chime in here. He KNOWS the 32 - 34's like no one else.

[Mart]

I think that sometimes we tend to think of the past as being similar to now, but simpler and in black and white. Thing is, the roads were much rougher and some of our early fords could have spent the majority of their early years on unpaved roads.

There was also a tendency for manufacturers to launch vehicles before they were really ready and let the customer do the development testing.

Hence the cracked crossmembers and the step by step improvement of the strength at the rear end of the 32 frames.

Mart.

[Bruce Lancaster]

There was a strap reinforcement added during '32 I think...the later cars had much greater overall stiffness with the X-member and also stiffer bodies and so there was less overall twist dumped into the end crossmembers.

[bobH]

I'd like to hear a technical reason that loose u-bolts causes cracking.
I've had a few 33-34's, and only one had a damaged front crossmember, and, it was a pickup that looked like it had been 'well-pounded'.

[Fe26]

IMHO the front cross-members are a little under engineered, I had a '38' Std Coupe with a cracked center section. One thing to consider is; when the Spring is in use energy is created by its flexing, that energy has to go somewhere and the center of the cross member is where the 'Buck stops'. When you consider how many millions of flex cycles these springs have been through it's not surprising that the one contact point gets a little stressed.

Also I'm not sure if during manufacture the cross members were ever stress relieved after the stamping process, that's a pretty deep draw to create in that piece of steel.
I've seen sections cracked from the center hole and also (split) along the radiused corners adjacent to the hole.

[rheltzel]

Originally Posted by bobH

I'd like to hear a technical reason that loose u-bolts causes cracking.
I've had a few 33-34's, and only one had a damaged front crossmember, and, it was a pickup that looked like it had been 'well-pounded'.

Impact. Hammer effect, if any movement between spring and cross member.

[36coupe]

Interesting. On my 38 the crossmember has been repaired and I notice the Ubolts are loose. It is. 67000 mile original car.
Makes me feel better to know why.

[TJ]

I've seen several cracked front crossmembers on the 35-40 cars. Most were on cars/pickups that were used and abused. Ford put an anti-squeak pad between the spring and the crossmember. When that deteriorated it left the spring to beat against the bottom of the crossmember. On the original cars that I have taken apart I found the anti-squeak pad to be a piece of body to frame welt.

[V12Bill]

Originally Posted by Kube

It was my understanding that after (during?) 1934, the cross-members were redesigned (strengthened) and the problem of cracking was, for the most part, eliminated. I have yet to experience a cracked cross-member in a 38 through 48 Ford.
I'd like Dave Rehor to chime in here. He KNOWS the 32 - 34's like no one else.

My 1939 front cross member had many cracks in it. It also had obviously been replaced, as it was bolted in. I have to assume that it was replaced because it had cracked. I repaired it, removed the bolts and replaced them with rivets.

[mrfliboy]

Interesting my 41 ford truck I'm rebuilding actually had a stiffener inside the front crossmember, riveted in place. I picked up a 40 car frame and am now shortening my U-bolts to adjust accordingly. Rough estimate of 1/4" thick. No stress cracks on the original or my 40 car frame either. Since I'm building a street truck, no need for additional support. If needed I can snap some pics of the old frame front addt'l support.

https://www.fordbarn.com/forum/showpo...9&postcount=31

[Binx]

My '41 pickup has a repaired crossmember. It was a Montana truck so most of its life was on washboard gravel roads.

Lonnie

[DavidG]

The riveted-in reinforcement was not a '32 running change, but rather was introduced as a service fix to cross member failures experienced with '32 cross members (of which there were three distinct versions). The high failure seems to have persisted into the '33 model year as many cross members were replaced with the '34 version.

Based on what I've seen of surviving original, riveted-in front cross members on '32s and '33s and those chassis frames with replaced front cross members, I think that the culprit was extensive rough road use.

[Randy in ca]

Here's a couple pictures of 1935-36 front cross-members. One is from a pickup and has what I assume is a factory (?) riveted in re-enforcement, while the other was on a car frame on which re-enforcement/repairs were made which also failed - must have seen a lot of hard miles!!

-

[Fe26]

The [factory] repair seems to have been made with a piece of spring steel, that would be a definite improvement. The other ones a disaster, I've never seen anything that bad.