Author Topic: Engine crossmember problem (Read 468 times)

66gt350 · « **on:** March, 08, 2010, 08:50:53 AM »

The other day when I was under the wife's mustang getting ready to put in the new trans, I noticed that something was missing...the lower crossmember. I was able to find a good used one at the local mustang shop. When I went to install it yesterday, i think I know why it wasn't on there...the bolt holes don't line up. I don't have a calibrated eye to see exactly how off it is, but it's probably in the ballpark of 1/8" (probably a bit more).

Now how the heck do I get the crossmember in? Do I have to try and pull the frame rails back, or should I just slot the holes in the crossmember and be done with it?

any advice (hopefully good :craz) is appreciated...

buening · « **Reply #1 on:** March, 08, 2010, 09:42:08 AM »

I'd measure the distance between the frame rails and check against the body dimensions of someone elses car or the diagram that has been posted on here before. 1/8" really isn't alot though, so slotting the holes shouldn't be an issue.

silverblueBP · « **Reply #2 on:** March, 08, 2010, 09:50:43 AM »

If it was me, I'd check the actual measurement with what it's supposed to be and bring the frame back to correct spec. I wouldn't slot the crossmember.

Mach1Rider · « **Reply #3 on:** March, 08, 2010, 10:17:24 AM »

Do not slot the crossover member. It will just cause you grief later with wheel alignments.
Use a comealong to pull ralis inward or a hyd jack to spread them apart to get bolts back in.

66gt350 · « **Reply #4 on:** March, 08, 2010, 11:25:59 AM »

Thanks guys. I'd prefer not to slot the crossmember if I don't have to. The challenge is right now the engine is in the car, so measuring will sure to be a royal biotch!!!

Does anyone have the distance between the centerline of the bolts handy? I could measure it off my fastback, but again the engine is in place and would be a challenge.

thanks

jmlay · « **Reply #5 on:** March, 08, 2010, 12:14:59 PM »

A google search should net you the chassis diagram. But you could also measure at the radiator support to get the dimension.

silverblueBP · « **Reply #6 on:** March, 08, 2010, 12:41:36 PM »

The chassis diagram I have does not show the crossmember dimension. The closet is where the front sway bar mounts, that bolt hole centerline is 24.92"

TB350 · « **Reply #7 on:** March, 08, 2010, 08:45:15 PM »

Could you just measure the hole spacing on the crossmember? That should not have changed over time. kip

Mach1Rider · « **Reply #8 on:** March, 09, 2010, 08:41:24 AM »

Just a thought, But the engine may have been installed without the crossover in place and PO couldn't get it back in.
Removing the engine mount bolts and jacking the engine up might allow the lower frame rails to sag inward enoungh to rebolt the crossover in.

I like to think of the easiest way to fix it first. :)

Fordrevhead · « **Reply #9 on:** March, 09, 2010, 03:51:46 PM »

I would guess the top of the towers are in and the bottom of the frame rails are out... the motor mounts become somewhat of a pivot point. So, if the bottom is out 1/16" per side the top of the towers might be in an 1/8" or so per side. Do you have the stock tower braces? Do they look like they're trying to buckle?

There's a lot of ways to relieve this stress and pull things back in order. Many of them unsafe if not done correctly. I definately wouldnt slot the holes as OP have already stated and it will definately pay off later to get this straightenned out now.

sigtauenus · « **Reply #10 on:** March, 10, 2010, 11:29:29 AM »

I'll chime in to concur with not slotting the holes.

Also, I think being able to measure around the engine is irrelevant. The crossmember is your yardstick. If you have doubts about the crossmember being off, check it against a second crossmember. If I had to bet between the frame being off 1/8" or the crossmember being off 1/8", my bet is the frame is off.

RyanG85 · « **Reply #11 on:** March, 10, 2010, 11:42:47 AM »

I also agree not to slot the holes. I would try jacking the car up from the center of the radiator support till the wheels just come off the ground and recheck the distance. If still off and its only about an 1/8, I would pull the frame rails together with a come along and bolt it in.

buening · « **Reply #12 on:** March, 10, 2010, 01:43:37 PM »

Are the frame rail holes too far apart compared to the holes in the crossmember, or the reverse?

Have you had the car aligned? Was it off when they checked the alignment?

If you have been driving without the crossmember it is likely that the frame rails have moved slightly. I agree with comparing it to another crossmember if you have access, or comparing frame measurements. All I have are 70 cars, otherwise I'd give you a measurement.

66gt350 · « **Reply #13 on:** March, 10, 2010, 02:55:49 PM »

We just got the car a couple of weeks ago, so I don't know the last time it was aligned or how long it's been missing. but it does drive pretty decent...doesn't wonder or pull to the side. The alignment can't be too far off. If I get ambitious, I can crawl under my fastback and yank that one to see what the difference is.

The challenging part of trying to the the frame back together is that the engine is in.

AzPete · « **Reply #14 on:** March, 10, 2010, 02:59:46 PM »

As stated before, check the shock towers also. If they are a bit close, you can jack them apart and the frame rails should tip in with the engine in place.

daveSanborn · « **Reply #15 on:** March, 10, 2010, 04:26:40 PM »

My $0.02..........

I've seen cars that have operated without that crossmember installed for years. I consider the crossmember an integral piece of the car, but obviously others have been driving around for 20+ years without it. I'd put it on my "list of things to do", but it wouldn't stop me from driving the car locally for a while. For instance if you know that the engine will be getting a rebuild sometime down the road, take care of it then.

Once you re-align the holes to allow the crossmember to fit, the car will need a fresh front-end alignment.