Subframe Install Questions

I had my MM subframe connectors installed today. The shop that I had them installed comes very highly recommended. They've done countless subframe installs on mustangs and are a mustang-specific shop (they know their concerning these cars).

Anyway, I've always heard that the suspension needed to be loaded while the subframes were being installed. These guys used a 2-post lift (only lift they have) to do the install, so the weight was off the wheels. They assured me that it really didn't matter whether or not the suspension was loaded and that it was just a manufacturer recommendation.

Second, for some reason, they completely forgot about the seat rails (which had been sitting on a cart 10 feet away) and were not installed. They assured me that the entire purpose of the seat rails was to add another connection point for the subframes and to secure them to the underbody a little more. They told me that regardless of the rails, they do extra welding along the connectors anyway (which I could tell that they did, they welded the hell out of them) which would compensate for the seat rails.

Anyways, after leaving the shop, the difference was unbelievable. It feels like a completely different car, so Im guessing that there really couldn't have been much more difference with the seat rails and loaded suspension?

007 said:

I hope you didnt leave without making them do the rails they forgot?

I always heard you wanted the chassis in its normal load bearing state when you weld them on. Heard rumors (maybe BS) about people doing it the other way and having issues.

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How could they have done the seat rails when the subframes were already welded on?

san~man said:

The car should be on a drive on lift (i.e. loaded) when installing the rails, check maximum's website.

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I know that, thats what I told them. They assured me that it wouldn't make a difference. These guys are the premium domestic muscle/pony car shop in town (epecially late-model Mustangs). In fact, just about every Mustang in town goes to these guys to do subframes. It's hard to believe that there are so many Mustangs (and other cars) running around with incorrectly installed subframe connectors.

Anyone know whether or not having the weight off the wheels will make a noticeble diffrence?

Clayton302 said:

your car HAS to be lifted with the weight on the suspension. are your doors shutting normal? if they are you have the rarest mustang on earth. your car just got welded while it was tweaked. i would take them off and lift the cars from the front a arms and the rear drive axle or a drive on lift. I have a hard time believing they know what there doing. just my opinion. good luck

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The way that they explained it to me is that they place the arms of the lift as close to the wheels/subframes as possible as to simulate the car having the weight on the wheels. I've checked alignment on the doors (door/fender gap and door rear quarter panel gap) and everything looks exactly the same. Both doors open and close flawlessly from what I can see.

These guys do hundreds of mustang subframe installs. They are the mustang destination shop anywhere in the city.