The one thing you definitely don't want to do is mount the transmission to the chassis without some compliance. If it is solidly mounted to the chassis, then the tailshaft casting is going to see bending loads which may break it. Even if it doesn't break, the bearings in the transmission are going to see loads that they are not designed to.

If you do use this Sumitt crossmember, you really need to make sure that you mount the transmission to it with a rubber or polyurethane mount.

I don't see how this crossmember is going to stiffen the chassis at all. The brackets that connect the crossmember to the frame rails are extremely thin and flexible. Without beefing these up quite a bit, I don't think the crossmember has any chance of doing anything.

 

As endorsed by P. T. Barnum.

 

Jack hit the nail right on the head.... I bought one since I have a convertible. Anything to stiffen up the chassis is of interest too me; so I bought & installed one....
a) I didn't notice any difference in chassis stiffness with it installed.
b) It is well designed, easy too install, & fit perfectly.
c) It requires longer trans mount bolts; regular T5 (long) bellhousing bolts worked perfectly with my Energy Suspension poly trans mount. I also used large flat washers to keep from galling up the aluminum surfaces around the slotted holes of the crossmember.
d) Suprising side benefit was found though; darned if it didn't dampen the 70mph driveline vibe. It's still there; i just hear the "vroom" instead of both hearing & feeling it through the chassis....
e) Jack was right about the thin stamped steel gussets that the crossmember mounts too; they now are likely taking all the chassis flexing stress. I plan on reinforcing them with plates that also tie into the frame rails.
f) The billet crossmember has very elongated \ slotted holes for the trans mount location. This allows the installation of the TKO series transmissions. It's an option for those whom would have to buy a FRPP crossmember anyways....

 

Anyone

Anyone else using one of these? I can't decide wether to buy one or not. I bought an energy suspension mount, but I can't decide wether this is a good option for me or not.

thanks,

Matt

 

Did you even read anything in this thread?

 

Wow. In my opinion, colossal waste of aluminum and cash.

 

if you got time and a welder i would box in your factory crossmember and add the solid bushings, some support to the frame tabs and be done with it. you will never see it anyway. as far as stiffing the chasic im sure it dose with the solid bushings to tie the frame rails togeather but you still need to support the tabs it bolts to. id rather spend a few hours cutting metal and welding up my own and only spend maybe $30 for everything then $140 for that. unless you got a show car with a detailed under body as well then ya go for it

 

From an engineering perspective, that crossmember will never truly stiffen the chassis, because each end is able to rotate on it's mounting bolts.

Since it is a very stiff component, all it will do is decrease the amount of crossmember flex which would have existed if the old crossmember had been left in place. Even if it were bolted to massively thick and stiff mounting brackets, it still doesn't increase chassis stiffness, since both ends can rotate on their mounting bolts.

To increase chassis stiffness the crossmember needs to mount to each subframe in such a way that they can not move or rotate relative to one another in any direction. The Mustang crossmember does not do this, it allows each subframe to rotate on the bolt axis.

 

I have it installed with my Tremec and poly mounts. Seems good. I didnt drive the car much with the stock crossmember so I can't compare. Car feels fine though.

 

It looks like it at least provides additional clearance for exhaust which was a problem with my kooks that required a good amount of $$ to get the H-pipe to work and then line up with the catback.

 

Looks like one of those things you buy when you have absolutely everything else you can buy for a Mustang.

Kurt

 

Xmember

Yeah I read it.......Just wanted some more opinions. I think that I am gonna pass on it too, since I don't have everything else on the car! The one thing that would be very nice about it is the ease of adjustability to a different trans, although after this TSI I probably won't be changing anytime soon.

Matt

 

If I had a show car i'd buy one and it would have probably helped me with my tremec install a bit but the AOD crossmember lines up fine