SpeedTech ATS T56 crossmember with BBC

[chr2002ca]

Just trying to get some important information out there about using the latest version of the SpeedTech ATS T56 ADJUSTABLE Crossmember in a first gen Camaro(or 68-74 Nova) runnig a BBC.

On the product description page on SpeedTech's website, there are no special notes about the BBC or links to the instruction sheet(PDF) that might allow you to read about any special notes or installation gotchas:

http://www.speedtechperformance.com/...rod/prd213.htm

However, when you pay the $38 shipping charge and open the box, the instructions immediately let you know about the following fitment restriction:

*Customers running a BBC will need to run SBC engine frame mount stands

This is a rather important note and it's a little frustrating that they can't post this on their product description page. For many of us BBC folks, we use BBC frame stands to offset the engine to passenger side by 3/8" so that our expensive headers will fit(steering box), and we've designed other things around that offset also. So switching to SBC frame stands to make a $369 adjustable crossmember fit is not an option.

So I'm just wondering about this restriction as I look at the crossmember itself. If Speedtech is reading this(Blake?) and can provide input as to why this restriction is in place and if there are any workarounds, please let us know. The only reason I'm asking on this forum is to create a documented discussion about it so that it shows up in internet searches for the next person.

My transmission comes in on Monday so I plan to do a trial fitment next week regardless and I'll post my notes here. I'm looking at the crossmember and the plates that bolt to the frame holes and those plates have slots, not holes, meaning the plates can possibly be moved (left/right) in the car. I'm not certain why I can't just position the crossmember 3/8" to the passenger side to match the offset of the engine, but I'll know more shortly when I actually try to put it in. It's a nice crossmember that allows great clearance for the exhaust which is critical for me so I want to make this thing work.

Anybody else who's done this install with a BBC, BBC frame stands, a T56, and this latest version of this crossmember is welcome to chime in here also.

[XLexusTech]

Yeah thats a bit of a piss off... I can see where that would boil your blood...

[chr2002ca]

Yep, it does, but at the same time, I'm hoping I can get this to work okay and in the end it wasn't really much trouble at all. Who knows, maybe it'll work with little to no modification. Regardless of my own results, I just wanted to get this information out there for the next person researching T56 crossmembers for this type of application.

[BBC71Nova]

I had my bbc w/t56 just mocked up in my oe frame using big block frame stands with the correct offset and the ATS crossmember. It did seem to fit good.

Previously I tried an older set of repop frame stands that were Listed as big block stands and that didn't work. Those stands had the driveline sitting a little farther back and outside the range of the ATS crossmember. Those frame stands also had other issues with my setup. I dont think they had any offset to them.

Anyway, dimensionally I think you may be ok. My only less than great comment about this crossmember is it seems to flex a lot. Mute point for me now since I'm moving drivetrain back which will require custom crossmember

[chr2002ca]

Originally Posted by BBC71Nova

I had my bbc w/t56 just mocked up in my oe frame using big block frame stands with the correct offset and the ATS crossmember. It did seem to fit good.

Previously I tried an older set of repop frame stands that were Listed as big block stands and that didn't work. Those stands had the driveline sitting a little farther back and outside the range of the ATS crossmember. Those frame stands also had other issues with my setup. I dont think they had any offset to them.

Anyway, dimensionally I think you may be ok. My only less than great comment about this crossmember is it seems to flex a lot. Mute point for me now since I'm moving drivetrain back which will require custom crossmember

Thanks John for the feedback. Glad to hear it fit okay for you in a similar setup(I have an OE frame also). Seems like it would just by looking at it. I'll know for sure next week. I can see how it might flex. That could a be a bit of an issue considering my new ZL489 motor should be fairly stout.

What HP/TQ numbers were you seeing that caused the flex? Do you think the main source of the flex is from the side brackets(which I might be able to strengthen) that bolt to the frame, or the bar itself?

[rchaskin]

I would have to say the flex he is talking about is up and down bounce.

Mine does this also. (My car is SBC & LT1 style T56)

I added some gussets from the downtubes to the bottom plate and it did not help much.

I currently have mine trans out, and will be adding a full 3/8" plate to cover the entire bottom of the bottom plate. There are so many cut outs in the ATS plate it just flexes.

---I am not saying that this is a bad part or anything, because it fits perfectly, just a little bouncy for me---

Good luck
Randy

[chr2002ca]

Just spoke with Speedtech by phone and they mention that this restriction is related to more easily setting pinion angles, not with the crossmember actually fitting. As long as you shift the crossmember to the passenger side by the same amount that the BBC frame stands do(3/8"-1/2"), you'll get the proper straight alignment for the engine/transmission to match the alignment of the rear diff, hence getting the left/right pinion angles to match on the driveshaft u-joints. Speedtech said the crossmember is left/right adjustable which makes sense due to the slots on the bracket, so this should not be an issue. Also, you have to deal with the up/down pinion angle caused by the height of the BBC frame stands, and that's something I was already aware of and realize some trans tunnel modifications might be in order to get the transmission high enough in the rear to get a minimal and matching up/down angle with the rear diff.

So Speedtech's restriction in their instructions is more of a warning than an absolute.

[chr2002ca]

Originally Posted by rchaskin

I would have to say the flex he is talking about is up and down bounce.

Mine does this also. (My car is SBC & LT1 style T56)

I added some gussets from the downtubes to the bottom plate and it did not help much.

I currently have mine trans out, and will be adding a full 3/8" plate to cover the entire bottom of the bottom plate. There are so many cut outs in the ATS plate it just flexes.

---I am not saying that this is a bad part or anything, because it fits perfectly, just a little bouncy for me---

Good luck
Randy

That's great info. Thanks Randy. I might as well do the same while it's out.

[Blake Foster]

Thanks for making the Call to talk to us about your concern.