Bundle of Snakes Clearance Issue

[Pasha Saleh]

So my exhaust headers just barely clear the crossmember. In fact, one of them is ever so lightly resting on it and the other has a tiny clearance (maybe 1/32"). You can see in the pix that the part that is interfering is the "thinner" diameter and where the collector slips over the header tubes is just touching the outside edge of the crossmember.

Would it be a good idea to put something in between there to reduce the likelihood of the pipes wearing through? I thought perhaps a strip of heat shield fabric (the kind that is woven ceramic with a silver coating on one side)? Or even thin strip of pine door shim? The idea being that the middle layer of the sandwich would wear before the pipes. The other side of doing that is that it puts more pressure on the pipes which, for now or not under much if any force resting there (at least not when cold).

I've got about 500 miles on the car so far with it this way and so far it doesn't seem to be an issue. I also can't tell if there is any movement back there between the Prothane engine mounts and the stiff bushing holding the ZF in place.

Any thoughts/suggestions?

 

[Walter]

Hi: Maybe it is possible to slightly reshape the one pipe which touches to avoid direct contact with the cross member? A competent custom exhaust fabricator should be able to help. I would not wedge anything in between. This could increase pressure and hence friction between the surfaces. Not many materials would take the heat from the exhaust anyway. Heat, on the other hand, should not be a problem for the cross member, given a small gap. A (small) gap will also protect ceramic coating, which I highly recommend. Good luck with your car!

 

[Pasha Saleh]

Good thinking and thanks for the quick response, Walter!

I'm not concerned at all about heat, but rather wearing that could rub a hole through the thin-walled exhaust. But then again, I can't tell if there's any movement at all back there. It is rigid as hell when I try to move it while cold. Maybe I'm worrying about something that's not an issue. That wouldn't be the first time, especially on this car!!!

 

[Randy V]

I think I would put a couple washers between the block and motor mount on both sides to see if that would buy you the needed clearance..

 

[Bill Kearley]

Motor mount and trans mount shims, an easy fix.

 

[Fred W Ballinger]

You only looking for a tiny bit. I would put a block on a convenient surface and put a long lever under the collector and try bend the assembly up a slight amount. The headers might move fairly easily, particularly if you do it while they are good and hot after a run

 

[Walter]

I think I would put a couple washers between the block and motor mount on both sides to see if that would buy you the needed clearance..

 

[Walter]

Motor mount and trans mount shims, an easy fix.

unfortunately not this easy if it's a RCR

 

[Brian]

The interference is the transaxle mount.

That being said, there may be enough slop in that mount to gain the clearance. Loosen those 2 bolts, jack the transaxle a little and retighten.

 

[Randy V]

unfortunately not this easy if it's a RCR

If your engine is a Ford small block or windsor block, the motormounts mount to bosses that are parallel to the ground. Pull those two bolts out on each side and put 1/8” washers between the block and motormount and reinstall bolts. Your engine will now be 1/8” higher in the chassis.
I had an RCR and played with this myself.

 

[Terry]

Unfortunately with spirited driving the headers will contact the cross member, trying to bend the tubes will only cause leaks = shim the motor mounts

 

[Randy Folsom]

I think a bigger concern than rubbing is cracking a header tubing because of the stresses, especially during spirited driving. I agree with other’s comments to use shimming washers to raise the drive train.

 

[Terry]

Yes they will crack, i have seen it happen also when they’re not supported correctly

 

[Bill Kearley]

After looking at the pictures again I take it that the trans is hung from that bolt. I don't know the RCR.
Is their any way to delete the bolt and make a mount to support the gear box from below so you can play with the height ?

 

[Pasha Saleh]

If your engine is a Ford small block or windsor block, the motormounts mount to bosses that are parallel to the ground. Pull those two bolts out on each side and put 1/8” washers between the block and motormount and reinstall bolts. Your engine will now be 1/8” higher in the chassis.
I had an RCR and played with this myself.

Shim up the motor mounts but leave the transaxle mounted as-is?

 

[Pasha Saleh]

The interference is the transaxle mount.

That being said, there may be enough slop in that mount to gain the clearance. Loosen those 2 bolts, jack the transaxle a little and retighten.

Thanks, Brian! That definitely would be the easiest fix. Even messing with the motor mount bolts is a nightmare in terms of access. And I definitely don't want to have to take each header tube off again -- it was near impossible getting them to fit into the collectors the first time! I'll give that a shot and hopefully I can get even just a 1/16" clearance if it doesn't sag back down again.

 

[Randy V]

Shim up the motor mounts but leave the transaxle mounted as-is?

Yes. Your transaxle mounts should have enough compliance to allow the lifting of the engine. If not, you may need to file the bushings a little. I think I would loosen your transmission’s support bolts while jacking the front of the engine up. Most of this effort will need to be done from the bottom of the car.
I had a Porsche G50 in my car and RCR did not offer any sort of transmission support. Instead there were bushings installed in the transaxle adapter which solidly located the engine. I did fabricate my own support system for the G50.

 

[Terry]

Yes it is an absolute pain trying to get to the motor mounts, if you shim the engine it will change the geometry at the cross member just a little, but with the aluminum cross member, it can be clearanced gently and made to look good, just a thought

 

[Terry]

Thinking about this for a day, when I get to the shop, I’ll see what I can do about building a couple offset bushings for the transmission / upper cross member, all the 40s I’ve worked on had the steel x member and there were no clearance issue , I’ll keep you posted

 

[Terry]

Actually looking a lot closer at the pictures, can you or can you have someone with a mill take some off the mating surface of the support block where it bolts to the transmission?