Exhaust system with NG3 Trans

[wilkrod]

Hi All,
I am getting ready to replace the exhaust system on my 72 TC. It is equipped with a NG3 trans. I want to use the R.D header, and exhaust system. So does anyone have experience on fitting this type of exhaust? I would hate to buy the system, and then find out it won't fit.
Thanks

[Bryan Boyle]

Hi All,
I am getting ready to replace the exhaust system on my 72 TC. It is equipped with a NG3 trans. I want to use the R.D header, and exhaust system. So does anyone have experience on fitting this type of exhaust? I would hate to buy the system, and then find out it won't fit.
Thanks

I just did a couple months ago.  it will fit.  It's not plug-and-play, however.  Couple issues to be aware of:

1. the header pipes are welded on the head side of the flange.  This, combined with the gaskets, pushes the flange about 3/32" away from the head when tightened down.  I'd bring the header to a good exhaust shop and have them weld around the tubes on the outside of the flange and surface the head side flat instead.  This will give you some additional clearance to make the solution in #2 below a little less.

2. Watch the clearance between the outer two down pipes (cyl 1/3) and the shift tube and clutch cable.  I had to apply a little 'percussive maintenance' to those two tubes to give me a 1/4' clearance between the shift tube and the header.  My clutch cable (which is mounted on the later version cable abutment) still scrapes the header.  The #2 downpipe also contacts the left engine mount at the block end of the mount.  Same solution as the 1/3 pipes. 

3. the lower cross pipe will have to be shortened on the horizontal run a bit.  Not a problem, but, he gives you a little more than you need.

4. I'd go with the Profusion Exhaust Lap Joint clamps instead of his strap clamps.  Yeah, a few extra $, but just work 'a treat':
https://www.profusionexhausts.com/1-75-inch-45mm-stainless-steel-lap-joint-clamp-heavy-duty-exhaust-band-lp175ss/

you will need 2 of them.  Same size.  they really seal everything up nice and tight, and lock the whole system together.

Now, I don't know about how to mount the muffler box to the NG3; that will be left as a exercise for you... 

(Not dissing RD's system, just think there are a few tweaks that would help make it a true 'drop in' system.   There isn't much out there unless you go with the stainless lotus-supplies system, or fab your own.  Neither path is cheap.)

[wilkrod]

Bryan,
Thanks much, I can deal with having to make minor adjustments, just didn't want to be a total no fit situation.
Regards

[Bryan Boyle]

Bryan,
Thanks much, I can deal with having to make minor adjustments, just didn't want to be a total no fit situation.
Regards

He does a good job for what it is.  If I had to do it all over again, I'd have done the welding and machining job, but just 'adjusted' the as-delivered kit.  Not autocrossing/racing her, so, going to live with the minor restriction in the system that I created by the 'percussive maintenance'.  I'd also have it ceramic coated....they come painted black...which disappears in about an hour leaving the bare metal (the muffler stays black..I painted that with high-temp paint...)

Do go with those lap joint clamps, though.  They really really are the hot ticket; take a look at the photo... (Don't mind the oil stain on the pipe...that's from the leaky rubber head/block oil return pipe...on the list to get sorted this week.).

I've a feeling that the Banks stainless kit would be better...oh, by the by, you CAN back the center heim joint on the shift mechanism out a turn or turn and a half (which would put center to center at aprox. 2 7/8" center to center as shown in the manual vs 2 3/4") to get just an RCH more clearance without significantly changing the geometry, just a couple degrees 'twist' to the right of the shift lever ball, but it all works just fine (or has, for my install).  Like everything else...every assembly has to be 'fettled' to get it all together.  But, it's not a reenginering disaster, just *ahem* fine adjustment...lol.

[wilkrod]

Hi Bryan,
Thanks again for the info.
I am waiting to hear back from Banks on the cost of their S/S system.
Another question, on your NG3 how do you drive the speedo? I am not seeing a cable drive.
Thanks

[Bryan Boyle]

Hi Bryan,
Thanks again for the info.
I am waiting to hear back from Banks on the cost of their S/S system.
Another question, on your NG3 how do you drive the speedo? I am not seeing a cable drive.
Thanks

I'm still running a 365 as was delivered with the car.   

[BDA]

Hi Bryan,
Thanks again for the info.
I am waiting to hear back from Banks on the cost of their S/S system.
Another question, on your NG3 how do you drive the speedo? I am not seeing a cable drive.
Thanks

Be aware that the speedo drive gear in the NG3 will put your speedo off by about 50% (at least in mine it did, don’t remember which way). I’m not aware if the proper drive gear is available. You can do measurements and send your speedo out to be calibrated. An alternate idea is to install an electronic speedo (Smiths makes one but the design doesn’t match the old speedo) and drive it either with GPS or a mechanical driver which creates impulses sent to the speedo based on the rpm of the speedo drive gear. Also know that trannies have been known to chew up speedo drive gears (like mine did!).

[SwiftDB4]

Another question, on your NG3 how do you drive the speedo? I am not seeing a cable drive.
Thanks

Get a VDO electronic speedo. Calibration is easy and it doesn't look all that different from stock speedo. Speedhut makes a GPS speedo that requires no calibration at all, but is more expensive. As BDA said the cable drive won't be accurate unless you send your old speedo out for modification.

[BDA]

For reference, the first picture is of my stock tach and electronic speedo. The second is of a past member's SpeedHut setup. The SpeedHut unit is nice in that you have a choice of type face, needle design, etc. The "can" is a little bit larger because it's in inches rather than mm but the past member said it was simple to install. Part of the reason I chose the Smiths speedo is that I chickened out on opening up the hole in the binnacle!

If I hadn't sold my original speedo and knew what I know now (having taken my speedo apart in a failed attempt to convert it for electronic ignition), I would have traded the needles between the original and new speedo.