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TR4/4A TR4A overdrive A-Type and "dual" Stebro exhaust

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Adrio

Jedi Knight
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I am working on installing an A-type overdrive into my 67 TR4A and have a problem the forum may have an answer to. My Stebro exhaust is two in and two out of the front muffler, two pipes (one to each) to the rear mufflers, and twin tips on each rear mufflers.

The problem I seem to have is the large drain plug (and casting for it) of the A-type overdrive seems to bump into one of the pipes between the front and rear muflers. I have not attached the overdrive to the gear box yet, and I would not want to tear appart my gear box and install the overdrive only to find out I have to undo all that work.

Does anyone have any experiance with this and what is my solution, if there is one.
 
Hi Adrio,

Ouch!

I know the TR4A stock exhaust system can be fitted alongside the A-type OD. What I'm not sure about is the Stebro system.

My TR4's setup is different than the 4A, of course. But, here's what I found, in case it helps.

At first, with the components out of the car, I was very concerned about clearance. But, there was more room than I realized. The header and exhaust I installed is the Falcon stainless steel *sport* system for TR3/4, and it uses the stock hangers. (In my case, it really helped that the body was off the frame!)

Still, it's a pretty tight fit in there, even with a single pipe and no forward muffler. You might have to route the dual pipes into a collector pipe instead of the front muffler and then split it again somewhere behind the gearbox, to route to the rear mufflers.

The system on my car has a 4-into-two header, leading to a large collector pipe, perhaps similar to what you have but without the forwad muffler.

That collector pipe doesn't go directly to a muffler. Instead it leads to a larger single pipe and eventually that leads to a single rear muffler. There is a joint between the collector (or front) pipe and the rear pipe, and a hanger/clamp (stock TR4 type) right at the rear gearbox-to-frame mount.

You might look at the exhaust systems illustrated on RevingtonTR, TRF, Moss motors, Moss Europe and Rimmer Bros. websites to try to get some ideas.

Let us know how it works out. Post some pictures if you can.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
 
Re: TR4A overdrive A-Type and "dual" Stebro exhau

Alan,

This tranny failure come tranny replacement come overdrive building has turned into a "project"! Thanks to you, Don and the folks of the forum it has been a tolerable forum.

As to what my Stebro looks like. If you take the "TR4A (as fitted)" that the Moss catalog has (the middle one of the page that has a forward muffler and two rear mufflers. That is what the Stebro I have looks like EXCEPT the Stebro has TWO pipes coming out of the front muffler (one to each of the rear mufflers). I suspect the stock front muffle has the one pipe on the right side and that would give the clearance I need. Mine has one on the left as well.

I took some measurements and I need to move the pipe eiter 7/16" down or 11/16" to the right. This does not seem insurmountable. So I have taken the entire exhaust off and will march it down to the muffler shop in the morning to see if they can "tweek" it for me.

My fingers are crossed. Yes I will post some pictures. In fact I might have some time tonight to add a section to my web site describing the O/D soap opera. I will let you know when/if it is up.
 
Re: TR4A overdrive A-Type and "dual" Stebro exhau

Adrio, I too have a 4A with overdrive, but like Alan have used a header with large single pipe, and had no clearance problems. (This pipe was 2.5inch o.d.)
I am now changing back to a port matched cast 4-2 "header" with the stock secondaries and in place of the front resonator a 2 into 1 pipe, from there back a single 2.25 inch pipe, which is big enough!
The only significant difference from a clearance point of view is that your resonator has two outlets; I think this should not be a problem as it will be quite far back at that point, but really cannot tell without seeing it or measuring.
Good luck! Simon.
 
Re: TR4A overdrive A-Type and "dual" Stebro exhau

I fudged around a bit and spread all the joints to give me max play. Things are tight but it may work. So today I started the tranmission tear down to move the guts of one into the case of an other so that I can attach the overdrive of a third. I hope to have it all together tomorrow and will let the group know how it is progressing.
 
Re: TR4A overdrive A-Type and "dual" Stebro exhau

Adrio,
Sounds about par for the course with Stebro's. They were good systems IF you could get them on. At my old shop it always seemed as if you had to cut, file, or hammer away to get them in. My guess is they were all designed on paper and put into production without putting it on a car first.
Tom Lains
 
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