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MG TD TF 1500 - Original muffler type

Can anyone advise as to the factory original muffler type (baffled or straight-through with packing) for the later-TD and TF series?

Old pictures show the inlets and outlets being offset from the muffler body centreline - that would seem to indicate a baffle design rather than for a pipe running straight down the centreline and fully surrounded by packing. Perhaps someone has disassembled an original unit?

Back-pressure issues aside, can a modern straight-thru design match or beat a baffle style for best exhaust quieting?
David Padgett

I thought they were all like that.
Dave H
Dave Hill

I have, what I believe to be, an original mufflet. It’s not quite. But I love the sound.

Jim B
JA Benjamin

Best of my knowledge was that the originals were baffled. It was all the rage in the 50's and 60's to swap out the original muffler for a "glass pack" straight through muffler. The tone on the straight throughs was generally a bit louder and sounded more sporty so many street cars got them just to turn heads.
Christopher Couper

I have an original with the bolt on front pipe.

The entrance and exit are in line and you can see through them. There is a mesh screen the length that allows the sound to be altered.



Bruce Cunha

Front side

Bruce Cunha

Screen





Bruce Cunha

Thank you all.

Great pictures Bruce. Obviously a straight-thru type.

With my 'crackling' exhaust, it looks like I'll have to dispense with 'originality' and go for a tri-flow (baffled) replacement. The local cops have restarted roadside noise checks.
David Padgett

How do they handle noise in OZ? Maximun decibel limit or within factory specifications? (obviously no specifications for an MG)

I assume they are following ISO 5130:2007. for noise measurement.

If you want to test it yourself, it is not hard.

My job included doing a lot of sound measurements, so if you want to test your muffler, let me know and I can write up the test.

While not as accurate as the meters used by the police, you can download an app for your smartphone that will give you a good idea if you are ok.

I actually beat a ticket my son got on his Ricer. Laws in Wisconsin are based on the factory decibel level.

Cop was basing his ticket on what he heard. I was able to show that the sound level (decibels) was fine, but the frequency of the noise was different.

The thing we commonly call a muffler is actually a frequency modifier. It just takes the engine sound and shifts it to a lower frequency so we don't perceive it as noise.
Bruce Cunha

I guess no one measured dezibel in the 50th. When I was young it was common to speak about Phon.

Here in D you must have a document for each car on the road. Mine is from 1991 and for my TD you can read 82D. May be that is "Phon" or it is dB(D). As far as I know there is no simple transfer from Phon to dB(A). Because lack of equipment no policeman is able to measure the right way if that value/unit in the document would be Phon ;-).


W_Mueller

Bruce,

Yes, in Australia, we have controls and standards for noise management within the community determined by government authorities, both at state and national levels, similar to the Environment Protection Agency in your country. This includes noise produced from motorised road vehicles.

The testing methodology is in accordance with the ISO 5130:2007 standard, specifically with the sound level meter microphone at 0.5m distance from the exhaust outlet, 45deg offset from the gas firing line.

For passenger vehicles manufactured before November 1983 (T-series), there is a maximum decibel limit of 95dB(A), with the box in neutral and the engine spinning at the specified max power output (wow!).

Cars built after that date (both local and imported) have to comply with an Australian Design Rule standard which is based on factory specifications for each model, rather than a blanket maximum decibel limit, as above. (The list is huge!)

Interestingly, in one document I noted that for pre-1983 cars, in addition to exhaust noise levels, measurements are also to be made around the engine bay - tappet clatter, perhaps???

I have a working sound level meter - I'll do some measurements, both with the current muffer (which is definitely crap) and the new replacement unit.



David Padgett

The more important reading is decibels and what scale they use. Usually A or C.

You can change the decibel reading just by putting on a muffler that changes the frequency. Get one that lowers it on the A or C scale. It will not change power, but the majority of sound will be below what we pick up as humans
Bruce Cunha

I manufactured my muffler for the TF 1250 and have been pleased with the resultant T type sound and function. Straight through 'Burgess Patten'.

Tubing(mild steel).
Barrel-16swg(1/16" or 1.5mm approx), 4" diameter,24" in length.

Inner Tube-16 or18 sag,1 and 3/4" in length x 32" in length. Inlet end to be swelled out to take 1 and 3/4" tube-compression slots(2) to be milled. Outlet end left plain. Projection of inner tube beyond Barrel ends i.e.4".

Perforate inner tube with 1/4" diameter holes, pitched 1/2" centres. Total of approx. 330 holes. Holes to be clear of Barrel ends by 1".

Barrel End Plates-16swg in mild steel.Cut circles to neat fit internal diameter of Barrel,then with hole saw cut out hole for inner tube centred 9/16" off centre of Barrel.

Weld end plate(inlet)to Barrel with inner tube in position and supported by Jig Plate IN correct attitude(offset) at outlet end of Barrel.

Weld inner tube to end plate.

Remove Jig Plate. Load long strand fibreglass into silencer to fill with LIGHT
tamping. Weld end plate in position (correct attitude)as done at inlet end.

Paint muffler with high temperature resistant paint.

Cheers
Rob Grantham
TF3719("Aramis"),TF9177("Athos").
Rob Grantham

My TF1500 has a Lukey, nice sound.

Peter
P G Gilvarry

Rob,

Thanks for the excellent detail of your muffler project.

With too much time on my hands these days, I have considered making one up myself. However, I'll see how I go first with another type that I have on hand.

By the way, why have you offset the inner tube from the barrel centre-line? At only 9/16", does this offer some sort of 'resonance fine-tuning' or does it just provide a better fit in the car? Or, is it a Burgess 'thing'?

cheers,
David



David Padgett

David,

The offset(vertically) allows for a better line up fit, ground clearance etc. I think originally the muffler was also constructed that way. As you no doubt already know on TDs and TFs,the fit is very close to the chassis member and of course the dreaded downpipe just misses the actuating lever on the sump pivot !

Glad you liked the muffler construction detail.

Cheers
Rob Grantham
Rob Grantham

I've had 2 TDs (new) and 2 TFs - both new. So I know about which I speak.

In both cases, at least in North America, the original muffler was not straight-through. It was baffled. But the only way of knowing this, is to saw off the actual muffler because it was a one-piece welded exhaust system running from the manifold to the tip of the exhaust - no bolts, no separation ... just a single pipe with a muffler (silencer) welded in, and about 6 feet long. I still have my original, one-piece, welded system and will be glad to send pictures (on request) as soon as I can get into my shed (blocked by snow for now).

Gord Clark
Rockburn, Qué.

Gord Clark

Gordon,

We do know that TFs originally had their exhaust system welded together ie.the downpipe to muffler to tailpipe. A given from relatively untouched cars.

However,have you already at some stage in your ownership actually cut up a muffler to come to the conclusion that it was originally baffled ?

Cheers
Rob Grantham
TF3719("Aramis"),TF9177(Athos").
Rob Grantham

On this topic, what do you make of this muffler on a left hand TD? Factory picture. When you blow it up, it has a huge muffler that appears to be polished ?

Bruce Cunha

Bruce,

You would certainly get a warm seat from that TD muffler. Ouch !

Cheers
Rob Grantham
Rob Grantham

And polished. Wonder if it was just thrown on to take the picture?
Bruce Cunha

Rob,

I didn't cut up mine. Mine (old one) is still (barely) intact. Its been patched many times, but was at the point that I was afraid it was going to blow up some day! David Sander, a frequent contributor to this forum, had an unused system that he gave to me, and that's what's on the car now. Doesn't sound nearly as original, and is a bit loud for me.

No, I found another (original) damaged one and in trying to rescue it, ended up cutting off the original one.

Gord Clark
Rockburn, Qué.
Gord Clark

Rob,

Early version of the modern seat-warmer perhaps?

A warm seat could be quite pleasant in colder climates.

Not here in Oz though!


David Padgett

I remember my first ride in an MGA. Friend and I installed a new muffler. Somewhere along the drive, I noted it was getting warm down by my feet. Yep. Just a little to close to the floor.
Bruce Cunha

I just noticed a correction needed in my write up of the Muffler making.

Under 'Inner Tube' it should have stated 1 and 3/4" in diameter, not length
as quoted.

Cheers
Rob Grantham
Rob Grantham

Per German and Australian regulations the rice rockets and Harleys here would never pass.
John Quilter (TD8986)

This thread was discussed between 28/02/2019 and 11/03/2019

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