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Standard Mini Exhaust Joint Solutions

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Andrewhurstca Avatar
Andrewhurstca Andrew Hurst
Port Williams, Nova Scotia, Canada   CAN
1961 Mini MkI "The Mini"
1965 Triumph Herald 1200 "The Herald"
I thought that I finally had the problem of leaking exhaust manifold to pipe joints licked when I installed a cast clamp last year. Now, after only a few hundred miles, the telltale black stains and noise tell me that once again, there is a small leak out each side of the clamp. I know it is a terrible design. I know that you used to be able to get a flexible repair piece that not only gave you a fresh flange but also reduced the strains on the joint (in theory anyway, I never got to try one). These seem to be no longer available. I have extra stabilizers to reduce engine rock. The bottom of the down pipe is connected to the transmission as intended, I always take care to clean the flanges and get them perfectly aligned before tightening the clamp (not easy!). The new clamp is still nice and tight but it seems to have pinched the pipe flange to create two bulges where the clamp halves meet which now leak. I have tried with and without exhaust sealant.

Has anyone had any success with gasket materials in this joint? Has anyone found a technique or descrete mod that eliminates this problem? My down pipe and exhaust are otherwise in great shape so I hate to replace the whole lot again. It seems that most folks have abandoned the cast manifold and have gone for headers and larger exhausts. My car is an otherwise original Mk1 850 and I would rather keep it that way. Until I get this sorted again, I am hesitant to drive much because of exhaust making it into the cabin.

Any suggestions, anyone? Andrew

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Andrewhurstca Avatar
Andrewhurstca Andrew Hurst
Port Williams, Nova Scotia, Canada   CAN
1961 Mini MkI "The Mini"
1965 Triumph Herald 1200 "The Herald"
I am amazed at how many views this post has received without a single reply! After more investigation and research, I have ordered parts to try another strategy. My '61 had a tab welded on the horizontal section of the down pipe for connecting with a vertical bolt to a part of the transmission casing. My tab broke off years ago and I replaced it with a strap clamp that simulated the tab and clamped the pipe when tightened. This seems to work itself loose which leads to the stress on the flange joint. I have ordered the bits for the later version of tranny clamp which will use a horizontal bolt to clamp from the back of the tranny casing to the vertical portion of the down pipe. Hopefully this will fit my early "magic wand" casing and will be secure enough to allow me to maintain a seal. Hope to get the parts before winter storage beckons.

zero250 Avatar
zero250 Jeff Steindler
Charleston, west virginia, USA   USA
MY solution on my 1967 mini 850 van is to use the stock, cast clamp ( 2 pieces ) , lubricate ALL the mating surfaces with grease ( clamp faces and headpipe flare ) and , as I tighten the bolts, SHAKE (or move around slightly ) the headpipe until all is tight................this has always worked for me........no leaks............

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Andrewhurstca Avatar
Andrewhurstca Andrew Hurst
Port Williams, Nova Scotia, Canada   CAN
1961 Mini MkI "The Mini"
1965 Triumph Herald 1200 "The Herald"
Thanks, I will try that. Which down pipe clamp arrangement do you have? Cheers, Andrew

zero250 Avatar
zero250 Jeff Steindler
Charleston, west virginia, USA   USA
I assume it is the stock arrangement with the cast " bulb " on the combined intake / exhaust manifold and the downpipe is simply exhaust tubing with a 'flare' at the end............and the clamp is the original 2-piece cast clamp................these parts were the original parts when I overhauled the engine back in 1977..............the vehicle DID sit unused for 24 years ( I made my own BARN FIND ), but it is still tight , quiet , and non-leaking as recently as yesterday, when I drove it last...............

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