Can anybody tell me the thread of the temperature sender unit. It is the exact fitting for the vacuum take off on my Mini Spares inlet manifold and I need to get a booster fitting. I've had no luck so far everyone only sells BSP, and I have a feeling it's actually UNF.

From a while back...

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

What Mick said ^^.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

What Mick said was what Doc said^^

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

OK that's what I get from skimming what `you wrote' I thought...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

My brain hurts.

If we keep this up we'll cause a tear in the space and time continuum leading to certain doom for us all!

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Well I talked to the local Pyrtec bloke and he reckoned my best bet is to run a 3/8 BSP tap through it and put a BSP fitting on. Seems my only option, especially as I want a right angle fitting. I can get a straight fitting that fits fairly well (still not 100% right tho), and I could put a 90* fitting on top, and it starts to get messy after that!

Send me a 3/8 BSP nipple or bush and I'll rethread it to 5/8-18 UNF in my lathe..
Only about 1mm diameter and 1TPI difference between `em.
I do this stuff all the time, I have all different thread taps and dies here at home...
It saves making the head non-std.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The thread I'm tapping is the brake booster hole on my inlet manifold not the temp sender. Same thread as the temp sender. In fact, the temp sender works better as a blanking plug than the plug that comes with it! Maybe I could use it to measure my intake temps....
What thread is the bypass hole on the cyl head? I found the adaptor for that is a close fit, however if is a straight attachment not right angle.

Bypass adaptor allegedly is 5/8-16 UNS (bastard thread).
However, I routinely remove rusted out ones by drilling then using my 5/8-18 UNF tap. It works fine. There are only about 4 threads in this hole anyway, it's very short, so whether actually 16 or 18 TPI is academic.
I make new adaptors from hex brass, they never rust out like the stockers all do.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

It's interesting, I was just out in the garage playing around with it, the current crop of new GTR104 sender units fit perfectly, yet the other two older temperature senders I have don't fit perfectly. Perhaps they are UNS (as they fit similar to the bypass adaptor) and the new GTR104 is UNF?? Probably would help if I had a thread gauge!
I'm no expert at using thread taps but I assume there is no problem running a 3/8 BSP tap on the manifold, making the adaptors and blanking plugs universal.

The older senders are a pretty neat fit in the head, not sure about the new.
If you tap the block out to 3/8 BSP, a 5/8-18 sender will no longer fit, it will be too small.
I come across this problem all the time in my welding engineer profession where people are forever mixing up 3/8 BSP (European standard) and 5/8-18 UNF (Oz standard) for gas hose fittings on welding machines.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

New ones are probably metric

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

The metric standard for pipe threads is R1/8, R1/4, R3/8 etc.
These are really BSP threads, not Metric at all..
Chong has a MG Metro head on his car now and the sender thread is same as all previous.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Well I got it sorted this morning, got the thread tapped and the fitting put in so now I have the booster up and running again. I quite like it! It's the first time I've run the booster in years and I'd forgotten what it was like, not overboosted, but does feel a little bit more responsive for 'normal' braking.

Anyway, I was bleeding the brakes, the old fashioned method (I have a pressure bleeder but wasn't using it) and the back brakes won't bleed properly. When I open the bleed valve a tiny bit of fluid comes out but the brake pedal barely moves... certainly won't go to the floor! I think the bias valve may have had it? The rear hoses have been replaced in recent memory and the wheel cyls aren't that old, but what concerns me is that both do the same thing. And although the brakes work on the road, with a bit of hard braking on slow corners I'm wondering if the back brakes are really working at all. Any suggestions?