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1275 Engine Rebuild


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#46 GraemeC

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Posted 11 February 2019 - 08:19 PM

New standard rubber mounts front and rear or ALL solid mounts front and rubber mounts rear. Forget poly.
And definitely forget springs - just install new, GENUINE donuts.

Little gain in increasing track (I’m assume you have disc brakes) and it will almost certainly mess up the suspension geometry.
Bad tramlining means you need to get the suspension alignment (tracking, camber and caster) measured, adjusted and optimised. This may involve fitting adjustable kit.

#47 KTS

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Posted 11 February 2019 - 08:29 PM

solid mounts should improve the way the car responds to steering inputs, and may improve handling under braking as the subframe can't twist as it can with rubber mounts

You'll get a little more noise transmitted to the shell through solid mounts, but a minor downside compared to the potential gains

If you go with solid mounts, the rear and tower bolt mounts (spacer top & bottom) must be done at the same time. The front teardrop mount I think is less critical. As long as the rear and top mounts are solidly fixed the front of the subframe shouldn't move, so the standard rubber teardrop mounts should be OK to hold the front panel in place

Also worth considering reinforcing the toeboard around the subframe mounts if you're switching to solids mounts

#48 Will96

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Posted 11 February 2019 - 09:09 PM

Thank you guys. Yeah you're correct in assuming I have disks. Also got hi-lo's set up so my ride height is around cooper ish. Purely for aesthetic as I thought the standard for the mini 850s were a bit high for my liking. If the noise isn't too bad then i think solid sound like a good choice then. As it'll be a 1380 I'm a bit concerned with vibration noise, as my current 998 is already ear bleedy around 4500 rpm. So if anyone has any tricks or tips, I'm open for suggestions :)

#49 grizzler73

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Posted 11 February 2019 - 09:50 PM

Steer clear of the coil springs. Dangerous. Stick with rubber cones.

#50 Cooperman

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Posted 12 February 2019 - 12:00 AM

If you want it to drive as the original Mini did with that special precision and great steering response, then fit the solid mounts to the sub-frame. Do not fit those horrible poly ones.

 

As mentioned before, the reason the car was fitted with rubber front sub-frame mounts was because at that time the target market had changed form younger drivers to middle-aged lady drivers, so NHV reduction was considered more important than dynamic steering response. So the question is whether you want an 'old ladies' Mini or a 'responsive' mini. The choice it yours. Personally, I never notice much difference in noise, harshness and vibration with solid rather than rubber mounts, but there is a great difference in feel and steering response with solid.



#51 Will96

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Posted 12 February 2019 - 07:59 AM

Excellent. Well looks like new rubber cones and solid sub mounts then. Thanks for the responses.

#52 Will96

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Posted 16 February 2019 - 10:03 PM

Right. Next bit of the journey while my pistons are yet to return from the garage. I'm coming up to fiting my water pump and I noticed it is the type for fitting a bypass hose. Firstly, I'm a bit confused as to where the other end of the hose connects to, my suspicion is it's for the cylinder heads with a take off on the front of the engine, but mine isn't like this, nore have I ever seen how it's set up. Also I've had a quick read through some of the threads on here about blinking them off or actually using them and the information is very back and forth, I do plan from upgrading to a modified head further along the line as current is just a standard 1275 A+. So does anyone have any recommendations as to blanking off or using the bypass?

#53 Retroman

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Posted 17 February 2019 - 08:23 PM

Just blank it off

 

When the head comes off you don't have to think about it, and its less to go wrong

 

It can be tapped out and blanked or capped with a rubber cap



#54 Will96

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Posted 18 February 2019 - 08:07 AM

Oh good. That saves me a job then. Thanks :)

#55 gazza82

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Posted 18 February 2019 - 11:31 AM

There was a factory-supplied blanking plug because the thread is an odd one .. I may have bought the last one in the UK about 18 months ago!! :-)



#56 Retroman

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Posted 18 February 2019 - 11:43 AM

For the water pump by pass take off ?  

 

Later heads and water pumps were all blank....with a plug in the head instead of the pipe 

 

and the water pump take off was a solid casting.



#57 Will96

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Posted 07 March 2019 - 03:09 PM

Update time. Progress has been a little bit slow due to cold and miserable weather but I've now got the block pretty much done, pistons, crank and cam are all happily in and turns over relatively easy. For reference so far the only upgrades made have been the Evo001 cam, and a minispares uprated oil pump, piston rings are for standard compression, and went with some pretty standard none lightened followers, simplex timing gear with "None-stretch" chain (as I'm not going to be sat beyond 5000 rpm). Working my way to the head, as I said, for now I'm sticking with a standard A+ head (12G I think) and looking at replacing that in the future once funding for a respectable one is in place, based on whats been said on here I've chosen to stick with standard push rods, and think I'll stick with standard springs (Although doubtful of that choice), and I'm unsure on whether to replace the valves, as they are setup for unleaded but i don't know whether there are further improvements which would be relevant to a road car, or whether to just regrind the current ones into their seats. Also I'll be running a standard fuel pump, and electronic dizzy (open to recommendations). So if anyone has any suggestions or thoughts on the setup so far or additional things which would help improve the overall usability and reliability I'm open to conversation. Going forward I'm also after suggestions for carbs if anyone has any favourites they like running with 1380's. Thanks  :proud:  



#58 Will96

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Posted 07 March 2019 - 03:37 PM

Also i know this is quite a loaded question, but since I'm after a comfortable motorway drive, I'll be after 70mph at around 4500  rpm in a 4 speed on 12", I'm yet to look at the 3 gearboxes i have to learn what diffs they're running, but I've been reading into 3.1 diffs and how its the right balance of acceleration and top end speed. Is anyone against this, or will this be a wise choice to make?



#59 Minigman

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Posted 07 March 2019 - 05:56 PM

Also i know this is quite a loaded question, but since I'm after a comfortable motorway drive, I'll be after 70mph at around 4500 rpm in a 4 speed on 12", I'm yet to look at the 3 gearboxes i have to learn what diffs they're running, but I've been reading into 3.1 diffs and how its the right balance of acceleration and top end speed. Is anyone against this, or will this be a wise choice to make?


70mph with a 3.1 and 12” wheels come at around 3600rpm so you could afford to go 3.44 which is about 4000rpm. It’s worth having a look on Guessworks website. He has a ratio calculator which gives indication of rpm at certain speeds.

#60 Will96

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Posted 10 March 2019 - 11:03 AM

Thanks, quite a useful website. I suppose in a realistic scenario do I really need to be splitting hairs for acceleration when running a 1380




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