Steel main centre bearing strap

[picky]

Ive got a midly tuned 1098cc engine, and I dont want to damage it, what is required to fit a steel strap to the main bearing? Ive read somewhere that bits need machining??

[les]

Basically it's just a steel strap, usually rectangular in section with two holes in it at the same centres as the cap. If the cap has a machined flat top the strap will not require machining, providing of course the strap is made from bright bar.

[Alec]

Hello all,

normally the cap needs maching flat for the strap to bear on. You will need spacers to go between the cap bolt seats and the strap and these spacers should be a few thou less in height than the bolt face to cap\strap seating area to give some pre load to the strap. Obviously longer high grade bolts are required also.

Alec

[picky]

So I would need to remove the cap, and have that machined, but the engine block could stay in the car?? Minispares are selling a centre strap for a 1275 mini block, will this fit? Im assuming the spacing is different on the bigger block.

[turbominor]

I think you need the 998 mini one to fit a 1098.

I have one on my last tuned 1098 and broke the rear bearing cap

[picky]

could you fit anoth one to the rear bearing cap aswell?? or would that be overkill..

[turbominor]

only if you run without the sump

[Alec]

Hello Iain,

as I haven't an engine in front of me, I'm making an assumption, but logically, as the rear cap bolts are within the confines of the sump, surely a strap could also be fitted within the sump. This would support the bearing section of the rear cap.

Alec

[turbominor]

Hi Alec

not sure if there is enough metal on the rear bearing cap that is not covered by sump when fitted..sure the bolts are not covered though

odd i have never blown an a'series up.. always broken the rear bearing cap..

[Alec]

Hello Iain,

lighter flywheel?

Alec

[turbominor]

had though of that.. Probable my do or die driving style when i was younger..

Was always towing something back then so the engines and box got a hard time!

[bmcecosse]

But a mildly tuned 1098 doesn't need a centre main strap. It's only for high revving highly tuned engines. I had one years ago on my Mini - made it myself - and just filed the flat on the cap. I used long Allen cap screws - never had any bother with that engine (and it was very highly tuned 998 revving to the heavens !) - and have never broken any caps on any A series engine - but I have broken a couple of 948 cranks - until I fitted a crankshaft damper from a Mini. That, along with an oil cooler, made the biggest difference for me. So if you want to improve your 1098 - get a crank damper !

[Alec]

Hello Bmc,

did you not get it tufftrided?, that can help with strength\wear issues.

Alec

[picky]

well my original intention of fitting the strap was to prevent any damage at high revs.. so bmc reckons that a crankshaft damper would be more appropriate than a centre strap.. anyone going to second that??

[bmcecosse]

Alec - I was a poor student at the time - now I'm just a poor engineer ! When the crank(s) broke - I wrapped them up in lots of oily paper and off to a far away BMC dealer in Glasgow for an exchange crank - carefully took the new crank out the box they had it in (for inspection !) , and slid the broken remains back into the box 'to save you getting your hands oily' !! Second time I used a different dealer !! And neither of them was the one I used for all my other regular stuff. Tuftriding had maybe not been invented back in these days (!) - and would certainly have been beyond my means anyway. The crank damper certainly worked for me - no more broken cranks, and it was well and truly thrashed on Rallies/Autotests/towing boats about/towing Autocross Mini on a trailer. It was very miserable of BMC to NOT put a damper on the in-line 1098 engines - the EastWest 1098 engines had them right from the start. Maybe they thought 1098 engines in Minors wouldn't be driven hard - little-old-ladies and so on. It's certainly easier to fit a damper than a centre strap (fit both if you can be bothered!) and you can still keep the starter dog.

[rayofleamington]

It was very miserable of BMC to NOT put a damper on the in-line 1098 engines

They probably thought it was rather miserable of people to tune the engine causing a broken crank, and to get the broken crank back for refurb

[bmcecosse]

Indeed !! Serves them right for not fitting a crank damper ! It was 948 cranks I broke.

[Onne]

So you broke 948 cranks.... quite a lot then.... LOL

[bmcecosse]

Just the two - and as a very poor student who relied absolutely on the car for travel to Uni - these were major catastrophies for me !! Crank damper and oil cooler were fitted - and no more problems despite thrashing it even harder - in fact next disaster was bursting the centre out of a clutch disk ! The only time I had to be towed home. At least with the broken cranks the car still got itself home !

[Onne]

Won't see a modern eurobox doing that!