Gearbox casing strengthening
Turbo Mini Forums

Has anyone done such a thing ?

My old car had a habit of cracking the centre web ( later 3 bolt type )

Whilst it never developed further than that, has anyone else experienced this ?
I have no idea how long the cracks where in place for, as as soon as I discovered them, the casing was replaced.

If so, have you attempted welding up the box to strengthen it at all ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I know that Matt 'Miniwilliams' Woods has broken a transmission case before... And Carl Austin did the rear-one in his twinny. But I've no more info than that.

I believe it'd be REALLY easy to brace up the case - ESPECIALLY if you were happy to do away with the the speedo drive extension on the end of the mainshaft, and use the space to bolt in a 'saddle' between the front, rear and base of the casing, tying into the existing centre web at the same time.

That'd work a real treat methinks - but take a while to do properly :)

Edited by turbodave16v on 19th Sep, 2006.

Stevie, lots of questions tonight, are you bringing your mini back into life??

Team Racing

Breakages aside, I dont intend spending much more time/money on my Granada.

My mini has been sitting outside and hasnt really moved much for about 6-7 years, and not surprisingly is extremely rusty.

Its about time I did something about that, so I do intend working on it over the winter ( or replacing the car/shell itself ) and building a new one.

No doubt I'll spend more than I can afford again, but it should be a cheaper project than my current one !!!

I'll re-use as much of my old parts as I can, but do intend major upgrades and changes.
Times have changed, and technology has moved on, so I'd like to try and make use of that.

Unfortunately some areas of the mini are still the same, with the same weaknesses.
Just fishing for info at the minute, but I'll probably start stripping my own car very soon.

Edited by stevieturbo on 20th Sep, 2006.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

good stuff, look forward to hearing about / seeing your project!
Good luck mate

Team Racing

i did indeed crack the centre web on an A series box, [dunnom if this is of any relevance]
and i dont know if it happened the first time i loaded up the engine or the last,
i have also thought about this subject and my basic plan was to shape a bit of good stuff roughly to the shape of the top of the web after a clean up, then epoxy past stick it on , and weight it down ,. when cured drill and tap some bolts through the lot away from the bearing tro hold it all in place , simple really , its got to help , espewcially when you hear of engine builder using similar methods to strengthen up old blocks which have weak spots,

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

could some extra webbing/ reinforcement be tigged in?

Is there a material prooblem or distortin problem with welding the case?

I was thinking of welding support in ???

Didnt some of the early 5 sped conversions have major alterations to the casing ???

I think the early A sseries casings had 4 bolts to retain the bearing, so this should have more chance of cracking. The later A+ had only 3 bolts. Its in the area of the missing bolt mine cracked, which is also pretty much the weakest section.

I'm sure I replaced 2 or 3 casings when I was driving the car.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

i wouldn't tig weld it ,too much heat at one time ,
if i had to i'd mig it , with quick short blasts , then let it cool ,then do some more, but leave an old bearing in .

carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

heres one i have just changed on my new build

what you cant see in this pic is where it started from on the top!

it was a casting imperfection and it started from there, so out it came before it exploded in the future



EDIT:- i have just found this pic of the imperfection althoug its not very clear

Edited by BENROSS on 20th Sep, 2006.

nice keks

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

as benross was saying, ive noticed theres always quite a few rough casting areas up ontop of that web

im no expert what so ever, so dont laugh at this suggestion, but....

would smoothing out the casing help?i.e. it would removed the rough areas where they may start from?

WWW.TURBO-MINI.COM

a few years back in KYMA, dunno which one, it showed a fully worked gearbox by Morspeed or MED, all the high stress areas were polished smooth, and some of the sides too.

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Exactly how mine looked...

No doubt removing any casting flaws or cracks should help....but how much material do you need to remove to achieve that ?

Would that in itself raise other problems ??

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

when dave built my box he ground down some of the casting lines.
Is the kind of thing you're on about?

I know... :)

Its common practice on preping VERY high power blocks to smooth the inside of the block to stop/slow/limit crack propergation.

alex

AlexF

And also to smooth/assist oilflow back into the sump.

I started doing it once with an old RV8....got bored 5 minutes into it and gave up !! lol

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Wouldnt a rough surface be better for that than a smooth one?

Alex

AlexF

I've seen them paint the inside of blocks for the same reason.

casting imperfections could lead to significant stress raisers thats for sure, probably at least 3 or 4 times concentration (not good!)

removing these stress concentrations would be a must if the box is to be 'well loaded'

shot peening this web area would definitely help too, as it should generate some compressive forces in the material that will offset some of the tensile force which i imagine break the web

has anyone actually broke one of these thats seen some prevention work carried out?