Strengthening the Minor axle.

Post by **JimK** » Fri Oct 13, 2006 2:36 pm

Several folks have said, and I have read, that the standard axle can take about 70bhp. Now leaving aside the point that it's torque not power that's the issue:

Where is the weakest link, and what could be done to strengthen it? Fancy half-shafts, stronger diff, that sort of thing.

What are the alternatives? I've heard about using Mk2 Excort axles but what others are possible?

Ta.

Post by **ian-s** » Fri Oct 13, 2006 7:03 pm

I think the weakest part is the halfshafts. These can be replaced by Heavy Duty race spec ones that should stand 100bhp as they are designed for racing 1380 sprites.
The next weak spot is the planet wheels in the diff . This can be overcome by fitting a Ford diff to your crown wheel and pinion. however this needs the half shafts to match so you need to decide how far youre going before you start.

Post by **jonathon** » Fri Oct 13, 2006 7:41 pm

Jim, what are your plans for the power plant. If its going to stretch the limits of the standard axle then to upgrade it to cope will be very expensive, as, soon as you strengthen one component , another becomes the weakest link until you have almost re built the axle.
I'd opt for the Escort axle anytime due to its correct width( it fits) multitude of diff ratios and options for 8",9" or discs. Certain companies can supply the hardware to fit it to the standard leaf springs, handbrake cables and methods of better location. The Marina or Ital axles will also fit, as will the Volve 340 and Toyota Celica. The advantage of the Escort axle over these is choice of wheels, the downside being you will need to change the front end to Ford PCD too unless you run two different types

Post by **JimK** » Fri Oct 13, 2006 8:06 pm

Ian, Jonathan - thanks.

My aim is first for an A+ with breathing improvements and then to add forced induction when budget allows, next year perhaps. I've had a little exchange of mails with Stuart Gurr at Vmaxscart, and he seems to have a very tidy installation of an Eaton blower (from the current Mini?) - he supplies a nice kit with head, manifolds, carb, etc. Output on an MG Metro-spec engine is around 130bhp.

Reason for going for forced induction is torque at reasonable revs, meaning I don't have to rev the nadgers off it to make "good progress" and making it easier when going slower.

I currently have some nice black Minator 14" wheels with 4" PCD and if I could keep them that would be nice. I'm not convinced I need rear discs - I don't think the car is heavy enough to overwhelm the front discs in road use. Is there an axle I can use that will take the pace while keeping the 4" PCD?

Post by **jonathon** » Fri Oct 13, 2006 8:20 pm

Sounds an interesting project, one of our customers is going the same route. Don't think you will find the axle with the 4"pcd, which is why most swap for Ford. If you go Ford, the customer going Vmaxscart is selling 5 compomotive 14" ML's in silver, easily made black.

Post by **JimK** » Fri Oct 13, 2006 8:53 pm

jonathon wrote:Sounds an interesting project, one of our customers is going the same route. Don't think you will find the axle with the 4"pcd, which is why most swap for Ford.

It would be galling to have a really nice set of wheels and have to buy another. I wonder if Wifey wants the black ones on her Trav...

Although one of the Sadmogs has been coveting them in a big way

If you go Ford, the customer going Vmaxscart is selling 5 compomotive 14" ML's in silver, easily made black.

Every man and his dog has silver alloy wheels. Black ones seem to be much less common.

Now, I'd go for some MO or TH in white...

Post by **jonathon** » Fri Oct 13, 2006 8:58 pm

Agree on silver wheels, I've just ordered some black and diamond cut 15" ML's for track use, and have just colour coded some Peugeot 1.9 GTI alloys for my trav for everyday use

Sorry but MO or TH ?

Post by **JimK** » Fri Oct 13, 2006 9:36 pm

jonathon wrote:Sorry but MO or TH ?

Other Compomotive wheels.
MO and TH.

Both would be ideal - MO for tarmac and TH for gravel...

Post by **jonathon** » Fri Oct 13, 2006 9:40 pm

Ahhh, know what you mean !!!!

Post by **paulhumphries** » Fri Oct 13, 2006 10:38 pm

jonathon wrote:J as will the Volve 340

Sorry but don't think the 340 Volvo is suitable.
It's a Dion unit with a transaxle arrangement even though front engined.

Paul Humphries

Post by **Peetee** » Fri Oct 13, 2006 10:43 pm

Although one of the Sadmogs has been coveting them in a big way

Post by **bmcecosse** » Sat Oct 14, 2006 5:04 pm

The Eaton blower route is very very powerful - and expensive. GAS on here has done this already. If that's your way forward then yes change the axle - but you will also need to change much much more to keep it on the road with all that power. For A series n/a upgrades stick to the normal axle - just don't do 'racing' starts. A decently upgraded A series Minor is more than capable of keeping up with modern traffic - without too much expense.

Post by **GAS** » Sat Oct 14, 2006 5:43 pm

My traveller has the A+ block with the BMW charger,I think that If you don't have a heavy right boot and treated halfshafts it will be fine.
maybe a 3.9 diff also.
My car pulls like a train,and is veary flexable to drive.
Overtaking now does not require miles of planning.(but it drinks like a fish, super unleaded to

)

Post by **bmcecosse** » Sat Oct 14, 2006 6:01 pm

I can confirm GAS's car is very very very nice !! But it's cost him a fair old bit in time and cash!!

Post by **JimK** » Sat Oct 14, 2006 9:13 pm

My first stage will be an A+ with decent airflow in and out. I figure the standard axle will be OK if I don't sidestep the clutch too often.

I'm going to consider the suspension first, particularly damping. Location of the back axle is a concern, it's bad enough now. I would say I have enough rubber (175/70R14) and the brakes are fine for now. Servo might be added later.

GAS wrote:I think that If you don't have a heavy right boot and treated halfshafts it will be fine.

I do have a fairly active right foot, and the odd trackday is a distinct possibility.

maybe a 3.9 diff also.

I'll leave the 4.2 in for the time being, the fifth gear will help. Once I get the blower the car will be able to push a much higher top speed, and also accelerate with the higher-geared diff.

My car pulls like a train,and is veary flexable to drive.

Exactly the combination I want. My Focus cruises nicely at 3000rpm/75mph, and I'd like the same from the Minor.

It drinks like a fish, super unleaded too.

What sort of mpg? I'm only doing about 5k miles a year so it's not such a big issue, but I'd like to know all the same.

GAS, could I see some photos of the engine bay? I'd like to see how everything fits in. Could you also say what is in the rest of your drivetrain, all the way to the wheels? What suspension? Any power and torque figures for your engine?
Ta.

Post by **bmcecosse** » Sat Oct 14, 2006 9:46 pm

My modified 1098 (with 940 head) will easily cruise at 75 mph - maybe not 3000 rpm right enough! If that's all you are planning then a s/charger is way over the top for you.

Post by **JimK** » Sat Oct 14, 2006 10:15 pm

bmcecosse wrote:My modified 1098 (with 940 head) will easily cruise at 75 mph - maybe not 3000 rpm right enough!

I've been impressed by the 1098 in the Lemming. Up to 60 or so it pulls really nicely, but the bigger engine in the Trav keeps pulling for another 15mph.

If that's all you are planning then a s/charger is way over the top for you.

It's something the car needs to do as my parents are 250 miles away and I want to be able to do the return trip in a weekend with ease.

But it's not all I have in mind, not by a long way.Do you know Cadwell Park circuit? When I can take off over the Mountain then it's fast enough

Post by **GAS** » Sat Oct 14, 2006 10:31 pm

My car runs an A+ block,ford 5 speed box to an Ital rear axle on the stock cart springs.
Up front I have the JLH coilover kit, marina front hubs and disks with MGB calipers and a split circut servo from a monteago.
stats. for the engine are still unknown but it does need some serious cooling.
I had to form the induction pipe myself as trying to make one from pictures was too much to ask Vmax to do.
I used a section of pipe from a satalite dish bracket as this had a 180 degree bend and the right inside diameter.

So far the engine alone has cost £2K

Have fun
GAS.........

Post by **bmcecosse** » Sat Oct 14, 2006 10:34 pm

I know Cadwell very well - I was mechanic on a full race Mini doing rallycross there (same time as Works 4 wheel drive Minis). Of course - it was early January - worst memory was changing a driveshaft between runs - in a snowstorm ! The car was of course on it's side and many hands were helping - the job was done in 30 mins - which included removing and re-fitting the sump guard!

Post by **JimK** » Sat Oct 14, 2006 10:45 pm

GAS: what cooling do you have now? I'm told the Minor radiator is very big for the size of engine - what do you have? Is it enough?
Do you have stock dampers on the back? I have stock dampers but I think they have heavier oil.

BMC: Anybody who spanners a race or rally car at any level has my respect.