Rods 'n' Sods - UK Hot Rod & Street Rod Forums banner
1 - 20 of 55 Posts

·
Registered
Joined
·
336 Posts
Discussion Starter · #1 ·
A quick update on the MG.

I ran my stock MGB V8 axle for a good few years until I got the engine making good power. Then i was snapping shafts every few passes. So I had the stock shafts copied by Moser in much better material. These proved to be fantastic for the last 3-4 years and have got the MGB deep into 9 second ET's on the Drag strip. That was up to the end of last season when I put the car away for winter. This was how I left off last year while still trying to tune the new modified Rover 3.9 that has so far proved to be fantastic. At the end of last year we put the car on the rollers and it made 525hp on fairly safe settings with AFR rich at high 10's and timing still knocked back by 8 degree's. So for the first day out this year we rolled the car out and ran 9.6 on the first pass to repeat last years PB times. After a quick check over all seemed ok so we went back and tried adding 2.5 degree's of timing. The car is pretty rapid off the line normally, but with the added timing it just lit up :) And then broke the shafts in about 3 feet :lol:

After a tear down the diff assembly looks like new. But the Moser shafts were knacked. So I had now found the limit of those shafts. To be fair to Moser the shafts are pretty good items but I got Moser to trim them down to the 1" splined ends so they would fit the stock Salisbury side gears in the MGB diff. The modified shafts were basically Ford 9" shaft blanks that were altered to suit my needs. They ended up costing about £580 delivered 4 years ago.

OK!,
So that the history bit sorted. What is the next obvious step forward? I guess fit a Ford 9" rear axle. So I needed to buy a Ford 31 spline 9" rear axle, then have it shortened to suit my car, then have the shafts shortened to suit the casing and then have the casing fitted with MGB spring mounts and other gubbins so it would drop back in ok. And then find a gear set that would be close to my 3.07:1 setup, and then modify the prop shaft to mate with the Ford diff, and then have to mess around with the Ford brakes to make them fit..... Estimate for this was around £4000.00 :shocked: £4000.00 ??? Holy Crap !!

No way can I afford that sort of wedge for a hobby car.... !

So I started looking at how I could fit fatter shafts into my stock rear end. The goal was to fit 31 spline shafts into my diff. I started asking mates about the project and one of them gave me a Ford 9" spool to play with as he had it laying around doing nowt.

So when I pulled the rear end I decided to see IF the Ford 9" spool would fit. Bugger me if it didnt drop right in to the old Salisbury axle case. This isnt a 4ha Salisbury. Its the smaller Westminster version that MG used in the MGB GT cars. The only difference between the rear axles in the MGB GT 1800 and the MGB GT V8 is the diff ratio. The 1800 is a 3.9:1 and the V8 is a 3.07:1 ratio. All the other parts are the same including the half shafts.

I was having bad dreams about how to fit the Ford 9" spool into the diff casing. This turned out to be no problem at all :)

The next problem was getting some Ford 9" 31 spline shafts at the right length. I found that I could buy 30" long shafts with longer splines cut in at 8" long from the USA. These are pretty common over there for rodders who want to chop them down to suit their builds.

Long story short.... A pair of 30" long 31 spline shafts with 8" of splines were delivered for £305 all in from Procomp / Speed master in California.

I now have to do some machining of the wheel flanges so they fit my brake drums, and then I can re drill the drums to a 5 stud bolt setup so I can find some stock 5 stud rims to fit my tyres.

I wont ramble any more. Here are the new shafts next to some stock shafts and a pic of the spool in the MG diff casing :)


#

 

·
Registered
Joined
·
336 Posts
Discussion Starter · #10 ·
That's unbelievable. Who'd have thunk it?
Are the bearings stock Ford or MGB?
The spool bearings are stock MGB. The shaft bearings are stock Ford that need 1mm trimming off the O/Dso they will fit in the axle case ends.
 

·
Registered
Joined
·
336 Posts
Discussion Starter · #12 ·
might want to brace the case somehow too, oh and buy every set of gears you find, you're gonna need them !
I was thinking about bracing the case actually. Maybe cut a new back cover flange in 6mm steel and welding a dome of some sort over the top to give it more strength like a sump girdle.
The diff gears are 39 years old and are in good condition. But at £400 a pop I wont be buying any spares soon ;)

When the crown wheel or pinion eventually lets go I'll be upgrading to a new axle I think. The diff gears are similar to a 7.5" GM gear set. They should have let go a long time ago. But as long as they hold out I'll keep on racing :)

When they do eventually let go I think I'll buy a new set and get them cryogenically treated to see how they will last. I had my old MBG half shafts treated and they held up twice as long before snapping than stock shafts did ? before I had the Moser copies made.

What axle do you run in the altered ??

Perry
 

·
Registered
Joined
·
4,630 Posts
the altered was sold on, but it has a 9" strange ally centre section, pinion support, 4.56 pro gears, full spool and 35 spline shafts. Putting another iron unit in my slingshot with 3.7 gears but using a curries hot rod case as it's better looking.

9" really is fit and forget but unfortunately you have to do everything in the driveline otherwise it just finds the next weakest link.
 

·
Registered
Joined
·
336 Posts
Discussion Starter · #14 ·
the altered was sold on, but it has a 9" strange ally centre section, pinion support, 4.56 pro gears, full spool and 35 spline shafts. Putting another iron unit in my slingshot with 3.7 gears but using a curries hot rod case as it's better looking.

9" really is fit and forget but unfortunately you have to do everything in the driveline otherwise it just finds the next weakest link.
I'm with you there mate!!

I've spent the last 10 years chasing breakages up and down the drive train. I break something, then make it stronger, then the next weak link breaks :) Thats Drag Racing eh ?? Especially on a DIY budget with Ebay parts ;)
 

·
Registered
Joined
·
336 Posts
Discussion Starter · #16 ·
Ha Ha!!

I got the shaft flanges turned down now so i can start mocking up for fitting the MG brakes. I've gone for the 5 x 4.5" pcd now so I'll need to start thinking about new wheels I reckon.. Before I start researching all things non MGB does anyone know what the 5 x 4.5" pcd is common to ?? Ford, Chevy etc ... Someone told me Ford Transit steel wheels could be an option ??

Regards
Perry
 

·
Premium Member
Joined
·
14,768 Posts
lots of nissans, hondas, mitsubishis, mazdas and toyotas are 114.3mm pcd (4.5") as well as english 5 stud fords, landrover freeloaders, american fords, amc, mopar, jeep cherokee/wrangler. the list goes on.
 

·
Registered
Joined
·
336 Posts
Discussion Starter · #18 ·
lots of nissans, hondas, mitsubishis, mazdas and toyotas are 114.3mm pcd (4.5") as well as english 5 stud fords, landrover freeloaders, american fords, amc, mopar, jeep cherokee/wrangler. the list goes on.
Cool!!
Now I have somewhere to start looking :)
 

·
Registered
Joined
·
336 Posts
Discussion Starter · #19 ·
Small update from today :)

Took a few measurements and slipped a shaft in to where it should sit with the bearing clamp and brake back plate fitted. It looks like there should be enough room for the brakes and wheel studs with no fouling !!!



 
1 - 20 of 55 Posts
Top