Ok So I am going to pull a “James May” on you all and bore you with a whole bunch of techy stuff. But I am so proud of my efforts I have to tell somebody.
Regular readers of this fine website will have seen the photo I sent in last week following a major failure with a broken rear axle. The upside was I was able to fit a complete new (old) differential I had in storage onto the MGA with a minimum of effort or expense. After a couple 4 hours sessions I had the old Differential disconnected out on the floor, parts swapped as needed and the new one in the car and bolted down. Only one casualty with a broken anti rattle spring ($.87) and I took the opportunity to put in new brake shoes and make a couple other fixes that made sense while it was in pieces.
I took it out for a spin in the rain last night (shop tip –adjust the brakes before you roar off across the driveway) and WOW what a difference in the drive, and that was just first gear. With the newly rebuilt engine the new Five speed transmission I had to calculate the difference in the gear set-up from original to now and have prepared a chart.
Gear Ratios First Second Third Fourth Fifth
Original MGA Standard Tranny with
4.3:1 original ratio rear end 3.65 2.21 1.37 1.0 -
New Ford Type 9 transmission 3.65 1.97 1.37 1.0 0.82
Now with 3.9:1 low ratio Differential
rear end from Wolseley 6/80 3.28 1.77 1.23 0.9 0.73
% Reduction in RPM
from original 10% 12% 11% 10% 27% final drive*
*At highway speed- 4500 RPM is now 3285 RPM
So a huge reduction in final drive will make this a real highway cruiser and save gas wear and tear on the car and the driver on those long haul drives. Anybody up for Stowe this fall?
Ralph
3 comments:
Ralph....just to let you know that your 4.3:1 gear set is in big demand by TD and TF owner, with a little modification they can replace our five somthing rear gears. If they are in good shape they would get snapped up on eaby. I have a set I haven't put in yet, but you could get some money back. I paid $250us for mine.
Joe Hine
Hi Joe
Thanks There is a snapped axle but easily replaced. If you are interested I may be able come by another one with a little digging.
Ralph
Hi Ralph
The axles don't fit a TD, just the ring and pinion. You have to modify a bit and fit them in the TD rear housing.
Joe
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