I would like to install an overdrive / rear disk brakes
85 mph is just not sufficient for freeway driving here in Arizona
I am under the impression that there is a rear end that contains both of these items and would like to find out which model that would be , what it would intail (ie.wiring, suspension/chassis modifications),& if anyone has done this ? any feedback would be helpful


thx in advance

The Idea of a two speed rear end is not new. When I was A young lad I remeber That a company made a overdrive rear end that was used on some Ford cars.Of course this was over 50 years ago.
Joel the locksmith
Webster NY
Where life is worth living

80-90% of the braking force comes from the front wheels. Changing to rear disks will not significantly change your braking distances, it will reduce overheating etc if you are racing or a very very spirited driver especially in Arizona which I remember as pretty flat. The overdrive is nice though and has nothing to do with the rear end as it is attached to the transmission.

Go to www.vclassics.com to read what JohnMc explained so succinctly amply expounded on in a great many more words.
Bob S.

The overdrive is part of the transmission. It's a fairly easy swap on a 122, once you've tracked down the M41 transmission. The overdrive unit is an 11.5(ish) inch long lump that bolts on to the back of a 4 speed transmission (no, unfortunately the transmissions are not the same - the OD trans has a very long output shaft). When installing, you will need to shorten your driveshaft to match - unless you got the driveshaft from the donor vehicle as well. You might also have flange issues - I think Volvo used three different flange sizes, . Worst case you could always just take your driveshaft to a driveline shop and have them shorten it and weld on an appropriate end.

Disc brake rear ends - might be nice to look at behind some wheels that show off your brakes. 1800E and ES (the late production injkected ones) had disc brakes on what is basically a 122 rear axle - and that is a near (or actual) bolt in for a late (67-) 122 sedan or coupe (wagons are different). You'll have to do a little fabrication to put one in an earlier car, though. Another issue with an E/ES axle is that the bolt pattern will change - from the 4.5 inch early pattern (shared witl Mustangs, Mopars, Jeeps, small pickups, lots and lots of cars) to the 4.25 (actually metric I think) late patter shared with newer Volvos and maybe the odd newer Ford product.
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I'm JohnMc, and I approved this message.

John,

I have a "somewhat" later model '67 122. Late enough to have the later style rear end, but not late enough to have the dual brake system that was introduced later in the model year, if I'm not mistaken.

I have ev-e-ry-thing from a '70 E that was too rusted to salvage, but probably saw only 36,000 miles of actual driving. Sat in a field and leaked thru dried, crack windscreen and rear glass seals and rotted the floors and subframe.

Everything mechanical is low wear, and in great shape, and I am contemplating the switch to 4 wheel disk and dual brake system, by installing the '70 E rear end into the 122.

My questions; can all (!?!) or part, of the FRONT end assembly from the '70E be used to convert the 122 front end to the later bolt pattern and dual brake system? Or is this a total mismatch?

I've only seen redriling the rear 70E rotors, or the front 122 rotors, as a solution to being able to match wheels front and rear, but is there a way to get those 70E rotors and hubs mounted on the 122?

Also, can the 70 E "in-line" master cylinder-brake booster be used for the dual brake system conversion, or is there a standalone master cylinder (like the typical 122 MC), for the dual brake system ?

gary - '67 122S, '72 ES, '70 E disassembled

Sifting throught the parts catalogs and comparing numbers , it looks like the only real difference in the front braking system within each group (single braking systems, and dual braking systems) seems to be the brake rotor. It looks like the front rotors are essentially the same for all disk brake equipped 122s and 1800s, with the exception of the bolt patterns.

Since you have a set of 1800 front rotors and a 122, a test fit would answer a question I (and many others) have had for a long time.

FWIW, instead of converting to the dual/diagonal system I am using a dual master cylinder to split the braking system into front and rear systems. Every American car since 1968 has had that type of system. IPD has the master cylinder and a neat little adapter to allow fitment to the 122 firewall.

Mike