VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1929 truck rear diff into a 1927 truck

Hello,
Can you put a 29 truck diff into a 27 truck?(the truck type,not the car one)
Are the axils the same or do I have to use the 29 ones?
Will the 29 torque tube housing,crown wheel carrier fit into a 27 housing?
I have a 29 diff but the saddles where the springs fit are extremly worn,and a few 27 diffs that appear ok.
Only doing the swap to make it go a bit faster.

How do the saddles seperate from around the housing once the U bolts are undone?
Thanks

Hello rusted,
Check your PM's(the flashing red envelope).

I was told once that by fitting a 29 crown wheel to a 27 or 28 diff will give the desired top end increase but was only by about 5 miles per hour.

I have used 29 truck crown hweel and pinjong in 2 of my trucks.1926 and 1928. No problem to use them.
To separate saddles. The are a screw in the bottom of each pockets. Wery rusty I think.

Hi Rusted

Ive had a 29 crown wheel and pinion in my 27 truck for over 20 years now but make sure you get the correct ratio for the increase in speed about 5- 7 mph and if you use 700 x 20 tyres on the rear it will increase the top end, be sure to redo the caster angle on the axle at the frontbecause of the bigger rear tyres. No you will not die bad on the hills as you are going faster in the first place so it is not such a drag up the hill. Remember the greater increase in speed also increases the vibrations so it is a good idea to have a balance flywheel or even the whole engine. The other thing is that there is no need to ghange the rear end housing or tailshaft tube etc the 29 crown wheel and pinion with 4 bolts will bolt straight in and just join the back section of the tailshaft in the original truck splined tailshaft joiner. Makes the whole job real easy once you have adjusted the gears. Same axles etc will fit straight back in place. Hope this helps

Thanks for the information.

CJP'S 29,I will give you a call.

I have a couple of diffs all with different problems with wear so I will try and build a good one out of the parts

I know this is an old thread, but here is a related discussion about rear end gear ratio options for '27 and '28 one ton trucks: https://vccachat.org/ubbthreads.php/topics/440186/typical-mpg-1926-1928-1-ton-truck.html

Cheers, Dean

If you use the entire torque tube and rear axle it will lengthen the wheelbase slightly. I had to make a bolt plate as the alignment pin was in a different location. (New one in use. Old one set on spring for comparison. ) .
. Lou