• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

I'm wondering if its possible...

Share this page

G

Guest

Guest
Guest
Offline
To mount a J type o/d on the diff instead of going through the trans swap. Just hear me out for a second. TTBOMK, the o/d doen't know or care where it's located. If you could remove it from the Spit trans, make a front plate for it with a bearing, respline the shaft to use a diff flange and shorten the drive shaft. You could make a mount that bolts to the front of the o/d where it normally bolted to the trans ( where your new plate is), and then bolt the back of the mount to the diff carrier bolts. The rear o/d flange would just bolt up to the diff yoke. There might be enough room in front of the diff to do this. I know it's sound slike allot of machine work, but it could be installed in a few hours on any Spridget and be completley reversible.
 
That, my friend, is flippin' <span style="font-style: italic">brilliant</span>. :banana: Y'know, if you're going to mount the OD on the pumpkin anyway, it doesn't even have to be a J type Laycock...there's probably a cheap(ish), readily available, electric OD unit out there somewhere that'll work...all we'd have to do is work out the attachment and clearances...
to the Bat-Computer!

... https://www.maximum--overdrive.com/products.html Hey, lookie here...a "remote overdrive"...Doesn't look cheap, but at least it's proof they exist. (It's a Laycock too!)

Titlephoto.jpg
 
Thinking further...someone has gotta have the machine sense to make a two-speed pumpkin (a la the Model T Ruckstell) for the Spridgets. I mean, if they were on Model Ts, how complex can they be??? Could this be the ultimate solution...?
 
Most definately worth looking into. I wonder why no one thought of or tried it before. You might have something here.
 
Gonna talk to my tranny friend and see which trans has an easily adaptible o/d that could be fabbed up to work outside the trans.
 
No.

Reasons?

The driveshaft is only 31-32 inches long, the OD will no longer be integral with the trans (still has an output shaft housing on the non-OD trans), and you will need to figure out a coupling for the input end of the OD.

Add to that the addition of more unsprung weight, and all of it hanging on the nose of the diff, well, pinion bearings, springs, rubber bushings, mounts, all are going to take some stress.

You will need to figure out how to couple the output of the OD (spridget) to the diff pinion.....and you can't take the nut off, or the bearings will unload. The housing will have to be fixed to the diff, as the way they work, there will be case torque from the different input and output speeds.
I am guessing it will take 6-8 inches minimum of space to adapt them, add the OD length, and whatever adaptor you figure for the nose of the OD, and you've lost half your driveshaft length.

On the shaft length, you shorten it enough to cob in a diff-mounted OD, your angels and bumps (and plunge) will be greatly increased, but U-joint life will be decreased.

The Laycock unit works good, IF you have enough room between trans and diff.
You mount a short shaft between trans and OD, MOUNT the OD to the underside of the chassis, then a shaft to the diff. I've seen them installed, and I think the Laycock shown is long enough to remove over half you driveshaft length.
You've got a 1971 LTD, it's a good deal.

Where do you intend to get a speedo cable long enough?

Model "A" Ford folks get it done, but that's a torque-tube rear end (rear end goes from the ball seal at the rear of the trans to the wheels) and they cut the torque-tube and insert it, later Fords (up to 1948) had a Colubia 2-speed rear, which (quick version) replaced one side of the rear axle housing.

But, go ahead.

Make sure you use other parts (like rear end and driveshaft) so when you find out it doesn't work you can put the original parts back.

You CAN do it real easy if you splice two or three spridgets together....

Dave
 
Okay, Negative Nelly...Don't cloud my head with facts. :smile:
I've been mulling this over thru the night.
You don't really need a remote mounted full hydraulic planetary overdrive, we're not talking thundering horsepower and pulling fifth-wheel trailers here. Just a simple gear-splitter will do. It'll take some fancy machine work with an engineering guy to work out the gears, but here's my thought. It doesn't have to be big and heavy; the case can be aluminum and mounted right to the diff, and may even be thin enough we can use the existing driveshaft.

Here's my cocktail-napkin sketch to show what I mean. Nothing's to scale and everything's exaggerated, but hopefully it'll get the idea across.

img034.jpg


The driveshaft and diff are offset slightly, and terminate in bevel gears. A selector arm holds two idler gears: one idler gear in mesh with both main gears at their common tangent, or a stepped idler that meshes with both main gears at some other point of their circumference.

Top-right sketch shows direct drive: the stepped idler makes up the difference between the main gears' sizes, and results in 1:1.

Clutch in, push the overdrive lever, and a rod rocks the selector arm, as in the top-left sketch. The single-size idler runs both main gears, the difference in sizes resulting in an overdrive reduction.

Bottom sketch is sort of an overhead view: diff to the left, driveshaft yoke on the right, bearing and case shown, and the rough arrangement of the bevel gears.

It would have to bolt very firmly to the diff, and may need some jiggery-pokery to use a gear in place of a diff yoke...but with some engineering geniusry, why couldn't this work? The gears would be at least as robust as those in the tranny. Few moving parts, light weight, easy to produce = profit for someone!

No synchros or anything: downshifting should be an easy matter of clutching in, and easing the gear in while the revs fall. Upshifting may be best done while you're stopped, but once you're in OD there'd be no reason to get out; as 3rd would be 4th, 2nd would be 3rd, etc.
 
Dave, look at the link I provided, the yokes are already there and will fit the spridget shaft and diff yoke perfectly. Rear o/d yoke bolts directly to the diff yoke, driveshaft directly to the o/d yoke. The unit hangs from a mount that attatches to the diff at the housing bolts. Pinion bearings won't take anymore load than normal and any "nose heaviness" is counterbalanced by the pinion trying to climb the ring gear. I do here what you're saying about drivshaft lenth, I have been concerned about that. I do think the Laycock might be too long to fit under a spridget. I have thought about mounting something in the tunnel, but the Laycock would be too big. Gonna talk to my tranny friend to see if something can be taken out of a auto trans and made to work.
 
I think you missed the bit about unsprung weight and nose-heavy....you had initially not indicated you were going to use the u-joints at the rear, from what I could decipher.

However, length, unsprung weight, nose-heavy, and SHORT diveshaft are going to give you reliability issues.

Keep your AAA towing insurance up-to-date.

Why do you think they put the OD on the back of the trans in the first place?
 
Ahhh, let me guess. Cause it had already been built for some other use and was on the shelf and thus cheep.

Do I get the prize?
 
I just went and looked under the car, allot less room than I remember.

...cause they couldn't put it in the front. :jester:
 
Because they could INTEGRATE the OD INTO the trans and keep roughly the same driveshaft length, and minimize unsprung weight and a nose-heavy issue on the axle (and you thought spring U-bolts worked loose BEFORE....)
 
You could buy that BugEye with the big-block and a fabricated frame and not worry about overdrive....
 
Did I miss a father/son relationship here? Or are you guys joking?
 
It's a joke. He once mentioned his wife wordked in a chucrch office for 27 years and so has my mother.
 
Trevor Jessie said:
Did I miss a father/son relationship here? Or are you guys joking?
Click to expand...

and that's how rumours get started
grin.gif
 
and just to keep pholks on their toes, some just keep throwing coal onto the fyre......
 
Back
Top