diff upgrade options

Quote:

---

Originally Posted by uninformed

socket or spanner haha. I cant see how you would get a socket with any driving device attached. I have some nice Snap-on Hi performance 12 point ring spanners. The 14-17mm version is their longest in 14mm so you can get some good torque on those double hex bolts.

but yes tool clearance was my reasoning for maybe a smaller dia bolt between the others? this may be of some help to the 7 bolt swivels. Or a person could cut off the axle flange machine a new one and weld up the holes in the swivels flange and add as many bolts as posible all the way around, allowing of coarse for tool size to tighten the bolts. I have seen high pressure flanges on pipe work that has bolts almost touching all the way around. I figure there must be some small similarity in these???

---

I realised after I posted that I should have said spanner, not socket.

Anyway I took some measurements as per my earlier post and pics and made the following comments.

The round bottom front diff housings, as found under early rangies, use imperial (not mm) dimensions and bolts for the bolted joint between the axle housing and swivels. They have 6 x 3/8" UNF bolts equally spaced (60* arc) on a 3.75" (95.25 mm) PCD (pitch circle dia).

These bolts sometimes suffered from loosening or breakage and when the later flat bottom housing was introduced an extra bolt was added (7 vs 6). Bolt size also changed to M10 fine (10 mm is 0.475 mm larger than 3/8" - from memory, comparing the root diameters, the M10 fine thread doesn't show as great an increase over 3/8" UNF). However the new 12 point bolt heads, given their larger intergral washer will improve the fatigue strength - see my earlier post about using a thick washer when the holes are slotted.

I have not measured the new PCD - I would be surprised if it was not changed slightly to a nice round number of mm's. From a quick look it appears that 5 of the bolts are still equally spaced on 60* arcs, but the lower bolt position was replaced with 2 new bolts on a spacing of 40* [40* = (2 x 60*) / 3].

For pricipally vertical (gravity) dynamic loads applied from the terrain at the tyres, the bolts located near the bottom of this joint carry most of the load - the other bolts see much less load. Note that the load tries to pull the joint apart at the bottom (increasing the pre-tension in the lower bolts) and push the joint together at the top (this compression reduces the pre-tension in the upper bolts).

In an earlier post I stated that for the early housing and swivels, an extra 2 bolts could be added, one either side of the bottom bolt, bringing the total number of bolts to 8. This would be somewhat stronger than the later 7 bolt version.

I have confirmed that the extra bolts can be the same size as the originals (3/8" UNF) - see comments and pics of an early housing below.

Check new bolt pitch if extra bolts are added mid-way between existing bolts, i.e. spaced on 30* arcs.

From simple trigonometry; chord = PCD x sin (arc / 2).

Then chordal bolt pitch will reduce from 1.875" (47.625 mm) to 0.971" (24.652 mm).

The new pitch is approx 2.6 x bolt dia (OK).

Check for spanner clearance between bolt heads.

Obtain the maximum allowable size across the outside of the spanner by subtracting the dimension of the bolt head across it's corners, from the 60* chordal pitch.

47.625 mm - 16.5 mm = 31.125 mm (OK for 9/16" ring spanner).

Also People have said about welding the flanges once back together I would just like to remind people just so no one makes a mistake that once welded or tacked etc etc remember its going to be near impossible to change any seals once this has been done especially if your on a trip and no grinding device is present!!!

John.
It's interesting that the bolts are of a different appearance (single hex) compared to as you have stated 12point or double hex with a collar like my later ones,what is the tensile strength for the bolts used on the earlier ones ?

Quote:

---

Originally Posted by rick130

The pinion shouldn't be out with the Nissan diff, should it ?

And being a high pinion centre, it at least reduces the uni angles.

BTW, you can't rotate the swivels easily on a Nissan (or Toyota) as they are welded on :(

If you need to alter castor and/or camber on a Patrol you use eccentric swivel bearing cups.

---

It's probably quicker on a Toyota. The swivel ball assy is pushed into the axle housing and then welded on at the end of the axle housing. When they do the castor corrections they make a fine cut around the axle housing next to the weld (but not into the swivel ball assy) and then rotate the swivel ball assy to correct the castor before rewelding. The swivel ball assy should keep the angles (camber) pretty close due to its fit in the axle housing but of course it depends on your work.

ok done some measurements on the diffs today and found that nissan centres will not fit in the later model rover front housings :(
note: bush65 has pointed out the the earlier range rover diff housings do not have the flat on the bottom where the centre fits and i do not have measurements for this diff like he has mentioned!

rover PCD = 215.5mm
toyota 80series PCD= 215mm
Nissan patrol 3.9 ratio and 4.3 ratio PCD = 240mm

the nissan long side axle would be lucky to be 1" longer than the rover long side...
the diameter of the hole where the axle seal sits in the swivel ball is obviously to small for the nissan axles and would need to be taken out to a larger diameter which i would start to be concerned about strength compared to the 0.010" that needs to be taken out of the "diameter" to fit the toyota axles...

the toyota front diff however would be a good candidate for a conversion but i am left with a few options now...

1.do the 80series conversion and see how much stronger it is compared to the rover which might end up being a pointless exercise.

2.try the whole gq front under and see how bad the castor is out whilst still maintaining a reasonable pinion angle.

3.keep trying to find a FC101 diff and be done with it.

4.see how long the rover setup lasts and not go to stupid offroad :angel:

Or contact Buds customs in QLD and see if he can make you a housing to suit your diff of choice with your ends of choice. I think its about $1k.

thanks slunnie i was about to ask who does this work :D

Any of the larger diff mobs who cater for drag/custom/rod guys generally build their own housings, and you could go 9" both ends and get cheap lockers and axles etc.

I think 9" Hi-pinion setups are expensive if thats what you're after otherwise the pinions are lower than normal as the 9" pinions are offset further than normal off the diff centre line.

Both good points and I have looked into it there is also places in America that make custom DIY kits and would be probably better than 9" with something around the 12" region they also use open CVs (uni type) and used in such races as KOH...the problems that would occur in modifying my housing or making one even though my largest lathe has a 4m bed and would be suitable for such mods is getting the swivel mount flanges on either end parallel and have the bolt holes in the same positions on one end as the other and also making sure that the bores line up however it would be possible and with a rediculous amount of marking out and setting up...

Quote:

---

Originally Posted by c.h.i.e.f

... i am considering drilling a 10mm hole through swivel ball flange and then assembling it all back together to new adjustment point then marking diff side flange then remove swivel ball again drill and tap diff side flange and then i will have a lock bolt so to speak...

---

Quote:

---

Originally Posted by rovercare

If you slot them in a mill over 5 degree's, they aill leave an edge that is good enough to stop any rotation, I ran these for years

...

---

Lots of people think (wrongly) that the bolt hole plays some part in preventing rotation of the swivel at the bolted joint.

The bolt holes only stop rotation while in the process of assembling the swivel to the axle housing. Once the bolts are properly pre-tensioned, the bolt shank bearing against the side of its hole does not prevent rotation.

The bolted joint relies on friction between the mating surfaces to prevent rotation. This is the way all bolted joints subjected to eccentric, dynamic loads should be designed - it is also the recommended method for any bolted joint where movement can't be tolerated. The only exception which comes readily to mind is where cone washers and their like are used, e.g. Toyota hub/axle flanges. Fitted bolts, fell out of fashion many years ago, because they expensive and not as reliable - bolts in clearance holes, even with less than 0.5 mm clearance are not suitable.

Once these bolts are tightened properly they are never subjected to any shear load whatsoever - this fact can be difficult to grasp.

BTW the only applied load that tries to rotate the swivel about the axle centreline (which is the rotation referred to here) is braking. With braking the horizontal (traction) force between tyre and road is transferred through the brake caliper mounts etc. to the swivel, then to the axle tube via the bolted joint in question. it is then transferred to the chassis via the radius arm.