Solid diff mounting

[gwak76]

Hi ya

been thinking as I do when bored, looking through previous posts regarding diffs etc I notice that most are bolted solid to the chassis, correct me if i am wrong.

Now, looking at me good old Sumo it has rubber bushes between the Pilgrim diff carrier and chassis, the carrier is much smaller than the donors and gives more movement under load. My concern is that sooner or later the excessive movement will knock out UJ's on the prop and driveshafts plus additional vibration caused by misalignment under load.

Question, would bolting the diff directly to the chassis have any downside, I know a bushed mounting will take up some of the shock, no direct contact with vibrating rotating parts etc, and its been used for years without problems. But is it the way to go with a large engine that can produce a lot of torque, compared to the engine and box mountings the diff is like a wet lettuce.

Views, opinions ?

[apearce]

hi - ive owned a sumo and agree that the diff moves too much (especially with your much larger engione).

However i now own a dax with the direct bolted diff and boy does it whine! (the diff is reconditioned and so thats not the problem. I also own a jag saloon with the same diff and that doesnt whine at all because on the Jag its rubber mounted!)

I think its a real mistake by dax to direct mount the diff and im considering putting in some rubber somewhere.

So, my advice to you would be to keep the setup you have but try replacing the bushes with neoprene or a stiffer compound rubber. If ford dont sell any alternatives (such as from a cossie ?), try fast ford mag or RS owners club who im sure stiffen their diff mounts all the time and if that doesnt work, you could have some turned (less work and cost than replacing the whole braket anyway)

If you want to discuss it im on 07881 857717
Andrew

[Grease Monkey]

What you need to do is... get a GD Diff bolts to the chassis, body on rubber mounts, best of both worlds.

What you could try is put a rubber gasket (3-5mm or so that you can buy in sheets and cut to shape) inbetween the diff and chassis, and then bolt it up. That way the diff wont wobble and flex under load, and the high frequency vibrations should be damped slightly.

I'm thinking of this approach for bolting my roll bars to the chassis, stop the diff whine resonating up the tubes so much.

[apearce]

thanks grease monkey but the bulk of the noise would still be transmitted through the bolts - like metallastic bushes, there needs to be no metal to metal contact between diff and chassis to really improve things, and if anyone has achieved this on a dax id be delighted to copy the design..... ??

Andrew

[kdavies3]

If your Dax roll bar isn't already filled with expanding foam fill it.
It helps to stop some of the vibration being transmitted from the diff. :thumb:
It won't cure it completely but it will help.

[gwak76]

So, from what I gather options ( other than buying a GD, thanks Funky Monkey ) would be to come up with a diff carrier using powerflex type bushes rather than the rubber jobs. Fixed in positions that will counter the action of torque as opposed to the present lets hang it there look. Or have some wine hic, whine and know it aint gona move.

One to ponder over with the old drawing pad.

Thanks chaps, any other ideas welcome other than changing the car ( bloody monkey) :thumb:

[Purple AK]

Gary.

Any idea what bushes the Pilgrim diff carrier uses?

[dave]

Originally Posted by apearce

thanks grease monkey but the bulk of the noise would still be transmitted through the bolts - like metallastic bushes, there needs to be no metal to metal contact between diff and chassis to really improve things, and if anyone has achieved this on a dax id be delighted to copy the design..... ??

Andrew

Hi Andrew.
The only way to rubber mount the rear axle would be to fit an E Type rear sub frame (6" narrower than an XJ6 one and just the right size to retain the same wheel off sets.)but then you would have to fit trailing arms with rubber bushes in like the E Type but these would fix to the chassis within the cockpit area right where you have to sit, you couldn't mount them under the floor level because the angle at which they attach the the wishbone would be wrong and you would get very bad bump steer on the rear end.
If you could fit the E Type sub frame it would probably drive like a Bouncy Castle.

The only real solution would be to sell the Cob and buy a Mercedes S class.......................You can even get double glazing in them. :thumb:

[gwak76]

Chris

the dif mount uses two bushes MRM201, should think they are Ford but from what I do not know, have to investigate further., the diff retains the orignal rear mount which is realy soft.

Its not just the bushes that are naff, the whole diff angles upwards, if you follow its line it ends up 4inches higher than the center of the flywheel.

[Purple AK]

Woudnt have thought they were ford More like "Metalastic Rubber Mounting 201". If they were a ford thing, Deflex are quite keen to make one off Polyurethane Bushes, provided there is gonna be a call for them, which i'm sure there would be :thumb: