Differential hanger bushes.....any ideas?.

#1
Hi all,

I have just removed the two differential hanger bushes from my 3500S for replacement.
The parts manual lists two alternatives, one has an overall height of 1.375", the other 1.700".

Mine measured 1.700", so they are part number 578080.

I ordered a pair of 578080 bushes from Geoff at Winns, and these are what came (left) compared against the originals (right)......




Although they are 1.700" overall height, the large rubber part is smaller in diameter and the bonded in steel tube sits about 3/8" lower in relation to the flange, meaning when the bushes are bolted into the base unit the diff bracket sits lower, and the original diagonal tie-bar won't fit back on without extreme adjustment.

The Metalastik numbers on the bushes are different, the originals are 17-1258, the replacements are 17-403.

What do we think?.
 
#2
ERF said:
Hi all,

I have just removed the two differential hanger bushes from my 3500S for replacement.
The parts manual lists two alternatives, one has an overall height of 1.375", the other 1.700".

Mine measured 1.700", so they are part number 578080.

I ordered a pair of 578080 bushes from Geoff at Winns, and these are what came (left) compared against the originals (right)......




Although they are 1.700" overall height, the large rubber part is smaller in diameter and the bonded in steel tube sits about 3/8" lower in relation to the flange, meaning when the bushes are bolted into the base unit the diff bracket sits lower, and the original diagonal tie-bar won't fit back on without extreme adjustment.

The Metalastik numbers on the bushes are different, the originals are 17-1258, the replacements are 17-403.

What do we think?.
The geometry difference will change the angle of the diff centerline relative to the propshaft and the engine/transmission by a small amount, maybe a degree or so. As long as your diff centerline stays fairly parallel to the transmission centerline (but not co-linear) and the angle between the prop shaft and the diff and tranny doesn't exceed 3 degrees, you should be ok. Otherwise you run the risk of introducing driveline vibration. And 3 deg. is a conservative number, the max allowed angle being a function of prop shaft rotational velocity.

I would try them and see what happens. If you do run into vibration problems, shim the new bushes to replicate the geometry of the old ones. Or you could always send them back and demand that the correct ones be sent 8)

Tom
 
#3
302Rover said:
The geometry difference will change the angle of the diff centerline relative to the propshaft and the engine/transmission by a small amount, maybe a degree or so. As long as your diff centerline stays fairly parallel to the transmission centerline (but not co-linear) and the angle between the prop shaft and the diff and tranny doesn't exceed 3 degrees, you should be ok. Otherwise you run the risk of introducing driveline vibration. And 3 deg. is a conservative number, the max allowed angle being a function of prop shaft rotational velocity.

I would try them and see what happens. If you do run into vibration problems, shim the new bushes to replicate the geometry of the old ones. Or you could always send them back and demand that the correct ones be sent 8)

Tom
Thanks Tom,
Shimming would be quite difficult to achieve as the shim would need to be the same shape as the flange to maintain sealing of the mounting in to the Base Unit, and a 3/8 thick shim would not be a quick thing to make.

I am reluctant to fit them unless someone has actual positive experience with them.
 

SydneyRoverP6B

Well-Known Member
Staff member
#4
Hi ERF,

The original 1.700" in height 578080 diff mounts are no longer available and it has been that way for many years. This taller bush was fitted to all series 2 cars, while the smaller 1.375" in height...539042 was fitted to all earlier cars. This smaller bush was also used on both series 1 and series 2 cars for the pinion extension case mount.

When the mounts were remanufactured both here in Australia and within the U.K, only the smaller of the two was offered, and this mount is now being substituted in place of the 1.700" diff mounts the series 2 cars.

The mounts that you have from Winns do look quite different in terms of the large conical section on the underside (or topside depending on how you look at it) to those that I have seen before. The ones that I have seen previously don't possess this cone, rather they are much closer in appearance to the original pinion extension case Metalastik bushes.

Ron.
 
#5
So what is the consensus then guys?.

I can't fit these new hanger bushes without winding the adjustment link on the diagonal tie rod right out, even then it sits at an awkward angle of compression in the coned bushes at the Base Unit end of the rod. It just does not look right - and shimming these smaller hanger bushes effectively would be a lot of work, and even then would they be up to the job?.

What would you recommend?.
 
#7
I have received a conclusive answer from Rover Parts Services.

The replacement bushes I have (17-403) are not in fact 3500 differential hanger bushes, they are Rover part number 553975 bushes fitted to one side only of the early 2000 diff hanger, and pinion nose of these cars.

The correct 578080 bushes are Metalastik 17-1258, as my originals were.
 

Scoob

New Member
#8
Hi there I've rang wadams yesterday and I need diff bushes too apparently they still do both sizes mine is the smaller of the too ,2.2 sc and the 3500 auto are the same that's what they have said they are listed on the website just thought I'd say may be usefull
 
#9
They still don’t make the 578080 1.70” bushes which are correct for the late 3500.
Wadhams have reproduced the 553975 1.70” bushes with the lower centre height.
 

cobraboy

Well-Known Member
#10
To try to get the same flange angles on the gearbox and diff I shimmed the diff mounts to tip the diff. If you can only get the shorter mounts maybe you can make up a shim pack to get what you need.
 
#11
It’s not that you can only get the ‘shorter’ mounts, you can buy 1.70” mounts, but as described above the centre tube is bonded into the rubber in a different place on 578080 mounts. To obtain the correct diff height for a late 3500 using the reproduced 553975 mounts, a 3/8 shim would be required between the mounts and base unit.
 

GRTV8

Well-Known Member
#12
Hi all,

I have just removed the two differential hanger bushes from my 3500S for replacement.
The parts manual lists two alternatives, one has an overall height of 1.375", the other 1.700".

Mine measured 1.700", so they are part number 578080.

I ordered a pair of 578080 bushes from Geoff at Winns, and these are what came (left) compared against the originals (right)......




Although they are 1.700" overall height, the large rubber part is smaller in diameter and the bonded in steel tube sits about 3/8" lower in relation to the flange, meaning when the bushes are bolted into the base unit the diff bracket sits lower, and the original diagonal tie-bar won't fit back on without extreme adjustment.

The Metalastik numbers on the bushes are different, the originals are 17-1258, the replacements are 17-403.

What do we think?.
I think mine need replacing as I get a "clunk" from the back when going into reverse.
Is it a job I can do on my back on the shed floor or do I need to go over a pit?
 

cobraboy

Well-Known Member
#13
It’s not that you can only get the ‘shorter’ mounts, you can buy 1.70” mounts, but as described above the centre tube is bonded into the rubber in a different place on 578080 mounts. To obtain the correct diff height for a late 3500 using the reproduced 553975 mounts, a 3/8 shim would be required between the mounts and base unit.
OK so the tube is bonded higher in the mount ? so to get the right height you need to lower the whole mount by 3/8" In that case you can shim under the mount between the diff and the mount tube. It does not matter where the mount sits, as long as the diff ends up at the right height.

I had to make up spacers between mount and diff to get the flange angles to become equal on gearbox and diff after doing a 5 sp conversion.
 
#14
OK so the tube is bonded higher in the mount ? so to get the right height you need to lower the whole mount by 3/8" In that case you can shim under the mount between the diff and the mount tube. It does not matter where the mount sits, as long as the diff ends up at the right height.

I had to make up spacers between mount and diff to get the flange angles to become equal on gearbox and diff after doing a 5 sp conversion.
No, the difference is to the other side of the mount, which is why you’d have to shim the mount.
It’s much easier to just buy the proper original mounts, which is exactly what I did 8 years ago when I started this thread!.
 
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