Rear diff change questions

[speedmunky]

Hi all, so the van made an awful noise the other week like proper clunking when you’re moving, put clutch in and if you’re rolling it still makes the noise. I put it down to gearbox so changed that to another and all was good for about 10 days then it made that same noise again on Thursday night. You can also feel it when you’re moving. All looked fine when changing the box and I can’t see it been the box again in the exact same way. Had it on stands and tried 1st 2nd and 3rd and all the same noise regardless of gear so it’s making me think it’s the diff ‘cause there is a good bit of twist in the propshaft so I’m assuming something in there has gone tits up.

So, the question is, I’ve seen a twin wheel for a decent price which comes with 3 leaf springs which is something else I’ve been looking for so it’s sorta 2 birds 1 stone kinda thing. Is it just a case of swapping the hubs and shafts over to make it a single wheel or is there more to it?

Mk7, 2.4 2008

[Airthies]

AFAIK the twins are narrower than the single wheels due to hubs being further inboard.

Springs just go for new rather than second hand, especially if the twin wheel has been a flatbed it's likely been on the bumpstops more than the springs.
Check midland road springs, they're very good if you call them for advice.

There's also a crowd around the Halifax area that do diff ratio repairs or replacements.

https://www.facebook.com/share/1FpE23p9bL/

[dumper]

Henderson Transmisions 01427 875 889. At Sandtoft Doncaster. Did my mk8/

[speedmunky]

AFAIK the twins are narrower than the single wheels due to hubs being further inboard.

Springs just go for new rather than second hand, especially if the twin wheel has been a flatbed it's likely been on the bumpstops more than the springs.
Check midland road springs, they're very good if you call them for advice.

There's also a crowd around the Halifax area that do diff ratio repairs or replacements.

https://www.facebook.com/share/1FpE23p9bL/

See I wasn’t sure if it was just the hub design that was slightly different to compensate for the wheel difference ‘cause looking at pics the calliper seems in the same place but the abs ring looks about 10mm closer compared to the single wheel but obviously they mount to the hub so was t sure if it was just slightly more of a lip or it had just not been pushed on the hub far enough

[knobby1]

See I wasn’t sure if it was just the hub design that was slightly different to compensate for the wheel difference ‘cause looking at pics the calliper seems in the same place but the abs ring looks about 10mm closer compared to the single wheel but obviously they mount to the hub so was t sure if it was just slightly more of a lip or it had just not been pushed on the hub far enough

The spring mounts are further inboard too...to accommodate the extra wheel....the diff ratio will probably kill you....more than likely a 5.xx!! Not a lot of fun in a normal van.

Lord Knobrot

[speedmunky]

See I wasn’t sure if it was just the hub design that was slightly different to compensate for the wheel difference ‘cause looking at pics the calliper seems in the same place but the abs ring looks about 10mm closer compared to the single wheel but obviously they mount to the hub so was t sure if it was just slightly more of a lip or it had just not been pushed on the hub far enough

The spring mounts are further inboard too...to accommodate the extra wheel....the diff ratio will probably kill you....more than likely a 5.xx!! Not a lot of fun in a normal van.

Lord Knobrot

Well I think I’ll just stick with finding a single wheel instead then but I’ve asked Dave (ChatGPT) for part numbers for rear axles and he’s given me a list so hopefully it’ll help find the right one that I want. Got a broken 4.27 at the minute but I’d like a bit lower ‘cause at 2k in 6th you’re doing 50mph so just feels like you’re flat out all the time on the motorway

[Airthies]

Part numbers are pretty much pointless for that age of axle but if you can find a seller that knows what ratio they've got then I'd suggest a 3.73 as a good all rounder.
With a bit of digging you can find the factory ratio of any van from the vin no. or reg if sellers have that info

[speedmunky]

Part numbers are pretty much pointless for that age of axle but if you can find a seller that knows what ratio they've got then I'd suggest a 3.73 as a good all rounder.
With a bit of digging you can find the factory ratio of any van from the vin no. or reg if sellers have that info

Dave did say it has a letter on the vin sticker that says what it should’ve come with but obviously there’s still the chance of it been changed. Would I be correct in thinking jumbos are more likely than not to have those lower ratio diffs in them? And also the euro 5 comes with slightly lower options than the euro 4 did?

[knobby1]

Would I be correct in thinking jumbos are more likely than not to have those lower ratio diffs in them? And also the euro 5 comes with slightly lower options than the euro 4 did?

Not necessarily, the diff ratio fitted to a vehicle when new was often at the buyer's discretion/choice...there are 9 ratios available for the Mk7's.....generally, the lower the ratio, the more power you need to pull it.

Would be a bit silly putting a 3.31 diff in a 2.4 100 as it probably won't have the grunt to pull top gear when it has a load in the back....this is why campers, Lutons, tippers and recovery machines usually have a 5.xx ratio, they need to carry a decent load and not often travelling over 70mph..

Good "all-rounders" are the 3.73 or 4.27...they both tow well and not too bad on the motorway.

Lord Knobrot

[speedmunky]

Would I be correct in thinking jumbos are more likely than not to have those lower ratio diffs in them? And also the euro 5 comes with slightly lower options than the euro 4 did?

Not necessarily, the diff ratio fitted to a vehicle when new was often at the buyer's discretion/choice...there are 9 ratios available for the Mk7's.....generally, the lower the ratio, the more power you need to pull it.

Would be a bit silly putting a 3.31 diff in a 2.4 100 as it probably won't have the grunt to pull top gear when it has a load in the back....this is why campers, Lutons, tippers and recovery machines usually have a 5.xx ratio, they need to carry a decent load and not often travelling over 70mph..

Good "all-rounders" are the 3.73 or 4.27...they both tow well and not too bad on the motorway.

Lord Knobrot

Well mine was a 115 but it’s got a few extra ponies now but it’s just the 3k rpm at 70mph that’s quite annoying so want to try get a lower one just to bring it down a bit ‘cause this doesn’t struggle in the slightest for setting off and if I’m honest, I hardly use 1st gea. But I’ve seen one and I’m gunna take a risk and cross everything that it’s a power ratio to mine but if it’s the same I’ll still be happy that it’s actually moving again

[Airthies]

You can work out the ratio by holding one wheel.
Mark the prop flange and opposite wheel inline with something convenient.
Then turn wheel 2 full turns, and count the amount of turns of the input flange.
Roughly:
3&¾ turns will be 3.73
3&½ turns will be 3.58
3&⅓ turns will be 3.31
Etc....