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[vauxsky]

Hi, got to change my diff, making awfull rumble sound, checked the rear wheels for movement and noise so dont think it is the wheel bearings. Also leak from rear drive shaft-diff on drivers side, sounds a bit clonky when I get hold of the drive shaft and turn.

My first question really is what is the Diff ratio on my 2.5 manual V6 24v, its a S reg 98 elite, and is there any identification info on the diff and do the 2.5 auto's use the same diff as I can get one of them now.

thankyou

[cem_devecioglu]

mine (opel) was auto 97 having 3.90 ratio (converted to manual later) .. manuals same year must be 3.70 ..
 
vauxhalls must be same imo..
 
http://www.omegaowners.com/forum/index.php?topic=90497.0
 

[tigers_gonads]

If you pm jimbob with your reg number, he will be able to tell you what it left the factory with 

[vauxsky]

hi, thank you for that, have sent message to Jim, will wait for reply, although I have just looked in Haynes, but the car is on the change over so it will be interesting to see what Jim comes up with.

[Jimbob]

3.9 in this case

[vauxsky]

thanks Jim, interesting, thats the Auto diff ratio, mine is manual, must have been changed at last minute by the customer who bought it.

I presume I could put a 3.70 in if one came up, are there any specific benefits or negatives from either diff ?

[cem_devecioglu]

thanks Jim, interesting, thats the Auto diff ratio, mine is manual, must have been changed at last minute by the customer who bought it.

I presume I could put a 3.70 in if one came up, are there any specific benefits or negatives from either diff ?

3.70 will give slightly better fuel , slightly lower acceleration.. I use 3.90 for manual, better acceleration , slightly higher consumption.. consumption differences are negligible imo unless you use 4.22.. driver and daily route traffic are the biggest factors on consumption imo..

[vauxsky]

Hi, just though I would come back and report:

Got a used diff from another 2.5 V6 auto, so probably ratio 3.9, anyway its running beautifull - famous last words, miles per gallon looking good too, appears to be better, do long journeys, before it was showing 31.3, I am up to 31.8 and I think theres more.

It took me a day on my own, basically

1. Backed the car up onto ramps

2. Undid the 3 star bolts on the side of the diff, but the new used diff had newer bush so you dont need to do this if you are keeping the bush and bracket from your old one.

3. Undo the prop side only on the diff doughnut, move out of the way - support.

4. Undo the drivers side Exhaust only and move out of the way.

-  2 bolts on streight - under drivers seat
-  undo exhaust bracket on back silencer to this section only.
-  I could not get to the bush bolt for the diff bracket with the tools I had so I had to move this part of the exhaust out of the way.
 - Undo the bush bolt - take out bracket

5. Took out the ABS sensors from the back, 2 off.

4. Loosen the two side bolts on the back of the diff - do not remove yet

5. Undo the Cap head bolts from the drive shafts on each wheel - remove - bit awkward but you can get to all of them with the right tools

6. Support the diff with a Jack and wood

7. Remove the two side bolts in the bushes on the diff next to the abs sensors

8. Drop the diff a couple of inches on the jack and move the drive shafts upwards towards the back of the wheek space, they will sit - but keep an eye them, then put a wedge in carfully to prize out the drive shafts from the diff, move out of the way.

9. Drop the diff on the jack and pull away from the car.

10. Put the new one in - pretty much reverse of extraction, and put a bit of diff oil around the seals and on the drivesahfts when I put them back


I rotated the old diff and I could feel a roughness on the bearings and or gears, also checked oil in new diff and topped up.

thanks for every ones input.