How Many Miles Is A DMF Good For?

Mike Noc · 29th March 2021, 21:28

Well I got 411216 miles out of mine. The radial play was 30mm, the axial play was negligible, and I only changed it because the clutch slave cylinder was leaking and I had a spare good one from a scrapper waiting on the shelf.

Big difference in play between the two, and the replacement certainly feels a bit smoother.

Odd Job · 30th March 2021, 07:05

Quote:

Originally Posted by Mike Noc

Well I got 411216 miles out of mine. The radial play was 30mm, the axial play was negligible, and I only changed it because the clutch slave cylinder was leaking and I had a spare good one from a scrapper waiting on the shelf.

Big difference in play between the two, and the replacement certainly feels a bit smoother.

That's impressive mileage!
Well done!

ashy90 · 25th April 2021, 07:45

Unless it’s mega low mileage, I would always change the dmf on a diesel when doing a clutch change. If you don’t it will contribute to early slave failure.

The Freelander’s don’t have anywhere near as many premature slave failures after new clutch’s as we do with the 75. Yet it’s the same engine, gearbox, clutch and slave, and even the dmf is exactly the same. What’s the difference? Well.... Freelander owners and specialists say fitting a new dmf is a must with every clutch change, and 75 owners and ‘specialists’ say you don’t need too fit a new dmf.

Mike Noc · 25th April 2021, 10:14

There are differences between Freelander engines and gearboxes compared to those fitted to Rover 75s. If you don't believe me try fitting a Freelander turbo to a 75 or a Freelander gearbox to a 75 - the differential for the front wheels in a Freelander is fitted in the IRD box, not the Getrag.

Having worked on both types of cars as we have had them in the family for years and still do, I haven't seen any difference in how long the slaves last in either one. The last slave I changed before my 75 was in the Landy.

steveharvey2001 · 26th April 2021, 14:24

Quote:

Originally Posted by ashy90

Unless it’s mega low mileage, I would always change the dmf on a diesel when doing a clutch change. If you don’t it will contribute to early slave failure.

The Freelander’s don’t have anywhere near as many premature slave failures after new clutch’s as we do with the 75. Yet it’s the same engine, gearbox, clutch and slave, and even the dmf is exactly the same. What’s the difference? Well.... Freelander owners and specialists say fitting a new dmf is a must with every clutch change, and 75 owners and ‘specialists’ say you don’t need too fit a new dmf.

Is there a technical explanation for why DMF issues impact the slave cylinder life?

Mike Noc · 26th April 2021, 22:00

Probably due to excessive axial play, as that could cause extra movement of the slave cylinder seals when the clutch pedal is depressed.

Funnily enough, as I mentioned in the opening post, there was negligible axial play in the DMF that was replaced, which makes sense as by far the majority of the loading is radial.

LUK give tolerances for both axial and radial play so you can check your DMF when you have the gearbox off to see whether it needs replacing or not.

.

29th March 2021, 21:28	#1
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,551 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	How Many Miles Is A DMF Good For? Well I got 411216 miles out of mine. The radial play was 30mm, the axial play was negligible, and I only changed it because the clutch slave cylinder was leaking and I had a spare good one from a scrapper waiting on the shelf. Big difference in play between the two, and the replacement certainly feels a bit smoother.

26th April 2021, 22:00	#6
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,551 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Probably due to excessive axial play, as that could cause extra movement of the slave cylinder seals when the clutch pedal is depressed. Funnily enough, as I mentioned in the opening post, there was negligible axial play in the DMF that was replaced, which makes sense as by far the majority of the loading is radial. LUK give tolerances for both axial and radial play so you can check your DMF when you have the gearbox off to see whether it needs replacing or not. . Last edited by Mike Noc; 27th April 2021 at 07:06..

25th April 2021, 07:45	#3
ashy90 Avid contributor MG ZT 160 V6 Join Date: Jul 2012 Location: West Sussex Posts: 132 Thanks: 1 Thanked 8 Times in 7 Posts	Unless it’s mega low mileage, I would always change the dmf on a diesel when doing a clutch change. If you don’t it will contribute to early slave failure. The Freelander’s don’t have anywhere near as many premature slave failures after new clutch’s as we do with the 75. Yet it’s the same engine, gearbox, clutch and slave, and even the dmf is exactly the same. What’s the difference? Well.... Freelander owners and specialists say fitting a new dmf is a must with every clutch change, and 75 owners and ‘specialists’ say you don’t need too fit a new dmf.

25th April 2021, 10:14	#4
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,551 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	There are differences between Freelander engines and gearboxes compared to those fitted to Rover 75s. If you don't believe me try fitting a Freelander turbo to a 75 or a Freelander gearbox to a 75 - the differential for the front wheels in a Freelander is fitted in the IRD box, not the Getrag. Having worked on both types of cars as we have had them in the family for years and still do, I haven't seen any difference in how long the slaves last in either one. The last slave I changed before my 75 was in the Landy.