Differential Upgrades
- Thread starter Mikey_Boy
- Start date
Mikey_Boy said:Thanks All!
Looks like I'll be going for rebuilding the standard diff with a 3.91 ratio - watch this space...
I did a diff ratio swap on my Z3MC in 2010 from OEM 3.15 to 3.46. When I did some datalogging from the ECU using various parameters, the swap didn't make any significant difference to on-road performance and just increased fuel consumption. For me, it was a waste of time/money and I went back to the OEM ratio.
I have just taken the plunge and purchased a Gripper 12 Plate diff & BMW 4.10 final ratio.
This is for my e46 M3 though (Track car)
After doing a bit of research is seams the 4.10 is the one to go for, Takes the top speed down to about 170 but it will get there pretty quickly! apparently its the equivalent of 40bhp
https://www.automac.co.uk are building mine.
Adam
This is for my e46 M3 though (Track car)
After doing a bit of research is seams the 4.10 is the one to go for, Takes the top speed down to about 170 but it will get there pretty quickly! apparently its the equivalent of 40bhp
https://www.automac.co.uk are building mine.
Adam
bradz said:
Cool 8) let us know how you get on with it! I've heard really good things about the gripper and been looking at the same solution, it makes a lot of sense in terms of performance and economics.
For me it'll be an 8 plate and the 3.91 cwp as my car is still supposed to be not too unpleasant on the road (think the 12 plate is a bit on the noisy side?).
Cheers I will do.
Automac who are building it said the 12 plate will be noisy at low speed on the road and will push the front at very low speed. (This was a concern of mine as I still drive to tracks & the ring) They said its not horrific and the way it hooks up on track will make it worth it, They also said when it goes in for its 12 month checkup if I wanted they could change it back to a 8 plate for no extra cost.
That was enough to persuade me to go all out!
Automac who are building it said the 12 plate will be noisy at low speed on the road and will push the front at very low speed. (This was a concern of mine as I still drive to tracks & the ring) They said its not horrific and the way it hooks up on track will make it worth it, They also said when it goes in for its 12 month checkup if I wanted they could change it back to a 8 plate for no extra cost.
That was enough to persuade me to go all out!
bradz said:Cheers I will do.
Automac who are building it said the 12 plate will be noisy at low speed on the road and will push the front at very low speed. (This was a concern of mine as I still drive to tracks & the ring) They said its not horrific and the way it hooks up on track will make it worth it, They also said when it goes in for its 12 month checkup if I wanted they could change it back to a 8 plate for no extra cost.
That was enough to persuade me to go all out!
Can't argue with that! Keep us posted
bradz said:
Thats the result of a very blunt calculation.
Its the equivalent of 44bhp for 77% of the time and a loss of ~82bhp for 33% of the time.
Only when you're in the same gear you have the 44bhp advantage, but with the shorter gears you have to shift up earlier, resulting in much much less wheel torque (and equivalent power).
Its a difficult exact calculation to make. The powerpart when you're in the same gear its easy, but the percentage of time and drop in power when going in different gears is difficult because not every gear is equally spaced. For the percentage I took gear 1-3 (so thats accelerating up to 100mph on the standard final drive), and the loss in power when riding in a higher gear I took the difference between 2nd and 3rd gear (the loss in power between 1st and 2nd is bigger as the corresponding difference in gearing is bigger).
0-60 will be faster with the short ratio but 0-105 will be slower (and 0-90 will be quicker).
So it really depends on what exact speeds you try to reach.
But the +40hp gain is not true (well, its true for 77% just as the loss of ~82hp is true for 33%).
In the end the gain is 0%. The ratio that maximizes the end speed reached wins.
Happy New Year everyone! I've just spoken with my local Indy and they are suggesting getting a standard diff rebuilt to standard spec is going to be tricky due to lack of parts availability. Not sure how true that is so any advice on that is much appreciated!
Just looking at the above, the gripper diffs are also a tempting option - is there a ballpark price for the build?? I'd probably keep the 3.64 ratio and something not too aggressive as the car is mainly used on the road.
It seems to me to be much easier to just swap the whole unit than have to go through the pain of taking the diff out and then have the car hanging about for weeks whilst the diff is sorted...
As ever, any advice is much appreciated!
Just looking at the above, the gripper diffs are also a tempting option - is there a ballpark price for the build?? I'd probably keep the 3.64 ratio and something not too aggressive as the car is mainly used on the road.
It seems to me to be much easier to just swap the whole unit than have to go through the pain of taking the diff out and then have the car hanging about for weeks whilst the diff is sorted...
As ever, any advice is much appreciated!
Standard diff is good enough for road use.
If you want a track focused car then I recommend the BMW Motorsport 4:10 diff.
Darragh Doyle (ex F1 tech) @ Everything M3’s can rebuild a diff to your specification at a reasonable price.
Skip to 12 mins 40 sec:
[youtube]UxLVmyK_WnQ[/youtube]
Website: https://m.facebook.com/pages/category/Cars/Everything-M3s-172075713409262/
If you want a track focused car then I recommend the BMW Motorsport 4:10 diff.
Darragh Doyle (ex F1 tech) @ Everything M3’s can rebuild a diff to your specification at a reasonable price.
Skip to 12 mins 40 sec:
[youtube]UxLVmyK_WnQ[/youtube]
Website: https://m.facebook.com/pages/category/Cars/Everything-M3s-172075713409262/
Mikey_Boy said:Happy New Year everyone! I've just spoken with my local Indy and they are suggesting getting a standard diff rebuilt to standard spec is going to be tricky due to lack of parts availability. Not sure how true that is so any advice on that is much appreciated!
Just looking at the above, the gripper diffs are also a tempting option - is there a ballpark price for the build?? I'd probably keep the 3.64 ratio and something not too aggressive as the car is mainly used on the road.
It seems to me to be much easier to just swap the whole unit than have to go through the pain of taking the diff out and then have the car hanging about for weeks whilst the diff is sorted...
As ever, any advice is much appreciated!
Sack your Indy, Rebuild parts are available from BMW even ebay! I bet they don't have the tooling/ Expertise.
Speak to Neil @ https://www.automac.co.uk/
Tell him Adam sent you 8)
I'm not far behind you Bradz... Mine's due in a couple of weeks!
I'm thinking I should replace the diff mounting bushes as well - anyone used powerflex or should I stay OEM? Items 20 and 21 on this link:
https://www.powerflex.co.uk/products/Z4M+E85+%26+E86+%282006-2009%29-3169/1.html
Any help or thoughts always appreciated!
I'm thinking I should replace the diff mounting bushes as well - anyone used powerflex or should I stay OEM? Items 20 and 21 on this link:
https://www.powerflex.co.uk/products/Z4M+E85+%26+E86+%282006-2009%29-3169/1.html
Any help or thoughts always appreciated!
I went with powerflex diff bushes on the Z4M, I noticed no negative effects.
I went with them on the M3 and you can hear the diff whine through the car... Very odd how they affect the M3 more!
Gripper and 4.10 fitted to the M3 yesterday! Unfortunately I cant try it out yet as we are waiting for a new centre bearing from BMW.
I went with them on the M3 and you can hear the diff whine through the car... Very odd how they affect the M3 more!
Gripper and 4.10 fitted to the M3 yesterday! Unfortunately I cant try it out yet as we are waiting for a new centre bearing from BMW.
Bradz - how are you getting on with your diff?
Mine (8 plate gripper with 3.64 final drive) has been fitted recently and I've done about 200 miles on it so far - nothing too heavy other than a few test corners. It's a fruity little number and mine does make quite a bit of noise at low speed - I've noticed some extra noise at motorway speed as well but I think that's down to the mounting bushes as I've gone for powerflex.
Any updates appreciated!
Mine (8 plate gripper with 3.64 final drive) has been fitted recently and I've done about 200 miles on it so far - nothing too heavy other than a few test corners. It's a fruity little number and mine does make quite a bit of noise at low speed - I've noticed some extra noise at motorway speed as well but I think that's down to the mounting bushes as I've gone for powerflex.
Any updates appreciated!
Its bloody loud!
I went with the 12 plate and 4.10... At low speed turns the car sounds horrific as you can hear the clutch binding - I was warned.
I too went with power flex bushes... I fitted them to the diff in the Z4MC and noticed no difference at all, fitted them to the gripper in the m3 and you can hear it resonate through the whole car! - going back to stock bushes.
Initial impressions on the road are... Its noisy, But the first time it locked and spat me out of a corner faster than I deemed possible I knew I made the right decision!
Booked a track-day on the 4th March at Bedford Autodrome - to really test it out! I'll keep you posted!
Adam
I went with the 12 plate and 4.10... At low speed turns the car sounds horrific as you can hear the clutch binding - I was warned.
I too went with power flex bushes... I fitted them to the diff in the Z4MC and noticed no difference at all, fitted them to the gripper in the m3 and you can hear it resonate through the whole car! - going back to stock bushes.
Initial impressions on the road are... Its noisy, But the first time it locked and spat me out of a corner faster than I deemed possible I knew I made the right decision!
Booked a track-day on the 4th March at Bedford Autodrome - to really test it out! I'll keep you posted!
Adam
Thanks Bradz...!
Glad it's not just me that thinks it's aggressive... 8)
Just to add to the points I made above - agree with Bradz - at low speed (anything below 30mph) it makes quite a lot of cracking noises - with the 8 plate I'm told this improves with miles so a good excuse to drive the car more to see how that works out. I've had aggressive diffs in other cars so this is familiar but quite a surprise the first time you hear it!!
At higher speed, the car feels super locked down with no clutch binding noises at all from the diff - and especially under braking the car feels much better.
In a straight line at motorway speeds, there is a slight whine from the diff and it does resonate a little at certain - like Bradz, I'm looking to go back to OEM mounting bushes to try and resolve that as I believe that's a mounting issue.
I'm also looking for a UK trackday to try the diff out in anger - on the couple of roundabouts I've tried it on, it is very impressive...
More to come!
Glad it's not just me that thinks it's aggressive... 8)
Just to add to the points I made above - agree with Bradz - at low speed (anything below 30mph) it makes quite a lot of cracking noises - with the 8 plate I'm told this improves with miles so a good excuse to drive the car more to see how that works out. I've had aggressive diffs in other cars so this is familiar but quite a surprise the first time you hear it!!
At higher speed, the car feels super locked down with no clutch binding noises at all from the diff - and especially under braking the car feels much better.
In a straight line at motorway speeds, there is a slight whine from the diff and it does resonate a little at certain - like Bradz, I'm looking to go back to OEM mounting bushes to try and resolve that as I believe that's a mounting issue.
I'm also looking for a UK trackday to try the diff out in anger - on the couple of roundabouts I've tried it on, it is very impressive...
More to come!
Hi folks,
Another quick update - the diff is getting better and better with miles - driving on A & B roads is doing the trick to run it in. It is still laugh out loud noisy pulling away from junctions, but at speed now it is much quieter.
I have changed the front bush back to OEM - that has taken away the whining at speed so a result there as well...
Hopefully I'll be on track with it at the end of April to try it out in anger! :evil:
Another quick update - the diff is getting better and better with miles - driving on A & B roads is doing the trick to run it in. It is still laugh out loud noisy pulling away from junctions, but at speed now it is much quieter.
I have changed the front bush back to OEM - that has taken away the whining at speed so a result there as well...
Hopefully I'll be on track with it at the end of April to try it out in anger! :evil: