[Coupes33]

I thought it would be worth while starting a thread that covers modifications to the driveline components such as diff, half shafts and driveshaft. There are a few members who have already made changes in these areas but to find the information is sometimes difficult because they are buried in other threads. If references to those threads and relevant pages could be made here, it will make it easier for members in the future to find what can be done in these areas and the cost of relevant modifications. I am currently looking at what options are available.

Currently, I am running a large pumpkin diff with a Quaife LSD installed. The size of this diff is 220mm (8.75").



I had an excellent discussion with Mike from Diff Lab yesterday about BMW diffs. My thoughts were that the large pumpkin diff would be just as strong as the M3 diff (210mm). Mike said that with a modification i.e. change the carrier ball bearings for taper bearings with a 10T preload which the M3 diff has, the diff would be just as strong. However, he is not a fan of the circlip that retains the carrier bearings in the 335 diff. Having said that, he has never seen one fail as yet but doesn't know at what power levels these may become an issue. The cost of replacement of the ball bearings for the tapered bearings is $459 for the tapered bearing/shim Kit plus $200 for installation into an uninstalled diff. Limitations to this option are the gear selections which are just the OEM ones that are available. There is also the concern over the strength of the driveshaft to diff connection.

Also, Mike rates the helical type LSDs (MFactory, Quaife, etc) very low compared to the LSDs with friction plates. The helical type LSD is quiet, low maintenance and robust but it has an issue when one wheel loses traction. The transfer of power between the wheels sometimes goes haywire and even traction from both wheels is lost. Mike said they are no good for circuit racing but with good even traction at a dragstrip, they are probably ok. The M3 E90/92 diff has a LSD with friction plates but is not a very good design because the steel plates have cross drilled holes which tear at the surface of the friction plates contaminating the oil and causing wear in other parts of the diff. Mike said the best BMW LSD design is in a E36 M3. He installs these into the E90/92 diffs. The benefit of a E90/92 M3 diff is that multiple gear sets can be purchased and installed. The cost of rebuilding a E90/92 M3 diff with new seals and bearing, new gear set and installing the E36 LSD was $4,305.

I also looked at the cost of DSS 1,000hp half shafts. These are $999.99US but you have to send them a set of half shafts. The cheapest shipping costs on the DSS website was $701.42US with UPS (United Parcel Service). As you would be waiting for a couple of months for them to complete the half shafts and freight both ways, it would be ideal to send over another set of half shafts rather than the ones in your car. But the cost is extremely high when you add it all together. $999.99US + $701.42US + cost of another set of half shafts + shipping of spare set to the US. $1,701.41US ($2,197.49AU) +. Could be around $3,000AU all up cost.

[Coupes33]

Some more information
http://www.e90post.com/forums/showthread.php?t=448809

[Brule]

When you send axles over there only need the outside part near your wheel.
I shipped mine for $60 in a small box.

[Coupes33]

Originally Posted by Brule

When you send axles over there only need the outside part near your wheel.
I shipped mine for $60 in a small box.

If you didn't want your car off the road for an extended period Brule, would you recommend getting those outside axle parts elsewhere?

[Coupes33]

Brule, what gear ratio are you running in the 8.8 Ford diff and how much did yours all cost?

[Brule]

Ad kit cost 5300us including shipping to Australia. I had to pay to get the old axles pressed out of the hub $200au. new bearings put in $300au. Shipping axles $60au. Axle nut socket $30.
I've got the stock 3.08 ratio but I can get pretty well any ratio.

[Brule]

Buy a set of stock 335i axles from the us and send them to DSS address.

[DR-JEKL]

kent (with the black E93 that had a tree fall on it) has a set of brand new DSS auto tranny axles, I do know he was having trouble finding them but...

[Coupes33]

Originally Posted by DR-JEKL

kent (with the black E93 that had a tree fall on it) has a set of brand new DSS auto tranny axles, I do know he was having trouble finding them but...

Tried to PM Kent but his message bank is full so I decided to go down the M3 option. I bought a M3 diff (3.15 ratio) with 63,000kms, half shafts and tailshaft for $2,700. I will have to buy all of the bolts for the half shafts and tailshaft and get the tailshaft modified to suit. I will get a 3.45 gear set installed as well.

[DR-JEKL]

Originally Posted by Coupes33

Tried to PM Kent but his message bank is full so I decided to go down the M3 option. I bought a M3 diff (3.15 ratio) with 63,000kms, half shafts and tailshaft for $2,700. I will have to buy all of the bolts for the half shafts and tailshaft and get the tailshaft modified to suit. I will get a 3.45 gear set installed as well.

Jeez youre not mucking around!!

Yeah unfortunately the bolts are all one time use, may I ask where did you buy the diff?

when you get it can you check the diff input flange for a coloured marking that should be on one of the bolt holes?

[DR-JEKL]

pic of coloured marking on flange

[Coupes33]

Originally Posted by DR-JEKL

Jeez youre not mucking around!!

Yeah unfortunately the bolts are all one time use, may I ask where did you buy the diff?

when you get it can you check the diff input flange for a coloured marking that should be on one of the bolt holes?

Shane, I bought it from ASV European Auto Spares. When I get the diff, I will check out what colour it has on the flange.

[DR-JEKL]

Originally Posted by Coupes33

Shane, I bought it from ASV European Auto Spares. When I get the diff, I will check out what colour it has on the flange.

Will be interesting to see how you go, who will you use to mod the propshaft?

Vince's guy in Melbourne sounds good, I certainly wouldnt recommend the co that advan used to do mine

[Brule]

Bravo.
Getting it done.

[donR]

Originally Posted by Coupes33

...Also, Mike rates the helical type LSDs (MFactory, Quaife, etc) very low compared to the LSDs with friction plates. The helical type LSD is quiet, low maintenance and robust but it has an issue when one wheel loses traction. The transfer of power between the wheels sometimes goes haywire and even traction from both wheels is lost. Mike said they are no good for circuit racing but with good even traction at a dragstrip, they are probably ok...

I looked into this issue also and Mike certainly knows his stuff and whilst the friction type LSDs are arguably better in some circumstances there are some other issues to consider.

What he did mention to me was a little bit of left foot braking (just a tap) sorts out the wheel traction issue in the helical LSD when one wheel lifts and tightens the LSD.

Now have you ever tried left foot braking on an off camber road mid corner with high gs

Then I thought I believe the 335i has an electronic diff lock (EDL) which uses the ABS to brake the spinning wheel. Kind of like automatic left foot braking.

So on those rare occasions when the inner wheel lifts it should be sorted by the EDL. So maybe the helical LSD can work well with the EDL in these situations.

I have not tested the theory as yet but perhaps someone out there could try.

And with an M-Factory helical LSD had for $850AUS on special I think its a no brainer for most.

[vtl]

Originally Posted by Coupes33

Tried to PM Kent but his message bank is full so I decided to go down the M3 option. I bought a M3 diff (3.15 ratio) with 63,000kms, half shafts and tailshaft for $2,700. I will have to buy all of the bolts for the half shafts and tailshaft and get the tailshaft modified to suit. I will get a 3.45 gear set installed as well.

Good work on sourcing the bits, I would make sure to inspect the propshaft as the CV joint in mine was shattered from an impact. Luckily replaceable but set me back $300. I would be very careful of who builds the driveshaft. A lot of places just cut up the propshaft in the middle and butt weld it together which is shit. The guy i used cut off the flanges from the parts and machined them on the lathe so the flanges fit inside of the propshaft tubing, locating it accurately and ensuring minimal runout and maximum strength. I used Knox Driveshaft services which is a guy who works at home in his garage, highly recommend his work.

There was a fair amount of special tools I needed to press out the axles and pull the M3 ones into my hubs, wasn't cheap but very happy with the retrofit overall.

Originally Posted by donR

I looked into this issue also and Mike certainly knows his stuff and whilst the friction type LSDs are arguably better in some circumstances there are some other issues to consider.

What he did mention to me was a little bit of left foot braking (just a tap) sorts out the wheel traction issue in the helical LSD when one wheel lifts and tightens the LSD.

Now have you ever tried left foot braking on an off camber road mid corner with high gs

Then I thought I believe the 335i has an electronic diff lock (EDL) which uses the ABS to brake the spinning wheel. Kind of like automatic left foot braking.

So on those rare occasions when the inner wheel lifts it should be sorted by the EDL. So maybe the helical LSD can work well with the EDL in these situations.

I have not tested the theory as yet but perhaps someone out there could try.

And with an M-Factory helical LSD had for $850AUS on special I think its a no brainer for most.

The eDiff is ineffective and will not help, its the whole reason why we get aftermarket LSDs in the first place. I found the ediff only really works when the road is fully wet and youre under 50kph. The brakes simply do not have enough power to control the rear wheels.

With the stock suspension and most coilovers available for the e8x/e9x theyre way too soft and the rear wheels unload all the time. You don't need to lift the wheel off the ground for the inside wheel to spin. Torquey engine and soft suspension will unload the wheels under cornering a lot, especially in mountain roads.

I have found with a Quaife fitted to a 335i with ST X coilovers the wheels unloaded a LOT. Would feel great but then whenever the wheels unloaded it just behaved like an open diff. Felt hard to predict. On another car with Ohlins R&T the car had 6/12K springs which are quite a bit stiffer than most street coilovers for BMWs. This setup controlled the body roll very well and the quaife worked very well and was a lot more predictable transitioning into oversteer. But really its a bit of a catch22, people want a helical because its great for a daily but unless you have a stiff setup the helical doesn't work that great.

[Coupes33]

Originally Posted by DR-JEKL

Will be interesting to see how you go, who will you use to mod the propshaft?

Vince's guy in Melbourne sounds good, I certainly wouldnt recommend the co that advan used to do mine

I have used Hardy Spicer before and they do a good job. I will see who Duck uses as well.

[Coupes33]

[QUOTE=vtl;22272816]Good work on sourcing the bits, I would make sure to inspect the propshaft as the CV joint in mine was shattered from an impact. Luckily replaceable but set me back $300. I would be very careful of who builds the driveshaft. A lot of places just cut up the propshaft in the middle and butt weld it together which is shit. The guy i used cut off the flanges from the parts and machined them on the lathe so the flanges fit inside of the propshaft tubing, locating it accurately and ensuring minimal runout and maximum strength. I used Knox Driveshaft services which is a guy who works at home in his garage, highly recommend his work.

There was a fair amount of special tools I needed to press out the axles and pull the M3 ones into my hubs, wasn't cheap but very happy with the retrofit overall.

Good advice Vince. I can imagine how much fun it will be removing the 335 half shafts from the wheel hubs. Can't wait. Initially, I will give it a go myself and if and when I fail, I might remove the hubs and half shafts and take them to someone with a press who has done it before. Today, I put together a list of bolts, nuts and reinforcements required for bolting the diff into the subframe, bolting half shafts to the diff and nuts for the end of the half shafts. At ECS Tuning, all of these + shipping cost $372AU. Then I rang up Brisbane BMW for their prices. Just the 12 bolts for bolting the half shafts to the diff cost $406.80. I wonder why we don't buy BMW parts in Australia.

[Coupes33]

Originally Posted by Brule

Bravo.
Getting it done.

Yes, I decided the M3 option was the easier way to go Brule.

[DR-JEKL]

Originally Posted by Coupes33

Today, I put together a list of bolts, nuts and reinforcements required for bolting the diff into the subframe, bolting half shafts to the diff and nuts for the end of the half shafts. At ECS Tuning, all of these + shipping cost $372AU. Then I rang up Brisbane BMW for their prices. Just the 12 bolts for bolting the half shafts to the diff cost $406.80. I wonder why we don't buy BMW parts in Australia.

Try FCP euro coupes much cheaper shipping ECS is just ridiculous...

[BSG335]

Originally Posted by vtl

Good work on sourcing the bits, I would make sure to inspect the propshaft as the CV joint in mine was shattered from an impact. Luckily replaceable but set me back $300. I would be very careful of who builds the driveshaft. A lot of places just cut up the propshaft in the middle and butt weld it together which is shit. The guy i used cut off the flanges from the parts and machined them on the lathe so the flanges fit inside of the propshaft tubing, locating it accurately and ensuring minimal runout and maximum strength. I used Knox Driveshaft services which is a guy who works at home in his garage, highly recommend his work.

There was a fair amount of special tools I needed to press out the axles and pull the M3 ones into my hubs, wasn't cheap but very happy with the retrofit overall.

The eDiff is ineffective and will not help, its the whole reason why we get aftermarket LSDs in the first place. I found the ediff only really works when the road is fully wet and youre under 50kph. The brakes simply do not have enough power to control the rear wheels.

With the stock suspension and most coilovers available for the e8x/e9x theyre way too soft and the rear wheels unload all the time. You don't need to lift the wheel off the ground for the inside wheel to spin. Torquey engine and soft suspension will unload the wheels under cornering a lot, especially in mountain roads.

I have found with a Quaife fitted to a 335i with ST X coilovers the wheels unloaded a LOT. Would feel great but then whenever the wheels unloaded it just behaved like an open diff. Felt hard to predict. On another car with Ohlins R&T the car had 6/12K springs which are quite a bit stiffer than most street coilovers for BMWs. This setup controlled the body roll very well and the quaife worked very well and was a lot more predictable transitioning into oversteer. But really its a bit of a catch22, people want a helical because its great for a daily but unless you have a stiff setup the helical doesn't work that great.

Not to deviate from the thread topic but I have to ask... in this case where I have a standard diff on my pre LCI and have factory sport suspension, what's the suggestions for coilovers / shock & spring setup for spirited street and daily driving without compromising too much on comfort? I think @ASN had a thread about initial harshness then softness of the sport suspension.

[Coupes33]

Originally Posted by DR-JEKL

Try FCP euro coupes much cheaper shipping ECS is just ridiculous...

Shane, I agree that ECS shipping costs are high but the difference in overall cost with FCP euro is nothing. The cost of the same parts through FCP euro is $373.07AU compared to $372AU from ECS. Shipping at ECS is $71.84US compared to FCP euro at $43.25US. Parts costs were $279.33AU at ECS and $317.76AU at FCP euro.