Home Forums Articles How To's FAQ Register
Go Back   Xoutpost.com > BMW SAV Forums > X5 (E70) Forum
Arnott
User Name
Password
Member List Premier Membership Search Today's Posts Mark Forums Read

Xoutpost server transfer and maintenance is occurring....
Xoutpost is currently undergoing a planned server migration.... stay tuned for new developments.... sincerely, the management


Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-26-2019, 02:42 PM
Member
 
Join Date: Sep 2019
Location: Frederick, MD
Posts: 149
Cyrix2k is on a distinguished road
6HP to 8HP conversion feasibility

Has anyone looked into if swapping an 8 speed transmission into the earlier E70s is feasible? I'm doing some preliminary research using my 4.8 as a reference and a 50i as the donor. So far, the bellhousing bolt pattern appears to be the same. I'm guessing overall length is close as well - the rear driveshaft is 1mm different in overall length, but of course that incorporates the transfer case as well. The E70 has seen a number of transfer cases over the years and it's another challenge to address - is the bolt pattern and splined output shaft the same between the 6HP and 8HP? If not, then the transfer case that goes to the transmission would have to be used and I'm not sure how that would integrate. From what I can tell, it does look the same (at least the bolt pattern). Once the mechanicals are addressed, we need to worry about the electronics. I've heard, though not confirmed, that the 8HP uses FlexRay for communication whereas the 6HP uses CAN bus. My suspicion is that while this might be true on F-series vehicles, the E70 likely retained CAN bus for its 8HP implementation. Assuming the message format is the same, I suspect the transmission may be plug and play... As far the immobilizer is concerned, I have the equipment to synchronize the ISN on both the 6HP & 8HP. It looks like the CAS is shared between 6HP & 8HP, so I again suspect it can be made to work. Any thoughts? Does anyone have wiring diagrams for the 8HP by any chance?
Reply With Quote

Sponsored Links

  #2  
Old 11-26-2019, 04:32 PM
Member
 
Join Date: Aug 2005
Location: Phoenix, AZ
Posts: 397
smassey321 is on a distinguished road
Wiring diagrams are available here. https://www.newtis.info/tisv2/a/en/

The 8 speed transmission uses a different transfer case than the 6 speed. I checked out some ebay photos and the output of the 6 vs 8 speed does not look the same. The best way to do this may be a complete donor vehicle so you can get trans, tc, driveshafts, diffs and mounts. I would love to have the 8 speed in my diesel. E70 LCI diesel in Europe has it.
__________________
2009 35d, 2006 325i & 330i
Reply With Quote
  #3  
Old 11-26-2019, 04:39 PM
josiahg52's Avatar
Member
 
Join Date: Dec 2014
Location: New England
Posts: 837
josiahg52 is on a distinguished road
Quote:
Originally Posted by smassey321 View Post
E70 LCI diesel in Europe has it.
Interesting. I did not know that.
__________________
8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim
Reply With Quote
  #4  
Old 11-26-2019, 04:52 PM
Member
 
Join Date: Sep 2019
Location: Frederick, MD
Posts: 149
Cyrix2k is on a distinguished road
Thanks. According to that, both use CAN bus and appear to be wired about the same. There's a couple pin differences and an additional connection on the 8HP for tiptronic (I think). None of that seems particularly worrisome.

At least on the V8, the transfer case bolt pattern does look the same to me? See these two auctions
https://www.ebay.com/itm/2007-2010-B...cAAOSwEFhdpLeq

https://www.ebay.com/itm/2011-2013-B...8AAOSwz~RdI3SR

On the plus side, I can reference a 2013 xDrive35i. I'd like to keep the swap as simple as possible so if the original transfer case can bolt on and the original driveshafts can be reused, that would be fantastic. If I ask really nicely, I might be able to get a CAN bus capture from the 2013 which would definitively answer if the messaging is the same.
Reply With Quote
  #5  
Old 11-27-2019, 09:42 AM
Member
 
Join Date: Aug 2005
Location: Phoenix, AZ
Posts: 397
smassey321 is on a distinguished road
To me, it looks like the output shaft is longer on the 8 speed.
__________________
2009 35d, 2006 325i & 330i
Reply With Quote
  #6  
Old 11-27-2019, 01:42 PM
Member
 
Join Date: Sep 2019
Location: Frederick, MD
Posts: 149
Cyrix2k is on a distinguished road
Quote:
Originally Posted by smassey321 View Post
To me, it looks like the output shaft is longer on the 8 speed.
You're right. I think the ATC450 could also be swapped in or it looks like it may be possible to put a spacer between the 8HP and the ATC700. In the pictures, the ATC700 has an almost flush mounting flange whereas the ATC450 is recessed. I also did some more research and found the diffs are different. Early models received very short gears - 4.44 in the gas 3.0 and 3.91 in the 4.8. Later models received 3.15s which works with the broader torque curve of the turbo engines & the wider ratio spread of the 8HP. While the 8th gear is about comparable to 6th in the 6HP, first gear is much shorter on the 8HP. I think I'd prefer to try and keep the 3.91s if possible.

I also looked up the immobilizer and it looks like the CAS3 was used for the entire production run of the E70. That means it should absolutely work with the 8HP.
Reply With Quote
  #7  
Old 11-27-2019, 03:07 PM
Member
 
Join Date: Jan 2019
Location: New Jersey, USA
Posts: 161
spyro235 is on a distinguished road
Very interested in how this goes. I know the ATC700 is thought to be much stronger- and my 35d would need it. I've looked into swapping to the 3.15 of the 50i, to bring my final drive down from 3.64, to increase fuel efficiency, run at lower RPM, and generally run quieter/ more efficiently on the long haul. If you were to swap the 8 speed, I'd be very curious to see a what it takes!
__________________
'10 X5 35d- 279k mi, deleted and DUDMD stage 2, daily and tow vehicle
'01 330i- Drift car: SLR Super angle, BC coils- keep it simple
'07 335i 6mt - Sold @ 171k miles- stage 2 daily commuter for 2 years
Reply With Quote
  #8  
Old 11-27-2019, 03:24 PM
Member
 
Join Date: Aug 2005
Location: Phoenix, AZ
Posts: 397
smassey321 is on a distinguished road
Quote:
Originally Posted by Cyrix2k View Post
You're right. I think the ATC450 could also be swapped in or it looks like it may be possible to put a spacer between the 8HP and the ATC700. In the pictures, the ATC700 has an almost flush mounting flange whereas the ATC450 is recessed. I also did some more research and found the diffs are different. Early models received very short gears - 4.44 in the gas 3.0 and 3.91 in the 4.8. Later models received 3.15s which works with the broader torque curve of the turbo engines & the wider ratio spread of the 8HP. While the 8th gear is about comparable to 6th in the 6HP, first gear is much shorter on the 8HP. I think I'd prefer to try and keep the 3.91s if possible.

I also looked up the immobilizer and it looks like the CAS3 was used for the entire production run of the E70. That means it should absolutely work with the 8HP.
Regarding the rear difs, the 3.15 for the 5.0 has a different part number than the 3.15 for the 3.0. This may be due to the larger axle shafts on the 5.0. Some of us diesel people are considering a 3.15 dif swap to get better highway MPG. A 3.15 dif alone will lower the highway RPM 50% compared to the 8 speed/3.15.
__________________
2009 35d, 2006 325i & 330i
Reply With Quote
  #9  
Old 11-27-2019, 04:33 PM
Member
 
Join Date: Jan 2019
Location: New Jersey, USA
Posts: 161
spyro235 is on a distinguished road
Quote:
Originally Posted by smassey321 View Post
Regarding the rear difs, the 3.15 for the 5.0 has a different part number than the 3.15 for the 3.0. This may be due to the larger axle shafts on the 5.0. Some of us diesel people are considering a 3.15 dif swap to get better highway MPG. A 3.15 dif alone will lower the highway RPM 50% compared to the 8 speed/3.15.
Where are you getting the 50% number from? By my math, it’ll lower our highway rpm by 15.5% from our 6 speed/3.15. I was under the impression that that would put us very in line with the engine speed of the f15/ 8 speed.
__________________
'10 X5 35d- 279k mi, deleted and DUDMD stage 2, daily and tow vehicle
'01 330i- Drift car: SLR Super angle, BC coils- keep it simple
'07 335i 6mt - Sold @ 171k miles- stage 2 daily commuter for 2 years
Reply With Quote
  #10  
Old 11-27-2019, 05:35 PM
Member
 
Join Date: Aug 2005
Location: Phoenix, AZ
Posts: 397
smassey321 is on a distinguished road
Quote:
Originally Posted by spyro235 View Post
Where are you getting the 50% number from? By my math, it’ll lower our highway rpm by 15.5% from our 6 speed/3.15. I was under the impression that that would put us very in line with the engine speed of the f15/ 8 speed.
Sorry for the confusion on the 50% number. I was using a final drive calculator on some website a while ago. If I remember correctly, my current 2600 rpm at 80 mph would go to 2300 with the 3.15 dif. Then 2000 with the 8 speed.
__________________
2009 35d, 2006 325i & 330i
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On





All times are GMT -4. The time now is 08:31 AM.
vBulletin, Copyright 2024, Jelsoft Enterprises Ltd. SEO by vBSEO 3.6.0
© 2017 Xoutpost.com. All rights reserved. Xoutpost.com is a private enthusiast site not associated with BMW AG.
The BMW name, marks, M stripe logo, and Roundel logo as well as X3, X5 and X6 designations used in the pages of this Web Site are the property of BMW AG.
This web site is not sponsored or affiliated in any way with BMW AG or any of its subsidiaries.