Transmission Ramblings (Long) - BMW M5 Forum and M6 Forums
E39 M5 and E52 Z8 Discussion 1998-2003 Advertiser's Forum

 2Likes
  • 1 Post By Foghorn
  • 1 Post By herrubermensch
 
LinkBack Thread Tools Rate Thread Display Modes
post #1 of 6 Old 7th February 2019, 10:39 PM Thread Starter
Foghorn
Junior Member, warming up (<31 posts)
 
Foghorn's Avatar
 
Join Date: Jan 2019
Location: Peachtree City, GA
Age: 48
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Garage
Transmission Ramblings (Long)

In my introduction post I mentioned that I am of the opinion that the Beast is geared poorly. I also noted that I was sure that there is more to the story and that the BMW engineers knew what they were doing – after all, this is the Ultimate Driving Machine…
After doing a couple of hours of pecking around the ol’ interwebs, I am now convinced that BMW is just like every other car manufacturer, just on a different price point – they are all ruled by the bean counters (no offense to any accountants on the board – I know many that are very lovely people) & the engineers have to make the best they can with what they have available. Case in point is the tranny in our cars – the Getrag 420G. There is no way you can convince me that the internal gear ratios were chosen specifically for the characteristics of the S62 engine in the M5 when those internal ratios are the same for multiple engines in various chassis, all with different Q curves and curb weights.

BMW Gear Ratios - E36 / E46 / E90 / E91 / E92 / E93 / E85 / E86 / E83 / E82 / E88

I apologize in advance for offending anybody’s sensibilities for making the following comparing the Beast to the Ford Mustang, even though Ford has publicly stated that the e46 M3 is their target. The 2011 – 2017 Mustang GTs have a 3.7 x 3.5 V8 (5.0 liters) with variable valve timing on all 4 cams, that makes very similar numbers to the S62 engine, especially when comparing area under the curve on the dyno charts. The MT82 gearbox (also a Getrag) uses the same type of semi-remote shifter as the beast. The Mustang weighs in at ~ 400 lighter that the Beast, with a clutch that is an inch larger in diameter and a steeper rear gear (3.31).

I know I am reviving a 10 year old thread, but the MT-82 wasn’t in existence when this thread was active, so I request some leeway on that. Thanks to CSBM5 for the link:

https://www.m5board.com/vbulletin/e3...2-s3-d-sc.html

I have three options for re-gearing the Beast which I think will make it more driver friendly, accelerate better, get better fuel mileage through lower RPM while cruising, reduce oil consumption (again, fewer RPM while cruising) and make the engines last longer.
If any of the contributors to that thread still have the software available, what does it say about re-gearing the Beast as follows:

1: 3.66
2: 2.43
3: 1.69
4: 1.32
5: 1.00
6: .65
Final Drive: 3.15

The second option, albeit much more involved would be to yank the 420G and replace it with a QuickTime bellhousing, Tremec T56XL 6 speed (and associated clutch disk) and a steeper rear gear (say 3.62 from the e46 M3). The T56XL was developed as a replacement for the MT-82 because all of the Mustang hotrodders kept binding up the shift linkage when the Coyote engine was subjected to forced induction, which almost doubled the output (the chassis couldn’t handle the power and the shifter, being attached to the chassis, would bind as the engine and trans twisted in the mounts). The T56XL uses a specific tail shaft housing that puts the shifter in the same location as the stock MT-82 semi-remote shifter. This would, of course, be dependent on the length of the 420G from the bellhousing mounting face being the same as the MT-82/T-56XL. The T56XL is available in the following ratios:

1: 2.97
2: 2.10
3: 1.46
4: 1.00
5: .80
6: .63
Final Drive: 3.62

The third option that comes to mind is the Tremec TR-6060 transmission that was offered in multiple vehicles in various ratios and uses a semi-remote shifter just like the 420G.
https://en.wikipedia.org/wiki/Tremec...0_transmission
This would require a custom bellhousing and probably custom length shifter rods / carrier, but that shouldn’t be anything we couldn’t shame M5 Jed into making for us I would use the first generation Shelby GT500 ratios:

1: 2.97
2: 1.78
3: 1.30
4: 1.00
5: .80
6: .63
Final Drive: 3.62

Hurdles to clear:

First Option – If the MT-82 gear set will fit in the 420G case (I have this RFI out to a Getrag Transmission specialist, but if any board members want to take it for action, then please do so), then that would by far be the most cost effective. I would get a good carbon-ceramic dual friction clutch plate because it will see more abuse, especially standing starts at max gross weight on a hill. My SWAG (Scientific Wild *** Guess) for this this option’s cost is $1500 to rebuild the transmission and buy the clutch.

If the gear sets don’t interchange, then this option is off of the table.

Second option – Overall lengths of the transmissions have to be the same or very, very close (a delta of
+/- 1” or less). The bellhousing is easy, it would just take time and $$$. QuickTime already has a custom order department organized to build one-off or low production pieces. Would also need a custom clutch disk, but that is easily sourced also, just time and $$$. The last time I can see is a hybrid U-joint or CV joint to attach the T56 output yoke to the Beast’s driveshaft. The cost SWAG for this would be between $4-5K, based on the market price for Mustang T56XL swap kits.

Third Option – a custom bellhousing, clutch disk and shifter rods. Again, all easily sourced if there is/was any interest. The cost SWAG for this option is ~ $2500 (the bellhousing would cost the same as option 2, but a used TR-6060 is much cheaper than a new T56XL).

Lastly, the probability of me doing any of these things is slim, but I like to think about making the Beast “mine”, and this is one of the ways that I would do it. I welcome all input, so long as it is constructive. I already know that I’m a dumbass, so I don’t need any further affirmation of that fact

Semper Fi
Foghorn
Foghorn is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 8th February 2019, 04:08 AM
gsfent
M5 Expert (>4000)
 
gsfent's Avatar
 
Join Date: Feb 2001
Location: west palm beach. fl.
Posts: 12,745
Thanks: 2,306
Thanked 1,619 Times in 1,227 Posts
Run the stock Getrag ratios with a 2.65 rear end and let us know what you find.

Regards,
Jerry

'01 Black/caramel
Dinan Stage 3 suspension, SS jet coated headers, ESS SC kit w/ 1 range colder NGK's, 92mm pulley, 440 Big Greens, TTFS alpha N tune for meth, RK plenum plates, SBC Endurance Stage 3 Kevlar performance clutch setup, "Jed" lightened DMFW, open brake ducts, TEC cupholder, U.S.(Euro style) tilt/slide armrest, 6k HID fogs, Umnitza bi-xenon flamethrowers w/6k super white low beams, rear fogs, V1/Stealth1, dual head LI, 2.65 diff w/40% lockup/2x dynamic, compact spare, M5 logo trunk carpet, Euro trailer hitch, Mocal oil cooler, ACS type rear spoiler, Rogue custom SSK and tranny mounts, ST 355 BBK (fronts), BP sway bar brackets, Bluetooth retrofit, Speedhut boost gauge (20 psi), Dinan TB's and VS, KB BAP, Howerton/HFS-3 Aquamist WI trunk setup (50/50), with 2nd gauge in rear view mirror, aftermarket trunk mounted sound system integrated into stock unit (amps, crossovers, sub and speakers).......
gsfent is offline  
post #3 of 6 Old 10th February 2019, 01:56 AM
herrubermensch
M5 Expert (>4000)
 
Join Date: Aug 2008
Location: New York
Age: 53
Posts: 8,707
Thanks: 4,472
Thanked 2,607 Times in 1,548 Posts
Quote:
Originally Posted by gsfent View Post
Run the stock Getrag ratios with a 2.65 rear end and let us know what you find.

Regards,
Jerry
I could have predicted that response with 100% certainty!

--Peter
herrubermensch is offline  
 
post #4 of 6 Old 10th February 2019, 04:03 AM Thread Starter
Foghorn
Junior Member, warming up (<31 posts)
 
Foghorn's Avatar
 
Join Date: Jan 2019
Location: Peachtree City, GA
Age: 48
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Garage
Thanks, Jerry. While I agree that installing a higher gear in the back will give the ol girl longer legs, it doesn't address the core issue of my thread.

I hope that Chuck still has the CarTest software in the linked thread above & would see what the sim returns with the gear ratio changes and an otherwise stock S62 HP/Q curve.

The following all use 6500 as the shift RPM.

The 420G gear spacing is not optimal (I rounded to nearest 100 for simplicity):

1-2 shift: 3800
2-3 shift: 4300
3-4 shift: 4800
4-5 shift: 5300

MT-82 gear set isn't much better:

1-2 shift: 4300
2-3: 4500
3-4: 5100
4-5: 4900

T56XL is the most consistent:

1-2: 4600
2-3: 4500
3-4: 4500
4-5: 5200

Lastly, the TR-6060 GT500 variant:

1-2: 3900
2-3: 4800
3-4: 5000
4-5: 5200




Unless you're a descendant of Ronnie Sox, manual shifting is the bane of accelerating, so why not take advantage of the VANOS and use the widest ratios available?
Foghorn is offline  
post #5 of 6 Old 10th February 2019, 05:07 AM
gsfent
M5 Expert (>4000)
 
gsfent's Avatar
 
Join Date: Feb 2001
Location: west palm beach. fl.
Posts: 12,745
Thanks: 2,306
Thanked 1,619 Times in 1,227 Posts
Quote:
Originally Posted by Foghorn View Post
Thanks, Jerry. While I agree that installing a higher gear in the back will give the ol girl longer legs, it doesn't address the core issue of my thread.

I hope that Chuck still has the CarTest software in the linked thread above & would see what the sim returns with the gear ratio changes and an otherwise stock S62 HP/Q curve.

The following all use 6500 as the shift RPM.

The 420G gear spacing is not optimal (I rounded to nearest 100 for simplicity):

1-2 shift: 3800
2-3 shift: 4300
3-4 shift: 4800
4-5 shift: 5300

MT-82 gear set isn't much better:

1-2 shift: 4300
2-3: 4500
3-4: 5100
4-5: 4900

T56XL is the most consistent:

1-2: 4600
2-3: 4500
3-4: 4500
4-5: 5200

Lastly, the TR-6060 GT500 variant:

1-2: 3900
2-3: 4800
3-4: 5000
4-5: 5200




Unless you're a descendant of Ronnie Sox, manual shifting is the bane of accelerating, so why not take advantage of the VANOS and use the widest ratios available?
Everything is a compromise. Remember, this is designed as a street car. So with enough money, you can change everything, including the motor.

But dropping a few bucks on a diff, and getting back the lost multiplicative torque by adding engine torque (headers good for at least 30 rwhp and correspondent torque) is plenty for this car and a lot less $$$ ( I would guess) than swapping tranny. In 1st, once you have enough power to spin the rear wheels, you really can't go faster from a dead stop. I think most of us use 1st to get the car moving, a short shift to 2nd shouldn't hurt much.

But if going fastest is the issue, then agreed, you don't want a manual. Manual is way more fun for most, but definitely not the fastest. PDK is probably the best way to go. Porsche has done a very good job with the dual clutch setup. Try a Panamera Turbo S and let us know if that 4 door sedan is fast enough!

But hey, your toy, your wallet. If you go ahead with your plans, keep us updated as to progress!

Regards,
Jerry

'01 Black/caramel
Dinan Stage 3 suspension, SS jet coated headers, ESS SC kit w/ 1 range colder NGK's, 92mm pulley, 440 Big Greens, TTFS alpha N tune for meth, RK plenum plates, SBC Endurance Stage 3 Kevlar performance clutch setup, "Jed" lightened DMFW, open brake ducts, TEC cupholder, U.S.(Euro style) tilt/slide armrest, 6k HID fogs, Umnitza bi-xenon flamethrowers w/6k super white low beams, rear fogs, V1/Stealth1, dual head LI, 2.65 diff w/40% lockup/2x dynamic, compact spare, M5 logo trunk carpet, Euro trailer hitch, Mocal oil cooler, ACS type rear spoiler, Rogue custom SSK and tranny mounts, ST 355 BBK (fronts), BP sway bar brackets, Bluetooth retrofit, Speedhut boost gauge (20 psi), Dinan TB's and VS, KB BAP, Howerton/HFS-3 Aquamist WI trunk setup (50/50), with 2nd gauge in rear view mirror, aftermarket trunk mounted sound system integrated into stock unit (amps, crossovers, sub and speakers).......
gsfent is offline  
post #6 of 6 Old 22nd February 2019, 03:30 PM Thread Starter
Foghorn
Junior Member, warming up (<31 posts)
 
Foghorn's Avatar
 
Join Date: Jan 2019
Location: Peachtree City, GA
Age: 48
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Garage
Update: The T56XL is 34.9" from the front of the bellhousing (back of engine) to the shifter with a 6.5" deep bellhousing. I know the shifter rod on the M5 is 14.25" (362.6mm) long, so if the 420G dimension from the front of the bellhousing to the shifter rod attachment is ~ 20", this might be viable. I know the total length of the 420G is 25", but that is to the output flange, not where the shifter rod attaches. Does anyone have any insight on this measurement?

Also, to Jerry's point about doing some bolt-ons (headers, exhaust system, CAI, tune) and a higher ratio final drive - the price point is about the same. If you go with M5 Jed's headers (arguably the best available), it is significantly more $$$.

Lastly, not advocating losing the manual tranny with my assertion that shifting causes a slower acceleration, jsut using that to make a point. I don't want a semi-auto with paddle shifters anymore than I want a full-on slushbox.

Last edited by Foghorn; 22nd February 2019 at 03:33 PM.
Foghorn is offline  
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the BMW M5 Forum and M6 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes Rate This Thread
Linear Mode Linear Mode
Rate This Thread:



Similar Threads
Thread Thread Starter Forum Replies Last Post
DIY: Transmission fluid flush WallyM5 E60 M5 and E61 M5 Touring Discussion 87 21st April 2017 02:33 AM
How long did your clutch last - Manual transmission whatheheck E63 BMW M6 Forum and BMW M6 Convertible | m6board.com 3 15th August 2012 12:27 AM
Nowack Tuning Report, The Truth (Long Version) CharlesW E39 M5 and E52 Z8 Discussion 90 2nd September 2011 09:49 AM
Official press release: Engine / Drive System enots E60 M5 and E61 M5 Touring Discussion 9 24th June 2004 12:50 AM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome