home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > performance & suspension

Reply
 
Thread Tools Display Modes
Old 03-11-2017, 07:44 PM   #1
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default Is the 3.31 final gear too tall for my 19t and AW71?

Just began today with a surgical reconstruction of the DD, my 940 that has served me well the last 4 years.

Of course the 3.73 final gear is presently installed in the 1041 Dana..... Volvo seems to have chosen this ratio for all the turbo 7's and 9's with the AW71. I'm sure they had their reasons to do so.

I've got a low mile '92 complete rear end fitted with the Eaton LSD and ABS tone ring (a rare bird); my current plan is to pull the LSD, remove the 3.31 ring gear and install the 3.73, set the backlash & preload those carrier bearings. Much less aggravation to just install the carrier, rather than the full pinion install.

With her sky high sitting on 6ton jackstands, I wondered if the complete 3.31 rear end assembly swap wouldn't be less work... perhaps? I've set up ring & pinions, so no worries there. I know the 3.31 final gear would give some relief to my 70mph cruise RPM of 3100.

However I wonder if the planned 19t turbo will be negatively affected by that tall final gear.
I'm guessing that the last 2 series cars with the B21 turbo didn't offer an automatic option.... but I don't know that for a fact. If they did, were they also fitted with the 3.73?

Anyone tried it? Please share your experience.
__________________
Project "cheap thrills" build thread: http://forums.turbobricks.com/showth...67#post4211467

Feedback thread: http://forums.turbobricks.com/showthread.php?t=198746
DET17 is offline   Reply With Quote
Old 03-11-2017, 07:52 PM   #2
cosbySweater
Board Member
 
cosbySweater's Avatar
 
Join Date: Jul 2009
Location: Monterey/Falun
Default

Honestly I would just swap the diff over. You won't have to set back lash or anything since you are just swapping the carrier
__________________
1979 Volvo 244DL 6.0/4l80e,8.8,microsquirt ecu and tcu, s366 clone.
2005 Honda Civic Hybrid, 5 Speed
1994 Corvette, 6speed, PNP special, gonna pill it to kill it

Quote:
Originally Posted by bricktop420 View Post
Thank you very much everybody... i now feel sufficiently retarded and will go cry in the corner...
Quote:
Originally Posted by mikep View Post
How come we get a Cosby sweater but no Boner in sweatpants in this thread?
cosbySweater is offline   Reply With Quote
Old 03-11-2017, 08:18 PM   #3
To old for this
Board Member
 
Join Date: Sep 2016
Location: Texas Panhandle
Default

Keep the 3:73 I went tru this. The 331 seem to lug the motor while the 3:73 seemed to keep it just on the edge of the sweet spot. Mpg also suffered. I reinstalled the 3:73 and swapped the carrier to keep the alb and correct speedo.
To old for this is offline   Reply With Quote
Old 03-11-2017, 10:25 PM   #4
Redwood Chair
K-jet For Life
 
Redwood Chair's Avatar
 
Join Date: Mar 2007
Location: SF CA
Default

It'll never spool.
__________________
Raise The Lowered


Image hosted by servimg.com

Quote:
Originally Posted by hiperfauto View Post
Folks on here don't know a good deal when they see it.
Redwood Chair is offline   Reply With Quote
Old 03-12-2017, 12:19 AM   #5
Wilford Brimley
enjoys the beetus
 
Wilford Brimley's Avatar
 
Join Date: Jun 2008
Location: Lake stevens, wa
Default

Nope
__________________

http://forums.turbobricks.com/showthread.php?t=316428 91'744T .57 t3/t4, big ic, greddy type s, 55lb/hr injectors, bosch 044, tloa ecu/ezk, 3"amm, rsi stg 3 cam, ttr cam gear, top mount header, 3" exhaust, kevlar tbelt, e-fan, 22 psi, intrax springs, cherry turbo brace, ipd rear sway, dual front sway bars, bilstein struts, camber mod, accum mod
Wilford Brimley is offline   Reply With Quote
Old 03-12-2017, 09:34 AM   #6
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Well I had forgotten the granny first gear in the AW70/71..... must have had 700r4 on the brain (first gear is 3.06)

From WIKI:

Gear Ratios

Gear AW70/71 AW72
1st 2.45 2.83
2nd 1.45 1.49
3rd 1.00 1.00
4th 0.69 0.73
Rev 2.22 2.70

Typically first gear * final gearing = 10~10.5 for a performance application

The AW70/71 provides 2.45 * 3.73 = 9.14, still a bit low of target

The AW70/71 provides with OPTIONAL rear gear is 2.45 * 3.31 = 8.11, really low

The AW72 looks better yet with 2.83 * 3.73 = 10.55, right on target

I'll keep the 3.73 final gear and watch for a 95 AW72 at my local PnP
DET17 is offline   Reply With Quote
Old 03-12-2017, 10:30 AM   #7
connorb850
Board Member
 
Join Date: Jan 2004
Location: North GA
Default

I believe the AW72 only came in the B234 powered cars.
connorb850 is offline   Reply With Quote
Old 03-12-2017, 11:21 AM   #8
Kjets On a Plane
Devoid of Luxury
 
Kjets On a Plane's Avatar
 
Join Date: Nov 2002
Location: Portland, OR
Default

^Correct for USA market.

If you don't tow in 3rd a lot, I didn't notice much (if any) actual difference in cruise RPM (and really no MPG difference) with the 4.10 axle which I liked in the turbo car everywhere else with the auto.

16V converter and AW-71L with a 4.10 is nice if you want to have a nice compromise for power and economy. I thought the converter lockup speed and shift points were weird with the 3.73 and considered the 4.10 basically mandatory with a stockfish B230FT car with the AW-71L. The 8V stock AW-71L converter is woefully dreadful for performance use. Good for N/A MPG though....just very, very slow.
__________________
How PSI a stock can support?
Quote:
Originally Posted by JohnMc View Post
If you send me $20 I'll send you a how-to explaining how to make $20 from people on the internet.
Kjets On a Plane is offline   Reply With Quote
Old 03-12-2017, 07:54 PM   #9
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Quote:
Originally Posted by Kjets On a Plane View Post
16V converter and AW-71L with a 4.10 is nice if you want to have a nice compromise for power and economy. I thought the converter lockup speed and shift points were weird with the 3.73 and considered the 4.10 basically mandatory with a stockfish B230FT car with the AW-71L. The 8V stock AW-71L converter is woefully dreadful for performance use.
By the numbers, the 4.10 final gear with the AW71 first gear 2.45 is nearly at the performance target with 10.05 torque multiplication. K-J is right, with the lockup converter of the AW71L it would balance out nicely with that final gear.... better performance "running thru the gears" and cruise OD nearly same as a plain Jane AW71 and 3.73 final. If you know the P/N for the 16V converter, would be nice to have in this thread. Perhaps TASCA can still get it.....

Was it the 960s that got the 4.10?
DET17 is offline   Reply With Quote
Old 03-12-2017, 08:08 PM   #10
cosbySweater
Board Member
 
cosbySweater's Avatar
 
Join Date: Jul 2009
Location: Monterey/Falun
Default

N/a lh2.4 740s and n/a 940s got them iirc. I think I still have a 4.10 r&p if you are interested
cosbySweater is offline   Reply With Quote
Old 03-15-2017, 08:33 AM   #11
Janspeed
Board Member
 
Join Date: Sep 2005
Default

a 3.31 rear end with a bigger then stock turbo and hotter then a T-cam in the head will be a dog to drive in top gear. 3.31 is way to tall.
if you want to accelerate from 50 to 75mph in top gear you will be forced to downshift because in top gear the engine will not turn in boost-rpm-range. If you mash the throttle in top gear you will be waiting, waiting, waiting for the boost to kick in and the real boost will only start building at speeds in excess of 75mph. That gets annoying realy quick.
3.73 is nice but a 4.10 will make the whole car even more punchy and enjoyable to drive. That would be my choice.
Janspeed is offline   Reply With Quote
Old 03-15-2017, 05:49 PM   #12
B20Paul
Board Member
 
Join Date: Jun 2005
Default

Quote:
Originally Posted by DET17 View Post
....the 3.73 final gear is presently installed in the 1041 Dana..... Volvo seems to have chosen this ratio for all the turbo 7's and 9's with the AW71. I'm sure they had their reasons to do so..... I know the 3.31 final gear would give some relief to my 70mph cruise RPM of 3100.
3.73 is the shortest diff for your carrier, 3.91, 4.10, 4.30, etc. has a different carrier.

So you have AW71, 3.73 and that gave you cruise rpm of 3100 @ 70mph? That seem very wrong to me. Speedo, Tacho or Gearbox has a problem. With my 205/60x15", AW71 + 3.73 = 2670rpm, which is 16% less, very wrong.
B20Paul is offline   Reply With Quote
Old 03-15-2017, 05:54 PM   #13
B20Paul
Board Member
 
Join Date: Jun 2005
Default

Quote:
Originally Posted by Janspeed View Post
a 3.31 rear end with a bigger then stock turbo and hotter then a T-cam in the head will be a dog to drive in top gear. 3.31 is way to tall.
if you want to accelerate from 50 to 75mph in top gear you will be forced to downshift because in top gear the engine will not turn in boost-rpm-range. If you mash the throttle in top gear you will be waiting, waiting, waiting for the boost to kick in and the real boost will only start building at speeds in excess of 75mph. That gets annoying realy quick.
3.73 is nice but a 4.10 will make the whole car even more punchy and enjoyable to drive. That would be my choice.
Agreed, I think 3.73 for T cam, 4.10 for a decent street cam.
B20Paul is offline   Reply With Quote
Old 03-16-2017, 02:33 AM   #14
Kjets On a Plane
Devoid of Luxury
 
Kjets On a Plane's Avatar
 
Join Date: Nov 2002
Location: Portland, OR
Default

Quote:
Originally Posted by B20Paul View Post
3.73 is the shortest diff for your carrier, 3.91, 4.10, 4.30, etc. has a different carrier.

So you have AW71, 3.73 and that gave you cruise rpm of 3100 @ 70mph? That seem very wrong to me. Speedo, Tacho or Gearbox has a problem. With my 205/60x15", AW71 + 3.73 = 2670rpm, which is 16% less, very wrong.
Volvos all use the "3.73+" D30 carrier. They make up the difference with the ring gear thickness...

Ratios are pretty close on the O3-71 gears 1-3, except OD is a big jump from 3rd.
Kjets On a Plane is offline   Reply With Quote
Old 03-16-2017, 09:48 AM   #15
linuxman51
BRANDSCHUTZVORSCHRIFTEN!
 
linuxman51's Avatar
 
Join Date: Dec 2002
Location: mont, AL
Default

3.31 isn't that rare, 960's have em, some 940's got em, etc.

I swapped one in to offset the .75 OD from the 4L80e
__________________
"They bum rushed them in their own crib, they drank all their beer, they partied with their ladies and they left with the trophy"

Now with in-house Dyno tuning!

Megasquirt Tuning!
Plug and play LH 2.4 Megasquirt, now with stealth mode!
linuxman51 is offline   Reply With Quote
Old 03-16-2017, 12:57 PM   #16
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Quote:
Originally Posted by B20Paul View Post
So you have AW71, 3.73 and that gave you cruise rpm of 3100 @ 70mph? That seem very wrong to me. Speedo, Tacho or Gearbox has a problem. With my 205/60x15", AW71 + 3.73 = 2670rpm, which is 16% less, very wrong.
Nice catch B20! Bad case of brain flatulence.... I was thinking of my 70 Malibu with TH350 and 3.55 final gear (3100 RPM at 70)

Here is the calculation from my Excel spreadsheet of trans. & gearing options for my 940; this option the AW71 and various final gears. Actually with the 3.73 final it calculates out just above 2400 RPM:

[IMG][/IMG]

Last night I pulled the G80 out of the installed 1041, and it slid out with not much of a pull (preload on carrier bearings). Couldn't have been an .006" preload on those bearings, as is spec'd in the greenbook. Then I went into the donor 1041 with the 3.31 and removed this:

[IMG][/IMG]

Now THAT guy had some preload! It took a good grunt with a pair of levers to disengage it from the housing. As K-J noted, this carrier should be good to accept all the Volvo ratios..... so that has me in a quandry. This discussion about how "peppy" the 4.10 final would be in my application..... only costs me another 240 rpm at 70mph cruise while hitting the performance target torque multiplication value of 10.05. DAMN it, y'all have me thinking to go find a boneyard 4.10!!!! I'm only 14 bolts away from having the 1041 housing out.

However, if the only donors are NA 740s and 940s, those have become suddenly scarce in these parts. I thought for sure there was also a 960 fixed axle that came with the 4.10 final gearing. The window is open right now, as I could put the rear work on the back burner while I source one. All help appreciated to confirm the exact suitable donors.....
DET17 is offline   Reply With Quote
Old 03-16-2017, 01:09 PM   #17
linuxman51
BRANDSCHUTZVORSCHRIFTEN!
 
linuxman51's Avatar
 
Join Date: Dec 2002
Location: mont, AL
Default

I've got one in the back end of a 1990 740. swap the diff cover, chunk, and ring gear and roll out.

*to clarify, I've got a rear end. I've got no plans to use another volvo 4.10 any time soon for any of my current or future projects
linuxman51 is offline   Reply With Quote
Old 03-16-2017, 02:01 PM   #18
sbabbs
Board Member
 
sbabbs's Avatar
 
Join Date: Dec 2006
Location: Rushing Lane, Scappoose, OR
Default

THis ain't a G80, looks like the rare factory LSD.. Powerlock. My 91 NA 740 had 4.10 ratio rear end gears.

[IMG][/IMG]
__________________

1977 242 16v AQ171C M47 3.73truetrac LH2.4 is the dream.
1988 245 White slicktop M47 Wagon! 0 oil pressure..
1990 745 B230FT M46 13c A-cam 3.54 540K MILES slippin clutch
1991 744 RSI rods pistons 2.5L 16v Holset Getrag 3.31 7.25 twin disc someday get it done.
1991 740SE B230FT NPR Strut braces IPD bar A cam 550cc EV14's. M90 to put in.

Last edited by sbabbs; 03-16-2017 at 02:09 PM..
sbabbs is offline   Reply With Quote
Old 03-16-2017, 03:14 PM   #19
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Keen observation Simon! The G80 is sittin' on my workbench. Yup, only one of them thar' 48 tone ring LSD's that I've seen.

"Hoping" the AW71 will protect those cross shafts from exploding..... or I might as well install the TrueTrac 588.
DET17 is offline   Reply With Quote
Old 03-16-2017, 04:21 PM   #20
Powder>Paint
Board Member
 
Join Date: Jan 2017
Location: Bay Area CA
Default

Quote:
Originally Posted by cosbySweater View Post
N/a lh2.4 740s and n/a 940s got them iirc. I think I still have a 4.10 r&p if you are interested
verified, +1 on 940 na for sure, no more single tire fire.

personally, most fun gear there is. I love the mechanical advantage in the 60ft, never looked back since i put the na rear in my turbo wag. i dont know if anybody really commutes these cars much(distances), phuck miles per gallon. Smiles per gallon is where its at.
Powder>Paint is offline   Reply With Quote
Old 03-16-2017, 04:28 PM   #21
linuxman51
BRANDSCHUTZVORSCHRIFTEN!
 
linuxman51's Avatar
 
Join Date: Dec 2002
Location: mont, AL
Default

Quote:
Originally Posted by Powder>Paint View Post
verified, +1 on 940 na for sure, no more single tire fire.

personally, most fun gear there is. I love the mechanical advantage in the 60ft, never looked back since i put the na rear in my turbo wag. i dont know if anybody really commutes these cars much(distances), phuck miles per gallon. Smiles per gallon is where its at.
running out of gear is a real mother****er.
linuxman51 is offline   Reply With Quote
Old 03-16-2017, 06:20 PM   #22
Broke4speed
Board Member
 
Broke4speed's Avatar
 
Join Date: Oct 2009
Location: Marionville, Ontario, Canada
Default

I've got a 3.54 in my sedan currently, from the BW55 days. Now I've swapped in the AW71L and am going to try it out with the tall rear end. I do a LOT of highway cruising, but speed limits peg at 60mph up here...so that's where I'll be staying. I'm a bit concerned my RPMs will be too low at that point...but I won't know until I try. The 16T will probably spool fine, and I'm not really concerned if it doesn't, so my only concern is whether or not it will be lugging too hard to remain fuel efficient at highway speeds.
__________________
1984 B21T (formerly A), AW71L.
Broke4speed is offline   Reply With Quote
Old 03-16-2017, 06:40 PM   #23
culberro
Ronald Culberbone III
 
culberro's Avatar
 
Join Date: Feb 2010
Location: Portland, OR
Default

Quote:
Originally Posted by DET17 View Post

"Hoping" the AW71 will protect those cross shafts from exploding..... or I might as well install the TrueTrac 588.
SAM, KG Trimning, or similar makes new cross-shafts for not much $. FYI.
culberro is online now   Reply With Quote
Old 03-18-2017, 04:36 AM   #24
per0lund
Board Member
 
per0lund's Avatar
 
Join Date: Feb 2004
Location: Stockholm Sweden
Default

Quote:
Originally Posted by DET17 View Post
Just began today with a surgical reconstruction of the DD, my 940 that has served me well the last 4 years.

Of course the 3.73 final gear is presently installed in the 1041 Dana..... Volvo seems to have chosen this ratio for all the turbo 7's and 9's with the AW71. I'm sure they had their reasons to do so.

I've got a low mile '92 complete rear end fitted with the Eaton LSD and ABS tone ring (a rare bird); my current plan is to pull the LSD, remove the 3.31 ring gear and install the 3.73, set the backlash & preload those carrier bearings. Much less aggravation to just install the carrier, rather than the full pinion install.

With her sky high sitting on 6ton jackstands, I wondered if the complete 3.31 rear end assembly swap wouldn't be less work... perhaps? I've set up ring & pinions, so no worries there. I know the 3.31 final gear would give some relief to my 70mph cruise RPM of 3100.

However I wonder if the planned 19t turbo will be negatively affected by that tall final gear.
I'm guessing that the last 2 series cars with the B21 turbo didn't offer an automatic option.... but I don't know that for a fact. If they did, were they also fitted with the 3.73?

Anyone tried it? Please share your experience.
With a 3,31 ratio and a AW71L, at cruising, lock up at 3rd will go in at 115 km/h and rev is some 2400 rpm, you hardly get any boost at all with a -19T from there, you have to make a kickdown.

I find it the best way to describe it.

At the other hand, its quiet fun to do kickdown in 165 km/h or more.
__________________
Volvo 745 -90 B-230FK , M90, 3,31:1 Eaton diff,-MS3X 83 lbs/hr injectors TD04HL-20T

No real power, just turbo sh-t
per0lund is offline   Reply With Quote
Old 03-18-2017, 08:36 AM   #25
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Side by side comparison of the Power LOK LSD and the G80, both with ABS tone ring:

[IMG][/IMG]

[IMG][/IMG]

Looks the majority of folks has cast their votes for the 4.10 final gear..... I'll start watching the ATL pull-a-parts for a 90-95 NA 7/9, and/or the hen's teeth GLE 16V cars. My UK source also shows the 95 960 with an option for the 4.10. Might as well do the job right, since I plan to be DONE with this car and move onto the next this coming winter.
DET17 is offline   Reply With Quote
Reply

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 On

Forum Jump


All times are GMT -4. The time now is 04:28 AM.

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.