Updating 3 speed auto TH400 to 4 speed w OD 1977 Mini

[Froggy1936]

Got the Winnie State Inspected and road tested it 100 Mi All seems good leaving for Pittsburgh Fri will report on fuel mileage and difference in RPMS (Approx 1000 RPM less @ 55 MPH )After trip.  Only thing not completed is the dash air just ran out of time it will have to wait. Along with a slight modification on oil filler pipe, Its in the way of the air intake wich i am going to run up to a hood scoop During round 2  Frank

[DaveVA78Chieftain]

Congrats - Good luck on your trip

[Wantawinnie]

Nice job Froggy...have fun with it.

[Froggy1936]

Well Bad News ! on the trip to Pgh yesterday on the turnpike i noticed suddenly the trans was staying in 3rd gear longer than previously after downshifting  Then i noticed the tranny temp climbing above 180o (where it had been running all day ) Then RPMs started climbing and speed was dropping off There was a pull off spot about 100 yds away wich i pushed to make wile trans started loud buzzing crawled into pulloff and stopped transmission cooling hose had developed a small leak and lost fluid . Jumping ahead now i have damaged 1st gear its hesitating and banging in  I belive this is either frt cluch or a band  So i will be redoing the trans instead of attending the rally i was so looking forward to  Sorry TJ i have your compressor on board BUT Sh-- happens  Frank

[Wantawinnie]

Sorry to hear about the troubles. Did you have to tow it home?

[Froggy1936]

No i was able to make a temporary repair Used a piece of the original unused fuel line and the good part of the original hose . Luckily my son was in Pgh and on his way home in north Wales He dropped off 12 qt of fluid so i was able to continue to Pgh  I found out that this trans is capable of starting out in 2nd gear (for driving in the snow)  So i am going to try to make the jam at Jims in ohio then return home to make repairs Fingers crossed Frank P.S. Good Sam & AAA cannot tow on a limited access highway  I dont know if they will reimburse for a turnpike commission tow or not .

[pvoth1111]

That sucks!

[Froggy1936]

Well all is not bad. After a local roadtest,  i added a container of Gunk Transmission medic and performance improved almost immeadiatly. The hesitation on first gear engaugement improved tremendously. I now beleive that instead of burning the forward cluch plates i just glazed them, and the solvents in the additive is cleaning them off. I was able to make it to Jimco,s and i feel sure i can make it back home where i will pull the pan to inspect for material on the filter. If there is a lot i will pull it out and do  a complete teardown . If there is none just a fluid change will be the next step. Results of 4 speed W OD avg MPG went from 9.2 to 10.6 and RPM @ 58 MPH dropped from 2900 RPM to 2200 RPM  This not best yet as all roads traveled are very hilly  Frank

[Wantawinnie]

That is good news! Hopefully, no internal damage. Mileage improvement sounds good.

[Froggy1936]

Well the adventure continues I was on my way back to north Wales via Pittsburgh to make some visits, When i noticed veh slowing down I was able to pull off roadway immeadiatly. Stopped checked fluids ck for leaks, etc. All was ok ,but trans fluid had the bad odor of burnt clutches , restarted put in reverse absolutly no engaugement just noise tried forward had a slight feel of pull but did not have faith in going any futher. Called Good sam Tow truck arrived 2 hrs later and towed back to Export (19 mi) I was able to pull back into parking place So now to Raise veh high enough to remove transmission and open it up It went 526.9 Mi since fluid loss and major slipping on Turnpike in July I was hope ing to make it back home to do repairs but fate intervined Luckily i was not on the Turnpike this time. Frank

[Stripe]

Yipes..  Hope it's an easy fix..

[Wantawinnie]

Ughh, sorry to hear this.

[Froggy1936]

Spent the day Raising the beast 1 1/2 ton NO !3 ton NO !Had to use both to raise ea side of the rear   The 3 ton handled the frt no prob . Filled all air bags to 90 Lb Hope its high enough gathering wood and lifting took 6 hrs ! Raining now hope to get it out tomorrow Frank

[ClydesdaleKevin]

Ouch!  Hope it works out well for you and doesn't cost you too much.

Kev

[Froggy1936]

Luckily my son stopped by on his way from Toronto to Philly and we pulled the trans out sat 9 hrs to remove . Had to remove engine dip stick tube and r/.s header, dissconnect l/s exaust @ header flange (Trans too wide to lower between exaust pipes ) Remove heat shields on ex also And unbolt rear cross member and slide (hammer) back 4 in  . Luckily we had a section of bowling ally to put down on the stones to make jack operation possible. With heavy cardboard for creepers . In the rain And down it came . It is very heavy about 250 lbs with convertor . Now veh has a mixture of sae and metric bolts . Had to go purchase metric tools to update toolbox in R/V . Its on the bench so Mon will dissessemble and clean . Frank

[Froggy1936]

Well due to aggrivation mostly updating was delayed . After tear down found major damage (a lot from tow i beleive as driveshaft was not disconnected ) The forward and direct lined clutch plates were no longer lined ( this most likely was from original fluid loss most likely) The major damage, Frt pump bushings spun in there housings, Overdrive planetary totaly destroyed, forward clutch drum overrun clutch totally destroyed, Input shaft overheated to point of sealing rings being frozen into grooves,  These hard parts were not damaged for a long time, as there was very little metal in the pan on the magnet . Another reason to beleive major damage was from tow 19 mi. Luckily my grandson has a friend in the trans parts business and he was able to get me the necc parts New,used, rebuilt For $670.00 along with parts from other suppliers total in parts was $940.00.  This incl update to wider second gear band, Teflon coated frt pump gears, And pressure booster kit. + Fluid 13 qts I am now home in North Wales 360 mi road test, Trans worked flawlessly, Still have to redo fluid line connections to aux cooler, heavy duty rubber hose was too strong to slip on far enough for double clamps & now i am paranoid of fluid leaks.  MPG Alleg Valley to Valley Forge @ avg 60 MPH, was 10.2 MPG There were a few bursts up to 80 MPH Cant seem to avoid idiots . Engine has only used 1 pt of oil, on original break in fill, Time for first oil change . Personally i would rather have my Quadrajet back FI has very little omph !!  And the adventure continues  !! Looks really good as it goes by at 60 MPH though ! Frank

[jkilbert]

I don't know if youve thought about it, but upgrading from a 7 vane to a 13 vane pump will help increase line pressure and reduce slippage. Since its already in pieces it not an expensive item.   It's a common upgrade in the 700r4/4L60/4L60E trannys.      John

[ClydesdaleKevin]

Ouch!  That was a pretty penny!  But at least you were able to fix it, and your gas mileage sounds great!

Kev

[Froggy1936]

Hi John. Its already back together , And it does not use a vane pump. It has a gear pump. The pressure booster kits main purpose is to limit hi pressure in reverse (wich has caused cases to break )  It incorporates a bypass feature . Yet increases lower speed pressures in all gears. It worked very well my RPM,s @ 60 MPH dropped from 2800RPM with the Turbo 400 to 2100 RPM with the 4L80E  in 4th gear lockup . This trans will downshift to 3rd gear and still stay in lockup wich gives it direct drive in 3rd & 4th (no convertor) I am very happy with the trans swap , But not so much with the fuel injection. With the Quadrajet @ 60 MPH W cruise control i could pull 16 in of vacuume  With the FI at same speed w cruise i can only get 11 in of vacuume. Now this may improve as rings seat better The engine only has a little over 1000 mi on it  Frank

[Froggy1936]

The latest update pertaining to engine (1995 rebuilt 350 W FI ) RPM with 4LE80 4 speed W OD & convertor lockup After engine break in & first oil change Latest Trip info.More info 4:10 gears W 8.75 x 16.5 tires  The 95 donner veh had 16 in tires  Frank

   
• @ 55 MPH = 1975 RPM
• @ 60 MPH = 2100 RPM
• @ 65 MPH = 2200 RPM
• @ 70 MPH = 2400 RPM 

Previous 3 speed Turbo 400 RPM @ 59 MPH was 2900 RPM

   Due to running for time I was not able to get best MPG.
                       

[tmsnyder]

Hi Frank,


I wonder what kind of mpg you would get if you just changed to throttle body EFI w/o the OD?   Maybe run it in D (or 3rd) not OD for a few trips to see what the effect on mpg was with just the EFI conversion. Maybe you did this?


Todd

[Froggy1936]

Hi I have not tried driveing in  3rd gear only, I did not install a OD lock out switch , And I do not have a 5 position gearshift (no manual low) I used the Turbo 400 floor shifter  I could not change the steering column for the 4L80E shifter ! But even WO the OD i would still get direct drive thru convertor lockup so it is not a feasable thing to do Plus i never have time to do a MPG check with purpose .  I just get no,s from normal traveling . But overall it is not worth the cost or effort ! My only reccomendation is if you want to update you have to go up to Port injection , also an Allison 6 speed might help Frank

[Rickf1985]

The 6 speed would hurt more than help unless you put lower gears in the rear. You need to keep the engine in the power band or you will start to bog it down and that is worse than overspeeding it. Once the rpm gets below about 2500 rpm with a heavy load you are going to lose mileage.

[tmsnyder]

That's what I'm thinking too.  Without driving it around in 3rd gear as if overdrive didn't exist there's no way to know the difference the  EFI made, if any.  Even though the wrong shifter is being used, can't you just back off one click on the shifter?  Running in 3 or D  is common when towing with a truck that has OD.  Just one click down on the shifter and the motor should be doing ~3000 rpm at 60mph, right in the heart of the torque curve.