"Death of a Differential" AKA guide my rear end revamp - Page 2

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  1. #11
    CelicaSupra.com Member ddd228's Avatar
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    May 2005
    N. Seattle.
    Now,you are looking for TWO diffs?
    You want 3.73's for your truck and your Supra.
    If you can go to taller tires on your truck,the 4.10's may do.
    Used is WAY cheaper,if you can find a few.

    WANTED: 3.73 LSD's (2 OF THEM) In the meanwhile,
    Grab that 4.30 LSD and see if is NOT a screamer.

    Too cold to crawl around on the ground for me. 8*? NO WAY.
    I'll do the diff oil in my springtime.

    You can choose what to do first, on both of your vehicles.
    I don't have a heated garage to work in.
    You are the latest drive line/diff guy this week.
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

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  3. #12
    No, I'm not after 2 diffs. The 3.73 in the Supra needs bearings and the LS rebuilt. The 4.30 would (maybe) go in the Supra (for now?) and if I want LS in my truck, I need the parts. It's an F code diff too, I've seen on more truck related forums, guys pop those pieces into their open diffs and are done.

    Or I could rebuild the 3.73 for the truck. Right now it's like a 3.52 or some such. Winds up quite high on the freeway as is though. No interest in taller tires, it's 2wd, and my favorite places go from 2wd roads to pack trails. Not much of a 4x4 guy. BUT now you can see why an LSD is desirable for my truck. I spent 20 minutes digging myself out to get to work Weds morning.

    Pardon the possible duh moment here, but 5M powerband really kicks in higher up right, so my brain tells me a rather fun experience would happen through a shorter gear set like a 4.30 to get you into the zone quicker.

  4. #13
    CelicaSupra.com Member ddd228's Avatar
    Join Date
    May 2005
    N. Seattle.
    Pardon the possible duh moment here, but 5M power band really kicks in higher up, right? So my brain tells me a rather fun experience would happen through a shorter gear set like a 4.30 to get you into the zone quicker.
    That's exactly why I wanted a 4.30: LACK OF TORQUE.Wait for it... and wait some more.
    I got past that after adding some intake mods.WAY better! Later, an '85 5MGE.

    Comparing my last (car), big block Ford , I thought that the 5 MGE was totally lame for torque. True.
    Fixed that.. and my 4.10's were OK,then.
    I even thought of buying a high-stall torque converter to fix the lack of torque.

    The 6,000 rippem's is fine,but it takes a long time to get there and the lower gear diff would be able to get past the lack of torque area to some REAL horsepower sooner/ faster.
    The torque curve on our engines happens at 4 K?
    Would you choose to cruise at that RPM?

    2,200 RPM is about right at your chosen high way speed,for our engines. Agreed?

    You drive/cruise at 80?
    You want the 3.73's to work,in your application.
    Sure,the 4.30's would be better for acceleration,but it will hurt your MPG's on the high way,considering the engine speed.
    You may wish for a 6th gear to mellow out the engine speed.
    You won't need down shift to pass a Volkswagen/Geo/slow driver,with the 4.30's.

    It has to be a balance of power and gearing to make you(and your engine) happy.
    MPG'S? Lower RPM is better,usually. That's why there are overdrives:Just cruisin'.
    I can tolerate the slight whine @ 50-60 MPH.
    I'll never go back to an open diff, as I have seen snow in Seattle, B-4: I had to get to work!
    I have also changed the spring's pre-load to compensate for the R.R tire spinning wildly out of control and left it that way for the LSD action. Better!

    Snow? You get used to the ass-end swinging out to the right,but it's fixable if you create more load on the R.R. tire with spring pressure/load.
    Ever driven a Corvette in the rain?
    Jim knows.
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

  5. #14
    No but this is winter number 13 in my truck Spinny spinny. Hell, I can "peel out" after a light rain, and I have a factory stock 22RE.

    I don't think that 4.30 is gonna sell out from under me. If a decent price on a 4.10 doesn't present itself soonish, it's an option. It's really the limited slip that I want. Drive train dudes already want at least $600 to redo the bearings and then I have an open diff, dumb to not do it all at once but here's a secret - that bill would be higher than what I paid for the entire car.

    I hit up the new guy in the for sale forum about a diff. Out of 5 cars I'd expect him to have ONE.

  6. #15
    CelicaSupra.com Member ddd228's Avatar
    Join Date
    May 2005
    N. Seattle.
    Good question.
    Why would anyone want a non-LSD differential in snow country?
    You could be late for work,on a Wednesday.

    I have been frustrated B-4 for the R.R. tire spinning and getting no where.
    Even in the rain ,on an uphill left turn lane.
    That's why I tossed the 4.10 open diff. (Shame on me.)
    You need the LSD unit to work.

    Like so many States,you need A/C in the summer and at least an LSD in the winter,or a 4 WD vehicle.
    That's what spoiled my move to upper Nevada.
    Way HOT and WAY too cold.
    The climate dictates your vehicle choices and chosen mods.
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

  7. #16
    These long-lasting mounds of snow are actually rare. I had to ask my mother if she ever remembered this much snow in the valley, to which she said "once...when you were two." That was two years after my car was made.
    Yes, we were born the same year.

    The AC in my truck still blows icy cold, probably because I never used it haha. AC is dead in the Supra...but it has big ass windows and WILL have an operable moonroof

  8. #17
    CelicaSupra.com Member Road Ripper's Avatar
    Join Date
    Oct 2006
    St. Cloud, MN
    You have the most anemic version of the 5M that came out, good for 150 peak hp. The 85 5M had 172 hp due to higher compression, intake manifold, electronic ignition, a potentiometer-style TPS, a knock sensor and a much better ECU system that could fine tune the fuel/ignition curves. Adding a header and bigger exhaust helps the power out a bit, too. I think the 3.73 gears are just too high for that weak of an engine, and would be better suited to a later model or modded engine. The turbo guys LOVE those 3.73s and the rare 3.42s to help build boost quicker, so you have gearsets that you could always sell.

    My first supra was an 83 p-type with an automatic. It was a feb. build date so it had the 3.73 gears in it. It was very slow on takeoff and I had to downshift to pass or climb hills, but it got decent gas mileage. I soon added a Pacesetter header and catback exhaust which helped it out a little. It never did have low end grunt though.

    Do you want more power, lower gears, or maybe a little of both? No one has mentioned the 3.90 gears that come in the Cressida sedans from 85 to 88. They usually have open diffs, but you could swap in the lsd center section along with the stub shafts from an lsd diff. Yes, there IS a difference in the little stubshafts between LSD vs. open, so keep the stubs with their corresponding center section. It's also good to keep the r&p with it's case, to make shimming the pinion depth easier.

    You can bolt on a few parts to make more power, but you can also tune what you have. I'm sure you already know about advancing ignition timing. On our engines, the cams can be advanced/retarded individually in relation to TDC, and you can also change valve overlap. Toyota uses a dowel and a series of holes in each cam and cam gear to allow for machining varience, but racers back in the day used them to fine tune the cams and move the powerband. 82's even got 5 holes in each cam instead of the later cams only having 3. There are threads on the forum or in archives all about this.

    The main reason for noise from the rear end is the pinion bearings losing their preload because the crush sleeve crushes more from pinion deflection. Weir makes a solid spacer and shims for us to eliminate that weak link. They also make an lsd gripper kit that replaces the weak parts in the lsd that break or wear and reduce the locked effect. You could also shim the springs tighter, and research the right kind of oil to use in the rear diff to make it perform correctly.

    *Horsepower figures quoted from engine specs that I looked up in a Motors repair manual in a public library back in 2002.
    Last edited by Road Ripper; 01-08-2017 at 02:18 PM. Reason: added info, sited source of specs
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  9. #18
    CelicaSupra.com Member
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    Nov 2012
    ^^1982 Celica Supra: 145 bhp
    1985 Celica Supra: 161 bhp

    1985 Toyota P-Type Celica Supra 5MT
    1993.5 Toyota Supra Turbo; 1994 Toyota Supra Turbo; 1995 Toyota Supra Turbo
    1991 Toyota Supra Turbo; 2006 Toyota 4Runner Limited V8
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  10. #19
    Quote Originally Posted by Road Ripper View Post
    *Drops knowledge
    Thank you.
    I didn't even know about a 3.90's existence. I think I've read some Cressidas had LSD too.

    I'm not honestly expecting a powerhouse machine from what I have. Look at it like this - a bare bones 22RE in an xtracab, long bed pickup has been my DD since Oct 2004. This "anemic" '82 5mge is a screamer compared to what I'm used to.

  11. #20
    CelicaSupra.com Member drjim's Avatar
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    Aug 2013
    SoCal / Long Beach
    Quote Originally Posted by KenHenderson View Post
    ^^1982 Celica Supra: 145 bhp
    1985 Celica Supra: 161 bhp

    And my bone-stock, 168,000 mile 1985 put 142 HP to the rear wheels.......
    1985 5-speed "Ms. Swan"

    OH, What A Feeling!

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