1987 TR: 32k miles to install diff or not to… | FerrariChat

1987 TR: 32k miles to install diff or not to…

Discussion in 'Boxers/TR/M' started by xplodee, Dec 4, 2021.

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  1. xplodee

    xplodee Formula 3

    Jan 3, 2017
    1,101
    Allentown, PA
    Full Name:
    Tim
    I have an 87 TR and just did my major last year. I am now in possession of a Newman diff. My car has 315 wide tires on back and I drive her to enjoy her. I don’t do burn outs or slides, but I drive hard and shift at high rpm’s (once fully warmed up of course). The hard shifts and wide tires have me worried. Plus I only owned it for the past 4k miles and the wheels have been on the car for close to the pasr 15k miles

    so…. I asked a good shop what they thought about putting in the diff. They thought a lot about it and came back to me saying its worth just pulling the engine for the install to keep things simple. Cost? About $10k for parts and labor excluding the diff.

    Do you guys think its worth it? I could have another 5k miles before the major is due and all the associated risk factors. Ugh. Obviously wish I would have done it last year but that is water under the bridge.
     
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  2. Zeff

    Zeff Formula Junior

    Oct 8, 2018
    678
    Cupertino, Ca
    Full Name:
    Ryan
    I would just wait till you do the major. I wouldn’t pay twice to have the motor pulled back to back like that. Would be a waste of money. Do it with the major makes a lot of sense.
     
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  3. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    5,561
    Central NJ
    Full Name:
    Dominick
    Or do major earlier ... splitting the difference in time

    Sent from my moto g power using Tapatalk
     
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  4. V4NG0

    V4NG0 Formula Junior
    Silver Subscribed

    Dec 14, 2018
    694
    Full Name:
    Charles Edward Cheese
    #4 V4NG0, Dec 4, 2021
    Last edited: Dec 4, 2021
    Three factory trained techs at three different shops (1 dealer, 2 indy) with probably 100 years’ combined experience wrenching on TRs told me not to worry about it—even if as part of a major service. I think it’s just one of those things that has accidentally gained undeserved notoriety.

    With one of those techs I did talk to him specifically about the fact that I (at the time before going back stock) had much bigger/wider tires than usual and he said it didn’t matter unless I was abusing the car on a track.

    That’s said, the whole diff issue has taken on a life of its own in many people’s minds similar to the Porsche IMS issue, and so if you plan to sell the car, it may be helpful with resale to do a retrofit.
     
  5. vincenzo

    vincenzo F1 Rookie

    Nov 2, 2003
    3,373
  6. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,866
    southwest germany and thailand
    Full Name:
    romano schwabel
    I would do the major earlier and change the diff then. it is not a question of if the diff will break, it is a question of when. but when the diff will break you not feel this just then, only when there will get more damaged, and then it will cost money. but it is your decision what or how to do.I think it would be a nice wintertime work to do it? ;)
     
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  7. jgmblair

    jgmblair Formula Junior
    Silver Subscribed

    May 27, 2010
    715
    Winnipeg, MB Canada
    Full Name:
    Jeff Blair
    The diff debate is interesting to say the least. I put in Newman’s diff years ago as a preventative measure. In my mind the probability of your diff going is highly unlikely but if it does go it can be catastrophic. I don’t think my house is going to burn down but I buy a home insurance policy every year ;)

    I was having a similar debate with another owner regarding the belts and bearings, his cars belts and bearings were last done 11 years ago. He’s comfortable driving the car and things might be ok for a few more years but if something goes we all know what could happen!

    Wow 10k to install is that the going rate? Don’t think there are many “parts” if you are providing the diff. Shop rate of $180/hr that’s a lot of hours to do this upgrade.
     
  8. xplodee

    xplodee Formula 3

    Jan 3, 2017
    1,101
    Allentown, PA
    Full Name:
    Tim
    I agree with your sentiment. Every actual tech that deals with these always says, “talk to me at 50k+ miles.” As for the $10k, its commonly reported to be a 20hr install AFTER and not including engine out and back in. Some have reported you can just jack the engine up after a lot of prep but its still a pita and engine out just makes it that much more straightforward, especially if the diff has to come out and go in a bunch of times.
     
  9. vincenzo

    vincenzo F1 Rookie

    Nov 2, 2003
    3,373
    Correctly setting up a diff requires a level of skill not frequently found in the average mechanic. When you get an exorbitant quote, the shop is saying that they are either;

    1) already busy and don’t currently want more work
    -or-
    2) are not technically confident/competent but will attempt it if they can charge lots of money to pay for their time climbing the learning curve.

    Either way - RUN away from stupid high quotes.

    Paint shop at 100k = can’t handle any more work
    ‘General repair shop’ at 10k diff = not confident/competent

    Run Forest…. RUN



     
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  10. versamil

    versamil Formula 3
    Rossa Subscribed

    Apr 28, 2013
    1,147
    Gaston, Oregon
    Full Name:
    Brian Healy
    For what it's worth, I have a 1986 that has about 39K on the clock, which has the engine out right now, and I inspected the diff. no damage, no signs of cracking. I'm replacing it obviously, but it DOES have 40 K on it. I also have the engine out on a 1990 that has sixteen thousand miles on it. Engine has NEVER been out, and running the original timing belts. They looked great. I haven't inspected the diff, but I thought the car sounded funny, with a different pitch from the ring and pinion on acceleration and decel. It will be interesting to see what I find.

    I don't think most shops have a lot of opportunity to get good at replacing the carriers. Nothing worse for a mechanic than quoting the first time of doing anything. Almost better to ship the car to a shop that's done LOTs of them. Shimming the differential is somewhat challenging. Doing the job with the engine installed, I don't think is worth it. I'd wait until the next major service.
     
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  11. JohnMH

    JohnMH Formula 3

    Jan 28, 2004
    1,625
    Dubai / Bologna
    I just completed this task myself on my 91 with over 50,000 km on it. The old differential case showed no cracks, but the quality of the visible welds 0n it were, uh, interesting. To make the part, these less than perfect welds are machined flat to fit in the case. I can see why they fail.

    I also had bought a Newman differential case about 5 years ago and waited until this major service to do the work.

    It is quite a job to get to the differential, and quite a job to get it back in correctly, at least for me. Getting the correct lash and pattern takes a lot of thought and trial and error. I had to ask for help to get the proper thickness shim on the left side installed (thanks Turbo-Joe!)and even then had to get a tiny fraction machined off. Also, replacing the bearings and races which are on either side of the differential is not as easy as it would appear. Finally, you can count on needing new LSD disks as the old friction plates will be worn.

    If you are going in that deep, split the engine from the transmission and replace the oil pump chain and buffer. They are not that expensive and they do wear and stretch.
     
  12. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,866
    southwest germany and thailand
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    romano schwabel
    so john your engine is in the car again and you did testdrive?
     
  13. JohnMH

    JohnMH Formula 3

    Jan 28, 2004
    1,625
    Dubai / Bologna
    No. I am in Bologna this week, I will collect a new clutch TOB from the dealer in Modena later in the week.

    Next week I am back in Dubai and can finish the engine, maybe I can put it back in the car the following weekend.
     
  14. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,866
    southwest germany and thailand
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    romano schwabel
    wish you good luck and all the best john
    I will go to thailand again next week ( if covid test will be negative ) for 6 month.
     
  15. MOSS

    MOSS Formula 3

    Apr 28, 2004
    1,619
    Yea, 4 Tr's, one being a 750hp TT and not one issue with the diff.
     
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