how many case gaskets for rebuilding a split case casale?? differing views.
+ Reply to Thread
Results 1 to 13 of 13

Thread:
how many case gaskets for rebuilding a split case casale?? differing views.

  1. #1
    Member
    Join Date
    Apr 2016
    Location
    Taupo
    Posts
    64

    Default how many case gaskets for rebuilding a split case casale?? differing views.

    Hi all

    I am rebuilding the split case v drive casale finally, managed to get all the bits from beaver fab. Now, exactly how many case gaskets need to go back into the rebuild? I have a 3/8" plate, and I understand that you need a thick gasket on one side and a thick and thin on the other. Some others have been saying different to that.
    Surely with the bottom shaft being diagonal (not perpendicular) in the case, you MUST have the two split halves a certain distance away from each other, which is only set by the gaskets and the plate, otherwise you will have the bearings not being run concentric between the 2 bearing housings? (on the bottom shaft). Of course with the top shaft being perpendicular to the case it's not crucial for that one.
    Note I'm not talking about setting up bearing clearances here.

    So, is it indeed a total of 2 x thicks and 1 x thin with a 3/8" plate? Which by the way equals .375+.030+.030+.015 = 0.45
    Which raises another question: if you have a 1/2" plate, you are already too thick?? I'm struggling to understand why this is not the most important consideration when positioning the split halves.

    Cheers

    Matt

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member
    Join Date
    May 2014
    Location
    Meadow Vista Ca. Huntington Beach Ca.
    Posts
    261

    Default 1/2" plate

    To run a 1/2" plate the cases have to be machined. .055" off of each side. Use this and your calculations will come out.
    I use 2 of the fat case gaskets.
    You set our bearing preloads and backlash with the cap gaskets.
    Last edited by speedtrap; 10-17-2016 at 07:39 AM.

  4. #3
    Precision Craft Marine
    Join Date
    Jan 2008
    Location
    Napa, Ca
    Posts
    1,563

    Default

    Generally the standard split case box with a .375 plate uses one thick and one thin on the engine side case, and one thick on the forward case. Do not bank on that, I have machined many v-drive cases to eliminate the thin gasket. I am sure others have too. I typically check the cases with a depth gauge from the mounting surface to the cap surface.. Once you understand how these V-drives evolved, you will understand that part #s and illustrations do not mean very much. When buying aftermarket parts, you have just added more checking and modifying to a v-drive. Gear mesh is always over looked during a gear change at the lake. I have a set of spacers for each set of gears that i own. If built correctly, with high quality bearings, synthetic oil, they can last as long as we are all alive.

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Member
    Join Date
    Apr 2016
    Location
    Taupo
    Posts
    64

    Default

    There are no aftermarket parts in ours as far as I know. How would I know how many gaskets are really needed? Should it be when both bearings look like being able to slide in without tipping the shaft? It looks like this case has had a bit of maltreatment in the past - i posted on another post about one of the internal shoulders having a circumferential crack. Nothing structural, but looks like the bearing has been tilted in there before.

    with my current test with 3 case gaskets, I'm going to need shims otherwise the bearings will settle down on the outside shoulder rather than the inside bearing race.

  7. #5
    Precision Craft Marine
    Join Date
    Jan 2008
    Location
    Napa, Ca
    Posts
    1,563

    Default

    I am not certain of what you are asking entirely. I would never run a case that has a crack on the bearing register shoulder. It will fail , but you have an option if you must use that case. Machine out the shoulder stop and fabricate one from 6061 and drill and tap the existing case to fasten the ring , if you will, between the existing bolt circle. double check your internals for clearance on the fabricated part. I am away from my bench, but the next time i get a chance, i will get you some dimensions to reference for your need. if i go from memory, I believe on the forward case (front of boat) the dimension should be about 1.750 from mounting surface to the bearing cap surface on the input race. i cannot remember the engine side case dimensions with out my notes. I am getting old. I hope this info helps you some. Joe

  8. #6
    Member
    Join Date
    Apr 2016
    Location
    Taupo
    Posts
    64

    Default

    OK, so I set up the backlash on the gears to about 10 thou. Then I used only 2 thick gaskets. I also had to add shims to the spacer on the top shaft as the bearing was mating up to the case shoulder before closing up on the shaft/spacer/gear etc. Which is bad right? those "front" bearings are effectively supposed to "float" in the front case half?

    Now, when I then put the front case on, all my backlash dissapeared and the box almost locked up. So my thoughts are that the case halves are too close together and this will cause the bottom shaft to tilt up slightly as you assemble the bearings, hence closing up the backlash.

    So now I will put in the thin gasket as well, but then I will need to get/make/find extra shims for BOTH shafts as now both front bearings will hit the alloy case shoulder before the inner race will butt up to the spacer.

    My plate is exactly 3/8" and currently have 2 thick gaskets. The old plate was a few thou less than 3/8" and not very straight. Home made gaskets by some other guy. I suspect the internal races were not tight hence the wear/cracking issues we are having.

    Weird that all the backlash got lost when I put the front case on (and did a test bolt up, which showed me I need 2 x .005thou cap gaskets to hold the bearings. Which is about right.

  9. #7
    Precision Craft Marine
    Join Date
    Jan 2008
    Location
    Napa, Ca
    Posts
    1,563

    Default

    Something is wrong. Do you have a matching set of cases? can you take pictures of the cases?

  10. #8
    Senior Member LiquidDan's Avatar
    Join Date
    Jan 2009
    Location
    Acton, Ca
    Posts
    1,231

    Default

    First off...I am not trying to hijack this thread from Joe as he is as good as they come at rebuilding V Drives
    Second....did you have all the bolts tight on the back side when measuring lash?.... before you tightened the front?
    When I get a drive in I disassemble and start from scratch with 030 on each side..make sure the spacers give the correct lash and take up the end play with cap gaskets after torqueing the front case on.
    Originally Posted by gn7 "Stick to making the worlds best engine stand."

  11. #9
    Member
    Join Date
    Apr 2016
    Location
    Taupo
    Posts
    64

    Default

    Quote Originally Posted by J Shelfo View Post
    Something is wrong. Do you have a matching set of cases? can you take pictures of the cases?
    Yes I believe so I dont have any reason to think otherwise. This vdrive was the original on this boat as far as I'm aware. There are no markings on the case that would indicate how to match them. No common serial nos or anything.
    Click image for larger version. 

Name:	IMG_1977.jpg 
Views:	33 
Size:	24.4 KB 
ID:	927594

  12. #10
    Member
    Join Date
    Apr 2016
    Location
    Taupo
    Posts
    64

    Default

    Quote Originally Posted by LiquidDan View Post
    First off...I am not trying to hijack this thread from Joe as he is as good as they come at rebuilding V Drives
    Second....did you have all the bolts tight on the back side when measuring lash?.... before you tightened the front?
    When I get a drive in I disassemble and start from scratch with 030 on each side..make sure the spacers give the correct lash and take up the end play with cap gaskets after torqueing the front case on.
    No please I need all the help I can get!
    Bolts - you mean in out housing and input shaft bearing caps? YES
    Thats exactly what I did, but as I torqued up the front case the backlash reduced, and then as I test fitted the bottom cap for gasket requirements the whole drive locked up.
    I have followed the pictorial post that is well known, I'm an engineer myself so quite handy with mechanical stuff, just never worked on vdrives before.

    Also, what is the torque on the case bolts and cap bolts? I'm just using tight-ish at the moment on my arm-ometer. (prob about 30-40 ftlbs)

  13. #11
    Senior Member LiquidDan's Avatar
    Join Date
    Jan 2009
    Location
    Acton, Ca
    Posts
    1,231

    Default

    If you have the drive elevated off the bench with the tail shaft pointing down and the in n out housing and input shaft bearing cap tight and everything spins free the front case half touches nothing in the rotating assembly until you put the bearings in
    Keep your torque in the 20 area
    Originally Posted by gn7 "Stick to making the worlds best engine stand."

  14. #12
    Member
    Join Date
    Apr 2016
    Location
    Taupo
    Posts
    64

    Default

    Quote Originally Posted by LiquidDan View Post
    If you have the drive elevated off the bench with the tail shaft pointing down and the in n out housing and input shaft bearing cap tight and everything spins free the front case half touches nothing in the rotating assembly until you put the bearings in
    Keep your torque in the 20 area
    Yes, there is no way the front half can come anywhere near any rotating assembly. 20 OK. ta.

  15. #13
    Member
    Join Date
    Apr 2016
    Location
    Taupo
    Posts
    64

    Default

    I realise I screwed up with the bearing caps. I bolted them up then measured with a feeler to get the gasket thickness, but by doing that I'm actually loading up the bearings, so, I should have followed the instructions and measured the respective distances and put gaskets to suit, or just do up the caps barely finger tight and then measure it. That's why my bottom shaft locked up....
    I'm still going to add the thin case gasket too.

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

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

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95