Section : Rear Axle

Rear axle, brakes, wheels and tyres.

That effin Diff!

Posted By : Andrew Szczecinski, 03-Mar-2007, 08:17pm

Just put a recon diff back on our Spit and its been a right barstool of a job.

Followed the Haynes manual and put the long rear bolt through first and . . . . the front carrier was nowhere near the two studs.
Did it the other way round and the two rear bushes in the diff were about 3/8 of an inch out.

After four hours of messing about taking it on and off and measuring it up against the old to see if the diffs varied i finally located the two front mountings and the put a great big bloody strap round the whole thing and around the rear chassis cross member, stuffed a scissor jack in and wound the thing in. The only slight prob is a little elongation or stretch in one of the front rubber mountings, i.e you can see a bit of a gap between the shaft coming down and the internal hole of the rubber insert which i expected.

Just worried about the amount of pressure i had to use to get the things in and the pressure all the mounts are now under????

Any thoughts - am i worrying about nowt?

Thanks - Andy

Followups :

That effin Diff!

Posted By : Chris Taylor, 04-Mar-2007, 00:59am

You ask yourself a sensible question and then fail to give us the answer!! Was there any difference in the diff measurements? I would not expect there to be so, and in that case the only difference, and therefore potential problem, would be in the front or rear diff bushes. As long as your chassis is not corroded in this area, then I very much doubt that you will have any problem. Once the much higher stresses of drive and braking, and suspension loads, are put through the diff housing and these bushes into the chassis, they will be knocked into shape! The very worst that is likely to happen is that the bushes will wear out a bit quicker; as they tend not to wear out anyway, I doubt there is a problem. I would certainly not bother taking the diff out again; just leave it be and check the bushes from time to time (like when checking diff oil levels).
- That effin Diff!
  
  Posted By : Andrew Szczecinski, 04-Mar-2007, 07:27am
  
  There was no difference in the diff dimensions. It did cross my mind that the problem could be with the new bushes in the rear of the diff being nice and stiff but i just couldnt see it being the problem when i had the front mounts in place and the centres at the rear were so far out.
  
  Anyhow, i think its good advice to leave it be. My arms are just not up to another four hour battle today!
  
  Thanks Chris
  - That effin Diff!
    
    Posted By : John Davies, 04-Mar-2007, 10:32am
    
    Andrew,
    I had a very similar problem on the Silverback last year.
    The same diff. would not go back in, after it had been reconditioned.
    
    After hours of toil, I realised that the front mount plate was BENT!
    Thedistances between the front and back mounting holes were unequal.
    This was traceable to a broken half shaft and losing a wheel earlier in the race season, but it could happen to a road car.
    
    Careful inspection of the front mount plate showed the bend, as a line of flaked paint.
    Correction was succesful, by judicious use of an FBH.
    
    Also, I recommend that you replace that long rear bolt by two short ones.
    Insertion needs doing twice, but its more than half as difficult.
    
    John
    
    That effin Diff!
    - That effin Diff!
      
      Posted By : Leon Guyot, 04-Mar-2007, 05:01pm
      
      Also, I recommend that you replace that long rear bolt by two short ones.
      Insertion needs doing twice, but its more than half as difficult.
      
      That is strange John, my original diff on my 1200 Herald that had been in for something like 20 years was attached with 2 short bolts, and one of them was rusted solid, I recall that it took me 11 hours to remove from below the car!
      
      I decided then, to only use the one long bolt, ala GT6, and have never looked back!
      
      I have always found one bolt roughly half as difficult to remove!
      
      Horses for course I suppose
      
      Rgds
      
      L&195;&169;on
      - That effin Diff!
        
        Posted By : Andrew Szczecinski, 04-Mar-2007, 06:00pm
        
        Never thought of that John
        
        I didnt send my own diff for reconditioning as i didnt want to wait to get the car back on the road.
        The front carrier on the new diff could well have had a knock but im buggered if im taking it off to check - i just too too long to get it on.
        
        Something to watch out for though and if its not right when i do manage to get it running then i'll probably know where to look.
        
        Thanks
        
        Andy
        
        That effin Diff!
        
        Posted By : John Davies, 05-Mar-2007, 10:07am
        
        Leon,
        
        "I have always found one bolt roughly half as difficult to remove!"
        
        It's not the removal, but the replacement that's easier!
        Corrosion is the Great Equaliser.
        There may be other advantages, as the single bolt stresses the two mount members towards each other, while the two bolts just clamp them onto the diff.
        
        But different horses, different drummers, different drivers - I'll agree to differ!
        
        John
        
        That effin Diff! - additional question
        
        Posted By : Stephen Pratt, 05-Mar-2007, 10:57am
        
        Whilst talking effin diffs, I have a couple of new Superflex mounts for the Diff that I want to fit, my question is - If I disconnect the propshaft flange and front diff mounts and slacken off the rear bolt, is this sufficient to lower the front of the Diff enough to fit the new mounts?
        
        Or do I have to follow the Haynes manual and remove the 4 securing bolts on the front plate and the pinion nut to do the job?
        
        That effin Diff! - additional question
        
        Posted By : Chris Taylor, 05-Mar-2007, 06:50pm
        
        Do NOT touch the pinion nut! If your diff has a collapsible pinion spacer, you will knacker the pinion bearing preload and soggy diff mounting bushes will be the least of your worries! These collapsible spacers were fitted to 1500s I believe, but may well have been incorporated into other diffs with swapping and reconditioning over the years. I THINK they should have a nyloc nut whereas others have a castellated nut and split pin, but personally I would NOT risk it.
        You should find that if you need to, you can slacken off or even remove the four mounting bolts in the nose of the diff to give extra movement to the front plate for "wiggling" around.
        The answer to your original question is "I'm not sure" but it could be worth trying, you don't have too much to lose. However I suspect that you will need to remove the rear mounting bolts. You may need to remove or at least disconnect the leaf spring so as to be able to manoeuvre the diff without fighting against any spring loads.
        Not such a simple job after all, but you can of course change the lower bush without moving the diff at all.
        
        That effin Diff! - additional question
        
        Posted By : Stephen Pratt, 05-Mar-2007, 07:08pm
        
        Thanks Chris - You may have noticed I posted another message with the same question, but thanks for your response - I think our messages crossed in the ether! - As I've disconnected and removed the spring I will try the swinging down method, if that doesn't work plan B will be tried!
        
        Thanks again
        
        Steve
        
        That effin Diff! - additional question
        
        Posted By : Alexander Cain, 06-Mar-2007, 10:33pm
        
        Hope this helps, but only if the body has been removed - I had a similar problem, I spent a whole weekend recently trying to re-fit my diff. The only way I could find to do it was to turn the chassis over, and fit it upside down, using a thick screwdriver to move the mounting forward, as for some reason the mounting bolts would not meet! I tried every possible method of fitting -the rear bolt first, second etc....... I really don't know what I would have done if I hadn't been able able to flip the whole thing over. Maybe it was down to it being a Herald diff on a Mk3 Spit chassis?
        
        Good luck,
        
        Alex
        
        That effin Diff! - additional question
        
        That effin Diff! - additional question
        
        Posted By : John Davies, 06-Mar-2007, 10:54pm
        
        Alex,
        Too late now, but I wonder if the distances between the front and back bolt holes on each side were the same?
        Too late, because they should be now!
        
        John
        
        That effin Diff! - additional question
        
        Posted By : Alexander Cain, 07-Mar-2007, 10:11pm
        
        Too true! Forgot to mention upon inspection, it may have had something to do with it being a Herald 1200 diff, maybe there is some degree of difference in the casing? Or another possibility is I put too much paint on the chassis!! Whatever it was, it came out ok - and went back with a bit of a squeeze, and it's all sitting nicely now!
        
        Enough rambling,
        
        Alex
        
        That effin Diff! - additional question
        
        Posted By : Chris Taylor, 08-Mar-2007, 02:33pm
        
        No difference in casing between Herald, Spitfire, GT6 or Vitesse diff casings, at least as far as mounting points concerned. (Those intended for swing spring cars should have 4 spring mounting studs whereas plain swing axle or rotoflex cars will have six studs in the casing).