• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Differential howl

Share this page

Westfield_XI

Westfield_XI

Jedi Warrior
Offline
After a very long struggle with persistent overheating, (turned out to be a head gasket) I am finally able to put some miles on my Spridget powered Lotus replica. Now it sounds like I have a problem with my diff. It howls on overrun, but not under load. This diff is a "bitza" made up of my '67 donor axle with an eBay 4.22 gearset. The problem is that I didn't think to check the gears for correct shimming, I just bolted it up and put it into the car. That was only 650 miles ago so I hope that I have not done permanent damage.

Any tips on where to look for instructions on setting up a diff? Or a good shop in Los Angeles that could do it for me?
 
I am sorry, but I haven't the slightest idea what you are talking about. Can anyone help, please?
 
Most any driveline shop can do it. Ask the local offroad crowd for recommendations on a shop.
 
First, check that the big nut on the yoke is not loose. It can come loose from some hot rodding or whatever. I would try re-torquing it first. They make a special fork shaped tool with two prongs to hold the yoke, or I use a pipe wrench(just be sure to hit any burrs you may cause with a file).
If that ain't it pull the pumpkin and clean it up with something good and check the backlash with a dial indicator. That is set by shimming the ring gear which is not that hard.
If you reshim or even if you don't, get some prussian blue and run through the gears and see how they are meshing.
When it comes to the pinion shimming,that is more of a PITA because you have to press it apart and try a shim and press it back together and check it.
There were special BMC jigs for checking the pinion depth and if I was going to pay someone to do it, I would take to someone who knows diffs and british cars. They are not quite like a Chevy.
Most of the guys doing trucks are never going to have a ring gear spinning near as fast on a truck unless that is one high speed truck.
That being said, a good diff guy will figure it out and honor his work and guarantee it not to whine. There are some doing trucks that won't even do that.
There is a part of it that is time consuming and tedious, and there is no way around that no matter who does it.
When I put another gear ratio in my pumpkin, I had to go through all that.
I wish you the best of luck and yell at me here if I can help you.


PS: Did you ever get that Westfield together? I wanted to see some pictures of it when you were done.
 
Kim, where'd you find ring gear shims? I've seen the ones for the carrier bearings but not the ring gear. I have a RG shim here that came with my 3.55 set, but that's for putting it on the early carrier. ( from what I understand)
 
kellysguy said:
Kim, where'd you find ring gear shims? I've seen the ones for the carrier bearings but not the ring gear. I have a RG shim here that came with my 3.55 set, but that's for putting it on the early carrier. ( from what I understand)
Click to expand...
I cut mine out of some sheet shim stock with some heavy gauge scissors. It was .002(I think), and I made 3 while I was doing it. I put just pieces under where each bolt is just to test and find out what I needed exactly, then I placed the whole round shims. You might get lucky and the old shim be right when you swap the gears.
First try it with no shims and you know it won't be right. Then put in the shim and check the backlash again. Its not a straight measurement because of the angle of the gears.
You can take calipers to the original shim and then you can figure out how much that thickness of shim affected the backlash from no shim at all and then figure out what more you will need to give you the .008-.010 backlash(going from memory 6-7 years ago).
 
Have you got a crush sleave? If you don't and can't find one for the Mowog pumpkin you can put a shim of .010 or so on the inside and crush it some more and get the correct preload and it will work. That is what I did and a week later, I bought some other junk on Ebay and a new crush sleave was in there. They might still be available, I don't know. The pinion might not be too bad for finding shims and the sleave but that ring gear is pretty small and I don't know if you could find ready made shims for it.
Car parts places might look at you like you are crazy asking for shim stock but industrial places should have it. We use it at my work in brass and steel on occasion so I know its around. Search steel shim stock on Ebay. Tin snips will probably just mess it up. Use some good scissors and a hand held hole puncher to make the holes. Wear gloves :wink:
 
Crush sleweve still avalible through moss I believe. I have three here I got from them.
 
Thanks for the help. I have found a guy here in my area who does a lot of English diffs and supposedly has all the tools as well as a good reputation.

I had a Devil of a time with overheating before I traced it to a blown head gasket and repaired it. Now I am starting to add some miles to the Westfield and turning up all the little details that need tweaking.
 
Yep, and one day you will be looking for another little car to love.
 
Back
Top