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Spitfire Spitfire diff question

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AustinJim

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Hi all,
The differential in my Spitfire is making a whining noise. I've replaced the outer bearings and oil seals but there was no change in the noise. I have a spare diff so I thought I'd swap them just to see if the spare is ok. It turns out one of the bolt holes in the spare diff is stripped so I got a helicoil to fix it. When I took the diff apart there was part of a copper washer loose in the case. My question is, where did this copper washer come from and what problems will I encounter if it's no longer there? What do you suggest I do to solve the original diff problem?
Thanks!
 
Probably the shim behind the side gear. In the diff assy itself, you have two spider gears and two side gears. These are the gears that actually make the differential a "differential" The British are renowned for the spacers/shims wearing behind these. Any competent diff repair shop can replace these and a lot of experienced tech can also.

Not that hard a job.
 
You are probably looking at a rebuild in either case, or you can try living with the 'whine' in the original.

They all seem to whine a bit. Sometimes just changing the gear oil helps. If its something you can't live with you will need to get it rebuilt/readjusted, rebuild it yourself, or get an already refurbished unit and swap it for yours as a core.

In your original diff, if the axle shaft and pinion bearings are ok, the whine may be from simple wear, either from the gears themselves and/or in the thrust washers that set the clearances of the internal sun/planetary gearing. There are also bearings inside the diff that support the crown wheel.

If the gears in your unit(s) are still good, but maybe a little worn, then getting it rebuilt would make sense. New crown/pinion gears are usually pretty expensive, and buying a swap unit can also be pricey. Last time I looked off-the-shelf rebuilds were in the $1,000+ range.

As RonMacPherson notes, looks like the shims are gone in the spare diff you have. This means backlash clearances are definitely out on that one, and I would trust it less than your original.

If you want to try rebuilding it yourself, the BL repair manual has specs and a description of the process. Haynes has a techbook called Suspension, Steering & Driveline. There is a 'Rear End' section in that book which explains the process fairly well, albeit not aimed at British cars. The two books combined give you a pretty good idea, although I would probably still opt for a professional rebuild.
 
Good answers;...In any case(no pun intended)you should see about installing a drain plug,I did on my 80Spit & it makes it easy to flush & fill.,30w non detergent is a good idea too.ALL the fill plugs are the same(tranny,diff,oil)Be cautious about drilling the drain for the diff as fileings should be flushed.
Ken
 
Thanks for the info. I'm going to take a good look at the spare this weekend. A friend in out Triumph club and I are going to see if it's a good rebuild candidate and maybe do it ourselves. I rebuilt the transmission and, even though it took 3 times, it turned out fine. I'll leave the whiney one in the car in the mean time since it doesn't seem to be getting any worse.
Thanks again!
 
I took a look at the diff this weekend. The washer that created hari-kari was behind one of the small pinion gears. My Haynes book does not go into detail beyond replacing carrier bearings and seals. Does anyone have any experience or information with replacing this washer? Can this be replaced without completely disassembling the inside assembly? The rest of the diff seems fine.
Thanks!
 
The shims behind the small gears can be replaced without taking the carrier apart. There is a pin that has to be driven out from the side of the carrier. Then a thick rod has to come out. The gears will then rotate around a bit and presto! The flat shims behing one set of gears are easy to change and are available. The cupped shims behind the other set of gears may no longer be available in the correct thickness. Seems they only make a thicker one that is difficult to machine down. May need to try Moss or Canley's.

The gears are called the sun gears and planet gears. Just don't remember which is which.
 
Sun gears, or spider gears?

The planet gears are alwasys the larger of the two sizes.
 
I was hoping driving the shaft out (after removing the retaining pen) was all that is required. It seemed feasible by looking at it. The Victoria British catalog calls them pinion gears. These are the smallest gears.
 
AustinJim said:
I was hoping driving the shaft out (after removing the retaining pen) was all that is required. It seemed feasible by looking at it. The Victoria British catalog calls them pinion gears. These are the smallest gears.
Click to expand...
It looks feasible without disassembling the carrier.

The small gears are 'planet' gears, the larger ones are 'sun'. The parts manual, however, refers to the larger gear simply as "Gear" or "Gear - Sunwheel", and to the smaller gear as "Pinion". So you are looking at the right ones.

You need to get the right thickness of thrust washers. There are 9 thicknesses. You should be adjusting for minimal end float and zero backlash between sun and planet gears.
 
Ross,
Thanks for the detailed responses. I notice that the Victoria British catalog has only 2 thicknesses, one for Sptifire and one for GT6 (0.04 and 0.041 I think). Moss doesn't show them available at all. Any suggestions on where to get an assortment from?
 
RonMacPherson said:
Sun gears, or spider gears?

The planet gears are alwasys the larger of the two sizes.
Click to expand...
Sorry to disagree, but a "planet" gear is one who's axis revolves around something else, the way the earth's axis revolves around the sun. Doesn't necessarily say anything about their relative sizes, but in a differential the planet gears are normally smaller.
https://mysite.du.edu/~jcalvert/tech/planet.htm

However, my Triumph documentation calls them simply "side" and "pinion" gears. Which is a tad confusing, since the input gear is also known as the "pinion" gear (as in "ring and pinion").

The term "Spider gears" covers all 4 of the gears in the carrier, because of the way they "crawl around" on each other.
 
AustinJim said:
Any suggestions on where to get an assortment from?
Click to expand...
TRF has .040, .044, .048, .052 and .056 listed. P/N 108935 through 108939 respectively. Assuming your car takes the same washers as a Spit Mk 3 (which is the parts book I had handy).

https://www.the-roadster-factory.com/
 
AustinJim said:
I notice that the Victoria British catalog has only 2 thicknesses, one for Sptifire and one for GT6 (0.04 and 0.041 I think). Moss doesn't show them available at all. Any suggestions on where to get an assortment from?
Click to expand...
Sorry Jim, I don't know where you can get these.

See billspit's previous post. He is pointing to the same problem. I think the 'cupped' washers he mentions are, in fact, the ones for the pinion (or 'planet') gears that you need. The only ones I could find anywhere (including Canley and Rimmer in the UK) were P/N 148805 (.041") and P/N UKC4788 (.69mm or about .027"). TRF does stock these particular part numbers, and Spitbits does too.

I'm not sure these two washers are the same shape. For some reason, it appears BL changed the part numbers for these washers around the end of 1977 and started using metric to specify the thickness (i.e. in mm's). If they really are the same shape however, you might be able to get by with just these two thicknesses or grind them as necessary to get what you need.

With reference to Randall's post, the part numbers are different for the 1500 from the ones he notes. But again, I have not seen them side by side, so I don't know whether there is a real difference or not, or whether Triumph just changed the part numbers.

Maybe you could ask one of the suppliers to have a look at them and compare? Or ask their tech guys for advice. VB uses their own part number system, so its hard to know, but TRF or Spitbits uses the Triumph part numbers.
 
My apologies, didn't realize it was a 1500. I have no reason to believe the earlier parts will fit.

And I note that the planet gears and carrier also changed at the same time the washers changed; which likely indicates the early and late 1500 washers are different as well.
 
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