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Success -- a pile of rear end bits

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drooartz

drooartz

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Went at the rear end with a BFH and some PB Blaster this morning, and had some success. Used a putty knife to split the axle and hub, and got the RR axle out. Then tackled the LR brake drum. Some more hammer work and a bit of prying with a screwdriver, and it came out too. I now have 2 axles in good shape (the stronger, later ones as far as I can see), a diff, and a driveshaft in my spares pile.

As a note, didn't know how the driveshaft came out, but it moved when I pulled it from the back and it came all the way out. Learn something new every day.

rear_parts.jpg
axle_end.jpg


How can I check if this is really a 3.9 diff? Should be by the year of the car, but this car is a bitsa (bitsa this car, bitsa that car) so can't be 10%.
 
It is stamped on the top side of the part shown in you pic, on one of the side flanges. Get it real clean. hehe.
 
Or count the teeth on the ring and pinion. Didide the number of teeth on the ring by the number of teeth on the pinion.

Phil
 
I'm going to display my ignorance once again. Which bit is the ring, which bit is the pinion?
 
Drew, the large gear is the ring, and the gear in the front is the pinion. In "British" the ring gear is referred to as the crown wheel.
Jeff
 
Here's what I found on the ring gear:

MOWOG BTA 1224 10-39

I'm assuming this confirms a 3.9 (39/10). I did count 39 teeth on the ring gear as well.
 
That is what you want for a 1275 is it not?????
 
Haven't really decided which I'll use yet. Probably keep the 4.22 for now, and see what it drives like up here in the hills. Now that I see how it goes together, it shouldn't be too hard in general to swap them and experiment.

I guess I'm becoming a real LBC guy--I've got old greasy spare parts in my garage now. At least they are all for a car I have! /ubbthreads/images/graemlins/grin.gif
 
Hehe, they can be cleaned up nicely. Keeps a guy busy and the wife knows where he is. I just use a stiff paint brush and mineral spirits from the hardware.
 
I'd had my bugeye 25 yrs before I got into my rear end, I felt like I had touched the last few untouched bolts. I guess you are a little quicker than I am.
 
Haven't gotten into the Tunebug yet, just working on the 74 Midget, stripping parts. The nuts holding the diff on actually weren't that hard to get off, surprisingly enough. Getting the drums off was far harder. That took a couple days and assorted tools of persuasion.

Bugeye rear end will happen eventually, but he drums will come sooner. One side seems to have a bad seal, I guess this is not uncommon with Sprite rear ends. That's a later project for once I've got the Midget stripped and out of here.
 
what would the engine speed difference be between a 4.22 and a 3.90 at 45mph? Does the 3.9 slow acceleration down a ton?
 
A 3.9 allows for a (slightly) higher top speed.
At 45, a 4.22 would do about 2750rpm in 4th, whereas a 3.91 would do about 2600 in 4th. Both if the tire diameter is 23 inches.
 
I know we've gone through this before, but do you have a calculation somewhere for gearbox ratio/rear end ratio/tire size/speed?
 
Thanks Baz...not too much of a difference then.
 
Thanks for the link. 3.9 doesn't make a huge difference, but it's not insignificant. Will be interesting to experiment with it next year.
 
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