Half shaft length differences between years?

[bflan2001]

I was under the impression that there were two different versions of the E21 half shafts. 77-79 had 8mm bolt holes, and the 80-83 had 10mm. I have a pair of each of these in my possession. I also have a third pair that I was hoping to use, but the CV joints are thinner and the overall length of the axle is almost an inch shorter. Did I somehow end up with a pair of 2002 half shafts or is there a third type of E21 axle?

[bflan2001]

Here's a picture to clarify what I have. I just noticed that they all have a different number of rings formed into the shafts. That might be an indication of what they came out of?

2809892F-70D6-4B3A-9F6A-CE21A97B991E_1_201_a.jpg

[ascot]

77-78 had the small holes in the output flanges like a 2002. 79-83 had the larger holes in the flanges. My guess is the 400mm three ring halfshaft is an E30 item.
shermanmartinez at Hotmail dot com

[mitsakosgt]

According to this site https://www.bmw2002faq.com/articles.html/technical-articles/engine-and-drivetrain/e21-diff-install-with-320i-inner-cv-joints-r157/
it looks like a 320i halfshaft. It appears to fit E12 also. E30 halfshafts should be longer IMO.

[amarino]

This article from Ireland Engineering says that the Early E21s "usually have 8mm bolts for the CV joints but some use the later 10mm bolts" so it's possible that both your 420mm half shafts are are early style?


https://www.iemotorsport.com/wp-cont...ferentials.pdf

Early E21 (’77 and ’78) 320I’s have 4 bolts holding the side covers, but the outputflanges are held in by a C-clip inside the diff. These diffs usually have 8mm bolts forthe CV joints but some use the later 10mm bolts. These diffs are the same width asthe 2002 diff so no spacers are necessary if you are putting one in a 2002.

Later E21’s have 6 bolts holding the side covers and the output flanges are held bya snap ring just above the splines. You can easily pop out the flanges with a screwdriver. These diffs nearly all use the 10mm bolts for the CV joints. These diffs arealso narrower than the earlier diffs. If you want to put these into a 2002 you shoulduse spacers to bring them to the proper width. Billet aluminum spacers and theproper bolts are available from Ireland Engineering.

[mitsakosgt]

Hope this helps too.

[okieflats]

I'll go measure mine tomorrow, I have an extra spare set.

- - - Updated - - -

Mine are definitely like the short ones. They have 3 rings. And measure about 400mm. I got 15 and 11/16 inches which converts to 398mm. They look like the ones in the center of the picture too. Notice the ends are different than the other two.

[okieflats]

This article from Ireland Engineering says that the Early E21s "usually have 8mm bolts for the CV joints but some use the later 10mm bolts" so it's possible that both your 420mm half shafts are are early style?

Early E21 (’77 and ’78) 320I’s have 4 bolts holding the side covers, but the outputflanges are held in by a C-clip inside the diff. These diffs usually have 8mm bolts forthe CV joints but some use the later 10mm bolts. These diffs are the same width asthe 2002 diff so no spacers are necessary if you are putting one in a 2002.

Later E21’s have 6 bolts holding the side covers and the output flanges are held bya snap ring just above the splines. You can easily pop out the flanges with a screwdriver. These diffs nearly all use the 10mm bolts for the CV joints. These diffs arealso narrower than the earlier diffs. If you want to put these into a 2002 you shoulduse spacers to bring them to the proper width. Billet aluminum spacers and theproper bolts are available from Ireland Engineering.

https://www.iemotorsport.com/wp-cont...ferentials.pdf

If the later diff's with the 10mm flanges are NARROWER then why are the shafts shorter? It would seem the narrower diff for the later models would need longer shafts.

There are other factors too though.

[320iAman]

This is a spare set- back up I re greased ect circa 1980 , they have 2 rings and fit 1980-83 e21 320i's, The ones on the car now are from 1983 e21 320i and have brand new boots, ect, I got at P and P for $40 for the pair. The 80-83's are same size direct fit. 16 1/4 "- 412.75 mm and 17 3/16 - 436.532 mm approximately, 1st is flat end plate to flat end plate and 2nd the end plate to end plate including the pop out portions.

DSCI0476.JPG

Randy

[Tom D]

brian,
all e21's have the same length half shafts overall.
77-79 used a 40mm thick CV
80-83 used a 29mm thick CV
77-78 used a 8mm bolt
79 -83 used a 10mm bolt
80-83, the actual shaft minus the CV's are 22 mm longer then the 77-79 shaft.

what i think you are showing in your picture is:
far left 77-78 shaft with 40mm CV's and 8mm bolts
far right 79 shaft with 40mm CV's and 10mm bolts
middle is either not from a e21 or it's a 77-79 shaft with 80-83 CV's installed.

the ireland engineering article is incorrect in stating the later e21 diffs are narrower, all e21's use the same diff housing and all measure approx 146 mm wide. i correct them years ago but they never changed the article.

Here's a picture to clarify what I have. I just noticed that they all have a different number of rings formed into the shafts. That might be an indication of what they came out of?

2809892F-70D6-4B3A-9F6A-CE21A97B991E_1_201_a.jpg

[bflan2001]

what i think you are showing in your picture is:
far left 77-78 shaft with 40mm CV's and 8mm bolts
far right 79 shaft with 40mm CV's and 10mm bolts
middle is either not from a e21 or it's a 77-79 shaft with 80-83 CV's installed.

That's what I thought too until I went to the junk yard to pick up a set of axles out of an '83. They're identical to the axles in the middle of my original picture. And they definitely measure about 20mm shorter than the 77-78 and 79 axles. I'm going to experiment tomorrow bolting up the '79 axles to my rear end. I'm running 80-83 trailing arms, diff, hubs, etc. now.

[bflan2001]

After some more test fitting I can confirm that the axles are all the same length. The newer axles just looked shorter because the joints were compressed.