Jump to content
FB73tii

2002 diff flange--use threaded or not?

10 posts / 712 viewsLast Reply

Recommended Posts

The diff drive flanges on my '69 2002 diff (4-bolt side cover, flange held in by large hex bolt) have 8.0mm I.D. bolt holes with no threads, so the CV bolts are held only by locknuts and not by threading into the flange itself. I have another 2002 diff that has what appear to be the same flanges (held in by large hex bolt), but they are threaded for 8mm CV bolts. I really don't like the unthreaded flanges for track use, so am thinking about swapping in the threaded flanges. Has anyone had more problems with bolts coming loose from unthreaded vs. threaded flanges?

Also noticed one of my stub axles is threaded for 8mm bolts, while the other is unthreaded like the diff. The unthreaded bolt holes range from 8.25mm to 8.34 mm I.D. Again, I don't like this arrangement. Due to the unknown history of the car I am putting in brand new stub axles and brand new 2002tii rear hub flanges.

Will be interested to hear if folks that race/HPDE have opinions on threaded v. unthreaded flanges.

Thanks, Fred '74tii & '69GT3

Share this post


Link to post
Share on other sites

I always thought the nuts were a better answer, since you can both

get them tight AND you're not having to turn the bolt

(which Carroll Smith says you're NOT supposed to do)

Having said that, I've run both, and neither give trouble-

WHEN torqued correctly!

t

Share this post


Link to post
Share on other sites

Good to hear. I'll locktite and safety wire them no matter what!

Fred (power still on but winds picking up now)

Share this post


Link to post
Share on other sites

never had a problem with the hex bolts coming out of threaded diff flanges. e30, e36 race cars, M2 track car. locktite, proper tq, and then grease pencil mark them so you can see at a glance if they move. no safety wiring needed.

if you must, with the threaded flanges you can use a 5mm longer bolt and add a lock nut on the back of the flange in addition to the locktite. i have never found that needed. have never had a bolt even move, let alone come loose. years of track abuse.

Share this post


Link to post
Share on other sites

I had a problem when I went from 6mm 2002 parts to 8mm 320 parts-

I simply wasn't torquing the bigger bolts tight enough. They want something

like double the torque. Plus some more.

I'd also had street cars loosen their 6mm bolts- again, insufficient torque.

Hasn't happened in at least 6 years tho.

t

Share this post


Link to post
Share on other sites
I had a problem when I went from 8mm 2002 parts to 10mm 320 parts-

I simply wasn't torquing the bigger bolts tight enough. They want something

like double the torque. Plus some more.

I'd also had street cars loosen their 8mm bolts- again, insufficient torque.

Hasn't happened in at least 6 years tho.

t

BTW Toby, I remember I've corrected you on this same subject once before. You really like your diff bolts small :)

Tommy

Share this post


Link to post
Share on other sites

oh, hell, you're right as always.

WHY can't I keep the inhex size separate from the shank size???

Thanks, Tommy

t

Share this post


Link to post
Share on other sites

I have had some problems with the smaller fasteners coming loose. My solution was cap screws by "Stage 8" that came with a plate that fit over the bolt head and had a small locking ring installed with lock ring pliers. Apparently Porsche 914's also use these smaller cap screws and they struggle to keep them tight. I don't have problems with the larger cap screws for the e21 output flanges.

post-611-13667666078354_thumb.jpg

Share this post


Link to post
Share on other sites

Thanks, I've come across the stage 8's before, have not used them. I am not sure how one would install them with unthreaded diff/stub axle flanges. They would have to be on the nut side, not the bolt head side, and that is a very tight fit.

While a nut on the end of a bolt (unthreaded flanges) should have as much clamping force as a bolt threaded into a flange, it would be a real pain to safety wire the nuts. So I am going to swap flanges and use my threaded diff flange. I've got the diff out already for inspection and new side seals. The flanges came out of both diffs easily after unbolting. Per the factory manual I will make sure the installation clearance is correct.

I am interested in the history of threaded v. unthreaded flanges. All of the replacement stub axles I have bought from BMW have been threaded. My '69 has one threaded and one unthreaded. I wonder if unthreaded was an early design.

Fred

post-290-13667666089903_thumb.jpg

Share this post


Link to post
Share on other sites

I like to run the threaded flange with the longer bolts for the unthreaded flange locktited and toruqed to spec and then add the nyloc nuts to the backside as a lock nut, no way will these come undone untill you do it.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.