Rear end issues - Page 2

169mph · #1 (**permalink**) 01-11-2022, 11:35 AM

Quote:

Originally Posted by hauss

listen to spdbrake his description is way more detailed then mine a few post back I had the same problem twice until I fixed it myself first time brought it to a local mechanic. This is something that I regularly check and keep a eye on. After the fix however it has been two years now and no more issues.

What was the fix? Limiting the suspension travel? Missing CV joint flange bolts? Thank you for your response.

Mike

hauss · #2 (**permalink**) 01-12-2022, 09:32 AM

Quote:

Originally Posted by 169mph

What was the fix? Limiting the suspension travel? Missing CV joint flange bolts? Thank you for your response.

Mike

My fix was retaping the threads on the flange installing new bolts with red locktight. Spdbrake has sent you pictures and goes even further than I that"s why I said to listen to him.

169mph · #3 (**permalink**) 01-13-2022, 10:58 AM

As recommended, this weekend I plan to remove the wheels, spring, shocks and check the full range of the suspension to see what may be causing the rubbing. If anything, I’ll have a better view of the suspension. Okay, I left out some potentially important info. My car started to shudder when I would take off in 1st gear about the same time I saw the scratches on the cv joint flange. I thought it was a pressure plate issue. Also, I noticed yesterday that there was grease splatter above each drive shaft yoke. The transmission rear seal isn’t leaking. The drive shaft looks like it may be at slight angle from the transmission to the differential. Does this info help or muddy the water? Again, appreciate all the feed back.

Tom Wells · #4 (**permalink**) 01-13-2022, 11:07 AM

169,

This may tell you what you're curious about with respect to driveshaft angles, and much, much more!

https://4xshaft.com/blogs/general-te...veshaft-angles

Enjoy,

Tom

hauss · #5 (**permalink**) 01-13-2022, 11:13 AM

Have you removed the dust cover on the flange side of the axle and checked the flange bolts? The grease you are seeing is coming from the cv joint they are packed full of grease I would bet that the bolts are broken or something is amiss with your cv joint.

169mph · #6 (**permalink**) 01-13-2022, 02:19 PM

Quote:

Originally Posted by hauss

Have you removed the dust cover on the flange side of the axle and checked the flange bolts? The grease you are seeing is coming from the cv joint they are packed full of grease I would bet that the bolts are broken or something is amiss with your cv joint.

No. I'm idiot. I just figured out what everyone was referring to when asking if the inner bolts were loose. I thought y'all were talking about the flange bolts.

I assume I need to pull the axle out to remove the dust cover so I can inspect the inner bolts. It cant be done in place?

Also, there are no noises coming from the rear end when driving. It's tough to hear anything other than the exhaust. There is very little movement of the axles/cv joints up and down or in and out. Very minimum. Less than 1/16"

Thanks, Mike

hauss · #7 (**permalink**) 01-13-2022, 05:01 PM

No you can remove the cover it will pull back far enough to check the bolts. Don"t just put back the new bolts tap the threads then locktight red then new bolts. I check this area often but like I said after I did this it has not failed .It has been about 2 years. Also I would do both sides even if the other side is good.

169mph · #8 (**permalink**) 01-15-2022, 05:10 PM

Quick update. I finally removed the rear wheels. Took me a couple of hours to remove the spinners. The spinner removal tool is well worth the money. Confirmed what I already knew. The differential inner cv joint flanges are both rubbing the sub frame. Checked cv joint boots for leaks. No grease spatter. Boots seem good to me. Now that I can see better it looks like the differential has moved in the carrier causing contact with the sub frame. Again there isn’t any clicking or banging or strange noises when I drive the car. Tomorrow l”ll pull back the inner boot. I’m afraid that I’m going damage the boot but it looks like need to pull the axles anyway. I was hoping to find the cause with pulling the axles snd cv joints. Thanks for the responses

spdbrake · #9 (**permalink**) 01-15-2022, 08:04 PM

Can you post a couple of pics that are panned back a bit. Its pretty much impossible to tell orientation, etc,,, when zoomed in like those pics are.

bobcowan · #10 (**permalink**) 01-16-2022, 11:03 AM

I've been watching this thread since last year.

I am very curious as to why the carrier moved backwards like that.

My car is in the paint shop, so I can't go out and look. IIRC, the diff is mounted to the car at three points - One in the front, and two in the rear. In order to slide rearward that much, all three points would need to fail. Certainly not unheard of. If on fails for long enough, the other two would eventually follow.

When I get my car back together, I plan to investigate this. I will R&R each bolt for inspection of the bolt and bushing.

I will also put a jack under the diff and see if I can get it to move.

A while back I came across this differential brace. I think I will install that as well.

https://store.activeautowerke.com/co...racket-dsb-e36

169mph · #11 (**permalink**) 01-16-2022, 11:53 AM

Are you saying that the differential slide back causing the inner output flanges to rub the sub frame above? It’s hard for to explain what I see because I’m ignorant when talking suspensions. Does anyone know how much clearance should I gave between the top of the sub frame / carrier?

Thanks again for the help. Mike

Gaz64 · #12 (**permalink**) 01-16-2022, 03:59 PM

Seems your pics are not displaying in the correct orientation for others to view.

Hence the confusion for which way is up.

To me, the inner CVs are rubbing, after the diff housing has moved UP not necessarily forward. So there is either some broken mounts, or the rear chassis frame is broken.

10mm gaps are more normal.

Gary

169mph · #13 (**permalink**) 01-16-2022, 04:37 PM

Quote:

Originally Posted by Gaz64

Seems your pics are not displaying in the correct orientation for others to view.

Hence the confusion for which way is up.

To me, the inner CVs are rubbing, after the diff housing has moved UP not necessarily forward. So there is either some broken mounts, or the rear chassis frame is broken.

10mm gaps are more normal.

Gary

Yeah I definitely need to label or rotate the pics. I sure hope you are wrong. Broken chassis sounds like a cut your losses type scenario. I live in the Houston area. Does anyone recommend a shop to send my car to? wow! Thanks again for the feed back.

spdbrake · #14 (**permalink**) 01-16-2022, 06:50 PM

Back to an earlier response to the two aft diff bolts.
You had replied: "Thanks for the picture. Those bolts are there. "

But did you check if they are tight?
They're 21MM if I remember correctly and most folk's home tool sets end at 19MM.

I ask again because your diff is sliding aft in the mount and the Bolt appears to have a gap where you can see exposed threads.

169mph · #15 (**permalink**) 01-19-2022, 06:01 PM

I'm still searching for the cause of the subframe rubbing before shipping the car to Radical Roadsters. I notice the springs top plates aren't in the same location. It looks like the passenger side has shifted towards the rear of the car by 1". The passenger side spring isn't square to the body like the driver's side. The passenger side trailing arm has a bunch washers between the bushing and the trailing arm bracket. This can't be normal.

169mph · #16 (**permalink**) 01-19-2022, 06:24 PM

deleted

169mph · #17 (**permalink**) 02-05-2022, 05:06 PM

I think I found the issue. Most everyone told me to check the the front differential bushing bolt. I checked to see if the bolt was there snd if it was make sure it was tight. The bolt was still there and didn’t seem loose. I tried to torque to spec but it would not get tight enough. I took the weight off the differential with a breaker bar and the bolt basically fell out. When I removed the pry bar the differential dropped back to its normal position and the output flanges are no longer rubbing the subframe. What should I do next? Install a new bolt? Replace the bushing and bolt. The bolt doesn’t look like it’s been sheared off to me. I really appreciate everyone’s help to this point. Any advice moving forward would greatly appreciated. Thanks

spdbrake · #18 (**permalink**) 02-05-2022, 05:55 PM

Yes it is sheared. The clue is the hang-nail thread where it snapped. Machine bolts and screws area chamfered 360 on the end to prevent cross threading. You also need to add the missing fender washer (large area washer under the head)
Your earlier pic:

which is also allowing the diff to shift aft due the two aft mount bolts being loose. You will have to drop the diff out of the car to extract the broken bolt.

While its out you might as well go in with Poly bushings
https://www.ecstuning.com/b-ecs-part...02447ecs04kt2/
https://www.ecstuning.com/b-ecs-part...02447ecs01kt1/
You don't have to go with ECS parts there are plenty of alternative brands for these items.

If your going to James Yale's shop let him advise you and procure the parts for you.
Nothing worse than bringing your box of parts to a shop and expecting them to assume all the risk. "Bringing your own eggs to Denny's" is the common term.

Another thing I'd ask James Yale while its in his shop is upgrading your front diff bolt to 14mm VS the stock 12mm
https://www.ecstuning.com/b-condor-s...me36diffbu~cd/

SBSerpent · #19 (**permalink**) 02-17-2022, 11:06 PM

Quote:

Originally Posted by spdbrake

Yes it is sheared. The clue is the hang-nail thread where it snapped. Machine bolts and screws area chamfered 360 on the end to prevent cross threading. You also need to add the missing fender washer (large area washer under the head)
Your earlier pic:

which is also allowing the diff to shift aft due the two aft mount bolts being loose. You will have to drop the diff out of the car to extract the broken bolt.

While its out you might as well go in with Poly bushings
https://www.ecstuning.com/b-ecs-part...02447ecs04kt2/
https://www.ecstuning.com/b-ecs-part...02447ecs01kt1/
You don't have to go with ECS parts there are plenty of alternative brands for these items.

If your going to James Yale's shop let him advise you and procure the parts for you.
Nothing worse than bringing your box of parts to a shop and expecting them to assume all the risk. "Bringing your own eggs to Denny's" is the common term.

Another thing I'd ask James Yale while its in his shop is upgrading your front diff bolt to 14mm VS the stock 12mm
https://www.ecstuning.com/b-condor-s...me36diffbu~cd/

I was told by a reputable BDR builder that Backdraft removes the 12mm bolt and replaces it with the 14mm bolt when they install these BMW differentials. Is that not the case?

Soundkillr · #20 (**permalink**) 02-18-2022, 05:39 PM

Quote:

Originally Posted by SBSerpent

I was told by a reputable BDR builder that Backdraft removes the 12mm bolt and replaces it with the 14mm bolt when they install these BMW differentials. Is that not the case?

I can tell you this...I just ordered the bmw brace kit for mine....it comes with a bolt smaller than mine so I would believe bdr does use the 14mm bolt

Mine is sheared as well...and I bought the kit that came with the bolt. So unfortunately I have to find a source for a hardened 14mm bolt...because the one in the kit is too small .