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Subframe and Steering Re-Enforcement

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The Sixer Kid

Subframe and Steering Re-Enforcement

Post by The Sixer Kid » Fri May 22, 2009 8:50 pm

This write up is intended to educate those with e28 based 6 series. Most of you know that the steering box bracket is prone to failure. There are plenty of threads floating around discussing how/why it fails and what can be done to fix it. Pictures are worth a thousand words, so I?d like there to be a central place to discuss this problem.

There are generally three states of the steering box bracket: intact, cracked, and completely snapped off. This procedure will allow you to re-enforce the bracket regardless of the condition of your existing bracket.

There are also multiple ways of re-enforcing the bracket.

The first and cheapest way is to use the ?bolt and spacer? method. This involves using a long bolt that extends all the way through the subframe. A spacer then sits between the top of subframe and bottom of the bracket. As the bolt is tightened down the head of the bolt is put into compression with the bracket and spacer. The compression force increases the lateral friction between these pieces. The frictional force is what prevents the bracket (and thus the gear box) from moving.

I?m not a huge fan of this set-up because frictional force isn?t the greatest way to prevent movement of the box. Its an adequate solution if your bracket is completely intact. If your bracket falls into the later categories, DO NOT use this solution. This solution will prevent the gearbox from falling way out of alignment but it will still move during hard turning.

The second solution involves using the Mwrench steel dowel from Ed Raether. The dowel fits through the subframe and features one end that is tapped for a grade 8 bolt. The dowel fits snuggly into the subframe. This fix can be done two ways, by removing the subframe and welding it into place or by simply leaving the subframe intact. The later method can be done in less than 30 minutes. I will be covering both of these methods in this write up. Here are the parts involved: Image

The third solution is to remove the subframe and ?box? the existing bracket. You can cut triangular pieces of steel and weld re-enforcements. This requires the existing bracket to be completely intact as well as removing the subframe. Personally, I don?t see the point in doing this because why remove the subframe if your bracket is still intact? Still, I?m just offering up another solution.

Now, onto the write up. The first method of using the Mwrench dowel is to completely remove the subframe. I happen to have a spare M6 subframe and gearbox so I performed the fix on this subframe and I plan to swap it in at a later date. The bracket on this subframe was completely snapped off. A tiny portion of the side wall remained so I used an angle grinder to smooth it out. The advantage to removing the subframe with the Mwrench dowel is that you can weld both ends of the subframe to secure the dowel.

Completely separate subframe: Image

The first step is to clean both sides of the subframe. You need a clean surface onto which you can weld. A wire brush or electric sander work great. Then sand some of the paint off of the dowel. It should look this when done: Image

Place the dowel through the hole in the subframe. It is meant to be very snugg so if need be you can tap it through with a mallet. The inserted dowel will look like this: Image

Now, I have a couple of spare gear boxes lying around so I used one of them to mock up how it was supposed to fit. Go to the hardware store (Ace is the place) and get a 6? long 15/32? bolt and nut (7/16? will work as well). Most places wont carry the correct metric size bolt of that length.

Image
Image
Image

With the gear box lined up, you can see how the dowel fits.

With everything lined up, you can insert the bolt into the dowel and secure the box into the correct position. I would place a tack on both sides of the dowel to prevent it from moving. With the dowel tacked into place you can remove the bolt and gear box and then weld the entire dowel on both sides of the subframe. It should look like this when done:
Image
Image
Image

Your subframe is now ready to be re-installed in the car.



Method # 2

This method involves installing the Mwrench dowel without removing the subframe. This procedure can be accomplished in under 30 minutes if you know how to turn a wrench.

Image

The first step is to remove the existing bolt from the bracket. You need a 17mm wrench on the top and a 19mm socket on the bottom. You can use an extension and fit the socket through the subframe. An impact wrench works great to remove the bolt and nut. Image

With the bolt and nut removed, you then need to clean the bottom of the subframe (as shown before) to assist in a good clean weld. Should look like this:

Image

Place the dowel through the subframe and then screw the bolt into place. In my case the dowel was snug enough to not move as I screwed the bolt into it. With everything locked down, you can now weld the bottom of the dowel. It should look like this when done:

Image
Image

Retorque the bolt and then clean off the surface again and spray the bottom of the subframe with some rust inhibitor paint to prevent corrosion.

Image


The first method of installing the dowel with the subframe removed will be installed in the future on my ?89 Turbo. The second method was performed on my ?87 635csi. The car was driveable again in under 30 minutes.

I realize that most people either don?t know how to weld or don?t have their own welding equipment. If welding is not something you can do on your own, I suggest install the dowel and torque?ing? it into place and then driving to an exhaust shop. Most exhaust shops will have welding equipment easily assessable and will do it for a small fee.

Of note: There are two different subframes used on the e28 based 6 series. The 633 and 635 up to 88 share a subframe and the M6/88-89 635 share a subframe. I honestly don?t know the difference between the two, other than the cars use different gear boxes. The M6/highline 635 use a short ratio gear box (and sometimes servotronic) while the earlier cars use the standard gear box. I sourced the later subframe for my turbo as I wasn?t sure what (if any) modifications would need to be done to install a regular subframe in the car. I also plan on adding additional support and re-enforcement to the subframe.


That?s it! You?re done. Now go enjoy your car.

The Sixer Kid

Post by The Sixer Kid » Wed May 27, 2009 4:12 am

Reflection time:

After a week of driving my '87 635csi, I can say that the feel of the steering is much improved with the Mwrench fix. No shakes, shimmies or flexing in the steering.

My personal opinion is that if you haven't installed already, you are living on borrowed time.

Do yourself a favor and install one now!

Euro cs No i

That's some...

Post by Euro cs No i » Fri May 29, 2009 6:20 am

Kid... that's some good stuff! Keep up the good work!

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Post by Corner Carver » Sun Jun 14, 2009 4:20 pm

Nice work! Gonna do this soon. Thanks!

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Post by Da_Hose » Sun Aug 30, 2009 8:02 am

I just installed my MWrench piece today. My bracket was not cracked, so I just bolted for now, but might go ahead and weld once I finish all the rest of the stuff I am working on. If installing it, I advise that you chase the bolt into the threads and make sure they go in smooth. Then, only tap the plug piece in about 3/4 of the way. It took me a good freaking hour to install mine, because I tapped the plug all the way up flush with my bracket. The little bit of offset on the steering box and not chasing the threads made it impossible to get the threads started. I had to use the bolt as a drift to push the plug back down far enough that I could get prybars in there and pop it back out. Once the threads were chased (and with the gap between plug and bracket) the threads caught immediately. I tapped the plug the rest of the way in and the friction fit to the subframe is perfect. I COMPLETELY recommend this upgrade. There are seemingly no negatives to be had.

Jose
1987 M6 - My dream car

mattjones

Post by mattjones » Tue Sep 22, 2009 1:46 pm

Where can I get the part from in the UK?

The Sixer Kid

Post by The Sixer Kid » Tue Sep 22, 2009 3:42 pm

Postage to the UK should only be an extra $5 or so.

jmitro

Post by jmitro » Thu Oct 22, 2009 2:36 am

very nice writeup.
where can I purchase this Mwrench repair kit?

The Sixer Kid

Post by The Sixer Kid » Thu Oct 22, 2009 3:04 am

jmitro wrote:very nice writeup.
where can I purchase this Mwrench repair kit?
You can contact Ed by way of his website: Ed at Mwrench dot com


I believe Ed is currently traveling, but I know he brought some of the kits along with him ship out.

Good Luck!

jmitro

Post by jmitro » Thu Oct 22, 2009 3:18 am

excellent, thanks;

EDIT -
I did this repair last night. The writeup here is excellent. The kit is very simple and yet will give an excellent repair or reinforcement. The only thing I have to add is....
my bracket was still intact. the inner width of the bracket was a little smaller than the dowel, so I had to grind my dowel quite a bit to get it to fit. I actually had to flatten two sides of the dowel, but once done, it fit snugly and I was able to push it in flush with the subframe and weld in place.

Thanks Ed!

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Post by sskang » Fri Oct 30, 2009 12:56 am

George,

This is a great write-up with easy-to-understand instruction on how to install it. I should get it in mine as well.

Once the kit is installed and the box is stable, perhaps the thing that may be of interest is the box itself. I tried to search the archive but seemingly there was no write up or articles related to the box itself.

I wonder how all of your boxes are, but mine has a small amount of play at steering center, which at some point want to get fixed. After doing some research, I was able to find one man through the E24 forum in Germany, a retired ZF employee who can rebuild a box for 700 Euros but a rebuilt box was not available (there was one online parts store that had it, but it was servotronic).

Are you not experiencing any sort of issue with the box?
sskang
1987 M6 Alpinweiss
Tokyo, Japan

"Aller guten Dinge sind Sechs"

The Sixer Kid

Post by The Sixer Kid » Fri Oct 30, 2009 1:05 am

sskang wrote:George,

This is a great write-up with easy-to-understand instruction on how to install it. I should get it in mine as well.

Once the kit is installed and the box is stable, perhaps the thing that may be of interest is the box itself. I tried to search the archive but seemingly there was no write up or articles related to the box itself.

I wonder how all of your boxes are, but mine has a small amount of play at steering center, which at some point want to get fixed. After doing some research, I was able to find one man through the E24 forum in Germany, a retired ZF employee who can rebuild a box for 700 Euros but a rebuilt box was not available (there was one online parts store that had it, but it was servotronic).

Are you not experiencing any sort of issue with the box?
SS, replacing the gear box is pretty straight forward. I did it on my '87 635si in a few hours. You remove the lines and drain the system (a little bit of compressed air can do the trick). You then need to unbolt the steering column.

Anyway, yes, the gear boxes I've had do have a little bit of play in them but it isn't anything significant. I've currently got 3 extra gear boxes (regular, M6 and M6 servotronic) that I can send out for rebuilding when the time comes. I'm planning on going through the dealer for that as I'd rather do it once and do it right. The price is ridiculous but whatever.

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Post by sskang » Fri Oct 30, 2009 1:12 am

George,

The box consists of a worm gear and several balls which I was told by the retired ZF employee that it has to be adjusted to one thousandth of a millimeter. Another component that is the cause of the box's leak is the shaft that becomes thinner over time.

If you have 3 boxes, you have nothing to worry. I was just thinking of getting the quick ratio box which is available through someone I know.

If you every decide to challenge rebuild, do let us know!

As always, keep up the good work!
sskang
1987 M6 Alpinweiss
Tokyo, Japan

"Aller guten Dinge sind Sechs"

The Sixer Kid

Post by The Sixer Kid » Fri Oct 30, 2009 11:52 pm

sskang wrote:George,

The box consists of a worm gear and several balls which I was told by the retired ZF employee that it has to be adjusted to one thousandth of a millimeter. Another component that is the cause of the box's leak is the shaft that becomes thinner over time.

If you have 3 boxes, you have nothing to worry. I was just thinking of getting the quick ratio box which is available through someone I know.

If you every decide to challenge rebuild, do let us know!

As always, keep up the good work!

Damnit! I actually through one out about a year ago because it was pretty well worn. I should have kept it to dissect.

Anyway, I like the challenge. I'll rip one open sooner or later and see how feasible a DIY rebuild is.

german performance inc

Post by german performance inc » Sun Nov 01, 2009 1:23 am

i am going to replace my box soon when i do the crossmember and suspension goodies ,i have all new control arms and bilstiens and the crossmember and steering box ,i adjusted my steering box play a long time ago in my old box but the adjuster is stripped now upon inspection not long ago,ill save the box for dissection purposes george if you want it,excellent tech write by the way =D>

Old_School

Post by Old_School » Sun Nov 01, 2009 1:50 am

I just got the M-Wrench fix done, but the car is still in the shop waiting for some other work, so I haven't driven it. My mechanic liked the fix - said it works very well - much better than the stack of washers the PO had used (with the associated clunking, vibration and other steering issues). I hope to get a chance to drive it a few times before I park it for the winter.

59Vampire

Post by 59Vampire » Sun Nov 15, 2009 3:57 am

perfect timing my steering box mount has cracked!

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EXCELLENT ARTICLE! BRAVO

Post by mitchcornacchia » Fri Dec 18, 2009 2:19 am

This is the perfect example of what blogs are for. this was a tremendous help to me thanks again
A man is rich in what he can afford to do without! Oh yea 9/86 Euro 5 spd

The Sixer Kid

Re: EXCELLENT ARTICLE! BRAVO

Post by The Sixer Kid » Fri Dec 18, 2009 3:04 am

mitchcornacchia wrote:This is the perfect example of what blogs are for. this was a tremendous help to me thanks again
I do what I can.

j24sailorboy

Preventing steering box bracket from breaking

Post by j24sailorboy » Sun Sep 05, 2010 1:10 am

I recently pulled out my steering gearbox, thinking that I needed a new one. Bracket wasn't broken, and the box was fine, but the aluminum U joint on the steering column was completely seized up in one direction. Symptom was extremely uneven motion as you turned the wheel.... easy, stiff, easy , stiff... as I tried to turn.
Anyway, when the u joint is seized there is a tremendous amount of side pressure on the gearbox, which is begging for the bracket to fail.

[email protected]

e24 dowel

Post by [email protected] » Sat Apr 23, 2011 11:51 pm

do u have info on ordering a dowel from ed raether . i cant seem access his web page thx

Viktor D.
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Location: Belgium

Ed raether dowel steering Re-Enforcement

Post by Viktor D. » Sun May 08, 2016 9:42 am

Does anybody know if Ed Raether still sells these dowels to reinforce the steering bracket?

I emailed him last week, but did not receive an answer yet.
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Viktor

1984 BMW 635CSi 5spd

VIN: 9402445

daz635
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Re: Subframe and Steering Re-Enforcement

Post by daz635 » Tue May 10, 2016 2:56 am

I bought one of these from Ed about a month ago. I have fitted it up and it works very well
'86 Euro 635 #1887204 Schwartz (086) Buffalo Schwartz Interior
Image

Viktor D.
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Location: Belgium

Re: Subframe and Steering Re-Enforcement

Post by Viktor D. » Tue May 10, 2016 8:28 am

I want to buy one as well.

But he hasn't answered my email yet.
But I'm happy to know they are still available. I'll send him a reminder :D
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Viktor

1984 BMW 635CSi 5spd

VIN: 9402445

Viktor D.
Posts: 41
Joined: Tue Oct 20, 2015 12:55 pm
Location: Belgium

Re: Subframe and Steering Re-Enforcement

Post by Viktor D. » Tue May 31, 2016 12:17 pm

Ed was on holiday and understandably tries to shut things off when out.
He answered my mail when he was back home two weeks later.

Today, packaged nicely, the part arrived at my home with a shipping time of only one week \:D/

Clear communication and fast shipping, Ed really seems to be a good guy! :D
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Viktor

1984 BMW 635CSi 5spd

VIN: 9402445

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