This is the end result:
Per
Subframe/crossmember remedied
Subframe/crossmember remedied
One of my winter projects, or in this case really a necessity, was to install Randy Forbes kit in the crossmember. This because of the dreaded "subframe" problem. Today I finished the job and those of you who are interested can follow it here: http://perkornhall.se/Per_Kornhall/Subframe.html
This is the end result:
Per
This is the end result:
Per
Re: Subframe/crossmember remedied
Good job Per, that is quite an involved job, how did you find the Randy Forbes kit and instructions?
why did you remove the coils and ECU? We're you just being cautious whilst welding?
why did you remove the coils and ECU? We're you just being cautious whilst welding?
Re: Subframe/crossmember remedied
Nice job. Good to see you fitted IE bushes.
Sent from my GT-I9100 using Tapatalk 2
Sent from my GT-I9100 using Tapatalk 2
Z3M with a few mods...and a little bit more power
Re: Subframe/crossmember remedied
Forbes kit was very good, his instructions very detailed and helpful, but best of all was his personal support which is very swift and appropriate! He is a guy I'd like to have a beer with one day. 
I detached the coils and ECU according to his instructions as a cautionary step. There is of course a whole lot of currents running around during the welding.
It was a big job especially since I changed all the bushings etc. The welding in itself was very fun and the difference in strength in the construction is amazing! When you start cutting into the paper thin sheet metal in the floor and the x-membar you really get to thinking about the engineers who could think out such a flimsy construction and then put 300+ horsepower into it...
Per
I detached the coils and ECU according to his instructions as a cautionary step. There is of course a whole lot of currents running around during the welding.
It was a big job especially since I changed all the bushings etc. The welding in itself was very fun and the difference in strength in the construction is amazing! When you start cutting into the paper thin sheet metal in the floor and the x-membar you really get to thinking about the engineers who could think out such a flimsy construction and then put 300+ horsepower into it...
Per
Re: Subframe/crossmember remedied
Hi Kornknarr,
Thanks for this post as I have just been told by my mechnaic about this problem in my 1999 Z3M... After being shocked and then furious, I have also found the randy forbes kit searching online. The issue in my car is very juvenile currently, so not a real problem now but would like to know what the kit cost to buy and have shipped to you in Sweden. What do you get in the kit other than the instructions, is it just the pre-cut strips of metal?
Elwood.
PS. Your pics and blog are great, well done for documenting this for everyone.
Thanks for this post as I have just been told by my mechnaic about this problem in my 1999 Z3M... After being shocked and then furious, I have also found the randy forbes kit searching online. The issue in my car is very juvenile currently, so not a real problem now but would like to know what the kit cost to buy and have shipped to you in Sweden. What do you get in the kit other than the instructions, is it just the pre-cut strips of metal?
Elwood.
PS. Your pics and blog are great, well done for documenting this for everyone.
1999 M Roadster (S50)
Porsche 911 RS hotrod
Porsche 911 RS hotrod
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Mroadster.au
- Joined: Tue 21 Apr, 2009 01:34
- Posts: 4
- Location: Melbourne
Re: Subframe/crossmember remedied
Hey Elwood,
I've think I've seen you around, is yours estrol blue, I'm in Melb and mine is that colour.
Cheers . . . Mike
I've think I've seen you around, is yours estrol blue, I'm in Melb and mine is that colour.
Cheers . . . Mike
Re: Subframe/crossmember remedied
Mroadster.au wrote:Hey Elwood,
I've think I've seen you around, is yours estrol blue, I'm in Melb and mine is that colour.
Cheers . . . Mike
Hiya Mike,
No, mine is black. I't'd be great to catchup and chat about our cars, I feel like the only one in the whole country at times. Where are you? I'm in the elwood, brighton area.
Elwood
1999 M Roadster (S50)
Porsche 911 RS hotrod
Porsche 911 RS hotrod
Re: Subframe/crossmember remedied
[quote="elwood158"]Hi Kornknarr,
Thanks for this post as I have just been told by my mechnaic about this problem in my 1999 Z3M... After being shocked and then furious, I have also found the randy forbes kit searching online. The issue in my car is very juvenile currently, so not a real problem now but would like to know what the kit cost to buy and have shipped to you in Sweden. What do you get in the kit other than the instructions, is it just the pre-cut strips of metal?
Hi,
What you get from Randy is the cut and formed metal. You also get a new impulse wheel that you need if you want to swap to a differential cover with two ears (only possible with non OEM exhaust). You also get very detailed instructions + on line support while doing the job.
I bought the kit from a friend who had it transported from America so I cannot give you an estimate. Mail Randy and get a quote!
It will cost you some money. I'd guess round 500 pounds for the stuff and then you need to have the job done and some paint etc.
What you get is a really good strengthening of a basically from the beginning flawed construction. It is scary to realize how thin the metal is in the floor and in the crossmember!
Per
Thanks for this post as I have just been told by my mechnaic about this problem in my 1999 Z3M... After being shocked and then furious, I have also found the randy forbes kit searching online. The issue in my car is very juvenile currently, so not a real problem now but would like to know what the kit cost to buy and have shipped to you in Sweden. What do you get in the kit other than the instructions, is it just the pre-cut strips of metal?
Hi,
What you get from Randy is the cut and formed metal. You also get a new impulse wheel that you need if you want to swap to a differential cover with two ears (only possible with non OEM exhaust). You also get very detailed instructions + on line support while doing the job.
I bought the kit from a friend who had it transported from America so I cannot give you an estimate. Mail Randy and get a quote!
It will cost you some money. I'd guess round 500 pounds for the stuff and then you need to have the job done and some paint etc.
What you get is a really good strengthening of a basically from the beginning flawed construction. It is scary to realize how thin the metal is in the floor and in the crossmember!
Per
Re: Subframe/crossmember remedied
Hi ya Per,
Thanks for this info. I'm not very techo though, can you explain this line more as my exhaust is not standard...?
"You also get a new impulse wheel that you need if you want to swap to a differential cover with two ears (only possible with non OEM exhaust"
What's an impulse wheel?
Differential cover with 2 ears? What does the std car have? do you have a pic of this?
elwood
Thanks for this info. I'm not very techo though, can you explain this line more as my exhaust is not standard...?
"You also get a new impulse wheel that you need if you want to swap to a differential cover with two ears (only possible with non OEM exhaust"
What's an impulse wheel?
Differential cover with 2 ears? What does the std car have? do you have a pic of this?
elwood
1999 M Roadster (S50)
Porsche 911 RS hotrod
Porsche 911 RS hotrod
Re: Subframe/crossmember remedied
The differential on the Z3s, including the Ms, are held in place with two bolts on to the subframe forward + one mounting point on one side of the differential cover in the rear. It is this mounting point that causes the crossmember to disconnect from the boot-floor and in many cases the mounting "ear" itself will be broken. You can see that in my images.
Installing Randys kit you have the possibility to exchange the differential cover to one from a E36 M3 one that has two mounting points, two ears. This will spread the forces out considerably. But, that cannot be done with the OEM exhaust because of clearance problems. The main point is that if the exhaust pipes enter into the rear mufflers in the center or outermost part of the oval they clear the dual ear diff-cover.
But, behind the cover sits the impulse wheel for the speedometer sensor. Because the E36 M3 cover is smaller than the OEM there is less room and you will have to either cut or replace the impulse wheel.
You can see the impulse wheel (the star shaped one) here: http://perkornhall.se/Per_Kornhall/Subframe.html#48
And the old (very dirty) differential cover on the differential here: http://perkornhall.se/Per_Kornhall/Subframe.html#23
And the new (and very clean!) after Randys kit have been welded in here: http://perkornhall.se/Per_Kornhall/Subframe.html#97
All of these procedures are covered in Randys instructions.
Hope this clarified it a bit?
Per
Installing Randys kit you have the possibility to exchange the differential cover to one from a E36 M3 one that has two mounting points, two ears. This will spread the forces out considerably. But, that cannot be done with the OEM exhaust because of clearance problems. The main point is that if the exhaust pipes enter into the rear mufflers in the center or outermost part of the oval they clear the dual ear diff-cover.
But, behind the cover sits the impulse wheel for the speedometer sensor. Because the E36 M3 cover is smaller than the OEM there is less room and you will have to either cut or replace the impulse wheel.
You can see the impulse wheel (the star shaped one) here: http://perkornhall.se/Per_Kornhall/Subframe.html#48
And the old (very dirty) differential cover on the differential here: http://perkornhall.se/Per_Kornhall/Subframe.html#23
And the new (and very clean!) after Randys kit have been welded in here: http://perkornhall.se/Per_Kornhall/Subframe.html#97
All of these procedures are covered in Randys instructions.
Hope this clarified it a bit?
Per
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Southernboy
- Joined: Thu 07 Oct, 2010 12:39
- Posts: 6437
- Location: Johannesburg
Re: Subframe/crossmember remedied
As said above, the impulse wheel is an issue...however it isn't a good idea to cut / trim the wheel...that will alter the space between each blade on the wheel and they will pass more frequently through the arms of the sensor and give an incorrect pulse reading and therefor speed.
The correct option is to fit a spacer between the cover and the diff face thereby extending the cover outwards by 9mm. I had this made specifically for that purpose... Also, it will not require the innards of the diff to be dismantled to remove the impulse wheel..the entire procedure is a quick, easy job, and will require a new diff mount to be welded to the side with the new ear and a new bolt.
Both faces are machined to provide perfect facing to the diff on one side and the cover on the other face...you will need 2 paper gaskets, a new diff mount bracket for the new ear and thereafter it's straight forward....
If anyone is interested I had 2 of these made up at the time I did the mod on my car, and I have a "spare" available, machined faces and ready to fit..
Once you have the twin ear cover fitted, you will notice a considerable improvement in the "spontaneity" of the pull away firmness...consequence of the decrease in flex at the diff... I fitted this back in March and it has beeen an excellent result...no leaks, and with the spacer fitted you will need to add extra diff oil to compensate the larger "volume" created by the spacer...aprox 300ml.
The correct option is to fit a spacer between the cover and the diff face thereby extending the cover outwards by 9mm. I had this made specifically for that purpose... Also, it will not require the innards of the diff to be dismantled to remove the impulse wheel..the entire procedure is a quick, easy job, and will require a new diff mount to be welded to the side with the new ear and a new bolt.
Both faces are machined to provide perfect facing to the diff on one side and the cover on the other face...you will need 2 paper gaskets, a new diff mount bracket for the new ear and thereafter it's straight forward....
If anyone is interested I had 2 of these made up at the time I did the mod on my car, and I have a "spare" available, machined faces and ready to fit..
Once you have the twin ear cover fitted, you will notice a considerable improvement in the "spontaneity" of the pull away firmness...consequence of the decrease in flex at the diff... I fitted this back in March and it has beeen an excellent result...no leaks, and with the spacer fitted you will need to add extra diff oil to compensate the larger "volume" created by the spacer...aprox 300ml.
Re: Subframe/crossmember remedied
I wouldn't say that that is the correct way. I'd say it is one way but it is technically more demanding than disassembling the innards of the differential (- unless one can by one of you Southern boy - . It is also a good possibility to change the dust covers of the differential. You can't use Randys kit without modification, with that solution since the slits for the pendants in Randy's kit will not fit.
Trimming the wheel will not alter the frequency with which the blades pass by the sensor. How could it do that? The frequency is determined by the number of vevolvings and the speed of the wheel not by the size of the spokes. Anyhow, a smaller wheel that fits can be purchased and Randy sends it with the kit.
. It is also a good possibility to change the dust covers of the differential. You can't use Randys kit without modification, with that solution since the slits for the pendants in Randy's kit will not fit.Trimming the wheel will not alter the frequency with which the blades pass by the sensor. How could it do that? The frequency is determined by the number of vevolvings and the speed of the wheel not by the size of the spokes. Anyhow, a smaller wheel that fits can be purchased and Randy sends it with the kit.
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Southernboy
- Joined: Thu 07 Oct, 2010 12:39
- Posts: 6437
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- Location: Johannesburg
Re: Subframe/crossmember remedied
It's quite a simple process to take the existing cover to a laser cutting shop...they will scan the surface complete with the holes and produce an outline for the laser to cut the spacer...once that is done it is a simple excersie to have both faces machined to a finish which will seal. Once you have made one spacer, it is as easy to make thousands...the initial drawing program may be time consuming, but once that is dealt with it takes minutes to cut a new spacer... also fitting is simpler...remove old cover, fit spacer, fit new cover and complete the installation with the addition of a new bracket for the extra cover ear...the diff doesn't need to be removed, dissasembled, or tampered with in any way...the cost of a spacer, and a twin ear diff cover is hugely less than the RF kit...but then...I may be biased, since I designed this route so that the average guy with a couple of spanners and a jack or two could do the mod within an hour on his own...and at a fraction of the RF cost...And yes, I do have a template of the spacer gasket made of 1mm steel...so it would be an easy thing to take it to any laser cutting works and have them use it to knock out as many as I wanted...each one a perfect fit.
But if you're genuinely interested in my "spare" ...let me know...
But if you're genuinely interested in my "spare" ...let me know...
Re: Subframe/crossmember remedied
I have no objections to what ingenious people do to their cars! But, for me it would be a bigger step doing what you did than what I did. I like the idea. What strengthening have you done to the cross member?
Per
Per
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Southernboy
- Joined: Thu 07 Oct, 2010 12:39
- Posts: 6437
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- Location: Johannesburg
Re: Subframe/crossmember remedied
I didn't do any additional strengthening except to have the 4 popped welds re-fixed, and to have the new diff mounting brackets made so that they are welded to the cross member over a much wider area vs the OEM bracket which was small, flimsy and spotwelded. The advantage of the dual ear cover is that it only requires a bracket on one side of the cover ears..so there isn't the difficulty in fitting or removing the diff. It's a hugely more stable diff fitting now, and I doubt it's something I will need to re-visit.
Perhaps the greatest advantage to the dual ear cover and that the brackets are only on one side of the ears, is that it's easy to place a bottle jack under the diff, remove the 2 bolts, and lower the diff for draining / servicing and refilling...although I haven't done this and doubt I'll do it for the next 10 years, it is convenient should I need to do repairs to drive shafts, suspension etc etc on the rear axle. It's the sort of thing that should have been done by BMW at the time they built these cars.
The two brackets I welded in are essentially like triangles with one corner facing directly down with the bolt hole for the ear...the wide "base" of the triangle is what I welded to the cross member...so it not only has 2 mounting points now, but each point has it's load spread wider onto the cross member. The width I made them was around 180mm across, and they are 3mm thick vs the .8mm OEM steel. I also think the added volume of diff oil is a benefit to the overall operating temp and lubrication of the diff gears etc.
Perhaps the greatest advantage to the dual ear cover and that the brackets are only on one side of the ears, is that it's easy to place a bottle jack under the diff, remove the 2 bolts, and lower the diff for draining / servicing and refilling...although I haven't done this and doubt I'll do it for the next 10 years, it is convenient should I need to do repairs to drive shafts, suspension etc etc on the rear axle. It's the sort of thing that should have been done by BMW at the time they built these cars.
The two brackets I welded in are essentially like triangles with one corner facing directly down with the bolt hole for the ear...the wide "base" of the triangle is what I welded to the cross member...so it not only has 2 mounting points now, but each point has it's load spread wider onto the cross member. The width I made them was around 180mm across, and they are 3mm thick vs the .8mm OEM steel. I also think the added volume of diff oil is a benefit to the overall operating temp and lubrication of the diff gears etc.
