740i Sport Plus Build

[KinkedChrome]

I'm assuming the M5 rear subframe is the left one, since I can see a sway bar endlink. Wish I could do 1 thing you've accomplished to your ride. Very good work!

The left is e65. The right is e39 m5. I bought the m5 subframe for the diff. I was originally just going to modify the e38 for the M5 diff. Then one late night of looking under all the internets couch cushions I found some info that leads me to believe I can fit the e65 rear subframe with minimal effort. I also think that the e60 m5 rear diff will fit in the e65 subframe. So if it all works out, ill get 3.62 gears, lsd and a lighter weight subframe and suspension in one shot.

[Bimmerbear]

KinkedChrome, I really appreciate the level of documentation you're providing here. I'm starting a similar build in the next few months and want to do some of the same retrofits you're doing.

On the M5 steering box retrofit: I'd like to do it the same way you did. My idea for retrofitting the box was to pull the E38 subframe with the stock box attached and then locate the input and output shafts in space with some pieces of tube that are attached to the subframe by means of tack-welded supports. After this is done, I'd pull the stock box off and slide the M5 box into the tubes to locate it perfectly. Then I'd take measurements and make the appropriate machining/welding modifications to the M5 box and subframe.

My question is: is this method unnecessary overkill? Is machining the box to fit the first two mounting points and moving the third point sufficient to locate the input and output shafts of the box in the correct points in space?

[KinkedChrome]

KinkedChrome, I really appreciate the level of documentation you're providing here. I'm starting a similar build in the next few months and want to do some of the same retrofits you're doing.

Glad to hear it. What kind of build are you planning?

On the M5 steering box retrofit: I'd like to do it the same way you did. My idea for retrofitting the box was to pull the E38 subframe with the stock box attached and then locate the input and output shafts in space with some pieces of tube that are attached to the subframe by means of tack-welded supports. After this is done, I'd pull the stock box off and slide the M5 box into the tubes to locate it perfectly. Then I'd take measurements and make the appropriate machining/welding modifications to the M5 box and subframe.

My question is: is this method unnecessary overkill? Is machining the box to fit the first two mounting points and moving the third point sufficient to locate the input and output shafts of the box in the correct points in space?

Overkill is in the eye of beholder. I believe the way I did it was sufficient, everything bolted in and fits. The car steers and handles great, no binding or anything. However, if I did it your way it would probably would be located better or at the very least give a guy more peace of mind. Is the extra effort worth it? Well that's up to you. If you don't trust yourself with measuring tools, building a temp jig is a sure fire way to make sure everything works and fits.

[Rhein Amacher]

KinkedChrome, now time to step up your game and get your vehicle looking like a E39 M5 as well!


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[KinkedChrome]

KinkedChrome, now time to step up your game and get your vehicle looking like a E39 M5 as well!


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I read your thread on that, that looks awesome! I'm pretty vanilla though when it comes to the aesthetic department. Most I'll do is get a different set of wheels, but mostly because I want to run 18x10 square.

[Bimmerbear]

Glad to hear it. What kind of build are you planning?

Overkill is in the eye of beholder. I believe the way I did it was sufficient, everything bolted in and fits. The car steers and handles great, no binding or anything. However, if I did it your way it would probably would be located better or at the very least give a guy more peace of mind. Is the extra effort worth it? Well that's up to you. If you don't trust yourself with measuring tools, building a temp jig is a sure fire way to make sure everything works and fits.

Thanks! I'm doing an LS swap, but keeping the suspension stuff more mild than you are. I'm going to stick with the stock subframes and control arms, but I do want the M5 steering box and diff. The spring/damper setup will probably be a set of KW Street Comfort coilovers. Also, I'm working with a 740iL, not a shorty.

[Bimmerbear]

Are the two hydraulic connections for the M5 box in the same location as the 740 box? Do the stock 740 lines bolt up or did you have to use M5 or custom lines?

[KinkedChrome]

Are the two hydraulic connections for the M5 box in the same location as the 740 box? Do the stock 740 lines bolt up or did you have to use M5 or custom lines?

They are in the same location, and they would bolt up to the steering box. They are different on the pump side though, so I had to use the M5 lines. Although, I'm guessing your changing the pump side connections anyway.

[cura]

My question to is did you get the e65 subframe to work was there any modification needed or it was a direct fit?

[KinkedChrome]

My question to is did you get the e65 subframe to work was there any modification needed or it was a direct fit?

I haven't had a chance to work on this yet, but it is not a direct fit. The width of the bolt pattern on the subframe matches, but the length does not. It is off by 10mm. My plan was to build some bushing housings that have an offset hole on them. The e65 subframe bushing are much larger diameter than the e38. So the bushing housing woild match the ID of the e65 frame and house the e38 bushing, but offset by 5mm per bushing.

FYI, the e60 subframe appears to be a direct bolt up to the e39. Both of which the bolt pattern is too narrow to fit the e38. Although, e39, e38, e60, e65, e52, and possible e53 have the exact same rear suspension geometry. So some mix and matching is possible there.

[cura]

I haven't had a chance to work on this yet, but it is not a direct fit. The width of the bolt pattern on the subframe matches, but the length does not. It is off by 10mm. My plan was to build some bushing housings that have an offset hole on them. The e65 subframe bushing are much larger diameter than the e38. So the bushing housing woild match the ID of the e65 frame and house the e38 bushing, but offset by 5mm per bushing.

FYI, the e60 subframe appears to be a direct bolt up to the e39. Both of which the bolt pattern is too narrow to fit the e38. Although, e39, e38, e60, e65, e52, and possible e53 have the exact same rear suspension geometry. So some mix and matching is possible there.

I have a E60 subframe once I take the e38 down I’ll check it thanks.

[TomE38]

Really cool to read all this and thank you for the good documentation.

I am currently in the same proces of transferring M5 bits into a 1995 E38 740i.

-front hubs
-suspension
-engine
-tranny
-steering box
-and much more.

Talking about the steering box; my idea is to manufacture a new sleeve to fit into the E38 box. Do you have exact measurements? Only length and outer diameter will be sufficient since I have the M5 box out of the car for the rest of the measures.

Greetings out of the Netherlands.

[KinkedChrome]

Really cool to read all this and thank you for the good documentation.

I am currently in the same proces of transferring M5 bits into a 1995 E38 740i.

-front hubs
-suspension
-engine
-tranny
-steering box
-and much more.

Talking about the steering box; my idea is to manufacture a new sleeve to fit into the E38 box. Do you have exact measurements? Only length and outer diameter will be sufficient since I have the M5 box out of the car for the rest of the measures.

Greetings out of the Netherlands.

Good to hear! make sure to post of some pics of your project! Probably not that many pre facelift s62 swaps around.

While I do plan on putting e39 M5 steering box parts into an e38 steering box, I haven't done it yet and don't have any measurements to do so yet. It'll probably be a while. I have a pile of house projects that need to get finished before I start working on my e38 again, but next on the chopping block will be that rear subframe swap and installing some supersprint headers.

[KinkedChrome]

I really ought to give this thread a proper update. I have done quite a bit of work to the car. Most of it is boring, but probably useful info to those problem solving swaps or working on S62s. In the mean time here is some fun stuff I have been working on.

E39 M5 rear lower control arms that have been fitted with monoballs. These should bolt right up to the E38 with the right spacers.

[haynes740]

I really ought to give this thread a proper update. I have done quite a bit of work to the car. Most of it is boring, but probably useful info to those problem solving swaps or working on S62s. In the mean time here is some fun stuff I have been working on.

E39 M5 rear lower control arms that have been fitted with monoballs. These should bolt right up to the E38 with the right spacers.

Any plans for doing mono ball bushings for rear control arms standard e38 I am in the market for some.


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[KinkedChrome]

Any plans for doing mono ball bushings for rear control arms standard e38 I am in the market for some.


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Yes, these parts should fit standard e38 also, if not Ill make some. Once I put these on and pull the stock arms then Ill know for sure, but Im thinking these will work on e38, e39, e60, e65, e53, and e52. The only difference might be spacers, if anything.

[haynes740]

Yes, these parts should fit standard e38 also, if not Ill make some. Once I put these on and pull the stock arms then Ill know for sure, but Im thinking these will work on e38, e39, e60, e65, e53, and e52. The only difference might be spacers, if anything.

I’ll be standing by and think these will finish my suspension project.


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[KinkedChrome]

A couple of little updates. I bolted the M5 rear wishbones onto my e38 with the monoballs in them. On key thing that I forgot is that the E38 has the camber adjustment on the wishbone vs the e39s have the camber adjustment on the the subframe. I bolted them in anyway to test out the monoballs. My rear tires are trash anyway right now. The E65 subframe that I plan to bolt in has the camber adjustment on the subframe, so I'll get my adjustment back once I put that subframe in. If it turns out that I can't get that subframe to work, I'll modify the stock frame to use an OEM cam bolt.

Now onto the fun stuff. I did a substantial amount of research on brakes for the front E39 knuckle. There are not a lot of options, so I had to make my own. I did come across a tid bit of information that led me to believe that F30 front caliper had a bolt pattern very close the E39 knuckle. So I gambled on it and picked up a complete used set of F30 Performance brakes. They 340x30mm front rotors with a 4 piston brembo, and 345x20 rotor with a 2 piston brembo in the rear.

I think the gamble is going to pay off. The front rotor has steel threaded bushings pressed into the calipers. I was able to build a new set of threaded bushings with an offset hole to allow the calipers to bolt up the knuckles. The 340mm F30 rotor has the same pilot diameter as the E39 hub, but a different hat height. So I built a set of spacers that fit between the caliper and the knuckle to center the caliper over the rotor.

I don't have them on the car yet, but at this point I can't see any reason why it won't work. For a little comparison, the 750il brake setup offers similar sized brakes to the F30 but incur a 6lb per side unsprung weight penalty over the stock 740i brakes. The F30 brakes offer a 6lb savings per side over the stock 740i brakes. In conjunction with the e39 suspension that I swapped, I will save nearly 20lbs per side in unsprung weight. This big boat of a car is on it's way to feeling like a medium sized boat. I'm working on fitting the rear also, but nothing excited to report there yet.

[kashmeister]

Looks awesome. Interesting that the calipers have a steel insert. Every ounce counts is a good mindset, the end product is gonna be worth it!

[KinkedChrome]

Looks awesome. Interesting that the calipers have a steel insert. Every ounce counts is a good mindset, the end product is gonna be worth it!

Thanks, I have just finished up a bunch of other projects, so I should be finally getting to this subframe swap......a year later now.

[Diskovod]

Hey man!
Great thread! I had the same thing in my mind, so I’m happy to see you accomplished it!

I have a question, being not that confident in BMW parts, but I had driven L7 E38 as a daily and E39 M5 as a daily.

It seems for me that E39 M5 is simply brilliant in suspension. Although it had uprated KW V3, the traction was crazy! Never had the front behave bad or understeer, really really loved it.

Can’t say the same about E38. It might need some arms/bushings replaced, but the feel is very different. I don’t mean the agility of steering behavior. Rather something within ackerman and overall bump control. It seemed for me as if M5 E39 ‘upper’ control arm bushings were hydro and the E38 were not. The M5 transmitted almost zero bad road inputs inside, as if it glides over imperfectness.

Given that I also tried to find the limit of traction on M5 while having 20” summer tires in winter/snow/ice it still handled well.

What is that different in between them that makes all that???

Thanks!

[rslifkin]

The E38 has a bit more unsprung weight, as more of the suspension bits are steel rather than aluminum. That might explain a slightly worse ride over bumps. The L7 is also a much longer, heavier car than the M5, so that combined with probably very different spring rates and shock valving will give it a different feel. I'd bet you find the feel of a short wheelbase E38 with sport suspension closer to the M5.

[Diskovod]

The E38 has a bit more unsprung weight, as more of the suspension bits are steel rather than aluminum. That might explain a slightly worse ride over bumps. The L7 is also a much longer, heavier car than the M5, so that combined with probably very different spring rates and shock valving will give it a different feel. I'd bet you find the feel of a short wheelbase E38 with sport suspension closer to the M5.

For me it is seems something is largely different. The front geometry.

E39 M5 arms are not direct fit on E38, likely because of the different geometry on the knuckle itself. So the question is if the E39 M5 knuckle + arms may work in E38 with stock struts and strut locations, it may deliver the feel too.

[rslifkin]

For me it is seems something is largely different. The front geometry.

E39 M5 arms are not direct fit on E38, likely because of the different geometry on the knuckle itself. So the question is if the E39 M5 knuckle + arms may work in E38 with stock struts and strut locations, it may deliver the feel too.

The geometry has to be slightly different, but I don't think it's much. I think most of the suspension differences between the E38 and E39 are related to the E38 being wider. From what I can figure from the alignment specs, the E39 M5 has a little more caster in the front end (non-adjustable) than the E38. Ackerman seems very similar from the numbers given.

Stock toe settings are a little more aggressive (less toe in, especially in the rear) in the M5. That actually might be part of the feel, as I've found a bit less toe in to make turn in much sharper in the E38 and the general feel in corners is greatly improved. With too much toe in, the car feels like it doesn't want to rotate.

It's also possible the KW coilovers on the M5 were just better shocks (and possibly better matched to the springs and car) than the setup on the E38. Or it's possible the much softer springs in the E38 are exposing some bad suspension behavior that's hidden in the M5. Stiffer suspension will move less over a given bump, which can hide some steering / suspension behaviors.

[Diskovod]

The geometry has to be slightly different, but I don't think it's much. I think most of the suspension differences between the E38 and E39 are related to the E38 being wider. From what I can figure from the alignment specs, the E39 M5 has a little more caster in the front end (non-adjustable) than the E38. Ackerman seems very similar from the numbers given.

Stock toe settings are a little more aggressive (less toe in, especially in the rear) in the M5. That actually might be part of the feel, as I've found a bit less toe in to make turn in much sharper in the E38 and the general feel in corners is greatly improved. With too much toe in, the car feels like it doesn't want to rotate.

It's also possible the KW coilovers on the M5 were just better shocks (and possibly better matched to the springs and car) than the setup on the E38. Or it's possible the much softer springs in the E38 are exposing some bad suspension behavior that's hidden in the M5. Stiffer suspension will move less over a given bump, which can hide some steering / suspension behaviors.

The key benefit and problem of BMW suspensions of that era is that the upper control arm (which I call longitudinal arm) is loaded a lot with high speed bumps - so the bushings need to be soft.
At the same time, the braking force is also transmitted through that bushing, so they need to be hard upon the braking.
As part of my study, I changed the upper/longitudinal arm bushings to spherical joints on E31 850. It was amazing, but transmitted some bumps to the chassis if you hit them at high speed.

The M5 E39 felt amazing for the reason of totally disconnected feel from the bumps, yet it could brake and felt right. So I called it too much comfortable, as even I wanted to feel some road imperfections, but I couldn’t. It was so well.

The KWs on mine were uprated springs, so it had a very little body roll overall. It might be the case too. But for me it seems that the strut/knuckle/control arms are minimal changes, but they achieved the ultimate perfect tune.

This suspension design first appeared on E24.

Also M5 steering is quite long in the center, then becomes super quick.