ZF Swap

[rcair3d]

If I am putting a ZF trans in my Ti. I am under the impression that there are a couple different versions of this in a manual(could be wrong??). Anyway, I want to know what all it entails to swap from a Getrag to a ZF. I found a post about it once upon a time, however I cannot find it now. Here is what I am to believe I am to do/obtain:
*Obtain ZF
*328/M3 clutch/flywheel(with the new flywheel the starter should line up correctly, right?)
*M3/328 front drive shaft to attach to ti rear

I know the throw of the slave is the same for both trans'. Will shifter linkage line up? What else it there to know?

[rcair3d]

Also from what I have heard your turbo will spool up sooner with a stock flywheel VS. an aluminum. This makes sense as the turbo won't build boost W/O a load, more rotating mass would create a higher load, and the initial additional strain would make it spool sooner. If this is completely true, how much of a difference will this make?

[cooljess76]

Why are you swapping transmissions?

[rcair3d]

From others past experience, the getreg trans will not hold the power of my new setup once it is all done.

[xxxJohnBoyxxx]

Originally Posted by rcair3d

Also from what I have heard your turbo will spool up sooner with a stock flywheel VS. an aluminum. This makes sense as the turbo won't build boost W/O a load, more rotating mass would create a higher load, and the initial additional strain would make it spool sooner. If this is completely true, how much of a difference will this make?

I would run a light flywheel since the load you want is from the car in gear pushing you forward not rotational mass to turn your heavy flywheel.

The heavy flywheel will only slow down how fast your motor can rev.

Someone needs to chime in on the drive-shaft since I don't know about it's fitment on a ti.

John S

[rcair3d]

Just ordered a 328 drive shaft.
Helpful reference:

328/M3 DS length:1492mm
318TI DS length:1544mm
318I/IS DS length:1561mm

Both front halves for 318 are same length, however the rear section is where they differ.(so I have been told)

I will chime in with an install and parts list when I am all done.

[J!m]

Originally Posted by rcair3d

From others past experience, the getreg trans will not hold the power of my new setup once it is all done.

What sort of set up did you have in mind that you plan to break the Getrag?

Curious mainly, as I have been running the Getrag behind my 3.2 (250 at the crank) for over 5 years now with no issues at all. Will you be over 500CHP? If so, the ZF won't help you very much either.

On a ti you will be hard pressed to fit more than a 275 width tire. I can spin that size tire (although I have gone to 265) with no problems- point is, the tire will break loose before the transmission breaks. If you enjoy red line clutch dumping, you will break everything- not just the Getrag.

Now, if you plan to drag race with REAL slicks on the back, you might be able to break it, if other parts don't break first.

What is likely to break far sooner is the diff. What have you done to address this? Also the half shafts. If the diff was done, were the half shafts also done? If not, did you plan to install a Ford 9 inch rear or something?

I have seen/heard a lot of chatter about how 'weak' the Getrag is; however in my experience, it is not a weak part at all. It, like all mechanical things, WILL break; particularly if abused.

[cooljess76]

Originally Posted by J!m

What sort of set up did you have in mind that you plan to break the Getrag?

Curious mainly, as I have been running the Getrag behind my 3.2 (250 at the crank) for over 5 years now with no issues at all. Will you be over 500CHP? If so, the ZF won't help you very much either.

On a ti you will be hard pressed to fit more than a 275 width tire. I can spin that size tire (although I have gone to 265) with no problems- point is, the tire will break loose before the transmission breaks. If you enjoy red line clutch dumping, you will break everything- not just the Getrag.

Now, if you plan to drag race with REAL slicks on the back, you might be able to break it, if other parts don't break first.

What is likely to break far sooner is the diff. What have you done to address this? Also the half shafts. If the diff was done, were the half shafts also done? If not, did you plan to install a Ford 9 inch rear or something?

I have seen/heard a lot of chatter about how 'weak' the Getrag is; however in my experience, it is not a weak part at all. It, like all mechanical things, WILL break; particularly if abused.

Thanks J!m, that's exactly what I wanted to say but figured I'd leave it open to someone more knowledgeable than myself. I've heard more cases of stock small case diffs blowing up or halfshafts snapping than trannys breaking. I've read a few threads on bf.c FI section about ZF's breaking, but those cars were all putting down well over 500hp and being drag raced. Heck, even if you were putting down 500hp, I'm sure the Getrag would hold up fine for track and street use unless you plan on dumping the clutch regularly, but as J!m said, anything will break under those conditions. I second J!m's advice on beefing up the rear end. You should upgrade to a medium case e24, e28, e30 or Z3 diff and e30 halfshafts with fresh CV joints at the very least. With the Getrag, you already have the correct driveshaft setup and again, the driveshaft or flex disc would probably fail before the tranny does. Don't get me wrong, alot of us run ZF trannys, but that's usually just because they came with our engines. Now if your Getrag is worn out, sometimes the syncros wear down allowing it to pop out of first gear or making it difficult to engage, I'd completely understand your decision to upgrade to a ZF. Or if you were doing a motor swap and your new engine came with a ZF, then sure, why not install it. Fact is, the ZF is hardly an upgrade. While it may or may not be a little stronger, they're subject to the same problems that all manual transmissions are prone to.

[J!m]

I sort of equate this to having "too much gun" for the job.

You also pay a ~20# weight penalty for the ZF over the Getrag. It is low in the car, but that 20# makes the car that much slower. That's like adding a second battery!

Many people focus on absolute horse power numbers. Torque gets you going, and HP keeps you going. What REALLY needs to be looked at is the HP:Weight ratio. A HEAVY car with 500 HP is much slower than a light car with the same power. If that heavy car has 1200 lb/ft torque, it will pull like a truck (and with those specs, probably is a tractor trailer). In the case of the BMW six, as you add HP, you typically remove torque. Forced induction restores it, but torque is proportionate to displacement. Horsepower is proportionate to RPM. So, raise you red line, raise your HP and torque stays about the same. Force more air/fuel mix into the cylinder (better air flow, more fuel available, larger pistons, forced induction) and the torque goes up. BUT, screw up the air/fuel ratio and you will loose more than you gain! (as seen by the 'home tuners' of smoky Honda products)

Ever notice staring at those cool HP & Torque curves that even as the HP increases in an engine, the torque curve stays more-or-less the same unless SERIOUS work is done to the engine? Torque peaks where it does, and it takes a lot to move it around. Forced induction simulates a larger combustion volume, so the torque goes up.

The entire package needs to be thought about. I mean, an Allison transmission will work behind a Briggs & Stratton, and move your lawn tractor just fine. However, the weight and strength of that unit make it a poor choice for the job.

Point is: if the car is lightened (as it should be if you are serious) the Getrag is more than "Man enough" for the job, AND you get a slight weight savings as well, which is key. Now, if you were swapping to get a six-speed, THAT is an entirely different animal, and I would gladly take the weight hit for the additional overdrive gear in my car!

Bit of a rant there, but some useful information nonetheless...

[rcair3d]

I now have everything to put the trans in. I appreciate the attempt at useful information. However the information provided was knowledge I have already taken into consideration. My reasoning for the swap was as follows: *Multiple members on this board and m42club are running very similar setups as I am, however they couldn't rely on the Getrag. *As far as horsepower in the near future I plan to surpass 250HP *BMW corporate stated to me in person how much stronger the ZF was, and why wouldn't it be? The getrag was intended to be an economically priced trans for the modestly powered cars, the ZF came with the more powerful M3. *I have to pull the trans anyway to place a stage 5 clutch, so while I am already there why not was my thought. There is low mile e30 diff of some sort now, Is the ford 9" even possible? As far at tires go wide body and tubs is always an option, but not my goal. I want to try to autocross this car eventually. To address the redline issue, I am not an idiot teenager who does redline dumps. This WILL not happen. My intentions are not to be haste, I do value valid input. My reasoning for posting was to gather info on the swap and maybe some input on upgrading the rest of the drive line, which I got. I like to keep an open mind. I know one formula isn't always the perfect formula for everyone, So maybe I will keep the Getrag for loosing weight later on. I can let people know my preference so they have a valid reference. I like to quote the saying "you never know until you try it". Thanks again

[J!m]

Originally Posted by rcair3d

I now have everything to put the trans in. I appreciate the attempt at useful information. However the information provided was knowledge I have already taken into consideration.

Ok...

Originally Posted by rcair3d

My reasoning for the swap was as follows: *Multiple members on this board and m42club are running very similar setups as I am, however they couldn't rely on the Getrag.

I would like to know who these people are, and their "Setup" and driving style/needs. I personally have not heard of a Getrag failing, so this is important information to me. I have however heard of LOTS of diffs failing. If you are using the M42 as your 'base' I cannot see making anything over 300 CHP with that.

Originally Posted by rcair3d

*As far as horsepower in the near future I plan to surpass 250HP

As I mentioned, a 2-liter engine with forced induction will yield around 300 CHP as the upper limit.

Originally Posted by rcair3d

*BMW corporate stated to me in person how much stronger the ZF was, and why wouldn't it be? The getrag was intended to be an economically priced trans for the modestly powered cars, the ZF came with the more powerful M3.

That highlighted bit is all I needed to read. BMW have more attorneys on staff than I have had sets of rear tires on my car (and that's a lot- another set on the way). Corporate would NEVER make any recommendation that might jeopardize their accountability. Frankly I'm surprised you were able to get anyone at BMW to give that sort of answer at all. Generally their 'canned' response is "That was not engineered with that usage in mind and we cannot give any advice as to the suitability as you describe." In other words: We don't know, and we don't want to know. Good luck. Who did you speak with by the way?

Originally Posted by rcair3d

*I have to pull the trans anyway to place a stage 5 clutch, so while I am already there why not was my thought.

Seems reasonable; just trying to wrap my head around why you need so much tranny. I would feel comfortable with the Getrag in a ti up to 300 CHP... The clutch probably does not need to be SO beefy either; an M3/M5 set-up seems to work quite well for the power level you are shooting for.

Originally Posted by rcair3d

There is low mile e30 diff of some sort now, Is the ford 9" even possible? As far at tires go wide body and tubs is always an option, but not my goal. I want to try to autocross this car eventually.

OK. Low mile E30 diff is at least 17 years old now. And how low is low? I know the E30 mid case fits the ti nicely (I even include detail in my swap manual); however you have to weigh the price of rebuilding it (because the seals are on their way out due to age) and you have no idea how it was treated in those miles. It is true for ANY used component, and I have found it is cheaper to buy a newer Z3 3.0 / M roadster sub frame than to spend the time and money to make a bunch of well-used and well-aged parts work reliably. They work; the question is how long before you have to tear it apart again to fix something (bad seal, noisy bearing etc.).

A 9" is possible, as is a Chevy small block (just ask Bluebimma!). The question is how badly you want those things. If the car was to be drag raced, this is what I would suggest: Tub it, full cage and set a 4-link and Ford 9" in the rear. Then you have at least one thing you won't have to worry about for a while.

Since you do want to auto-x the car, you should be mindful of what the "setup" ends up being. You could very easily find yourself up against other modified cars that will drive circles around you, which is not much fun. If you plan to auto-x, get a rule book and determine exactly what class you want to be in (and who you will be against), and adhere to the rules for that class. This will keep you competitive. Otherwise, the guys running the race will lump you in with the other 'open' cars, such as cobra replicas and modified 911 turbos, or trying to keep up with a Lotus. I don't care how much power you have, you will have your hands full against these (if experienced) guys for sure.

Originally Posted by rcair3d

To address the redline issue, I am not an idiot teenager who does redline dumps. This WILL not happen.

This is good. You don't need the 9" in this case...

Originally Posted by rcair3d

My intentions are not to be haste, I do value valid input. My reasoning for posting was to gather info on the swap and maybe some input on upgrading the rest of the drive line, which I got. I like to keep an open mind. I know one formula isn't always the perfect formula for everyone, So maybe I will keep the Getrag for loosing weight later on. I can let people know my preference so they have a valid reference. I like to quote the saying "you never know until you try it". Thanks again

That is all good advice anyone can learn from. I would just like to see some clarification on the "setup" so all us readers know what were looking at. And, I await your report back on how things went- this is valuable information to other people who perhaps have a bad transmission, and NEED to change it for whatever reason as well as for those who (like you) WANT to change it.

The give and take of the forum is fantastic; however we all have to remember that the less detail we give about our particular project, the less valuable it is to the person contemplating the same (or similar) project (and then you get a ton of PM's, e-mails or threads go on for ever in circles). You are going to get a bunch of good data for the community and I look forward to seeing it!

[xxxJohnBoyxxx]

J!m, my Getrag on my 318is started to go so I went to a ZF transmission. I was instructed to do so by Metric Mechanic for numerous reasons. I did the whole package, driveline, medium case LSD, half shafts. 320 stiff mounts.

My Getrag was ready to go when I pulled it. I drag race and daily drive this car. I have a 2.1L M44, GT-30 turbo and boost up to 25psi with meth injection. I do run it hard and bang shifts at 8,000rpm. I will run slicks this winter when I try to get into the low 11's. I don't need a transmission coming apart and tossing parts into my legs. It all comes down to what the owner wants in their car.

Sometimes people like to put in the best they can and try to bulletproof the car, Some Getrag transmissions are solid but the 250 is not and has failed on my car and failed on Nicks so when we replaced them we decided to install a ZF instead of putting back in the same transmission that failed.

I fully know about weight being a factor and I consider it in everything I do with my car. The 20 pounds was worth it when I made the decision to install the ZF.

I have run the ZF for over 1 year and I'm 100% happy with it.

John Smith

[J!m]

Good post, John.

For what you are doing, you did absolutely the right thing. I don't fault it at all, other than to say why the heck don't you have a blast shield on your tranny if you are dragging the car?

Otherwise, good luck! With the slicks you may be the first to rip the rear subframe mounts on a ti...

[roadrash]

Originally Posted by J!m

With the slicks you may be the first to rip the rear subframe mounts on a ti...

Except that he doesn't have a ti. :

[J!m]

Originally Posted by roadrash

Except that he doesn't have a ti. :

Well, we all have our crosses to bear now don't we...