Newbie - S38 & 280 Gertag Questions - Help Please!!!

[nydesmo]

[FONT=&quot]I've finally joined the club purchasing my first CS. [/FONT]

[FONT=&quot]Serial #[/FONT][FONT=&quot]2240377 was found in Nashville Tennessee, parked in a garage in 1993 with a bad alternator. With less than 35,000 miles, it did not again see the light of day until last month when I trailered it back to New York. It's color is Nachtblau and options are a stick, A/C and a beautiful / original non leather interior. The body is in excellent condition and there is a small amount of rust in the front two fenders, no where else. From sitting for 18 years the motor has seized and from the beginning my plan was to update the motor.[/FONT]

[FONT=&quot]The original plan was a 3.5 and 265 transmission, but found and bought this week was a 88' M5 in rough condition and good running order as my donor motor. I drove the M5 a 100+ miles this weekend, it pulls hard, shifts great and I cannot wait to transplant its motor into the CS.[/FONT]

[FONT=&quot]I have been reading the forum and the information is incredible. Has anyone placed a S38 / Gertag 280 (Combination) into a CS? If so, I have a bunch of questions I hope those more experienced than I can assist with. [/FONT]


[FONT=&quot]1. Manifolds - I assume will fit from the S38 - What are suggestions for exhaust?[/FONT]

[FONT=&quot]2. Transmission cross bar - From M5, will it work on the CS to support the Gertag 280?[/FONT]

[FONT=&quot]3. Gertag 280 - [/FONT][FONT=&quot]Is it the [/FONT][FONT=&quot]the same length as the 265 - Do I need to remove 3 3/4" from the drive shaft?

[/FONT] [FONT=&quot]4. Radiator / fan from the S38 - Are there tricks or is it straight forward mounting?[/FONT]

[FONT=&quot]5. Gauges - North Hollywood can help with the tach and speedo. What is there to do with the oil pressure light?[/FONT]

[FONT=&quot]6. Master brake cylinder - I have read 2002 and 733 are smaller - What is the best available that will fit under the hood?[/FONT]

[FONT=&quot]7. Fuel Tank - There is a return line needed for the fuel pump - Is there any tricks?[/FONT]

[FONT=&quot]8. Suspension - Are there bits that can be upgraded from the M5 to the CS such as swaybars?[/FONT]

[FONT=&quot]9. Brakes - Planned for - From the M5 will be done with new lines and 16" Alpina's.[/FONT]

[FONT=&quot]What problems will I face I have not yet identified?[/FONT]

[FONT=&quot]Two friends are trying to convince me to change my plan and rather rebuild a 3.5 large valve motor with 11:1 compression pistons, Schrick cams and 40mm Webers. Upside is reliability of a newly build motor, downside is cost ... How much would a rebuilt motor like this cost? I possess a 265 Gertag, so it would ease the plan.[/FONT]

[FONT=&quot]Thanks for your suggestions, input and knowledge.[/FONT]

[FONT=&quot]Greg[/FONT]

 

[HB Chris]

Congratulations on your purchase. Did any records come with your coupe? Even with only 20 years on the road it might be 135000 miles which is still quite low. All coupes that came to the US had leather interiors thanks to Mr Hoffman. Is yours vinyl or velour? Lots of info available here if you use the search feature too. Good luck in bringing your coupe back to life.

Chris

 

[nydesmo]

Chris,

Thanks for your post. The interior is velour (see attached).

I have a few records going back to 1990 (nothing prior and no history) when the last owner purchased it and they show mileage between 29 - 35,000 miles. If you look at the car's interior, I believe the odometer to be true.

I've been searching the forum from end to end and will continue.

Greg

 

[HB Chris]

Very nice, would love to see more photos.

Chris

 

[decoupe]

S38 installation

A very extensive discussion and photo file on this excellent S38 build by rb1971. Some of your questions can by answered there.

http://www.e9coupe.com/forum/showthread.php?t=9902

Doug

 

[rb1971]

Welcome to the club! I just finished this build over the summer (although nothing is ever really finished - more details below). I've given some of my opinions below, but at the end of the day unless you have a CSL with race history you should do whatever makes you happy.

[FONT=&quot]1. Manifolds - I assume will fit from the S38 - What are suggestions for exhaust?[/FONT]

The plenum fits, but interferes with the hood spring. We are still working on that but will probably go with the CSL-style hood prop. Exhaust - many ways to go, if you're doing a full rebuild you could tub the trunk and then you have tons of options.

[FONT=&quot]2. Transmission cross bar - From M5, will it work on the CS to support the Gertag 280?[/FONT]

[FONT=&quot]3. Gertag 280 - [/FONT][FONT=&quot]Is it the [/FONT][FONT=&quot]the same length as the 265 - Do I need to remove 3 3/4" from the drive shaft? [/FONT]

I'd reconsider the 280. Although I'm running it right now, reverse is in an awkward place for the CS console and the transmission is not known to be that reliable. Instead I'm going with a 265CR which is currently being rebuilt, but you could also go with the 265OD you already have. You also don't have to fool around with speedometer issues in that case. (FYI if you decide to go with the 280 anyway, and you need a digital-to-analog speedo converter, my brand-new one will be for sale shortly.)


[FONT=&quot]4. Radiator / fan from the S38 - Are there tricks or is it straight forward mounting?[/FONT]

We had clearance issues so mounted an electric fan instead.

[FONT=&quot]8. Suspension - Are there bits that can be upgraded from the M5 to the CS such as swaybars?[/FONT]

I went with the La Jolla kit which is very good.

[FONT=&quot]9. Brakes - Planned for - From the M5 will be done with new lines and 16" Alpina's.[/FONT]

Not sure if this fits, probably depends on wheels. I went with the Wilwood big brake kit on the front. Frankly, the car is already sufficiently braked even with stock equipment.

[FONT=&quot]What problems will I face I have not yet identified?[/FONT]

Probably a ton. These cars were partially hand built, and you will discover a lot of interesting adjustments as you go forward. One thing I don't think you discussed is batter placement and air intake, both issues when covering over the S38.

[FONT=&quot]Two friends are trying to convince me to change my plan and rather rebuild a 3.5 large valve motor with 11:1 compression pistons, Schrick cams and 40mm Webers. Upside is reliability of a newly build motor, downside is cost ... How much would a rebuilt motor like this cost? I possess a 265 Gertag, so it would ease the plan.[/FONT]

Not sure reliability is the biggest upside ever when you're talking about a detuned race motor. Educated guessing leads me to believe you can get the same street able power out of other M30s with similar or better reliability for the same or less money due to part issues, etc. I went with my S38 in part because I already had one.

 

[nydesmo]

RB1971,

Thank you for sharing your experience and knowledge. The photo's of your car are incredible (decoupe - thank you for directing me), I have looked through the 200+ photo's twice tonight.

Your fuel cell and exhaust are both very thought provoking. The cell is a very easy solution for the return line.

My thought for the battery is the trunk. Airflow ... Whatever I can figure out behind the headlights.

I've been driving the M5 and the 280 seems find. I assume the shifter linkage for the 265 / 280 is the same?

Again, thanks.
Greg

 

[TodB]

motors

I've got a M30 hi comp, modded motor in my E28 5 series which includes ~10.5-1 compression (b34 lower end/head and B35 pistons). Head includes bigger intake valves and double valve springs and cam. Also have headers, Miller MAF/warchip. I am at 250+ Hp and 300+ lbs torque. Love it.

If I was starting over, I'd look for a later M30 motor (89+) which already has the better flowing head, a bit higher compression (9 to 1 I think) and motronic v1.3 and then add a Miller MAF/warchip (or go Megasuirt) along with a cam from Paul Burke. That should get you to near 250 hp and will be rock solid dependable. Paul can build you the head ready to install if you want. His contact info is in another recent thread.

But those S38 motors are oh so nice...

 

[2800csm5]

Greg,

Go to the CS Registry, select 1970 cs and search on the second or third page for serial
number 2270173. There you will see pictures of my coupes.

I have two coupes, one with a 1991 S38 engine and 265 OD transmission from a 80 E12,
the other have a highly modified M30 from a 89 635csi with a 265 OD transmission from
a 528i. Both installations were relatively easy to do. Both have the brake booster from
a 2002TII and both drive shaft were shortened and rebalanced tho fit the five speeds.
One other note. You have remove the speed pickup plate from a diff. and mount it
between the diff and half shaft, then make up a plate to hold the speed pulse pickup
that feeds the computer. If the computer dose not see that pulse, the engine will not
rev over 6000.

To fit the S38 engine, I had to remove the bar across the hood as it would hit the top
of the intake manifold.

The 280 transmission will not fit in the coupe, the rear end of the transmission is too
high and will hit on the top drive shaft tunnel.

The S38 powered coupe runs like a bullet and gets to 150 in a hurry, but you have to
keep the revs over 3500.
The M30 has better low end torque and is a much better in city or light traffic driving.
Actually I prefer to drive the M30 coupe as it pins you in the seat with each gear shift.

If founds were limited I'd say go with the fuel injected 3.5 M30.

 

[rb1971]

To fit the S38 engine, I had to remove the bar across the hood as it would hit the top
of the intake manifold.

The 280 transmission will not fit in the coupe, the rear end of the transmission is too
high and will hit on the top drive shaft tunnel.

I should have mentioned in my post that you have to lose the stock hood springs and go some other way, that's a good point. You could use the CSL type hood prop or something similar.

Re the 280 tranny, I've got one in my car right now - and I didn't have to cut anything in the tunnel. I wonder if that difference is due to anything that happened between 70 and 74 in manufacture? Weird.

 

[rb1971]

RB1971,

Thank you for sharing your experience and knowledge. The photo's of your car are incredible (decoupe - thank you for directing me), I have looked through the 200+ photo's twice tonight.

Your fuel cell and exhaust are both very thought provoking. The cell is a very easy solution for the return line.

My thought for the battery is the trunk. Airflow ... Whatever I can figure out behind the headlights.

I've been driving the M5 and the 280 seems find. I assume the shifter linkage for the 265 / 280 is the same?

Again, thanks.
Greg

No worries, I love to talk about my car. (And my wife is sick of hearing about gear ratios, so this is really the only place I can come!)

We had to make a custom shift selector linkage to get the 280 to work with the CS console. Maybe this is the issue 2800csm5 was referring to?

-John

 

[John Buchtenkirch]

The S38 powered coupe runs like a bullet and gets to 150 in a hurry, but you have to
keep the revs over 3500.
The M30 has better low end torque and is a much better in city or light traffic driving.
Actually I prefer to drive the M30 coupe as it pins you in the seat with each gear shift.

If founds were limited I'd say go with the fuel injected 3.5 M30.[/QUOTE]

It almost sounds to me like your S38 coupe could use a slightly lower (numerically higher) rear end ratio. Just curious what ratio you’re running ? I’m intending to do the same swap hopefully in a few years down the road. Thank you. ~ John Buchtenkirch

 

[rb1971]

The S38 powered coupe runs like a bullet and gets to 150 in a hurry, but you have to
keep the revs over 3500.
The M30 has better low end torque and is a much better in city or light traffic driving.
Actually I prefer to drive the M30 coupe as it pins you in the seat with each gear shift.

If founds were limited I'd say go with the fuel injected 3.5 M30.

It almost sounds to me like your S38 coupe could use a slightly lower (numerically higher) rear end ratio. Just curious what ratio you’re running ? I’m intending to do the same swap hopefully in a few years down the road. Thank you. ~ John Buchtenkirch[/QUOTE]

John - I know I'm not the person this was directed towards, but I've got a S38 with a 280 connected to a 3.45LSD rear. For my taste, the car could use a higher numerical ratio, but I live in a city and much of my driving is either light-to-light or secondary roads. When I get the car out on the highway, the car doesn't really want to be in 5th until I am the fastest car out there. (When you're also bright orange, you don't want to be that car.)

My solution is going to be to swap in a 265CR (currently being built), then see where I am on the rear end. My builder tells me that most folks run a higher (lower numerically) ratio in a car with a S38 + 265. My plan is to run with the 3.45 for a few weeks and see how it feels, then build a new diff with the proper ratio and higher lockup, but I would bet I will end up at 3.45 or 3.65 due to how I drive the car.

 

[2800csm5]

I'm using using a 3.65 diff with the S38 engine.

 

[John Buchtenkirch]

I believe that I read that early 1991 M5 cars had a 3.91 rear end ratio and then changed it to 3.73 half way thru the year. While tire diameter also comes into play a 3.91 rear would certainly liven up the low end performance and help the engine stay at higher RPM where it might be happier. Obviously gas mileage would suffer from the lower ratio. ~ John Buchtenkirch

 

[nydesmo]

Pulled the S38 today

From an 88' M5 and I hope in the next week will be going into my E9. I have a few questions and hope those who've done this conversion can share their knowledge.

1.) The connection from the motor to the fuse box has 10+ wires. Does anyone have a diagram of what needs to be used from this connection?

2.) Power steering Unit - What is the difference between the CS and M5 and if I use the CS unit, will the pulley's align with belts?

3.) AC Bump - My CS system blows cold and has been upgraded, should it be changed out to the M5 and will the CS unit's pulley align with belts?

4.) Fuel lines - Is there a way to pull the High pressure lines through the body? What diameter should be used?

5.) Fuel Tank - Any tricks to tapping a return line?

6.) Is is possible to install the motor with a 265/5 trans already in the car and be able to bolt the engine/trans together at their tops?

Thanks for sharing.

Best,
Greg