635 Csi manual gearbox

[givan.givan]

Hello everyone,

I have recently tested on 635 CSI from 1984 for a possible purchase and the seller mentioned to me that the car has "sport getrag" which basically means that the gearbox has a different layout compared to the normal gearbox. First gear is back, not front as usual.
The seller explained without any documentation to back it off that this "sport getrag" gearbox was used only in 2% of the entire production of the 635 CSI.

Could any of you help me out with some extra about this particular gearbox? I need to specify that the car is the European model.

Appreciate it

[LeonardoL]

Hello there

The car has a Getrag 265/5 sport gearbox, so called "dog-leg" gearbox. It not that rare all 635s until 1980 had it, it was an extra equipment part after but its still quite common (on 635s not the rest).
But for most it makes the car more desireable.
I personally do not like it, in 1984 you would still have the 3.07 rear diff and that makes 2800rpm on 100kmh/62mph. In europe where we have 130kmh/80mph limits and even more in some countries so the drive it 3-4 hours on 3500-4000rpm makes you want to die

[DesktopDave]

As mentioned, your prospective purchase has the quite desirable and rare close-ratio 265/5 "sport" version of the Getrag gearbox. They seem to be worth $3K-$4K if the synchros are still in good shape. I don't believe they were ever offered on the NA market cars.

I recall that the same gearbox was also fitted to BMW's DTM homologation specials & other fun cars such as the E30 M3, E12 M535i, SA E23 745i, SA E30 333i. It was also optional on the E24 & E28 and a lot of other quite desirable European sports cars. I believe it was also fitted to the Benz 190e 2.3-16 Cosworth and even a few 6-cyl Jag XJ-S. I'd bet a lot of other RWD Euro sports cars used it as well. The detachable front bellhousing makes it quite easy to fit to other cars.

The Getrag 265/6 is the overdrive version of that /5 gearbox, although they apparently have few interchangeable parts. Many 80s BMWs were built with the less durable 260/5, then later cars switched to the updated 260/6.

[givan.givan]

Thanks so much guys for the clarification about the "dog-leg" gearbox, it simplifies my decision.

I had the opportunity to test drive the car two times so far and I have to admit that I am impressed with the quality of ride for a 40 year old car. One thing that I noticed and you might help out with some info, is that the gearbox does not seem so precise. I am not able to explain in car terms so well, but it feels like it has quite some movement even when you are in a particular gear. I specified this to the seller and he mentioned that most likely the bushings are the fault. In case that's the real reason for this movement, are bushings easy or difficult fix?

[LeonardoL]

Does it have a "rubbery" feel when shifting? Or a side wobble on neutral? Or both? All can be attributed to a few small parts which can be repaired in an hour. The 2 aluminium bushings that hold the shifter mechanism have rubber inserts, rubber becomes something like tar. The side wobble is repaired by getting new plastic washers on the shifter link bar, i like putting metal ones instead of plastic.
What you dont want is grinding when getting in a gear or the gearbox popping out of gear.

[givan.givan]

Does it have a "rubbery" feel when shifting? Or a side wobble on neutral? Or both? All can be attributed to a few small parts which can be repaired in an hour. The 2 aluminium bushings that hold the shifter mechanism have rubber inserts, rubber becomes something like tar. The side wobble is repaired by getting new plastic washers on the shifter link bar, i like putting metal ones instead of plastic.
What you dont want is grinding when getting in a gear or the gearbox popping out of gear.

I would say it's more like a side wobble on both and for this reason it feels that it is not as precise when shifting.

Luckily I haven't noticed any grinding when getting in gear or popping out of gear.

The seller mentioned that I would probably need to replaced parts numbered with 1. He mentioned that those are normal to wear/age of the car, so I suppose that's fine considering that it's almost 40 years old.

Screenshot_20230606_155733_WhatsApp.jpg

[DesktopDave]

Rebuilding the shifter is a BMW tradition. The gearboxes are relatively durable (especially your 265, it's nearly bombproof in my experience).

If you can get the car up on a lift you might be able to see the shfter mechanism above the driveshaft & heat shields. There's two different types in this era, the 'sheet metal' type and the 'aluminum carrier' type. They both fail in different ways, but both can easily be refurbished with plastic cups and rubber bushings.

I have the sheet metal version myself, the biggest culprit on mine was actually the small rubber bushings inside the two console carrier blocks and the rubber isolator on the rear chassis mount. They're parts 01 & 10 in this assembly:
https://www.realoem.com/bmw/enUS/sho...diagId=25_0145

Parts 02, 08, 13 & 19 are problematic on the aluminum carrier type:
https://www.realoem.com/bmw/enUS/sho...diagId=25_0071

[givan.givan]

Cheers for sharing all the info about the gearbox.

One other thing that was highlighted in one video by some business where they restore E24 and other old school Bmw's, is to make sure when buying one E24 that the clutch is not difficult to press or seem to stiff. As I said, I had been driven the car twice and of course I felt that the clutch is more difficult to press but I might be the fault since I am jumping from a relatively new car to a 40 year old car. Is that something to be worried about?

[DesktopDave]

I'd guess the clutch itself is the culprit. Mostly all my BMWs have had fairly heavy clutches. It could be a weak slave or master cylinder, worn fork pin, bent clutch fork, stiff throw-out bearing, pedal return spring dropped off the mount, air in the lines, pressure leak, etc.

I suppose it's possible that a bad gearbox could cause clutch problems, but in my experience it's always been the clutch causing problems with the transmission rather than the other way 'round.

[givan.givan]

Good to know.

One other thing that I have noticed after couple of test runs, it happened a couple of times that the clutch pedal stays on the floor when it is pushed in. The clutch does not disengage the transmission. The temporary solution to make the car run normally again, is to simply put the edge of my shoe under the pedal and lift it up. It's operation then returns to normal but it could act tricky if you are in heavy traffic. Does this sound like air in the system?

[JimPA]

When I bought my most recent e24, the transmission sometimes wouldn't disengage. That can get your attention in traffic. I believe that was caused by the master cylinder. I replaced both the master and slave cylinder. There were no more transmission troubles after that.

[givan.givan]

Slave cylinder was changed before I picked up the car but now we have found out that the clutch hose master cylinder to slave cylinder was cracked, so most likely the issue was coming from that. Now it's fixed, hope the master cylinder won't be next. By the way, is it difficult to change the master?

[JimPA]

By the way, is it difficult to change the master?

I will defer to others for that answer. That job was done by my local independent shop.

[DesktopDave]

The master cylinder isn't that hard to get to, it's bolted onto the pedal cluster bracket. Removing the hose isn't a lot of fun, I prefer to do it under the car before I start. It's a little irritating. The biggest problem is that you'll have to do it laying on your back, in the footwell, upside down. Here's what you should see:

Late E24 clutch master.jpg
The clutch master is the silver tube in the middle of that picture. If you look closely, you can also see the return spring. It's a rusty coil spring, behind the clutch master cylinder, just to the right of the accelerator linkage.

But before you do that, check to make sure the clutch pedal return spring is correctly installed, I have a hunch it's fallen off the mounting perch. That's a clever little setup. It's a so-called 'overcentering' spring, the spring tension is highest at the bottom and top of the clutch pedal travel. In the middle, it really has very little tension. The spring tension can also be adjusted, it has a threaded stud for adjustment. Look for parts #20-#23 here in the pedal diagram.

The incomparable Rob Siegel wrote up a post about his clutch troubles. Admittedly, his early Euro will be much different from your later model, but the spirit of the post is still relevant. He does have a great picture of the early model clutch return spring though.

[givan.givan]

Looks like a fun job to do

Appreciate it for sharing all this valuable information.