Another gearbox option

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minorv8
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Another gearbox option

Post by minorv8 »

Here are some pics showing a BMW 6-speed box that got adapted to RV8. This will be fitted to my new engine (that is still being assembled…).

The main parts are Getrag GS6-37 box and P38 auto bellhousing. Clutch is a Sachs 240 mm 765 diaphragm and ACT 240 plate.
Loota_2.jpg
Attachments
Leikelty kytkinkoppa.jpg



minorv8
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Re: Another gearbox option

Post by minorv8 »

Is it just me and my lack of Computer skills or why I keep on having the attached photos diasppearing when they are placed inline …

Anyway, a pic of clutch:
Attachments
Kytkin.jpg

minorv8
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Re: Another gearbox option

Post by minorv8 »

And the end result:

Converted box.jpg
So why such a conversion ? Well, currently I have a TR7 derived LT77 that has survived behind a healthy 4.6. I do have a rebuilt R380 but both have the same ratios and I would prefer to have 1st gear around 2.90:1 number like T5. Now, T5 boxes and matching bellhousing are not exactly cheap.

Now, we have a local source that has converted BMW boxes to a lot of different engines. All you need to provide is a bellhousing (and a block if your engine is a new to him). He has a stock of boxes or you can supply your own. I bought mine from Germany (50 € + shipping 80 €), bellhousing from UK (£50 + shipping) and the actual labour (around 400 €). Being a diesel box the 1st gear is useless at 5.1:1 but others are what I needed. Clutch parts are all heavy duty BMW and there are plenty to choose from.

Total length flange to flange is about 1 1/4" less than LT77. Gear stick is very close to LT77 location with the matching BMW gear Shift assembly.

DaveEFI
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Re: Another gearbox option

Post by DaveEFI »

I've often wondered about this as regards the SD1. The T5, etc that seems to be a favourite there seems nothing like as sweet to use as the box in my brother's noughties BWM. When seems to have near zero value as scrap, meaning parts should be cheap.
Dave
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stevieturbo
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Re: Another gearbox option

Post by stevieturbo »

5.1 first ??? holy feck, never heard of one that short.

Although most BMW cars do tend to run a 1:1 6th or top gear with a very tall diff instead.

Always think this video is cool...

9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

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Re: Another gearbox option

Post by ChrisJC »

Impressive machining!

Chris.
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Re: Another gearbox option

Post by SuperV8 »

Interesting, what is the weight like vs the LT77?

So the Getrag GS6-37 box has a torque rating of 370Nm?
Gear ratios (37BZ for gasoline-powered engines):
1 2 3 4 5 6
4.350 2.496 1.665 1.234 1.000 0.851

Gear ratios (37DZ for diesel-powered engines)
1 2 3 4 5 6
5.14 2.83 1.79 1.26 1.00 0.83
Dax Rush 4.6 supercharged V8 MSII

DaveEFI
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Re: Another gearbox option

Post by DaveEFI »

A real crawler 1st on the diesel version. Very useful when towing. If reverse is equally as low.
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minorv8
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Re: Another gearbox option

Post by minorv8 »

Getrag weighs 45 kg with gearshift assy. I only had R380 to weigh and it was 49 kg without bellhousing and remote.

That lathe video is scary, I have also seen one where they cut an auto box.

minorv8
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Re: Another gearbox option

Post by minorv8 »

One thing that this box lacks is a drive or signal to a speedo. I solved this with a ABS trigger wheel. I machined the rear flange to a press fit and Loctite´d the ring gear on the flange. A Hall sensor will be fitted.

Compared to LT77 or R380, this flange is a very precise fit on gearbox output shaft and required a puller to get it removed.

Hammaskehä.jpg
Last edited by minorv8 on Thu Dec 12, 2019 10:54 am, edited 1 time in total.

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Re: Another gearbox option

Post by minorv8 »

Another thing, I decided to use the BMW gear change assy for simplicity. I fitted urethane bushes. The rear mount is bolted to the body in Beemers but I did not want that so I made a simple support structure. It is bolted to the end of the box. The actual gearbox rear mount design is still open. I cut the Beemer gear lever and threaded it with a M12 die. The shift is precise and throws are very short.

Vaihteensiirron tuki.jpg

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Re: Another gearbox option

Post by DaveEFI »

minorv8 wrote:
Thu Dec 12, 2019 10:47 am
One thing that this box lacks is a drive or signal to a speedo. I solved this with a ABS trigger wheel. I machined the rear flange to a press fit and Loctite´d the ring gear on the flange. A Hall sensor will be fitted.

Compared to LT77 or R380, this flange is a very precise fit on gearbox output shaft and required a puller to get it removed.


Hammaskehä.jpg
Neat way of doing the pulse drive. Mate used the bolt heads on the universal on a T5. But then you'll likely need a pulse converter for your speedo. A toothed wheel with the right number of teeth would get round that.
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stevieturbo
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Re: Another gearbox option

Post by stevieturbo »

With the output flange having 3 legs and 3 bolts...could easily have rigged up a sensor to read those.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

minorv8
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Re: Another gearbox option

Post by minorv8 »

Too easy !

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Re: Another gearbox option

Post by unstable load »

SuperV8 wrote:
Wed Dec 04, 2019 10:35 am
Interesting, what is the weight like vs the LT77?

So the Getrag GS6-37 box has a torque rating of 370Nm?
The R380 fitted to the Sherpa is rated at 380Nm, and compares in weight and size to the LT77.
The 2wd versions are scarce, though.
Cheers,
John

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