Another gearbox option

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DaveEFI
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Re: Another gearbox option

Post by DaveEFI »

stevieturbo wrote:
Sat Dec 14, 2019 7:15 pm
With the output flange having 3 legs and 3 bolts...could easily have rigged up a sensor to read those.
You could, but are the number of pulses per prop revolution correct for your speedo head? You can convert electronically, but making a toothed wheel with the correct number of teeth seems a much more sanitary way to me.


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Re: Another gearbox option

Post by DaveEFI »

unstable load wrote:
Wed Jan 15, 2020 11:05 am
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.
We had V8 Sherpas at work, back in the day. And the ratios seemed wider than the car version?
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stevieturbo
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Re: Another gearbox option

Post by stevieturbo »

DaveEFI wrote:
Wed Jan 15, 2020 12:58 pm
stevieturbo wrote:
Sat Dec 14, 2019 7:15 pm
With the output flange having 3 legs and 3 bolts...could easily have rigged up a sensor to read those.
You could, but are the number of pulses per prop revolution correct for your speedo head? You can convert electronically, but making a toothed wheel with the correct number of teeth seems a much more sanitary way to me.
Piece of piss for a pulse converter and easier.
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unstable load
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Re: Another gearbox option

Post by unstable load »

DaveEFI wrote:
Wed Jan 15, 2020 1:01 pm
We had V8 Sherpas at work, back in the day. And the ratios seemed wider than the car version?
I have never even seen a 2wd version, so I can't speak for the ratio spread, but there was a bloke on the Rover Forum who fitted one to a P6 and he was happy with it.
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Re: Another gearbox option

Post by SuperV8 »

There were two versions of the 2wd of R380; the van (Sherpa) and sports car (Morgan/MG) with the Sherpa version having very low first ratio.
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Re: Another gearbox option

Post by minorv8 »

Yes, commercial boxes have 4.1 or something first gear, also 2nd and 3rd ratios are a bit different.

My R380 box came from commercial vehicle and I had to rebuild it with passenger car gears. I got all I needed from Ashcroft. By the way, input shaft is also longer on commercial R380 boxes.

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Re: Another gearbox option

Post by minorv8 »

Finally some progress with the gearbox swap. Old engine and box was removed as a complete package. BMW box was fitted to a spare block and trial fitted to the car. The space was almost perfect. I shaped the tunnel around the LT77 when I did the conversion over 20 years ago and deliberately left some space around the box. The only real issue was in the front. There I had to raise the floor about 1/2" plus some clearance. Maybe 1" total.

So, currently the box fits the car, tunnel is almost welded back together. I ordered gearbox crossmember parts from Sweden (BMW to volvo 700 conversion). They were relatively cheap so making them myself was not cost-effective. Am I getting old and lazy ?
20201212_110903.jpg

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Re: Another gearbox option

Post by GDCobra »

unstable load wrote:
Wed Jan 15, 2020 11:43 pm
DaveEFI wrote:
Wed Jan 15, 2020 1:01 pm
We had V8 Sherpas at work, back in the day. And the ratios seemed wider than the car version?
I have never even seen a 2wd version, so I can't speak for the ratio spread, but there was a bloke on the Rover Forum who fitted one to a P6 and he was happy with it.
Fitted one in my GD a year or 2 ago, it is the 2wd version (obviously) but NOT the Sherpa, I believe first is still lower than my previous LT77 but not a problem, don't even notice the difference.

One thing though, I found many indications on t'Internet that this was a direct replacement for LT77, it was not. The R380 has a larger rear housing (the amuminium piece on the back which I think contains 5th gear) which pushes the gear shift further back, not a problem if still building the car but as my 'stick hole' was already in place I had to shorten the housing, no biggie. More important (for the GD) is that the rear of the housing moving further back also intersected a chassis cross-member. I reduced this in width thinking that it is in tension so should not matter, strength reduction will be minimal in that direction, only to find on some later GD chassis this memeber is removed anyhow!

Output flange location unchanged so no problem there.

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Re: Another gearbox option

Post by minorv8 »

My R380 is different in the front cover area too. Maybe because it is a commercial box, maybe not.

Here is a photo of the R380 front cover plate. Two things: yellow arrow marks the release bearing arm pivot point. It´s roughly 1/2" taller than LT77. Red arrow shows the general shape of the cover plate. It is also more robust than LT77 one.

Normal SD1 V8 release bearing carrier did not fit between the diaphragm and cover plate (McLeod items). Also the pivot boss+pin height means that you can´t fit the slave cylinder. It won´t reach the bellhousing.

The easy fix is to machine the pivot pin boss down and shorten the release bearing carrier. But this means that it is not a direct swap.
R380.jpg

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Re: Another gearbox option

Post by GDCobra »

minorv8 wrote:
Fri Dec 18, 2020 5:40 am
My R380 is different in the front cover area too. Maybe because it is a commercial box, maybe not.

Here is a photo of the R380 front cover plate. Two things: yellow arrow marks the release bearing arm pivot point. It´s roughly 1/2" taller than LT77. Red arrow shows the general shape of the cover plate. It is also more robust than LT77 one.

Normal SD1 V8 release bearing carrier did not fit between the diaphragm and cover plate (McLeod items). Also the pivot boss+pin height means that you can´t fit the slave cylinder. It won´t reach the bellhousing.

The easy fix is to machine the pivot pin boss down and shorten the release bearing carrier. But this means that it is not a direct swap.

R380.jpg

That's a good point, my front cover is also different to the LT77 (and to yours), mine is more of a rectangular block, no contour at all.
Reason I didn't mention this (aprart from the fact I forgot) is that this was not an issue to me as I changed to a concetric slave cylinder so didn't have to make any of the original parts fit or use the release arm pivot.
In fact the flat face at the front of the bearing cover plate was an advantage to me for this job.

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Re: Another gearbox option

Post by minorv8 »

An update. Crossmember finalized and gearbox is now more or less in final position. There is enough room in the tunnel after bit of a hammertime. Here is a photo showing the LT77 and BMW box next to each other.

20201217_171744.jpg

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Re: Another gearbox option

Post by minorv8 »

Here is another photo showing the boxes from above. ZF is way bulkier even if the length is just about the same. I bought a new 3500 SD1 propshaft from Rimmers. Even with the spacer replacing the BMW rubber donut the current propshaft was too short. The new propshaft needs to be shortened roughly 1,5 inches.
20201217_171818.jpg

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Re: Another gearbox option

Post by minorv8 »

I got lazy with the gearbox crossmember. I used to tease my late father about him getting old when he no longer fabricated everything himself and bought something ready to fit instead. Seems that I have reach the same age. I bought a Volvo 760 + ZF box set of gearbx mounts and crossmember from Sweden since they were relatively cheap and speeded things up. Naturally the crossmember did not fit but it was a good starting point. The box mount was further modified by fitting a Hall sensor bracket for speedo signal. The 130K miles old rubber donuts are here for mocking purpose only and will be replace with poly donuts.
20201221_173527.jpg

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Re: Another gearbox option

Post by minorv8 »

Here is the final package. The spacer for propshaft is a 1,25" thick piece of aluminum.

20210104_182849.jpg

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Re: Another gearbox option

Post by ChrisJC »

Nice work!

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