Differences between R380 gearbox installed in V8 D1 models and those with 300TDI ?

terryjm1

Well-known member
I know the bellhousing is different. However can anyone tell me with certainty the difference between R380 gearboxes installed in V8s and 300TDI those in the Discovery I? Input shaft different? Gear ratios different, if so, what is the difference? My first thought is 1st gear must be different.
 
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Uncle Douglas

Well-known member
Callsign: delete
The input shaft for the V8 version is larger diameter and a different spline configuration.
Ie the transmissions are not interchangeable.
 

terryjm1

Well-known member
Follow up question...

I have seen adapter plates available to make it possible to fit the 300TDi to the V8 R380. Would it be correct to assume by using a pilot bushing sized for the larger input shaft and a V8 clutch disc paired with 300TDI pressure plate this is how they would be made compatible?

If not, how is this accomplished?
 

terryjm1

Well-known member
Think I have found the answer to my question. Searched earlier and didn’t find this. However, with more effort, here is what I found in another forum.

“the Defender V8 R380 and both Discovery and Defender 300Tdi R380 are geared the same. 1st and 5th are different on Discovery V8 R380s. If you put a 300 Tdi input shaft into your Defender V8 R380, you will have converted it. It is the only change necessary. I would not recommend running the V8 input shaft behind a 300Tdi. The input shaft is about 0.25" shorter and the pilot size on the V8 is 0.750" while the pilot on the Tdi shaft is 0.875". It would physically bolt up, but the input shaft would be unsupported in the back of the crankshaft and the clutch splines would also not be fully supported. It will not live long this way. If you're converting to a 300Tdi, it is money well spent to convert the transmission, too.“
 
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