1970 Datsun 510

Vintage Race Car



1977 Lancia Scorpion / Montecarlo




2 L, 155 hp

What the Scorpion should have been!

La Scorpion complètement transformée


Lancia Beta

Longer ratio 5th gear conversion

5e plus longue

Gear set for all Lancia Beta models (including Scorpion and Montecarlo). Reduces engine rpm by 700 for much quieter running, 15% less fuel and less wear.


Conversion pour toutes les Beta (y compris Scorpion et Montecarlo). Baisse de 700 tours du régime moteur: plus silencieux, 15% d'économie d'essence et moins d'usure moteur. FACILE À INSTALLER!

Info: Lancia 5th Gear




 Please read the instructions fully to make sure you have everything on hand before starting.

1. Disconnect the battery

2. Locate the gearbox end case (Fig. 1)





3. Drain both the gearbox and differential by removing both drain plugs (Fig. 2 and 3).















4. Remove all 8 bolts securing the end case. The bolts are of varying length. On the Scorpion, the longer bolts will have to come out while still in the end case because of interference with the chassis. Mark the bolts order to relocate in the same positions for installation (Fig 4 and 5).















5. Once the end case is removed, you will clearly see the two 5th gears (Fig. 6) and the shift fork. The gears are held by two special ring nuts with 4 indentations. The nuts are also crimped to the shafts at 2 points around their circumference.

In order to remove and install the nuts, you need a special four-legged tool that can be fabricated by grinding a 1 1/16 inch socket (fig. 7). It is recommended that your order a pair of special nuts before attempting to fabricate the tool. This will help to ensure that you grind the socket properly and that it fits the nut well before you attempt to dismantle the gears

*See below for ordering the nuts.


6. Before attempting to remove the nuts, you must straighten both crimped sections on each nut with a center punch. DO NOT ATTEMPT TO REMOVE THE NUTS BEFORE PROPERLY STRAIGHTENING THE CRIMPED SECTIONS. OTHERWISE YOU RISK RUINING THE SHAFT THREADS.






7. If you have difficulty loosening the special nuts with the fabricated socket, you can do this by carefully using a straight punch and hammer by positioning the punch radially, as seen on Fig. 8. A couple of sharp hammer blows on the punch should loosen the nut which can then be removed with the special tool.

8. Remove the bolt securing the shift fork to its shaft (Fig. 9). Make sure the synchro ring on the primary shaft (on the right side of Fig. 9) is in the disengaged position, that is pulled back from the gear box. This is necessary so that the springs, balls and pins do not jump out of the synchro. Hold the gear and synchro assembly firmly together and carefully slide the assembly off the shaft. Should the balls and springs jump out of the synchro, you will have to use patience to put them back in before reassembly.

9. Remove the ring nut from the end of the mainshaft and remove the gear (left side of Fig. 9).

10. Note on Fig. 10 that 3 of the hex bolts (8M 1.25) securing the retaining plate behind the gears have been replaced with 3 Allen-head bolts in order to allow the larger gear to clear the bolts. Allen-head metric bolts (Fig. 12) are available at Ace Hardware. Make sure you install the new Allen-head bolts at this stage.

11. In order to clear larger gear, it is also necessary to grind the shift fork as seen on Fig. 10. DO NOT overdo it. To make sure the fork clears the gear teeth, install the fork all the way in on its shaft and turn the gear by hand to check that it is not touching the fork.

12. Remove the fork.

13. Start reassembly by fitting the new larger 5th gear larger to the primary shaft (upper one on Fig. 10).

14. Place the new smaller 5th gear on the synchro mechanism and hold as an assembly. Slip the fork over its synchro groove. This is not easy to do, so be patient.

15. Fit the assembly on the mainshaft and mesh the gear to the larger primary gear while slipping the fork on its shaft.

16. Refit the fork bolt and tighten.

17. Refit the ring nuts and torque to 100 lb-ft with the special tool.

17. Before crimping the nuts, turn the gears over to make sure they turn smoothly and engage 5th gear with shift lever in the car. All gears should engage normally.

18. Crimp the two ring nuts.

19. Install the end cover.

20. Fill the gearbox and differential with oil. I use RedLine MT 90.

* Ring nuts are available from Midwest Bayless Italian Auto, part no 82310116-OE - 5th Gear Retaining Nut



 Figure 1


 Figure 2


 Figure 3


 Figure 4


  Figure 5


  Figure 6


  Figure 7


 Figure 8


 Figure 9


 Figure 10


 Figure 11

 Figure 12