780 Bertone D24T conversion

[v8volvo]

X1/9 sounds right. Seems like in many ways the '80s were Bertone's heyday. Designs that fit the era just right.

With the D24T/ZF swap, I guess the Volvo will be a 3-way cocktail of flavors from Sweden, Italy, Germany. Hopefully the best features of each.

My information shows that the 780 has 3.73 gears in the diff. So should make for a little taller overall gearing than the factory 3.91 setup in a 740 TD. Wonder if that will be a good or bad thing, but probably helpful for easy cruising at highway speed.

[ngoma]

Might make the speedo displayed speed closer to actual? All mine seem to display higher than actual. Even with oversized tires.

ZF 4HP22L has a pretty low 1st gear, should be OK there. On the other end, the taller geared axle could defer TC lockup until low 50s MPH instead of high 40s?

Probably overall similar to running +2 tire size.

[v8volvo]

This project has progressed to the next stage. The Bertone is here after completing a ~400 mile trip back from Boise Idaho, where I picked it up a few weeks ago.

It was fun -- more or less! I don't think this car had really seen the road in 7 years or more, thus deficiencies from sitting were evident. Not long after departure the brake pedal feel changed, still worked safely but with excess free motion, no external leaks so seems like I will be changing the master cylinder and giving it a good flush here soon. I was worried about the timing belt but it held up. No functioning radio or A/C (converted to R134a but not currently working for reasons I will need to investigate), plus a falling headliner that made me loath to run the windows down too much in case it got sucked down all the way, made the trip not especially comfortable even with the fancy Italian leather seats. The handling and ride were nice in this car, though the left side Nivomat rear shock is failing and letting that corner sag a little lower than the others so I will need to replace those expensive self-leveling shocks or convert to standard shocks and coils (more likely, as this car is not a wagon that will haul heavy payloads, hard to really see the value of load-leveling suspension here). The power seats need some adjustment and lubrication as well, they want to bind and jam when attempting to move. Cruise control doesn't currently work either.

Aside from those issues and a couple previously-known spots where the body and interior need some rejuvenation though, the car looks and feels good, a nice candidate starting point for putting effort into, and fun to spend time in a 7 series car that is different from the more familiar models.

The B230FT/AW71 stock turbo powertrain gave a strong demonstration of why a D24TIC swap will be a great improvement in this car. Power from the turbo gasser is snappy for sure, but 19mpg on premium fuel plus lots of buzz and thrash are reminders of the value of a smooth, balanced inline six and turbodiesel power that is comparable with much less fuel use. I found a redblock fan locally who is excited to take the low mile turbo engine and related parts when it comes out of the car. So the next step will be getting the gasser components pulled out, cleaning up the bay, swapping in the diesel crossmember, and installing the D24T and ZF. Hopefully this winter sometime.

Photos to come in the next post.