Still looking

George Coleman · Dec 10, 2019

Still looking for a 3.70 gear set out of a Alpine GT 69-70 model. Thanks

RootesRooter · Dec 10, 2019

Are those new ones from the Netherlands(?) still available?

George Coleman · Dec 11, 2019

I do not know but I got one years ago and they are not up to Std. after a few years they really got loud. I have heard that others have had the same problem. The Alpine GT would be a better set up for sure.

RootesRooter · Dec 12, 2019

Alpine GT's are getting mighty scarce. The automatic GT's with the 3.7's even more so. The last time I had a chance to pick one up, 15+ years ago, the friend who was going to do the transaction for me made the mistake of telling the owner that it was going to be scavenged for parts for a Series V. The owner promptly put it back in the barn, where it's probably still rusting away, or maybe gone to the crusher.

I still have an old set of 3.7's that 'burned up' when the front seal expired and the oil drained out. After replacing the seal, the gears still howled like crazy. Question: once the teeth are burred in any way, can they be repaired? Economically?

hmihm · Dec 12, 2019

Just wondering if a complete 3.7 rear axle assembly from a GT will fit into a series 5 Alpine? or will just the ring and pinion interchange?
thanks

Barry · Dec 12, 2019

RootesRooter said:
I still have an old set of 3.7's that 'burned up' when the front seal expired and the oil drained out. After replacing the seal, the gears still howled like crazy. Question: once the teeth are burred in any way, can they be repaired? Economically?

Never say never, but I don't know of any practical / cost effective process to return "burned up" hypoid spiral bevel gears back to "as new" condition. Reshaping the gears might be possible with metal spraying and machining, but getting the metallurgy and surface hardening correct would be like trying to put the Genie back in the bottle. The old school "fix" was to put sawdust in the gear lube and sell the car before the noise came back. Bought one of those back in the day.

65beam · Dec 12, 2019

hmihm said:
Just wondering if a complete 3.7 rear axle assembly from a GT will fit into a series 5 Alpine? or will just the ring and pinion interchange?
thanks

The complete rear end unit with the housing will not fit. It's wider than a series Alpine unit and has a different shock mount and spring mount. The entire gear unit is a bolt in on any series 5 as long as it has the original fine spline axles. It also fits a series 4. This green car has one of the 3.70 units as does our series 5.

alpine_64 · Dec 13, 2019

You can fit the later arrow series rear but its wider and you either have to roll the lips on the rear arches ir raise the body a little and fab some different top shock mounts on the body.

A local club member fitted one to his sII so he was making top telescopic mounts anyway. He had a bit of a suprise intially of the tyres scrubbing the rear lips so had to trim and roll the seams

65beam · Dec 13, 2019

alpine_64 said:
You can fit the later arrow series rear but its wider and you either have to roll the lips on the rear arches ir raise the body a little and fab some different top shock mounts on the body.

A local club member fitted one to his sII so he was making top telescopic mounts anyway. He had a bit of a suprise intially of the tyres scrubbing the rear lips so had to trim and roll the seams

There are a couple minor things that would need changed in order to install the Arrow range housing under the series Alpine. The spring mounts of the Arrow range housing won't line up with the series Alpine springs so you would need to cut them off and move them inboard. If you want to continue to use the braking system of the series Alpine you would also want to swap backing plates since the Arrow range braking system is Lockheed instead of Girling.

RootesRooter · Dec 14, 2019

Why would anyone want to swap the complete rear end from a fastback or Arrow into a Series Alpine? Besides being too wide, the dual-piston slaves had got to be tough to source these days, as well as the shoes. But the diff gears are a straight swap. The only difference is that the input yoke is longer on the fastback diff. Some people say there's still enough slack in the driveshaft but I prefer to swap the coupling and not chance cracking the tailshaft housing or ruining the seal if I hit a big enough bump.

65beam · Dec 14, 2019

RootesRooter said:
Why would anyone want to swap the complete rear end from a fastback or Arrow into a Series Alpine? Besides being too wide, the dual-piston slaves had got to be tough to source these days, as well as the shoes. But the diff gears are a straight swap. The only difference is that the input yoke is longer on the fastback diff. Some people say there's still enough slack in the driveshaft but I prefer to swap the coupling and not chance cracking the tailshaft housing or ruining the seal if I hit a big enough bump.

I've often wondered if the longer yoke was used due to the two piece drive shaft of the GT and the movement in the center carrier bearing. I forgot about having to change that part before installing in the series 4 and 5. I do have a couple one piece drive shafts that was standard in the Alpine fastback that used the cast iron head engine. Some may have wondered why I mentioned changing the backing plates but you're right about the wheel cylinders and the entire brake system. I found that a similar wheel cylinders was used on some BMC cars of that era so kits are available.