Ribcase transmission with 948 engine

[lbcfan]

In fitting a ribcase transmission to a 948 engine- do I need to use a 1275 throwout bearing or use a 948 bearing? I'm assuming that the smoothcase tranny slave cylinder works on the ribcase.

I'm also wondering about the drive ratio for the speedometer. Is it the same with both transmissions?

Thanks in advance.

 

[Gerard]

You should use the clutch kit that matches the engine. However, you also need to use the cast steel engine back plate. You should not use the stamped steel plate with the curled edge that is standard to the 948.

The slave cylinder is the same as is the drive gear. The differences in clocking MPH are in the speedo itself. you don't say which car you have, but there may be some speedo differences, but it shouldn't matter if it's original to the car.

 

[lbcfan]

Gerard-

Many thanks. I hadn't been aware of the engine backplate issue.

The car is a 1960 bugeye that I've had since 1969. Every 20 years I do a little work on the car, whether it needs it or not. This time I've gotten a little carried away...

 

[Gerard]

Gerard-

Many thanks. I hadn't been aware of the engine backplate issue.

...This time I've gotten a little carried away...

I'm sure you are the only one that has happened to... :thumbsup:

 

[TulsaFred]

Hey let me know how the 948 does with the 5 spd in a Bugeye.

I'm rebuilding a 1275 and plan to put a 5 spd behind it. However, if I booger up the rebuild it may be back to my 948, which runs great. I've wondered how the car would do with the 948 vs. the 1275.

Fred

 

[lbcfan]

Fred-

I'm only replacing the smoothcase tranny with a ribcase. Both 4 speed, but the ribcase is supposed to be more robust- bearings instead of bushings, and different synchros I believe. Hadn't considered a 5 speed conversion- I would miss waking the neighborhood with first gear...

Michael

 

[Gerard]

Fred-

Hadn't considered a 5 speed conversion- I would miss waking the neighborhood with first gear...

Michael

Mike,

If you ever decide to go that route, I have a top notch kit available.

https://gerardsgarage.com/Garage/Tech/5speedKit.htm

You should takes some time to explore my web site anyway.

 

[TexasSprite]

When I got my 59 Bugeye, it came with a smoothcase gearbox which was trashed. I ended up getting a refurbished ribcase gearbox from the late Eric Jones to replace the smoothcase. At the time, I read several opinions on whether or the combination would work or not. Some said that you had to have a backing plate off of a 1275 for the ribcase to work, others said it just bolted on to the 948 backing plate. I was not looking forward to having to pull the engine multiple times to get this figured out. It was clear to me in looking at both transmissions that the geometry of the pivot point for the clutch release lever was different, so I was concerned about having enough extension in the clutch hydraulics to fully disengage the clutch. Eric's trick was to adapt the front cover of the smoothcase to fit the ribcase. That way, you had the same geometry as the original smoothcase. I think all he had to do was to drill two new holes in the smoothcase cover. Anyway, it all fit together perfectly using the 948 backing plate. I even had to shorten the slave push rod a bit to get the feel of the clutch to be perfect. Please realize that I don't have the expertise of many of the posters here on the forum, but so far the setup works perfectly for me!

 

[lbcfan]

Texas-

Thanks for the info. Before I bought the ribcase I was talking with a shop that rebuilt the smoothcase units with the ribcase guts. Maybe the situation is similar.

I've decided on a clever, fail-safe solution. I'll buy a rebuilt 1275 to attach to the cheap, original ribcase. My wife just loves the idea...

Michael