Rifle bolt shifter for 930?

[Andrew Robertson]

Hi All, planning a simple and effective shifter on my McLaren M1 replica with SBC and inverted 930. Driver sits RHS, shifter on extreme RHS. Have scanned the archives and found nothing that answers the question I have.

As I understand it, standing at the back of the box the 930 shift pattern is anticlockwise-in = 1st, out=2nd, clockwise-in=3rd, out=4th. Reverse hard anticlockwise and in.

I have built an ultima GTR before and wanted to follow that general rod-style approach, but given the shift pattern above it looks like I don't need to reverse the movement of the shifter knob before it generates rotation and fore/aft movement of the main shift rod, and the shifter can literally be a completely solid rifle-bolt rod with a handle and knob simply welded on directly.

The fore/aft component of the shift would be short, but otherwise would it be OK, and would the H pattern that resulted be conventional?

Thanks for your help.

Cheers, Andrew Robertson

 

[Russ Noble]

Yes to all of that Andrew. That's what I have done. See my build thread post #282. Haven't had it on the road yet, another few weeks. It shifts good stationary in the car. The movement might be a bit quick for the poor old Porsche synchros though. Time will tell.

 

[Andrew Robertson]

Russ thanks very much - great thread and I think I'll copy your set-up closely - where did you get the acetyl blocks, and what kind and size of tube are you using? I think I might go with the screwdriver set-up for the shifter too!

Cheers, Andrew

 

[Terry Oxandale]

Love you're reference material Russ. This is exactly what I will attempt with my M8B attempt.

 

[Randy V]

I have built an ultima GTR before and wanted to follow that general rod-style approach, but given the shift pattern above it looks like I don't need to reverse the movement of the shifter knob before it generates rotation and fore/aft movement of the main shift rod, and the shifter can literally be a completely solid rifle-bolt rod with a handle and knob simply welded on directly.

The fore/aft component of the shift would be short, but otherwise would it be OK, and would the H pattern that resulted be conventional?

Andrew - my only concern is that having that solid rifle-bolt does absolutely nothing to increase your leverage of the shifter. Some transmissions shift as smooth as silk - others not so much. It all depends on Tolerances, Temperatures, Synchronizer composition and lubricant...

 

[Dave Deerson]

It sounds like you will have a very similar setup to what I have.I have a LS6/inverted 930 equipped tube chassis GTU Fiero.Here are some pics of the rod style shift linkage.
****NOTE*** The 930 with original syncros have a shift travel(measure at the trans) of .870in from the neutral position to gear engagement. Shifter assemblies fabbed up for formula and sports racers using Hewlands are designed for a much shorter throw(the Hewlands need only 1/2in from neutral to gear engagement).I had to design a shifter thet accomidated this longer traver while still providing a reletively comfortable throw and force at the knob.
I ran this configureation for all of last season and upgraded for this year by re-gearing the trans with ratios more suited for a V8 and dog engagement.This enabled me to use a shifter made by Craig Taylor for Hewland equipped sport racers which has a great feel ( the "rifle bolt" action you are looking for)

 

[Russ Noble]

Andrew, you'll get the acetyl from any plastics supplier. Mine came from Engineering Plastics. A mate of mine used to work for them and gave me a large box of offcuts. Very handy. EPL have been bought out, I can't for the life of me remember their new name!

The rod is just el cheapo 22x1.6 ERW tube because that's the size that fitted nicely over the UJs. Also I think any smaller would be prone to flex in compression. Larger is excess weight. I am now onto the MK2 'lever/handle', the screwdriver was a bit rudimentary, I found an old angle grinder handle that had a nice grip and that is ideal for the rifle bolt action.

BTW I think I remember your twin turbo XJ from Targa NZ a few years ago when I was running my TR7V8. That must have been some handful!!

 

[Andrew Robertson]

Hi Russ,

yeah after a DNF and a unsalvagable shell in 2000, and a big hole in the scenery that required a day off for running repairs in 2002, I finally finished every stage and ended up 4th in the allcomers class in 2005. Needless to say the boost was turned down and we proceeded with caution! Sold the engine to a guy up north who is putting it in a Chevelle.

Cheers, Andrew