Quaife gear box & paddle shifter questions/answers

Last modified on:  11/10/07 Return to home page links       

Purpose of article:

I've had several questions about my Quaife forward/reverse gear box and the paddle shifter. This page is a compilation of several email answers and LocostUSA forum posts I've made. Included are details of my paddle shifter setup, the reverse lock out mechanism and how my Quaife is mounted..

NOTE: You may click any picture to see it full size.


If you've gotten this far on the site you probably know what a Quaife gear box is. But just in case, let me explain why Bike Engine Cars [BEC] sometimes use one. Most motorcycles do not have reverse. So if you don't provide some mechanical means of backing up you will have get out of the car or ask someone to give you a push when you want to back up.

Some people have incorporated electric motors that engage the drive shaft in various ways to back up. Another way is to use an external gear box that has a reverse gear in it.

The Quaife is one of the small gear boxs that is installed between the engine output shaft and the rear end. It has three positions on the fore/aft gear shift lever, forward (1:1 gear ratio), neutral, and reverse (also 1:1 gear ratio). Two short drive shafts are used with the Quaife. One is installed between the engine and the Quaife input and a 2nd drive shaft is installed from the Quaife output to the rear end. In affect the Quaife also provides for a center bearing in the drive train.

Quaife questions-answers

Do you know what kind of oil the Quaife uses?

I emailed Quaife and this is the answer they gave me.  "You will want to use a quality 75W90 GL4 or GL5 gear oil in the unit. It may be synthetic or conventional."

Are you using a Quaife? If so how do you like it. I seem to remember from the movie clip I saw of your car, that you backed up!!!

Yes, I have a Quaife. It works fine and is a great addition to the car.

Here's a little info about the box:  The Quaife doesn't use synchronizers. On my car, if I have the Quaife and the motorcycle transmission both in neutral the drive shaft between the Quaife and the engine will usually spin up to an equivalent of 3 MPH or so . If I then try to shift the Quaife with the clutch pushed in, the gears will crunch because of the lack of a synchronizer.

I find the best way to do the reverse shift is to push the clutch pedal in and shift both gear boxes at the same time (left hand on the transmission paddle shifter, right hand on the Quaife shifter). If you are already in low gear and the Quaife is in forward or reverse you should come to a complete stop and then shift the Quaife quickly into the other gear. In that case when the shaft starts to spin a little it helps align the gears in the Quaife for the shift.

An undocumented "feature" is that you can go as fast in reverse as you can go forward!  Just what we need, a car that can go 100+ MPH in reverse! But I guess that's not as crazy as the motorcyclist who holds the record for the fastest wheelie at 210+ MPH!!

The top mount for my Quaife is a thick piece of sheet metal welded to the lower edge of the forward ends of the top tunnel tubes "C" and "D". My Quaife is located just aft of tubes "K". The sheet metal is shaped lengthwise to a sort of squarish "U" shape so it is flat against the top of the Quaife where the bolt holes are and parallel to and touching the underside of the top tubes.. This makes a very sturdy mount. See the first picture for some detail. The cut out area turned out larger than I needed but it allows for access  to the gear shifter bracket bolts.

The placement of the Quaife fore/aft isn't too critical at all since you will have to have the two drive shafts made up after it is mounted. In affect you position the gear box so the gear lever is located where it is easy to reach. In my case, since the RX-7 rear end has an offset pinion gear the whole tunnel is offset towards the passengers side of the car by about 1-1/2".

And of course you want the drive shaft(s) offset to have as small an angle as possible.  1 to 3 is a good angle for the drive shafts to have so there is some small movement of the U-joint needle bearings to keep them lubricated.

My Quaife lower mount is a ~8" length of 1-1/2" x 1/4" thick 90 steel angle welded to the top of the lower frame rails. The angle is notched on the ends so the vertical part of the angle extends 1/2" below the frame rails. This part is VERY strong and really holds everything together.

The reverse light switch is rather strange in that it closes when the Quaife is in reverse AND neutral. Sort of an English "sorry 'bout that".

Quaife location in chassisQuaife lower mount          
                    The rear of the car is at the top in this picture.                               Bottom mount as seen through the door. The rear of the car is towards the right.

The next picture gives a good view of the upper gear box mounting metal and how it is bent to meet the upper frame tube and the top of the gear box..

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Reverse Lockout Information

Reverse lockout detail

The rear of the car is towards the right.

I'm using a lawn mower throttle lever as the gear shifter until I come up with a prettier one. I made a reverse lock out from a spring loaded 10 speed bike shifter. I used an old type shifter that has a lever that rotates 90 degree clockwise. I attached a 1" long x 3/4" wide  x 1/8" thick piece of aluminum strip to the rotating lever with two small screws. The metal strip blocks the reverse lever from going from neutral into reverse. The shift lever is in neutral in the picture.

To go forward you push the lever forward.  To go into reverse I put the palm of  my right hand on the lockout lever, rotate it with my palm while pulling the shift lever towards the rear of the car with my finger tips. When you shift out of reverse the lockout  will rotate back to the position shown in the picture.

It took quite awhile to come up with the design but it works great. The lockout system is bolted to the sheet metal upper Quaife mounting plate with two 1/4"-20 round head screws. A small block of wood  is used to keep from bending the aluminum body of the bike shifter when the mounting bolts are tightened.

I cut a circular slot in the tunnel cover centered around the bolt that the reverse lock out lever pivots on so that the lever is the only part of the lockout that is above the tunnel cover. There is another slot in the tunnel cover for the shift lever. The tunnel cover is actually in two pieces, one square  piece between the tunnel side rails and extending from the front of the upper gear box mounting metal to the rear of the mounting metal. (Roughly the area shown in the picture.) The rest of the tunnel cover overlaps the square piece about 1/2" and extends to the rear bulkhead. There is a separate cover for the slopped portion of the tunnel (to the left in the picture.) The tunnel covers are held on with #8-32 Pan head screws. I glued strips of bicycle inner tube to the top rails as a sealing gasket.

The two stainless steel hoses in the picture are the fuel lines. One is the pressurized line from the fuel pump to the pressure regulator. The other line is the regulator bypass line back to the fuel tank. The copper pipe is the breather tube for the Quaife gear box. The copper tube is bent downwards and has a plastic fuel line filter on the end to keep dirt out of the system.

Drawing of the Quaife reverse box as supplied by Quaife Design & Development.

Click on the drawing to see a clearer view of it.

Quaife dwg

Paddle shifter information.

Is it worth the trouble to install a paddle shifter?

By all means, use a paddle shifter if you can.  They are great! After building the rest of the car don't skimp on the part you will be using quite often while driving.

There are several reasons that I like a paddle shifter.  The main one is that it is very easy and fast to shift gears with it. A very important safety concern is that you can keep both hands on the steering wheel while shifting.

It also confuses the dickens out of people who are looking at the car. Especially if you also have the Quaife shifter and reverse lockout on the transmission tunnel. If you want to gage the knowledge of lookenpeepers don't mention to them about how you back up when you tell them you are using a motorcycle engine power plant. Even my local Suzuki dealer "technicians" didn't pick up on that one.  But they were -extremely- interested in the car.

The only complicated part of making your own paddle shifter is the pivot bearings on the paddle where it mounts to your steering column. Some builders have made their own paddle using two small Heim bearings as the pivot points. My paddle has two 5/16" diameter steel balls as pivot bearings.

My shifter was made by Stuart Taylor, in the UK. It is really a professional looking device. It looks like it came from a Formula car. Unfortunately it was priced like it came from a Formula car.  I had to machine out the inner bore .050" so it would fit over the RX-7 steering column.

I use a push-pull shifter cable from an automatic transmission Mazda 1991 automobile to connect the paddle shifter to the transmission. At the transmission end of the cable I used a rear wheel brake arm from an old Japanese motorcycle. After the scuttle and dash were installed I shortened the brake arm to 2" length to reduce the movement of the paddle shifter so it wouldn't hit the GSXR-1000 instrument hood.

      Paddle shifter close up                 Paddle shifter as seen by driver

The picture on the left shows the upper end of the cable with the built on mounting bracket. By pure chance the bracket is angled in the horizontal plane such that the end of the steel rod fits right into the clevis on the paddle shifter. Also notice the split block mounting block that I made from a 1/2" thick piece of aluminum. The "U" shaped portions of two muffler clamps might also work but wouldn't look as good [even though it would be hidden by the dash board]. I like solid mounting brackets for things so I don't have to worry about them working loose later.

I later positioned the cable bracket forward against the steering column mount plate [towards the right in the 1st picture] so it would be out of sight inside the GSXR instrument cover. I lengthened the rod by cutting it about 1-1/2" from the rubber seal and threading it 1/4"-20. I then internally threaded a hollow valve push rod from a Corvair engine to 1/4"-20 and welded the cut off end of the cable rod into the other end of the tube. I use the slotted bolt holes on the bracket as a coarse cable length adjustment and the threaded tube as the fine adjustment.

Paddle shifter lower end

This picture shows the lower cable mounting. The stock Mazda mounting brackets are used to hold the lower cable in position. The cable fit the installation like it was made for my Locost. This whole cable assembly and brackets cost the fabulous sum of $5 from the junk yard plus many hours of fiddling, measuring, welding etc. In the end, it was time well spent.

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Drive Shaft Information
Would you mind telling me who you hired to make your prop shafts?

The drive shafts were made by:

Drive line services of North Atlanta
6285 Euford Hwy
Norcross, Ga, 30071
Phone: 404-242-9365

They are very well made, balanced and are very sturdy looking.

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