15 replies to this topic

[Alexandre34]

Hi everybody,

 

A friend of mine and I both have 5 speed Minispares gearboxes.

 

The gearboxes are the helical ones and are the same exept mine which is fitted with the Minispares cross pin diff.

 

Those gearboxes are fitted as standard with a 3.44 FD and we want to change for something taller 3.21 for me and 3.1 for my friend which is running 10 inches wheels.

 

Has anybody ever done a FD on this type of gearbox and would be happy to help us ?

 

Thanks for any help.

[ACDodd]

The pinion will need grinding down a stock one won't fit. It's not a straight swap.

A far easier option is to fit the economy overdrive drop gear set from a metro. You will get the same effect.

AC

Edited by ACDodd, 09 November 2013 - 09:50 AM.

[Alexandre34]

Thank you for your answer and for the information about the economy overdrive drop gear set from the metro.

 

Do you know what are the gains in rpm of such a drop gear set ? I would be tempted to fit one than changing the diff on my gearbox...

 

My friend Michel has already started to dismantle his gearbox, here are some pics of what he has done:

 

 

 

 

 

And now we are stuck, we don't know how to go further to get the FD pinion out of the gearbox.

 

Impossible to find how to dismantle what is needed to be, it is really different from a standard gearbox.

 

Any help would be appreciated.

 

Thanks a lot.

Edited by Alexandre34, 09 November 2013 - 01:48 PM.

[Guess-Works.com]

You need this...

 

http://www.guess-wor.../Tech/ratio.htm

 

To continue with dismantle, you need to withdraw the layshaft from the gearbox from the other end

 

It's a while since I pulled a Minispares 5 speed apart but I believe I have some photo's somewhere.

 

Found a couple of photo's, however I know I had to make a tool from a 1/2" hex bar which needs to undo a cap screw which is down the middle of the layshaft which locks the shaft in place.. Once that cap screw is undone then I seem to remember it comes apart fairly easily.

 

If I had one in front of me I'd be able to guide you through it.

Edited by Guess-Works.com, 09 November 2013 - 03:40 PM.

[ACDodd]

Fitting the 0.933:1overdrive set will take the effective fd ratio from 3.44 to 3.21:1.


Ac

[Alexandre34]

Thank you guys for all those useful informations.

 

We're going to have a look at the gearbox this afternnoon, I will let you know about it.

 

I think that I will follow your advice of fitting an economy drop gear set than replacing the final drive ratio for my car.

 

Now I need to find one...

[Guess-Works.com]

Now I need to find one...

 

That's the easy bit....

 

http://www.guess-wor...argument=dam633

[ACDodd]

Perfect solution and a good price too!

 

AC

[Alexandre34]

Good advices, perfect solution for me, good price, everything is ok.

 

 

 

 

Is the cap screw (in red) that we are talking about ?

 

To undo it is it necessary to engage two gears to lock the rotation ?

 

Thanks a lot.

Edited by Alexandre34, 11 November 2013 - 10:40 AM.

[Guess-Works.com]

Yup, that'd be the chestnut...

 

And yes, when undoing any nut/bolt it's wise to have the gearbox locked.  I stick them in 4th and reverse.

[Alexandre34]

Thank you,

 

the nut has been undone, the layshaft moves from 1 cm to 1,5 cm but impossible to withdraw it.

[Guess-Works.com]

I'm afraid I cannot remember any more about removing the layshaft, you may have to undo the 3rd motion bearing retainer, but don't take this as gospel as it's over 5 years ago that I last rebuilt one, and at my age trying to remember what I was doing 5 minutes ago is sometimes a bit of a struggle.

[Guess-Works.com]

Ahhh.... just found this on Minispares site...

 

Your 5 speed gearbox has a special 5th gear, laygear, and reverse idler shaft assembled with a modified gearbox main case and a different speedo end casting.

These parts must be removed before the main gearbox cluster can be removed. When a clean work area has been prepared, the removal of the 5th gear and laygear is as follows.

1. Remove the new speedo end casting assembly with the two bearings. These are a slide fit in the casting and are not positively retained.

2. Remove taper bearing No LM11749 off the 5th gear shaft along with the needle roller bearing carrier from the bore of the 5th gear, leaving the gear loose on the shaft.

3. Remove diff and housing as per workshop manual, turn the selector rod at base of diff housing area anti clockwise-and with the spool pull out as far as possible to enable locking the synchro hubs in 2 gears, preferably 1st and 4th to undo all relevant mainshaft nuts.

4. Manually slide back the 5th gear outer track as if selecting reverse gear this will expose the splined thrust washer between 5th gear and the 5th gear synchro hub (this is visible through the synchro ring location cut out in the inner synchro hub).

5. Slide the splined thrust washer back towards 5th gear, this will expose the thrust washer locating pin (visible through one of the three location out-outs in the hub). Remove the pin out through the top or by rotating the shaft as necessary to allow the pin to drop from its drilled hole. Remove pin from the gearbox and store safely. Remove layshaft retaining plate held with socket screw-use a 3/l6” Allen key, withdraw laygear stub axle from flywheel end of transmission. Insert a 13mm hex key into the layshaft hole and undo the socket nut. As the nut is undone the 5th gear shaft will move towards the speedo casting end of the gearbox. When the nut disengages the thread, the 5th gear shaft can be pulled from the gearbox.

6. Support 5th gear and remove the 5th gear shaft from the gearbox through the speedo casting aperture.

7. Remove 5th gear, 5th gear synchro hub, splined thrust washer, counter bored spacer and taper bearing LMIZ749 through the top of the gearbox.

8. Replace laygear stubaxle and the 5th gear shaft back through the gearbox casing and into the laygear assembly. Tap off the 2 bearings on the end of the 5th gear output bell, slide back the output bell which is against the pinion until it is engaged only on the lock nut spline. Place a 22mm socket on the end of the output bell hexagonal drive and undo anticlockwise this will then allow the splined spacer and pinion to be removed.

9. Pull out the laygear stubaxle and 5th gear shaft from the laygear and lift out the laygear assembly from the gearbox ease with thrust washer. The only purpose of the thrust washer is to control the bearings in the cud of the laygear, the position of the Iaygear within the casing is now being controlled by the taper roller bearings referred to earlier and set when originally built.

10. It is important to note the assembly order of the parts fitted to the 28mm bearing bore. Particularly, this order is referred to in the assembly instructions.

11. Remove the nyloc nut from the end of the reverse gear shah, unbolt the centre web bearing carrier bracket and remove from the gear case.

12. Slide the reverse idler shaft towards the transfer gear end of the main case to expose the “E” clip in its groove near the end of the shaft. (at this point reverse gear position should still be engaged). Remove the clip (store it safely) and extract the reverse idler shaft out through the speedo casting aperture. Remove the reverse idler gear. You should now be left with your main original gearbox cluster for removal and refer to workshop manual if required.

 

 

Just read that.. and remember the trouble I had until I happened across these instructions....

 

Steps 4 & 5 are the crux to removing the layshaft...

Edited by Guess-Works.com, 11 November 2013 - 02:58 PM.

[Alexandre34]

Thanks a lot for those precious informations John.

 

This afternoon we have finally removed that layshaft and been able to remove the final drive pinion from Michel's gearbox.

 

Tomorrow Michel will go to the machine shop to have the new final drive pinion thinned down.

 

I will let you know for the rebuild.

 

Many thanks for all the time invested to help us John, you are really a top guy.

 

I keep in touch with you for the economy drop gear set and other bits.

[Alexandre34]

Hi everybody !

 

Some good news of the FD change.

 

The final drive pinion as been thinned down, and the gearbox has been reassembled without problems.

 

Thanks a lot for your help.