Manky Monkey Motors

Got a bit of a problem with the prop on the speedster.
It's too long !
Not a lot, but it won't fit. The engine and gearbox were positioned with minimal clearance on the prop while it was on it's wheels. Now the springs have been arched and with the vehicle suspended the prop is 6mm too long.
I can only come up with three ways around this.

1. Have the prop shortened by 10mm
2. Move the engine and gearbox forward. 
3. Move the axle back on the springs by 10mm

Any suggestion or advice? At the moment I am favouring number 3

I'd go for number 3 also.

what happens when you add a bit of weight ,,

how long is it going to be before the springs settle a bit


its all youre own fault  :D :D :D  youre engineering is tooo precise  ::) ::) ::)

I'm sure with your skills you can do the propshaft and have it rebalanced ?

1 or 2 because then its right.

Moving the engine and box forward would not only require new mounts but some new body panels and relocating the radiator. It really is that tight up front.

Shortening the prop is possible. Though unlike the trike prop, it is far too big to get into my lathe.

Doesn't really matter what happens when a bit of weight added or the springs settle. With the way I drive, there will likely be times when the back end is, "unloaded" and I'd prefer that the output shaft of the gearbox, didn't have to support the axle. I suppose I could add check straps.

Skim 3mm off each of the mating surfaces?

Good idea but the flanges are not thick enough. The prop end is only 5.5mm thick to start off with.
I could possibly shorten the gearbox output shaft. :-\

Could you just cut the flange off freehand tight to the weld,
Then turn the weld off the flange refit and weld.

It's the yoke I will have to cut off and I'm not sure how I'd get that held in the chuck.
Managed it with the trike prop by having a short length of tube left on untill I'd machined off the weld.
Looks like it's already been modified once before.
May look for a Minor prop to play with.

Hacksaw or 1mm cutting disc AROUND  ( not through) and there is a plug that will pull out . You can then remove the amount you need , slide it back in, make sure the phasing is correct and weld up, should all be self aligning with no balance issues ( but only if done at the back).

The sliding joint in the back of the box shouldn't be fully home as when the rear suspension unloads , say over a bump, it cna wreck the tailshaft . Joint is normally in something like 2/3 or 3/4 of the joint length but there is normally a witness mark.

Hope I'm not 'teaching Grandma' but use to sell props for a living and so went specific training courses.

You were a propshaft salesman?! How does that work then Kev? Did you go door to door or is there some sort of mail order catalogue?

I think Kev may show you where to put your propshaft Andy ?  :'(..he.he

Unfortunatly Kev, this has been done once before. If I remember correctly, the plug or spigot is only 1/2" long. Judging by the width and position of the second weld, I don't think that there will be much spigot left to locate back into the tube, without machining the yoke to remove the old welds. Hence the thought of looking for another prop, where it might be easier to do as you suggested.

What about the other end.

Just be grateful for Sercks liking to train their sales guys well ! One of my other specialist products was braking ;)

The other end would be easier but then it would definitely have to be re balanced. Still sticking with the 'if I can't do it at home, then it don't get done' rule of building.
Think I'm just going to go for it at the diff end and see what happens. :) With a bit of luck there may be enough spigot left to hold on the chuck.

 ;D

No such luck. Not enough spigot to grip so some slightly iffy use of the 4 jaw chuck and a running centre.
Last cut and it's a light press fit, into the tube. ;D
Damn I hate machining welds. Even tungsten carbide tips go blunt and they are not cheap.

Where there's a will ......... even if its iffy ....... there's a way ;D ;D

 ;D
Is this what you mean Kev ?  ;)
OK so the light press fit turned out to be a slightly heavy press fit. Think i will assemble it all with the old spider just to check all is fine before welding.

Tried it on the car and it fits with clearance, so welded it up. Not my best welding to date, but it's good and strong.
Thanks for all comments and suggestions folks.

Slightly off track, I'm putting together a project and the gearbox end is a doughnut, rotoflex? coupling. So that cannot slide in and out, so how do I manage?? There was a fixed diff but this car has a live axle, working with a jack and stands it doesn't seem to alter in length much. Have I boobed??

As far as I know, rotoflex are used where there is little or no linear deflection. Such as certain drive shafts or between gearbox and a fixed diff where the only deflection is caused by by the likes of changes in temperature or vibration.
Might be worth checking that the prop is not limiting the axle movement both in loaded (bump stops) and unloaded (wheels off the ground) conditions.

Looks good to me.

Proper job Dave, she'll be right! and if a tremor be detected, then the old "Jubillee" trick will cure it I'm sure! ;)..Morrag

 

When  using the rotoflex coupling and movement is normally a slide joint in the middle of a 2 piece prop . Rotoflex should have NO misalignment as it will eat it in very short order.

many thanks for the pointers. This morning, I went and investigated the prop shaft and at the centre bearing there is indeed a slide fitting, trouble was it was siezed. Big fire axe and a trusty hammer soon freed it up, now have it soaking in special brew to keep it free. Any idea how much it should be engaged? Cannot see a rub mark. 

I did one for a mates kit car, exactly the way your doing it, then fitted it to the car, with a dti. Turned  the prop, tapping to eliminate throw, tacked it,  then took it off to weld. It was spot on, even though i say so myself. For balancing a jubilee clip to find where to tack a weight on will do.
Diy city :)