Overdrive gearbox for Pootle?

There is sometimes a plate mounted just under the rad that acts as an extra scoop but not always. One little mod that is often done is to take out the original duct and turn it upside down, It needs the mounting lugs adjusting to enable it to line up with the bolts but it gives a bit of a 'chin' scoop and forces more air in

You can just see it in this pic

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It's easy to then add a bit more to the back of the scoop if needed.

Suckers are more efficient than blowers but there is limited room even with the mechanical fan removed. I moved the rad forward a little to enable me to fit one but that throws it's own problems up like the throttle bracket, hoses and rad cap fouling the engine lid. I did use a chunky old Escort diesel fan though so a modern slim line one might be better. I did remove the mechanical fan but found that, when driving, the temperature slowly crept up until the electric fan cut in. I cured this by fitting a small bike rad in the heater return and mounting it underneath the scoop, the temperature now stays below the fan cut in temp (88 deg C) and only it only cuts in when stuck in traffic - usually queuing at the tip :rolleyes:
 
So new Revotec fan has arrived but before fitting I thought, I'll flush cooling system, then run some coolant cleaner through, then fit the fan.....
Easy!
Eerm....
So disconnect feed to dashboard rad and connect hose in order to flush the dash and series connected radiators through.....
No workee!
Hmm, blocked radiator?
Remove the dash radiator and the 'extra' rad that was blocking the front grille and both passed water through no problem...
Disconnected feed pipes from engine and connected air line to check them - one pipe clear and one blocked but cleared with a bit more air pressure.
With the dash radiator on the bench I tested the electric fan and found it didn't work so stripped the housing to access the motor.
Motor felt nice and smooth but drew no current from a 12V bench power supply so strip it down for a look-see.
Brushes look good and motor is all nice and clean inside but commutator a bit tarnished so cleaned it all up with emery paper, oiled the bearings and reassembled,
Now runs nice and sweet.
Will repaint the radiator housing next and then refit under the dash.
Then I can flush/clean out the engine and main radiator before fitting Revotec and connecting back the pipework.....
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Hi all
So a bit of progress on Pootle - delayed a while whilst I rebuilt the engine on my 2004 Celica engine which started burning oil like a 2 stroke (30:1 petroil!).
Right, so Pootles gearbox out this morning and alpine box is ready to go in - box all nice and smooth and overdrive working after solenoid rebuild. First question is - can I fit alpine box with alpine bellhousing or do I need to fit housing and input shaft from Pootles box?
If I can use alpine setup as it is I think I need to shorten propshaft by about 5".
Anyone advise?
Cheer Tony & Helen
 

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It can be done (I think Sunbeamsam did it) but the gearbox will be tilted over about 15 degrees and the change rod adjustment will be at it's extreme extension and you will need to get creative with the reverse gear change rod, I think you need to bend the gear lever too.
It is better to fit the Commer bell housing but as well as the input shaft you will need to fit the Alpine gear wheel to it as the first gear ratios are different in the two boxes. This does mean stripping the both boxes down to extract the input shafts.
 
Hi Panky
Hmm needs some consideration methinks. I can do either I guess but changing the gear change rods seems less daunting than stripping gearbox to swap gears. Stripping the box also means removing the overdrive and getting that back on with springs etc is sometimes a challenge I think?
I assume the 15 degree twist comes about because the engine on the alpine is canted over?
One question that springs to mind is - how can you fit an overdrive interlock switch to the box to only allow overdrive in 3rd/4th?
Tony
 
Personally I would go for swapping internals, it's a bit of a faff but ultimately satisfying knowing you've done it right. I did initially offer the Arrows box up as it was but after checking and measuring decided to split the boxes. Yes the angle the gearbox sits at is due to the Arrows engine sitting at an angle, I'm guessing at 15 degrees, it may be more.
The inhibitor switch is easy, there should be brass plugs either side of the top cover of the gearbox, take the right hand side one out and screw in a switch - the left hand one operates a reverse light both work off the selectors on top of the box.

ndCW3GW.jpg
 
Pootle's Owner said:
Hi Panky
Hmm needs some consideration methinks. I can do either I guess but changing the gear change rods seems less daunting than stripping gearbox to swap gears. Stripping the box also means removing the overdrive and getting that back on with springs etc is sometimes a challenge I think?
I assume the 15 degree twist comes about because the engine on the alpine is canted over?
One question that springs to mind is - how can you fit an overdrive interlock switch to the box to only allow overdrive in 3rd/4th?
Tony
Click to expand...
Yes it's quite a job, but these gearboxes are some of the most straightforward to rebuild, so shouldn't be that daunting. It's a while since I did mine, but IIRC the only special tool needed is a dummy layshaft, so I used a length of 19mm 3/4" plastic overflow pipe which was quite OK. There is a YouTube video of a rebuild.

For me the difficulty in removing the overdrive was that it was torque locked on to the gearbox output shaft. (J type overdrive). Once released the overdrive comes off and is replaced as a complete unit. There are articles online about this (MGB club?) Here's how I removed mine https://forum.commervanfan.co.uk/threads/jennings-restoration.7437/page-12#post-134819

The overdrive inhibit switch looks exactly like a reverse light switch but screws into the boss on the other side of the selector housing on top of the box. If the boss is undrilled (it probably will be) it will need drilling and tapping. I think the thread is 5/8" x 11TPI from memory. The inhibit switch looks exactly like a reverse light switch, but IIRC it opens when pressed, whereas the reverse light switch closes when pressed. Perhaps someone will correct me if I'm wrong here. The switch needs to be carefully adjusted with shim washers to get it to operate reliably when selecting 3rd/4th, or it will operate in reverse as well, which would wreck the overdrive.

I see Panky has posted while I've been typing, so I've probably repeated some of his advice...................
 
Hi
Thanks for input on this. Once I cleaned up the gear selector box from Pootle the tapped holes for reversing switch and overdrive switch were obvious and I have some new switches in the post as old Alpine ones not really worth the risk.
The selector mechanism is surprisingly good after 50 years though the arm for selecting between 1/2 and 3/4 and reverse was very worn so I have cleaned it all up and refitted it with a shim so that the rectangular hole in the arm fits the rectangular shaft snuggly.
Whilst the box is out I want to examine the long selector arm the runs from the gear-stick back towards the gearbox to ensure there is minimum slop in that - are there generally any problems associated with that unit at the base of the gearstick?
 
Sorry to disagree with you Trev but the gearbox is off an Arrows series car and does need the work described to fit properly. It will certainly bolt straight on but nothing will line up because of the length and angle of the bell housing, you can see from the pics PO posted that it is longer and the bolt holes on the bell housing to engine are not in line with the centre line of an upright engine also you can see the depression in the bell housing casting is out of line with the gearbox case.
 
Panky said:
Sorry to disagree with you Trev but the gearbox is off an Arrows series car and does need the work described to fit properly. It will certainly bolt straight on but nothing will line up because of the length and angle of the bell housing, you can see from the pics PO posted that it is longer and the bolt holes on the bell housing to engine are not in line with the centre line of an upright engine also you can see the depression in the bell housing casting is out of line with the gearbox case.
Click to expand...
Hello all
Thanks for input on the gearbox saga. No resolution yet but some progress....
At the moment I have a bit of an Eric Morcombe gearbox - all the right gears, but not necessarily in the right order....
So I removed the input shafts from both gearboxes which was not as bad a task as I'd feared and longest bit of the job was making a dummy layshaft - I wanted to make it accurately as I wasn't sure initially what might happen if it was a poor fit and in order to do that I had to sort out the saddle and compound slide on the lathe that I had been ignoring for ages..
I now have both input shafts out and had thought I could swap them over but I can't because the gears are different.
- From this I assume that those of you who have done this upgrade have created a commer gearbox fitted with commer PB ratio gears but with the overdrive output shaft?
- This would mean that the gear ratios on 1, 2, 3, 4 haven't changed but you have overdrive available on 3 and 4?
Is that right or am I missing something here?

Not really which way to jump now because one of the things I dislike about the commer box is the crazy low 1st gear so I had assumed fitting an alpine box would have raised all the gears.....
On the plus side I have gearboxes largely dismantled so swapping things about to get a short input shaft and an overdrive output shaft is doable but short input shaft means commer ratios on 1, 2, 3...

As regards what gearbox I actually have, I'm not sure but the cant of the box wrt the engine is 10 degrees (or VERY close) so nottwogearboxes.jpgpootle box.jpgsun alpine box.jpg a big issue if I want to go with big bellhousing and 'alpine' ratios.
Does anyone know if the numbers cast into the gearboxes help identify the boxes origin and ratios fitted?

Another possible change of course would be diff ratio - are there options here? At some point I'll have to sort out oil leak on that - probably when I have to replace the collapsed leaf springs...
Then there is the bodywork to tackle....
Not sure if i have enough years left to be honest!
Off to work for a rest tomorrow.
Cheers
Tony
 
Panky said:
Sorry to disagree with you Trev but the gearbox is off an Arrows series car and does need the work described to fit properly. It will certainly bolt straight on but nothing will line up because of the length and angle of the bell housing, you can see from the pics PO posted that it is longer and the bolt holes on the bell housing to engine are not in line with the centre line of an upright engine also you can see the depression in the bell housing casting is out of line with the gearbox case.
Click to expand...
My apologies to you both. Having enlarged the picture of both boxes together, I can now see the difference. I obviously didn't read all posts properly. I think i should keep my opinions to my self until i know what i am talking about.o_O:(
 
The easiest way around it is to swap the Alpine gear wheel onto the Commer input shaft, that way you will have the taller 1st gear and is what I did when doing the same job.
Not sure what the casting numbers refer to I'm pretty sure all the casings were the same.
 
Hi Panky
Sorry if I'm being dim but I'm not sure which alpine gear wheel you mean.
I have the alpine input shaft stripped as below and I don't think this gear can come off the shaft?...
The gear on here must match the alpine cluster of gears on the layshaft I think and they are all machined together from one block?
Similarly the 1, 2, 3, R alpine gears must also match to the alpine layshaft cluster?
How can you swap commer and alpine gears around if the layshaft cluster is a 1 piece assembly?
I think I'm missing some vital bit of info here - perhaps I need to fully dismantle the box to understand what to do?
Input shaft.jpg
 
Apologies it's been a while since I did the swap (10 years plus). Thinking about it now I remember using a night shift at work to strip both boxes and transfer the Commer gear train onto the overdrive primary shaft. I must have swapped the layshaft over too - basically all the Commer internals.
Once again sorry for the confusion :confused:
 
No problem Panky
Given current situation I'm going to refit the input shafts temporarily and then check gear ratios on both boxes I have.
Then I'll jack up a wheel on Pootle to see what diff is fitted (5.125 or 5.625).
I'll then at least understand what options I have.
Looking at the numbers given the standard Commer box and diffs there is no wonder the engines rev to burst over 40mph is there?
Clearly an overdrive will improve matters but I would like to use the Alpine box if possible to raise first gear to something more usable too.
Fitting a 4.22 diff might also be worthwhile perhaps?
Anyone know if the Alpine or Minx diffs will fit the Commer axle?
Tony
 
It needs to be off a Humber Super Snipe or Hawk as the other car diffs are too small. A Rover P5 axle swap is pretty popular as they have the same bolt pattern as the Commer but it does mean welding on new spring perches. The later Spacevans had a higher ratio diff but they are pretty difficult to get hold of.
 
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