Spicer 20 spd

Thanks for that Lang.
A 6 speed OD box would be perfect by the looks of it.

I wonder has anyone got one...

And yes, I though about tyres again but as you say, not much gain and the 10.00s already touch occasionally so clearance is an issue...

But still a diff would be great...

I have been through all this over the past 6-8 months or so to speedup Inter AR 160. Finally got an overdrive box out of an AACO and got an adaptor plate machined up and then had to lengthen input shaft to compensate for extra length created by thickness of adaptor plate and then have to shorten tailshaft. Finally got sick of chasing all sorts of combinations and decided to go this way to get job done but reckon will not be done in time for Mount Gambier which is disappointing

Cliffo

If you look at the Turner parts drawings it looks like the extra length is only about 20mm. The odds are the original tail shaft could be used (or if it bottomed cut 20mm off the male spline to allow it to go in that extra bit.

Lang

Lang The difference in length is 68mm which has to come off the tailshaft......50mm longer gearbox and 18mm for adaptor plate. Seems a lot of messing around over several months I got sick and tired of looking into different ways to do it and this seemed the least messy of all the other options so bit the bullet and went ahead or it would never get done. No doubt when it is finished and fitted a simpler way will turn up such as higher crownwheel and pinion but thats life

Cliffo

Is the ACCO box the same as the Commer box? If he is swapping a Commer/Bedford Turner 5 speed for a similar 6 speed the only difference I can see is the small overdrive section adaptor plate (I guessed 20mm but you have seen it at 18mm). Where is the extra length, in the box or on the output section?

Lang

I dont want to disagree with anyone,but Turner Manufacturing Co of Wolverhampton, in 1962 recieved a licence from Clark in the US to produce the Clark 265 as the Turner T5-300 box.The deal was setup by Bedford who felt they needed a 5sp for the new 300 petrols and diesels.Turner didnt make truck gearboxes prior to 1962.Bedford and Ford were the main users,but Leyland also fitted the boxes in the Redline trucks,as an alternative to the Eaton 475SMA.Later Turner made a larger box for Bedford for the bigger diesels.T5-300 series.The Turner boxes were never much good,synchros falling to pieces and going thru the gears,and shifter clutch teeth backing off were the main issues.Turner ceased making the Clark boxes in 1974,but US Clark were still making spares up to the Volvo takeover.Turner made lots of things,diesel engines ,tractors,delivery vans,winches,etc,none of it very good.

John

Thanks for the history. I only knew the gearbox in the Commer is a Turner and as you say built under licence from Clark.

My experience is limited to a brand new vehicle only up to about 100,000 before sale, never having a problem. I had a couple of very high mileage Commers and TK Bedfords in our pile driving business back in the 80's and my current 450,000 68 ex-farm Commer toy, none of which I put much mileage on . I have never had a moment of problems, even noise or strange shifting. I did find they were all a delightful gearbox to use and worked really well split-shifting with a two-speed diff.

Only limited to my personal experience with them which is not very much and you, having worked on them, would get a much wider picture.

Lang

Lang The overdrive in the AACO box is internal and part of the gearbox

The Commer gearboxes were made by Commer,not Turner.I dont want to cause any more confusion with details.The IHC T34/T35/T36 5 speed AACO box was made by Fuller in the USA.It was a special for IHC,and not used by anyone else.Now for the confusing part........Commer copied the design of the IH/Fuller for their 5 speed box,but made it somewhat larger.The Commer 4 speed was also a copy,this time of the Warner T98,again bigger.Both Commer boxes could have an OD tacked onto the back.Many other boxes used this idea too,including the Japs in the sixties onward.Note that the bigger AACO boxes (non synchro} were also made by Fuller,but not as specials.....The T53/T54/......T63/T64

kwakatriple

Do you want me to crawl under the Commer and measure the 6 speed box for you to see if it will suit your purpose?

Lang