Doris NP Super Dexta rebuild

This forum is about the Fordson Dexta, Super Dexta and Petrol Dexta.
Dextrous
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Doris NP Super Dexta rebuild

Post by Dextrous »

Now that I have finally decided to focus on the rebuild after buying her about 8 years ago as a just running wreck, I thought I would start a thread on the rebuild with occasional photos.

So far I have dismantled most of her and I've just started to renovate components. I renovated the steering box a couple of years ago but apart from that, this is the start of the renovation proper.

I took the half shafts to the local agricultural engineer as I didn't have the means to take off the half shaft nuts without buying or making a spanner and I didn't have the ability to torque them back up to around 230 Ib/ft. These are now done and back in the workshop with new outer seals and bearings waiting for me to finish off the painting of the brake back plates and put in the inner seals.

While stripping the back axle before painting, I took out the PTO shaft and replaced the oil seal, not too difficult a job. The shaft is a little rust pitted where the oil seal runs. I've polished this the best I can and will look around for a shaft in better condition at some point, or put a sleeve on it.

A mystery has been resolved, when I took the check chain bracket bolts out from around the PTO last year, suddenly a stream of oil shot out of the bottom left hand bolt hole. I ended up draining the back axle through this and thought at the time it was a weird way of draining oil when there is a perfectly good drain plug underneath. I now know it's because somebody has used a bolt that is too long, or omitted the washer and has cracked away the back of the bolt hole into the back axle. It's not the end of the casting, it can be repaired or at least the oil can be retained. I will try and repair it with Belzona 1111 as I need some to fix the ovality in the front axle pivot hole. Hellish expensive though, if anybody has a small quantity they want to sell let me know. If this doesn't fix it I will just make sure the bolt threads don't leak oil.

That's it for a couple of weeks due to kids & work however I have a few things being delivered this week. An engine stand, zinc paint and degreaser from Bilt Hamner, thin gasket paper, some small punches for riveting (for brake shoes and bonnet rubbers) and some whitworth box spanners for those bolts where you can't quite get a socket or ring spanner on it and an open ended spanner just won't do.

I've looked at all the parts sites I was using before, Emmark, Southern tractors, Dunlops, Agriline, Forge services (for Sparex) and others, why o why don't they put the Forsdon part numbers next to the products? If I was selling that would be the first thing I would do, set me apart from competitors.

Regards
Andy
Last edited by Dextrous on Tue Oct 09, 2012 9:21 am, edited 1 time in total.

Bensdexta
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Re: Doris NP Super Dexta rebuild

Post by Bensdexta »

Dextrous wrote:I've looked at all the parts sites iIwas using before, Emmark, Southern tractors, Dunlops, Agriline, Forge services (for Sparex) and others, why o why don't they put the Forsdon part numbers next to the products? If I was selling that would be the first thing I would do, set me apart from competitors.
Andy,
Forge is quite good about quoting equivalent Fordson part nos - I've used it for reference quite a few times.

Good to see you're back on the trail. I'm sure that with your thoroughness, it'll be a great rebuild. Look forward to hearing more! :wink:
Bensdexta - 1961 working for a living!

Tubal Cain
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Re: Doris NP Super Dexta rebuild

Post by Tubal Cain »

The nuts and bolts on the Dexta are either UNF or UNC for which you will require AF spanners not Whitworth!

Gerald

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Hi Gerald

I have lots of AF spanners, some good old King Dick, some cheaper brands however the Whitworth spanners I have seem to be a tighter fit when you get a difficult bolt that needs a good snug fit. I took a bolt off the handbrake linkage that the correct AF spanner just took the corners off but the Whitworth did the business. I couldn't get an AF socket on it due to the proximity of the casting and I don't use the bi-hex sockets if its a tight one, full hex only.

So I'm not questioning you, I know your right, just bought these for those difficult so and so's :wink: When I mean snug fit the spanner needs a bit of a tap.

BTW, I bough the punches after seeing your video on brake shoe replacement :D

EDIT - forgot to mention that the previous owners seem to have used a random selection of bolts, so although it may have started off as purely AF it now has a goodly selection of types of fixings, including bent nails, plumbers horse hair on threads, odd bits of string as well as none AF bolts. :? I need all the help I can get to remove some of this stuff :lol:

2nd EDIT! - I've got my eye on some AF box spanners on ebay too - no point hammering a whitworh spanner on if the AF fits and frees the bolt.

Cheers
Andy
Last edited by Dextrous on Tue Oct 09, 2012 9:28 am, edited 2 times in total.

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Bensdexta wrote:
Good to see you're back on the trail. I'm sure that with your thoroughness, it'll be a great rebuild. Look forward to hearing more! :wink:
Thanks Ben, I'm looking forward to getting on with it :D

One dilemma, where metal is pitted but serviceable, should I replace, fill or just paint. For example, brake back plates, hand brake bars and misc other bits of visible metal? :scratchhead:

I'm not after a concourse rebuild but while I'm at it I may as well make a good job of it.

Cheers
Andy

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Here's a few pics before I head off to Sherwood forest Center Parcs for the weekend, I will be quite a few pounds lighter when I return, however the kids will love it.

Here's a general view of the status of Doris - I'm removing stuff from the back to the front. I'll replace any bushes or seals before giving her main castings a coat of Sodium Hydroxide gel (caustic soda) to remove all paint and grease before giving a coat of zinc primer. I'll take care around aluminium components such as the hydraulic pump cover as it attacks some metals readily. You can just see the renovated half shafts in the top left corner, I've marked them left and right, not sure if they are handed but seems a good idea. Note the plastic take-way tubs - perfect for putting parts in and labelling them - especially things liek woodruff keys :wink:
Image

Here's a picture of inside the rear axle casing showing where the bolt holding the check cahin bracket has broken out casuing all the axle oil to exit when you take the bolt out. There was some plumbers horse hair on the back of the bolt so this is not recent so I'm hoping all the little bits of casting have been fished out, I will have a good look to see if I can find any.
Image

Here's the engine next to the new engine stand, very sturdy it is too. I intend to take off the clutch and flywheel then use the bolt holes behind to fix the block to the stand. I haven't work out exactly how yet but looks feasible.
Image

The parts cleaner has proved invaluable to wash off all the crud, I use bilt hamners Surfex HD for degreasing.
Image

I can't find a cheap source of Belzona 1111 to repair the back of the bolt hole casting or the ovality in the front axle bush hole yet - still looking.

Cheers
Andy
Last edited by Dextrous on Fri Oct 12, 2012 2:51 pm, edited 1 time in total.

Bensdexta
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Re: Doris NP Super Dexta rebuild

Post by Bensdexta »

Looks like you are well equipped! Keep the photos coming! :clap:
Bensdexta - 1961 working for a living!

Tubal Cain
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Re: Doris NP Super Dexta rebuild

Post by Tubal Cain »

I can reccomend the following for removing wasted bolts and nuts, and they are universal and I can highly recommend them. Try a search on ebay if you are interested as there is an additional set which expands the range.

Searh on ebay for Irwin bolt grips

Gerald

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Tubal Cain wrote:I can reccomend the following for removing wasted bolts and nuts, and they are universal and I can highly recommend them. Try a search on ebay if you are interested as there is an additional set which expands the range.

Searh on ebay for Irwin bolt grips

Gerald
Hi Gerald

they look interesting, I may have to invest in some of those, they may stop the air from being quite so blue in the workshop :wink:

A lot of the bolts are up against a shoulder and you can't get a socket or a ring spanner on but a box spanner might, and the combination of soaking in a bucket of diesel (if small enough) then using a very tight open ended spanner
"persuaded" to fit seems to work. I have only had to drill out three bolts so far, rear mudguard brackets on on side and one bolt on the top link. Don't think they will be the last though!

cheers
Andy

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Just back after a weekend away and I had an hour before parents evening at the kids school and have a couple of hours later tonight. I've made the gasket for the PTO and will put that back in later this evening.

My last task is mounting the engine on the stand. I need to take off the clutch, flywheel and engine adaptor plate first. I've loosened the nuts on the clutch and marked the position of the clutch in the relation to the flywheel with a centre punch. Not essential but my dad taught me its generally good practise to put stuff back on the way it came off :D

The next bit I'm not too sure about, the part list isn't detailed enough and the engine removal and replacement section of the workshop manual is a bit sparse. There are marks on the flywheel for TDC etc. so I'm guessing the the flywheel must be keyed onto the crankshaft in some way. I'll find out later.

I'll then remove the engine adaptor plate and bolt the engine block to the stand, I haven't got Tool No 6091 as per the manual :roll: but I'll use bolts just at the end of the block above the crank so I can get to most things. That's the plan - I'll let you know how it goes........

Cheers
Andy

Bensdexta
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Re: Doris NP Super Dexta rebuild

Post by Bensdexta »

Dextrous wrote:The next bit I'm not too sure about, the part list isn't detailed enough and the engine removal and replacement section of the workshop manual is a bit sparse. There are marks on the flywheel for TDC etc. so I'm guessing the the flywheel must be keyed onto the crankshaft in some way.
Andy,
IIRC it is physically possible to bolt the flywheel onto the crankshaft in any one of six positions.

Howeve the correct position is when the two untapped 'seventh' holes, one in the flywheel and the other in the crankshaft, line up. See page 12 of the Engine Wk shop manual

Keep up the good work :wink:
Bensdexta - 1961 working for a living!

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Thanks for that Ben - I was reading the wrong section. :oops:

I've got the clutch, flywheel and backplate off, pictures later. I need some longer 9/16 UNF bolts to get the engine mounted on the engine stand, I also need to consider anything else I need to do at this end of the crankshaft. As I will be checking the crank then probably nothing until I renew the rear oil seals.

Cheers
Andy

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

While I've been waiting for bolts to mount the engine block on the engine stand I've been stripping the back axle ready for degreasing, stripping and painting. The only really difficult bit is the top link bracket or rocker as its called in the parts list. The bush or pin that holds it in place must be a push fit into the rear diff casting and doesn't want to move.

Do I clean it up and paint it in situ or get the tinker out? The rocker is a bit loose on the bush but I think it will take some heat and pressure to get it out, I've been soaking it with penetrating oil for a month.

Anybody managed to get one of these out before? What technique did you use? Here's a pic, if you can't see the pin on the far right then you need to right click and choose "view image" some browsers at some screen resolutions seem to truncate the picture.

Image

Bensdexta
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Re: Doris NP Super Dexta rebuild

Post by Bensdexta »

Dextrous wrote:Do I clean it up and paint it in situ or get the tinker out? The rocker is a bit loose on the bush but I think it will take some heat and pressure to get it out, I've been soaking it with penetrating oil for a month.

Anybody managed to get one of these out before? What technique did you use? Here's a pic,
Here's a thread which may help
http://www.fordsontractorpages.nl/phpbb ... ker#p31088
Bensdexta - 1961 working for a living!

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Thanks Ben - just what I needed :beer:

I'll have to start using the search box a bit more :wink:

Cheers
Andy

marcusgs
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Re: Doris NP Super Dexta rebuild

Post by marcusgs »

Hi.

If you have a stick (ARC) welder, simply run a bead of weld through the bush and it will tap out relatively easily. :D

The new one should go in without too much hassle, I put a little copper grease on mine... not sure if it was a good idea or not, but it's not fallen out yet!!
Mark

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Hi Mark

That sounds like a plan, I'll give that a go.

Here's today's progress, I got the engine on a stand at last, and now I'm stripping it down. I got the head off, I think I may need a bit of citric acid to clean out the water system :wink:
Image

Here's afew of the pistons, the left hand one looks very different. Not sure what it is yet. There is definitely some water action, its been dried stored for years and the engine is not seized.
Image

A closer look a that piston
Image

A view over the valves, it is taken from the underside while it was suspended from a hoist.
Image

I also managed to change an O ring in the lathe gearbox which had gone hard and was weeping oil. The 1958 Colchester lathe manual referred to a pioneer O ring part number which I couldn't find anywhere. However I found a cross reference to a US military part number, which in turn was cross referenced to a standard BS O-ring. Good old military store keeping :)

Cheers
Andy

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

I'm just about to order some parts - I'm looking at the dual clutch at the moment.

I've no reason to believe the clutch is faulty, we drove it off the delivery lorry 8 years ago, however there was a lot of oil in the bell housing, so much that the previous owner cut a drain slot in the bottom of the bellhousing with an angle grinder. So the plater are probably contaminated with oil. The oil was black so probably engine oil. I'm renoveating the engine so will fix the rear rope "seal" when I put the crank back in.

Questions I have :-
Is it worth changing the gearbox/clutch seal while I am in there?
It's about £55 for both clutch plates versus £250 for a new dual clutch assembly. What are the main issues with just replacing the plates?

Cheers
Andy

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Re: Doris NP Super Dexta rebuild

Post by ol'Blue »

Any chance the exhaust valve for the front piston was open and some rain water got in from the exhaust?? Otherwise, you have a puzzle to figure out.......Thanks for the posts. Old Doris will live again with your patience.....

dave
1964 Super Dexta, ol'Blue

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Hi Dave

It is possible. She was stored outside to begin with but with the exhaust removed and a fitted tractor cover over her. After that she was moved to the barn where she was dismantled before being hauled up into the workshop above. The barn was in the process of being constructed and didn't have all the boarding on it. The exhaust manifold was facing the leeward side which is covered in trees so it would be difficult to get water in that way but it was stood for 18 months or so and we do get wild weather up in the Pennines (at least by UK standards!) so that may be the obvious culprit.

I ordered a Sparex engine kit from Dunlop's of Northern Ireland on Monday so she will have new pistons and valves/guides soon and I also ordered a gallon of 42% phosporic acid to remove any remaining rust in the water galleries. I also discovered that my local Agri engineer about a mile away has all his own kit for pressing in liners, boring and honing, head skimming etc. :beer: The only thing he doesn't do is crank grinding but I know a man who does.

So I'm all set to accelerate the build of Doris after 8 years. My aim so to take her to the local classic car show in Hebden Bridge in August next year with the back box full of beer, I brew my own.

Regards
Andy

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Here's tonight's progress

Took the hydraulic cover off with the hoist
Image

Looks OK inside however on closer inspection there's a thick layer of gunk at the bottom and a bit of water. I want to check out the oil inlet filter tomorrow, I have a new one on order.
Image

Found the broken bits of the casting from the back of the check chain bolt hole in the bottom, I'll get the rest of the gunk out tomorrow and see if there are any more bits.
Image

Regards
Andy

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

At lunch time I quickly cleaned the rest of the gunk out of the bootom of the hydraulic chamber and the back axle - I had the tractor tipped up at about 45 degrees all night so there was not much left in it. I changed the hydraulic filter then decided to slip the PTO shaft back in before taking off the PTO selector so I can paint the main castings and change the selector O-ring. I had already replaced the PTO oil seal.

Now I didn't want to smash out the back of one of the bolt holes in the axle casting like a previous owner/mechanic had done, so I checked the bolts for the PTO shaft and the check chain. They are as follows

Check chain bolts - part no. 21447-S8 which turns out to be 7/16 14 tpi and 1 1/2" long but has a 11/16 AF head
PTO shaft bolts - part no 20410-S which are also 7/16 14 tpi and 1 1/8" long but with a 5/8 AF head

So the same UNC bolt size but different length and different spanners sizes. The 11/16 AF head on a 7/16 bolt is normally associated with a nut size not a bolt size - however I am definitely no expert on this :?

Anyway, if I use the correct bolts they tighten up on the casting before gripping the PTO shaft or check chain bracket so I need to clean out the threads with a tap or get a slightly shorter bolt. 7/16" UNC 1" long sounds like the one to get if I cant find a tap for the PTO, however for the check chain I guess 7/16 UNC 1 1/4" but how do you specify a fat 11/16" AF head on fleabay :D

I think I need a beer :beer:

EDIT- after sharing rather a lot of homebrew with a neighbour who ha shad a garage business for many years, and a lot of old buses, vans, bikes, cars and tractors he told me that the bolts with the big head are almost certainly Whitworth bolts, similar thread, different head. A previous owner must have had all 4 check chain bolts swapped for BSW bolts rather than UNC for some reason and cracked the casting in the process. :? :cry:

The good news is he has the tools in his garage to refurbish injectors and is doing the Doris the Dexta's for free :D

He's broken the casting on the top of his Fergie 130 that connects the top link to the rest of the tractor so if you know where he's likely to find one near the north of UK ne let me know - hic! :shock: :D
Cheers
Andy

Mervyn Spencer
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Re: Doris NP Super Dexta rebuild

Post by Mervyn Spencer »

a neighbour who ha shad a garage business for many years,

Proof that you guys had a good party. :wink: :beer: go for it .

Dextrous
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Re: Doris NP Super Dexta rebuild

Post by Dextrous »

Now I'm over the post party hangover, I'm stripping the head and block and hydraulics - or rather I'm finding where I need more tools.

Valve spring compressor ordered, however the "crankshaft ratchet nut" inside the fan pulley is a bit more problematic and either involves buying a large and expensive 1-5/8 AF box spanner, or visiting my neighbour with the garage business - guess which one wins :wink:

When I say neighbour he's about 2miles away up in the hills and I only borrow tools that I can return the same day, its a business and you can gurantee he'll need that tool he hasn't used for 2 years if I have it.

Compulsory position control arm stop pin wear photo :D
Image

Regards
Andy

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Re: Doris NP Super Dexta rebuild

Post by Bensdexta »

Dextrous wrote:.... however the "crankshaft ratchet nut" inside the fan pulley is a bit more problematic and either involves buying a large and expensive 1-5/8 AF box spanner, or visiting my neighbour with the garage business - guess which one wins :wink:
I found that not all 1.5/8" box spanners will fit, but my cheapo chinese one did.

Also you will need to lock the crankshaft somehow to prevent it turning whilst you undo the pulley, unless you have an impact wrench (and toughened box spanner). I made a long spanner which I bolted onto the pulley bolt holes. This worked but I later discovered my pulley had a hairline crack (spotted by an eagle eyed reader after I posted a photo on here!) by the key way. I can't help wondering if the spanner attached to the pulley was the cause. Better to lock the crankshaft itself rather than the pulley, so maybe bolt your spanner on using the flywheel holes. :wink:
Bensdexta - 1961 working for a living!

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