jatco update results

wished to report back of my findings with my jatco gearbox

firstly massive thks to hippo and nodge for the great advice

fault , slipping up hill in 3 - 4 th gear

occasional rough gear change

done the resistance checks by the ecu plug instead of at the gearbox connector as I found it easier

at connector co 932

everything was within the manufactures spec range apart from

pins 3-17 / 2-4 brake duty solenoid valve , my reading was 4.1 ohms

it should be between 2.6-3.3 ohms

also the 2-14 brake timing solenoid valve has a manufacturer spec of

between 14-18 ohms

mine read 17.6 ohms , which is within range but feel as they are both next to one another and at its close to the higher ohms reading to replace both of them

don't know yet what these solenoids do in the way of function


so here are my thoughts

do a level check only , top up if required until i do futher checks of the

high/ reverse clutch assembly

on reading the jatco service book it says the box has pressure testing points

to use the reverse clutch pressure tap and the readings in reverse should be between 80-109 psi

also reading it says if I put the gearbox into any forward gear it should read 0 ,

so that should then tell me if its above zero the plates have a hairline spilt into it and will need to replace the high/ reverse assembly inc friction plates

am trying to work through this step by step

so if after doing the pressure test and the gauge shows above zero whilst in a forward gear and using the reverse pressure port i will then need to get the parts replaced

whilst I've got the gauge to also use the other port called a low clutch pressure point to test the

drive-4-2-1 and check the readings with the manufacturers specifications

then the solenoids changed and then finally replace the oil with new

it does look very involved though of replacing the high/ reverse kit

just wished to report back of my findings

hope this makes sense and that I have indeed followed advice and made progress towards finding out 100% of the faults within this box

Keep up the good work, always good to know as much as possible about these gearboxs.

jedi said:

Keep up the good work, always good to know as much as possible about these gearboxs.

Click to expand...

am trying to understand the box as much as possible

but know it will take a while due to its complexity

nice though to learn in how to test it properly and not having to solely rely on garages

as a recon box comes out around a grand

whereas parts for this repair consisting of the friction plates, solonoids and oil come out around £250 so a huge difference in comparison

will update this to add to the already growing subject in order I can contribute in a small way and may be helpful

The more you read, and trial and error the more you will know....It may take a while but you will get there in the end....one step at a time... you will be a Jacto master soon..:darth_vader:

If mine went faulty I`d be doing the same... Good work!

jedi said:

The more you read, and trial and error the more you will know....It may take a while but you will get there in the end....one step at a time... you will be a Jacto master soon..:darth_vader:

If mine went faulty I`d be doing the same... Good work!

Click to expand...

serious heavy reading that's for sure , lol

If a measured resistance is at one end of the resistance range, this doesn't mean it's failed. It's within spec. If you look at mine some measurements are similar in being at one end of the range.
Low/flat battery in the meter will give unreliable readings.
Resistance won't advise what we think is sticking solenoids.
The pressure tests are covered in the rave disk but only briefly.
If you think the piston is cracked then look up freds by others who have had similar, and compare your symptoms.

There are different types of recon auto. Some are reconditioned in the sense that they have had the fault repaired, and are therefore up to standard for use. There are others like Ashcroft Transmissions who take it all apart, repair/replace what's required and measure/check everything before assembly and replace as required. They also have a test rig to test it on.