7 replies to this topic

[AlexMozza]

I am currently investigating an issue with an automatic, Its a SPi Auto. Its got a rebuilt gearbox that's done about 15Miles in it. Rebuilt by TES Transmissions.

The gearbox selects all the gears, and moving up and down the selector works fine.

The only issue is that when you floor it, the kick down seems to go a bit erratic, In first and second, the revs slightly rise, before selecting gear. But when it comes to third and fourth, the engine revs up to about 4500 before selecting.

It is almost as if the transmission is slipping, but only when selecting 3rd and 4th.

Its got 20/50 oil in it, correct levels and the engine is in good condition.

 

I'm definitely no Auto expert so any help would be appreciated!

[alex-95]

I thought that the autos should have 15w40 oil in.

[AlexMozza]

I've always been told that its 20w50 :/

[dyshipfakta]

Nah I'm clueless hope you get it sorted though.

Edited by dyshipfakta, 12 October 2015 - 07:46 PM.

[Spider]

I'm certainly no 'expert' on these, but another thing to check is the Oil Pressure. The Auto section of the Oil Circuit runs higher pressures, in all forward gears, they need to run at 75 - 85 PSI at 1000 RPM and in Reverse, 115 - 125 PSI at 1000 RPM, these pressures ate when the Oil is at 80⁰C. There is a test port on the Oil Filter head for checking this. The engine itself runs 'normal' pressures.

 

Something else to check is the shifter adjustment, though I'm not sure if that would cause these problems, but I have previously been cautioned that they need to be in fairly precise adjustment.

 

I also have to say, I've found they respond better on 15W40 rather than 20W50.

[Guess-Works.com]

Does if flare when accelerating on full throttle, or is it just on kickdown? ie, when it selects 3rd from 4th

[AlexMozza]

Its just on kick down, when in gear,drives fine.
I am going to check the kick down rod next, just to see if it is correctly adjusted

[Wim Fournier]

In an automatic gearbox there are several clutches. In the Mini they have to work in engine oil. Point is, that there is a lot of (hydraulic) pressure needed to bring the sufraces in direct contact with each other. The (lubricating) oil  has to be pressed away. Do you agree, that with thinner oil this is an easier task? Yes? Well take 15W40 in stead of 20W50.