bW35 Gearbox rebuild and Dexron2

[Al_Stag]

Hi forum,

I think I've rather answered my own question, particularly after the Spanish trip and researching the intertubes and SOC forum (lots of posts saying that Dexron is bad unless it's being rebuilt in which case the builder knows best) but I'll ask anyway:

Back Story
In the middle of Spain our BW35 lost a bit too much fluid and we needed to fill up at a local garage. Not knowing anything other than a few rudimentary words (Google Translate is a godsend!) we ended up having to use Dexron-4/5 based fluid to get us home. By the time we got home, 2k miles later, we had lost reversed with a very clunky gear change into 1st etc. Rather resigned to a gearbox rebuild.

Fast forward: Current situation


So the box is now being rebuilt by a "transmission specialist" in Hampshire (remaining nameless for the moment). On taking it on Wednesday morning I explained what had happened and asked whether it would be possible to include "bands suitable for modern fluid". He explained how the parts you could get for the BW35 were OEM quality and as such the answer was no. SO I asked which fluid, wanting to make sure it was the Ford standard M2C-33G fluid and, rather dismissively, stated "nah mate we use Dexron 2 for all these [35/65] boxes."

This has been playing on my mind rather as all searching and my own experience leans so strongly towards Dexron-based being the wrong "stickiness" for BW35.

So - my questions are:

1. Am I worrying over nothing? As an experienced pro I'd presume he knows what he's talking about. And there's a warranty there I presume as wel
2. He's meant to be a specialist - I'm hesitant that if I phone him up and demand he puts in AQF it'll "invalidate" any comeback I might have later [if required].

Thoughts please?

A.

[V Mad]

Its worrying when that happens.

Since they have confirmed the box is being rebuilt to original spec then the correct fluid is as you state, and as stated in the manual.

I have read somewhere that the Ford spec has a higher resistance to slipping of the brake bands, and that if you use the Dexron type this could lead to early failure of them.

Unless the paperwork that comes with the rebuild states any deviation from standard I think you should use the correct fluid.

[Mike J]

Had my 35 rebuilt last summer and have been running on Dexron 2 since then without any problems. Mike.

[GDPR]

I would be concerned about this - if the frictions being used are suitable for Dex2 then there is no reason to use atf - but - I would want a signed statement attached to the invoice/warranty to state the fluid to use just in case he is not properly aware of the consequences.

Russ

[Staggard]

I spoke to Jpat on this very subject, I don't know where your guy's are getting their parts from, but as far as I know these are the main suppliers of parts and they only supply bands and clutches that are compatible with Dexron. For peace of mind google JPAT and give them a ring a nice bunch of guys. Hope this helps. Graham

[harveyp6]

As an experienced pro I'd presume he knows what he's talking about.

That's a very risky presumption to make, and not one that I'd make. "Professional" could just mean he does it for a living, it doesn't mean that he knows what he's talking about.

And there's a warranty there I presume as well. He's meant to be a specialist - I'm hesitant that if I phone him up and demand he puts in AQF it'll "invalidate" any comeback I might have later [if required]

Correct, if you go against what he says he will have a valid reason not to honour it in the event of problems. However the warranty will only be for a specific time, and after that the damage may already be done, but you're on your own.

The friction materials may be suitable for use with Dexron, but the extra heat generated by the slip that Dexron introduces means that the box will be running permanently overheated.

Have a read of this:

http://www.castrol.com/liveassets/bp_internet/castrol/castrol_australia/STAGING/local_assets/downloads/a/Auto_Trans_Fluids_B1191.pdf

About half way through it explains the differences, and outlines the problems, and I'd prefer to rely on information from Castrol than elsewhere.