904 torque convert problems

Posted By: onig

904 torque convert problems - 10/10/12 02:47 AM

Who is using a 904 trany in their race car and has had a converter hub/snout problem.
If so, what was the problem and what was the fix.

Thanks
onig

Posted By: rickraw

Re: 904 torque convert problems - 10/10/12 03:01 AM

i found a crack in my hub( corner of the pump gear slot). sent it to lupo. they welded on a chromemoly hub & rebalanced. u have to have the ring on the stator shaft machined off if there is one there. it restricts flow.

Posted By: MR_P_BODY

Re: 904 torque convert problems - 10/10/12 03:11 AM

Cracked hubs are common on the 904... send it to a
conv company for repair

Posted By: GTX5877

Re: 904 torque convert problems - 10/10/12 04:13 AM

Need to index the bellhousing like a 4 speed or it can happen again.

Posted By: mshred

Re: 904 torque convert problems - 10/10/12 04:15 AM

Quote:

Need to index the bellhousing like a 4 speed or it can happen again.

how would you do this with the automatic?

Posted By: MR_P_BODY

Re: 904 torque convert problems - 10/10/12 05:10 AM

Quote:

Quote:

Need to index the bellhousing like a 4 speed or it can happen again.

how would you do this with the automatic?

The proper way is to use the case(empty) that you will
be running and index the pump housing with the dial
indicator then build the trans

Posted By: Evil Spirit

Re: 904 torque convert problems - 10/10/12 03:53 PM

My converters now use A500 front pump gears and converter snouts. A500's have flats to drive pump gears and eliminate the crack issue. This is the best fix. Have your converter switched to this drive and use late A500 pump gears.

Posted By: onig

Re: 904 torque convert problems - 10/10/12 08:36 PM

Quote:

My converters now use A500 front pump gears and converter snouts. A500's have flats to drive pump gears and eliminate the crack issue. This is the best fix. Have your converter switched to this drive and use late A500 pump gears.

Will the A500 pump gears just drop in the 904 pump housing?

Posted By: onig

Re: 904 torque convert problems - 10/10/12 08:37 PM

Quote:

Quote:

Need to index the bellhousing like a 4 speed or it can happen again.

how would you do this with the automatic?

I was also wondering this myself.

Posted By: onig

Re: 904 torque convert problems - 10/10/12 08:40 PM

So are these cracked hubs due to alignment/indexing issues or are there other reasons.

Posted By: dizuster

Re: 904 torque convert problems - 10/10/12 09:43 PM

A500 pump gears are the best solution in my mind. Another solution that turbo action uses is to make the converter snout thicker. However this requires the stator support lube dam to be machined off.

I don't think it has anything to do with indexing. There isn't an inherant problem with 904's that 727's wouldn't have. The issue is the diameter of the converter snout (small), that crack from the pump gear load. My guess it happens in race cars more because of the increased pump pressure.

Posted By: mshred

Re: 904 torque convert problems - 10/10/12 09:44 PM

Quote:

A500 pump gears are the best solution in my mind. Another solution that turbo action uses is to make the converter snout thicker. However this requires the stator support lube dam to be machined off.

I don't think it has anything to do with indexing. There isn't an inherant problem with 904's that 727's wouldn't have. The issue is the diameter of the converter snout (small), that crack from the pump gear load. My guess it happens in race cars more because of the increased pump pressure.

so just changing the pump gears to A-500 stuff and getting a converter with an A-500 snout is the solution? Is there any issue with dropping the A-500 pump gears into the 904? or is it a direct swap?

Posted By: mshred

Re: 904 torque convert problems - 10/10/12 09:56 PM

Quote:

Quote:

My converters now use A500 front pump gears and converter snouts. A500's have flats to drive pump gears and eliminate the crack issue. This is the best fix. Have your converter switched to this drive and use late A500 pump gears.

Will the A500 pump gears just drop in the 904 pump housing?

oops, looks like I asked the same question as you

Posted By: mshred

Re: 904 torque convert problems - 10/11/12 04:17 AM

anybody have the answer for this? my local transmission parts house has pump gears 78-92 pump gears (2 lugs style on inner gear) and pump gears for 93-04 (2 flats style on inner gear), the latter which I am assuming for the A-500. If these will just drop right in, I should be good to go.

Can anyone confirm this?

Posted By: ultimatelenny

Re: 904 torque convert problems - 10/11/12 12:50 PM

I recently built a few 8" converters for the 904 with the A500 pump. You could give Chris Andrews a call at Andrews Racing in Colorado, his number is 720-939-4896. He has done a few of these with good results. Hope this helps you out.

Posted By: dizuster

Re: 904 torque convert problems - 10/11/12 04:26 PM

Yes they just drop right in. You just need the converter updated.

Posted By: dartman366

Re: 904 torque convert problems - 10/11/12 05:09 PM

they also have a replacement snout that is not only thicker but has a larger radius at the bottom of the drive slots, that is how my new one is done, but the newer style with the flats is interesting to me, I believe Ford used that style for years.

Posted By: Evil Spirit

Re: 904 torque convert problems - 10/12/12 03:14 AM

Quote:

they also have a replacement snout that is not only thicker but has a larger radius at the bottom of the drive slots, that is how my new one is done, but the newer style with the flats is interesting to me, I believe Ford used that style for years.

This is another one of the best kept secrets that for some reason nobody seems to have caught on to. I know I've personally posted this quite a few times myself. These 904/A500 pump gears with the flats instead of the drive tabs came out in the early 90's.

One of the inherent flaws of the lugs can be partially corrected - by shimming the converter back into the pump, so the tabs on the pump gear go deeper into the slots on the converter pump drive (snout). Most of the drive hubs I saw cracked or broken showed that the lugs were towards the outside end of the slot. While I try to make it so you only pull the converter forward about 1/16" to the flexplate, sometimes at that depth the weld that holds the drive stub on is poor and will tear up the seal.

And as others have said - there are redesigned (tab style) drive stubs and pump gears, but they are more pricey than the stock "flats" style parts.

Posted By: mshred

Re: 904 torque convert problems - 10/12/12 03:18 AM

Thanks for all this information guys! I have searched high and low for this stuff and never found anything about the different pump gears mentioned, or the different updated hub. When I order the converter I will more than likely just go the A-500 hub route with the later pump gears, especially if they almost totally eliminate the broken hub issue that the standard style seems to have

Posted By: Evil Spirit

Re: 904 torque convert problems - 10/12/12 03:24 AM

Quote:

Thanks for all this information guys! I have searched high and low for this stuff and never found anything about the different pump gears mentioned, or the different updated hub. When I order the converter I will more than likely just go the A-500 hub route with the later pump gears, especially if they almost totally eliminate the broken hub issue that the standard style seems to have

A bit of advice - have a set of the flat drive style gears in your hands before you have the converter built for them. There have been times my supplier hasn't been able to get them - they were back/ordered.

Posted By: mshred

Re: 904 torque convert problems - 10/12/12 03:25 AM

Quote:

Quote:

Thanks for all this information guys! I have searched high and low for this stuff and never found anything about the different pump gears mentioned, or the different updated hub. When I order the converter I will more than likely just go the A-500 hub route with the later pump gears, especially if they almost totally eliminate the broken hub issue that the standard style seems to have

A bit of advice - have a set of the flat drive style gears in your hands before you have the converter built for them. There have been times my supplier hasn't been able to get them - they were back/ordered.

will do! I plan on disassembling the entire trans first just to double check what it has, what it needs, what I thought it needed but doesn't need, etc. before ordering anything

Posted By: Mcode69

Re: 904 torque convert problems - 10/12/12 07:24 AM

Anyone know where I can get the late convertor neck by mail order?

Posted By: onig

Re: 904 torque convert problems - 10/13/12 08:46 PM

Great info here.
Thanks guys.

Onig