308 w/pump altering design old to new

Hello from Germany,

I would like to try altering the design of an old 308 waterpump I have here to the newer design.
I know some of you have done this in the past. It's just widening the seal seat in the housing, manufacturing a ring for the new seal and reducing the diameter shaft. Problem is; my newer pump is in the car and my old one on the shelf
Does anyone have the correct dimensions for the housing bore where the seal will be installed and the diameter of the shaft ?

Best Regards and thank you in advance

Martin

 

of course; but there are a lot of numbers
earliest design was housing 103705 for small bearings with shaft 103795.
Next design was housing 116156 for large bearings with shaft 103795.

Latest design - actually found on 328 cars and what I have - is housing 121252 and shaft 151253.
On the earliest designs there was a two part seal no. 100433 and on the later designs a two part seal 120948 & 121553, which was eventually superseded by a one part seal 152051.
For altering the design from old to new it is necessary and possible to make a reducing ring for the housing with an outer diameter matching the existing bore in the housing ( press fit ) and an inner diameter for the seal 152051.
Furthermore the diameter of the old shaft has to be reduced to accept the inner diameter of the metal sleeve of seal 152051 ( also press fit ).

These two dimensions are what I need for machining my old design housing and shaft, because like mentioned in my first post, the newest pump I have is on my car and I have no sample at hand.

For completeness; there was also a different impeller 121254 with a shoulder for the late design two part seal, holding 121553 in place. This isn't necessary any more for the latest one part seal. Therefore one can use the old impeller 103806 together with the newest one part seal.
There's a small ridge on the old impeller which might have to be dressed to size on a lathe.

Best Regards from Germany

Martin

 

Steve; yes I want to use the latest one piece seal 152051. This IS the reason for my initial question. One could order a new design shaft for ~ 60 GBP at Superformance but since the modern design shaft diameter is smaller at the seal I can reduce it on my lathe. For the housing there's definitely a bushing for the seal's outer sleeve necessary.
I don't know yet if it's really necessary to modify the impeller. And the pulley is the same. Fits old and new design shaft.

Actually it's quite simple to perform -provided, that there's a lathe within reach - but I have no dimensions and tolerances.
I would have to dismantle my working w/p, what would be insane.

I know, that Dave Helms once told, that he does this job regularly. I hope he will chime in But others who have done this also.

Best Regards from Germany

Martin

 

o.k; but this design would involve much more design changes. Much too complicated. But since the latest w/p design for the 308/328 cars was the one and only reliable one - and it IS reliable - I want to go for this. The original design isn't worth the rebuilt process in my eyes. I rebuilt two, the second with the biggest effort and never got it completely leak free. Not even after dealing with the important seal surfaces on body and shaft, so that they were perfect.. The last w/p I rebuilt, was the modern one with 152051 and it's absolutely dry since 6000 mls. And rebuild wasn't even necessary because of leaking, but because the bearings began showing significant play. Seal was perfect, but unfortunately it will get destroyed when dismantling, while pressing out the shaft.
One FChatter - Rifledriver, IIRC - once told, that he is scrapping all of the old design w/p and only installs or rebuilds the new design, but scrapping would be a pity for me.
Even more, because the 'new waterpumps', which are available, are complete scrap.

Best Regards

Martin

 

Brian; this is absolutely the same what I intend to do. What seal did you use ?
I have Ferrari part 152051 here, which was not too expensive and is the most modern design of such seals.
How did you determine the press fit on the shaft and and ring ? Trial and error ?
And the height of the ring, which will affect the necessary prestress of the seal. Say, the overall height when installed and spring compressed.

Best Regards and thank you

Martin

 

Hello,

in the meantime I have got a detailed engineering drawing from a german manufacturer of such seals. The drawing shows the exact equivalent of the italian manufactured 152051. The only difference is the better quality of the materials ( stainless steel ).
Now I have all the necessary data ( dimensions shaft and housing with tolerances, prestress say working height of the installed seal, etc. )
There's even a drawing which shows the dimensions for the correct special tool to install the seal properly.


Best Regards from Germany

Martin

 

I even got a 3D CAD model of the correct seal from them this morning. So I can design this modification in my CAD before screwing something up on my pump housing
I will document this task and post the dimensions.
I cannot post the engineering drawing I got, because they said, it's confidential.

Best Regards from Germany

Martin
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o.k., I will make a small story about the process of converting an early style waterpump to accept the most modern seal design.
This afternoon I began with the housing.

Like you see on the first picture there is some machining on the housing necessary to adjust the seal's working height specified by the manufacturer.
I don't know if it really doesn't matter a lot if you skip this step, but since I'm aware of it I did it.
I machined the face of the original seal and turned down around 0,5mm based on my calculations. If I would skip this step I would end up with 0,5mm more prestress on the seal. Maybe it doesn't matter, but o.k.... I will go for what the seal manufacturer says.
First I clamped the housing on my lathe and checked / adjusted axial runout which shouldn't be more than 0,01mm.
I don't know, whether all pumps are identical regarding this dimension, but if you measure like shown on the second picture the final depth has to be 19,8mm. For measuring this I put a second caliper across the pump flange and checked the depth till the original seal's end face.
The above mentioned 19,8mm are AFTER subtracting the thickness of the helper bar ( in my case the caliper ).
Then I manufactured the aluminium ring. Its dimensions are OD 41 n6 (+0.017/+0.033mm). ID = 36.45 +0.05mm. Height is 8.15mm. OD is a press fit for the original seal bore which is 41H7. ID is manufacturer's default, and the height is due both to the seal's outer housing height and my calculations.

After all I pressed in the ring and added a small amount of Loctite 648 to be sure, that the press fit will be leak free.

Next step will be the shaft.

Best Regards from Germany

Martin
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this dreaded inch / metric thing
But these are identical measurements. Only difference in hundredths of mm, which result, because you made the ring with the seal and I had a manufacturer's drawing telling me the mating dimensions for that seal. Seems, that there is actually some standardization between the manufacturers.

Best Regards from Germany

Martin

 

Hello from Germany,

I could proceed a little with my waterpump.
Once again after adjusting runout I turned down the shaft to the new dimension 16mm and installed the seal.
BTW; I purchased this old style shaft some years ago from a well known parts dealer and it showed radial runout of 0.1mm between bearing seat and seal seat. Manufacturing fault. I eliminated this; radial runout is now ~ 0.01mm.

Installing the seal without damaging the seal or the bearings is the crucial step.
After a thorough discussion with the manufacturer we came to the conclusion, that it is not the best way to install both bearings and finally the seal.
If you do this, it may pre-damage one of the bearings. The force needed for installing the seal is up to 1500 N depending on the surfaces and tolerances. This is too much for going across the rollers.
Therefore I did it that way:
First step; insertion of the inner bearing. No conical washer and snap-ring so far.
I heat the housing on ~80 centigrade; so I can insert the bearing with my fingers.
Next step; insertion of the shaft supporting the inner race of the bearing.

For installing the seal I fabricated a helping tool you can see on one of the pictures. It maintains the working height between outer and inner portion of the seal and avoids that the spring will be compressed solid damaging the seal silicon carbide rings.
Then I pressed the seal into the housing while supporting the inner bearing's inner AND outer race.

Next step is installing the conical washer and circlip. It's a little bit cramped because the shaft is already installed, but it works.

Now I could insert the spacer and the outer bearing. For this I will heat the housing once more. If heated enough I must just support the shaft while pressing on the inner race. Due to heat there's almost no axial load on the outer ring, which could damage the bearing.

Unfortunately I dropped the second bearing onto hard concrete on Saturday evening and don't want to use this bearing any more.
Therefore I have to wait till Monday, when I can purchase another bearing.

BTW; I would prefer showing my pictures step by step with descriptions between them. Don't know how this works on this board. Any hints ?

Best Regards from Germany

Martin
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Finished !
O.k.; some steps sound complicated, but I think it's crucial to do the conversion that way, to avoid pre-damage to the bearings.
I heated the housing once more and pressed the outer bearing onto the shaft. Installed the impeller with a little Loctite on the thread, torqued it down with 25Nm, because I think this nut is prone to undertorquing.
Bending the new lock tab - picture shows it still unsecured - and now I have a spare waterpump with most modern seal design which once was an early big bearings version with the out-dated, unreliable seal.

Best Regards from Germany

Martin
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Peter; I just compared my parts books Euro 308GTB/GTS '80 and 308GTB '76.
Since the earliest pump with small bearings and the later one with big bearings use the same out-dated seal 100433 and shaft 103795, I can state, that my conversion also works on the small bearings pump.
I think, that this seal design is just unreliable and prone to leaking and if some grime has plugged the drain holes ( seen on my first waterpump ), bearings get damaged, no matter big or small.
Like mentioned in one of my first posts in this thread, I tried to rebuild two waterpumps with the old seal and never got it completely leakfree. I don't think, that I botchered, but finally gave up. The last one I rebuilt with the similar seal design like on this conversion (152051), I have now in my car and is absolutely dry.
You're welcome for any further questions regarding this conversion.
Talking about the seal; the very same design is available with different mating seal materials. Carbon / Ceramics; Carbon / silicon-carbide.
I used the most modern version: silicon-carbide / silicon-carbide. Housing elements made of brass and stainless steel.
The manufacturer sent me one for free for testing purposes
Normally it's around EUR 25,-- (US$ 35,--). If you have problems obtaining a seal, let me know.
The genuine Ferrari seal with identical dimensions ( 152051 ) is much too expensive for what it is.

Best Regards from Germany

Martin

 

Peter; coolant doesn't matter a lot regarding this seal. Manufacturer told me, that those seals are designed for truck and coach applications, and they took into account, that maintenance is not always the best.
Materials are chosen for the worst case, say plain tap water.

They also told me, they got back samples, which began leaking after around 1 million kms.

Therefore using a 50/50 mix with conventional anti-freeze and distilled water is more than good enough.
This is the same, what I use since years. Even less anti-freeze (~ 60/40 )

Best Regards from Germany

Martin

 

Due to Peter's conversation it came to my mind, that I forgot an essential information throughout that thread.
No matter big or small bearings, one should use C3 bearings, which are more suitable for these high operating temperatures.
Ferrari also put them into their late waterpumps. The last quality waterpumps, they sold some years ago. Not that crap which is now offered as 'genuine Ferrari w/p'

Best Regards

Martin