BE3 Gearbox Temps

[SRDT 182]

So in this case thicker oil offer more drag and more energy is wasted, it may also not flow as well inside the shafts and to the bearings.

Could a more fluid oil be the solution then?

[petert 588]

I'd have to agree with you. Thicker oil, more drag. However, the viscosity of the Motul at high temp is less than as the Penrite. TBH, I'm stumped and I'm going to have a go at cooling. I don't think it really matters which case I use.

[SRDT 182]

So if it's not viscosity what could it be.

Some oils are more tacky than others but in this case is it better to have a lot of it stick to the gears? The oil that's projected on the case is probably cooled a bit.

On the same idea if the oil is coating the gears then there is less of it on the bottom that can exchange heat with the case.

If that was the problem you could probably overfill the gearbox and see a lower temp.

 

But again we don't know how it is inside. The average oil temp is up but maybe it's lower where it counts.

[Spesh 31 1 Cars]

Any progress Peter? I've been thinking a little more about it and wos pondering if an air to water cooler might be a better idea as it'll also help get the gearbox up to temp quicker?

[petert 588]

Unfortunately a major crash earlier in the year dented the research curve. I’m definitely going to do it, as per the diagrams. Just not in the immediate future. 

[SRDT 182]

10 hours ago, Spesh said:

Any progress Peter? I've been thinking a little more about it and wos pondering if an air to water cooler might be a better idea as it'll also help get the gearbox up to temp quicker?

You mean oil to water right?

It should be usefull to keep oil temp on a narrow range, that way you can manage heat expansion / bearing preload.

[petert 588]

No, just air, like the Saxo T4 you posted earlier. We don't have any problems in Australia getting the gearbox temps up. When we eventually fit a Motec dash, I'm hoping we'll be able to control the temp via pump duty cycle.

[Spesh 31 1 Cars]

On 12/13/2022 at 8:45 PM, SRDT said:

You mean oil to water right?

It should be usefull to keep oil temp on a narrow range, that way you can manage heat expansion / bearing preload.

I do, senior moment :p

[Spesh 31 1 Cars]

So I fitted a temp sensor in a modified drain bung on the back of the diff and have just done a full day trackday at Anglesey.  Air temp around 19c all day.

 

After about 20mins of full tilt (for me) driving the temps were up around 105 to 110 but didn't seem to go any higher, got there and stayed there.

 

Stock 1.6 box with 3J plated diff using miller's crx ls 75w90 nt+

 

 

https://cdn.opieoils.co.uk/pdfs/millersoils/MOTORSPORT-CRX-LS-75w90.pdf

 

 

[petert 588]

That's encouraging to hear. I suspect I have something more sinister happening, which is creating heat.

[Spesh 31 1 Cars]

At castle Coombe today, ambient 18c and I'm seeing 120c after about 10 laps 

[Spesh 31 1 Cars]

Had this email back off miller's about the oil I use, encouraging.

 

[Spesh 31 1 Cars]

update.  Did Cadwell Park last week, ambient around 25c and was seeing temps peak at 102c.  Not quite as fast a circuit as coombe so that is likely a factor but I've also increased the endfloat on the box towards the upper limit (I forget exactly what right now) 

[welshpug 1,661]

Shouldn't be any end float, a small amount of preload, I don't recall how much but it is detailed in the 205 haynes manual.

[Spesh 31 1 Cars]

35 minutes ago, welshpug said:

Shouldn't be any end float, a small amount of preload, I don't recall how much but it is detailed in the 205 haynes manual.

went off that? 0.08mm 

 

I 

[welshpug 1,661]

should be +0.03mm preload.

 

Add a second shim/washer and tighten the seal carrier down until you just feel drag on the shaft, disassemble and measure the depth of the bearing, subtract the depth of the seal carrier shoulder less 0.03mm.

 

 

 

[petert 588]

Good result and good data. Thanks for the update.