DOHC MT75 ground clearance

[voucht]

Hi,
Sorry I multiply the threads for my engine/gearbox set-up problems, but I'm still struggling. Thinking again about installing the DOHC+MT75 and modifying the trans. tunnel. Not sure yet, but I have a question about this set-up :

Did anyone fit a 2.0i DOHC + MT75 gear box in the Roadster ? If someone did, could you please explain me how you managed the ground clearance problem ? The lowest point of the MT75 gearbox is leveled with the lowest point of the DOHC oil sump. So it is useless to shorten the sump if the gear box is lower anyway, but the ground clearance problem remains. What is the solution ?
Thank you for your answer and advices.

[Matthew]

Hi

I've fitted the DOHC + MT75 into my car and have hopefully solved the ground clearance issue by cutting the bottom two mounts off the bellhousing flange, leaving the base more or less flush with the curved section. This gains you about 25mm and I'm planning to shorten the sump by the same amount.

With the scuttle/nosecone I've got this still leaves me with a need for a bulge in the bonnet

Matt

[voucht]

Hello Mat,
Thank you for your reply. OK, I see what you are planning. My problem is shortening the sump : it is in aluminium and I can't weld aluminium
I still have to think about that. Thank you for your help. Could you please keep me posted on your work with pictures, would be great to see what you did and what you are going to do with the sump.
Thanks a lot.
Regards.

[Oscar]

I love reading random posts about a problem I haven't gotten to yet!

Will be making a note of this for when I eventually get round to working on the gearbox.

Quick question, (haven't got the gearbox handy for a peek) are those 2 mounts used or are they just extras for a different setup? I'm a bit cautious about cutting off any mounting points if they're needed!

[deezee]

I chopped the two lower gearbox bolt holes out of my sump when i reduced it by 35mm. I'm using sierra dohc 8v sump on my engine. I'm using the type 9 gearbox though. Engine is solid. Its ok without using those bottom sump to gearbox mounts.

[voucht]

I second Deezee : assuming that the type 9 has no lower mount points, removing the ones from the MT75 for ground clearance seems to be OK. It is necessary anyway to shorten the sump.

Speaking of that Deezee, how did you shorten your DOHC oil sump? Do you have pictures of it you could post here please? Did you do it yourself?

Thank you

[Matthew]

Hopefully losing the bottom 2 bolts isn't going to cause a problem. There are another 2 just above that I've retained as you can see in this picture



Once the sump has been cut back the end of the bellhousing will be flush with the bottom of the sump.

Matt

[deezee]

Yeah, did it myself with a TIG welder. Not pretty, but doesn't leak. Its welded inside and outside.

Edit: I don't have a photo of it fully assembled, but the sump sits the same height as the gearbox bellhousing.

Sump offered up against the Type 9 Gearbox


Sump and oil pickup have had 35mm removed from them


Sump trial fitted onto the engine

[voucht]

Thank you very much for the pictures, very instructive.

So you actually reduced the oil capacity of the sump, as the part you removed is not compensated by increasing the volume of the front part of the sump, am I right?

I roughly calculated. The inside of the part of the sump you cut off is more or less a 15x15cm square. Height of the cut-off part is 3.5cm, the lost volume is 15x15x3.5=787cm3 = 0.787 litres, so about 16% of the 4.75 litres the sump is supposed to hold.

May be it does not make a big difference, but could you please confirm it is OK and why?

If it is OK, I will definitely shorten my sump in the same way

Thanks a lot.

[deezee]

I've not had any problem with oil surge since cutting the sump down. I can only say what my experience has been, which has been spirited road driving (that is to say quick enough to squeal the tyres as the car tends to lift a wheel on cornering)

I fitted an Accusump to the car to control oil surge, but its not actually kicked in as the pressure has never dropped that low So a rather expensive and heavy backup system. Whether it would drop low on a trackday, I couldn't say.