oil in overdrive

[Lee Dutton]

Hi all,

 

got the overdrive now installed on my 4a......been checking through the forum but couldn't find a definitive answer, question is how often should the large brass nut and I guess filter be cleaned is there a tool for this...I used Castrol EP90 oil also what is the best method of engaging OD using clutch or keep full revs up, can OD be left in when changing from 3 to 4th for instance

 

 

regards Lee

[Motorsport Mickey]

Lee,

 

Just as in life there are quite a few different opinions about oil in the gearbox, and you may have seen a few of them on the forum, how do you expect any of us to define what's right ?

The overdrive will mostly work with any old oil but the guys that build them and have done thousands over the year say Penrite 30 or 40 work best, I guess I'll be guided by them. Check out the Buckeye site where they carry out testing using a variety of oils amongst them EP90, and they don't regard it as being a long term good idea to put in the gearbox, "oil too thick cone clutch lining in the overdrive doesn't like the additives" etc.

Cleaning the oil and filter under the big nut ? how many miles do you do ? if you use the Penrite oil as recommended and in the absence of other confirmed information I'd suggest every 2 years or 30k give it a clean, that's what I'd do.

As for engaging the overdrive your picture shows a TR4 like mine which means a big ol jam pot piston and when I engage the o/d at 5000revs accelerating hard it engages even before my finger leaves the switch. If using the later o/d from the IRS cars they have 2 smaller pistons which slluurrr the o/d operation and hopefully allow them to minimise shock loadings going down their drivetrain.

 

You can leave the o/d activated as you change gear but sometimes the gap between the gears with it engaged doesn't suit your application, there are "Logic" overdrive devices which will automatically disengage the o/d for you if it bothers you.

 

Mick Richards

[MikeF]

My o/d was rebuilt and filled with 20/50 works a treat, there will be others who say the same for other oils. Some with pro's and cons' comments. What does your rebuilder suggest?

 

So far as engaging disengaging is concerned: Don't change on a trailing throttle that's for sure. I would suggest forget trying to sync dipping the clutch and adjusting engine revs type stuff. Just keep slight positive drive (in normal driving) when going in either direction. You should be rewarded with a jerk free change in engine note just like a modern flappy paddle system. , For more spirited style the same will apply but you will likely get a jolt 2>o/d2.

 

 

Mike

[ctc77965o]

Overdrives run on most oils, as others have said, it's a subject of much debate here.

 

In terms of use, don't worry the units a quite unbreakable in normal use, so you won't damage it by how you drive. The trick is learning to drive smoothly with overdrive...the changes are smooth when the drivetrain is under load...either braking or accelerating. Light throttle changes are much more tricky and using the clutch like a normal gearchange can help.

 

A full power 2nd gear overdrive engagement is a beautiful thing!

[RogerH]

MikeF above refers top 20/50 oil. Whenever I see that I think of engine oil. This is probably the last thing you want in the O/D.

However recently I became aware that Penrite 40 grade is also 20/50 - it is a multigrade centred around 40(ish).

 

Roger

[jamie hart]

I certainly would not use an EP 90 grade oil as there can be a problem with additives and the clutch cone. I have used ordinary SAE 40 grade engine oil in 3 of my overdrives and this seems to work well. Sometimes the additives in a multigrade oil do not go well with the cones, this seems to vary with the make of oil.

I have also used automatic transmission fluid with success but have reverted to SAE 40 as it seems to work.

Hope this helps.

Jamie

[Lee Dutton]

Thanks to all for your advice and guidance, so I will replace the oil with SAE 40,and engage O/D while accelerating hard

 

best regards to all Lee

[peejay4A]

You'll soon learn what works for you. You won't break it.