Gearbox grinding - what to do?

[evoman]

Anyone have any experience with Redline Shockproof Oils in the FTO?

With my limited mechanical knowledge, I believe I have worn synchros.When my car is cold its a real task trying to stop it from grinding from first to second and second to third. Even when warm the shifts are no longer smooth between these gears.

I have a GPvR and would like to see if the Redline shockproof oils could help me out, but with the LSD box I'm not sure which one would be appropriate (lightweight shockproof?) and if I need friction modifier and if so how this is applied.

Furthemore, I've heard a lot of conflicting reports about the shockproof range, and am not even sure if it would be appropriate for use in the FTO, and particularly a LSD box. Some people even say it's best to use the shockproof range on good gearboxes NOT worn ones, so I am confused. Can anyone shed some light for me?

Failing this, I guess I would have to look into reconditioning, which judging by previous posts on this site sounds like it would be a very expensive and painful process. Does anyone in Sydney (Castle Hill area) have any suggestions on who I might want to see, and how much I might be looking at to get this box reconditioned?

[Shane001]

I ran the lightweight shockproof in my gearbox on Sat at EC. Was better with the synchros than the Penrite SIN 75 I had in it, but very, very noisy with the LSD. I've now drained it and putting in Motul FF-LSD Type 2. The only reason I tried the Redline was cause I've got 3 lts of it. If you're buying it new go with the Motul. This is the best oil for this type of gearbox. Try Geoff at SS Auto at Girraween, though he'll have to order it in for you, I think I just bought the last of it lol!

[evoman]

Thanks for your input Shane.
Did you put any friction modifier in with the redline? If not then would I be right in thinking that would be the reason you found it so noisy?

I did a lot of research on this a while ago when I first got the car and ended up putting in the Motul FF LSD type 2 oil during my first service. As you say, from all the research I did it is apparently meant to be the best possible oil for LSD box.

Originally when I put the Motul oil in, I was using the car 1-3 times a week for medium to long drives so the car had enough time to warm up and get the oils flowing and the synchro issue was less of a problem.

Unfortunately, I've moved to the big smoke and now have to use the car as my daily and the grinding is much more of an issue as the car has less time to warm up and I'm constantly having to use gears 1-3.

[Shane001]

hmm, so you've been using the Motul and the synchros have worn??

Didn't use any additive with the Redline. I expected it would be a little noisy but sounded like the gearbox was falling out! With limited practice days available I've just decided to go with the Motul and be done with it. But now u've got me thinking twice again...

[Bennoz]

If its crunching when cold then the grade of Motul you've used is to heavy. Try a lighter grade & you'll find that issue will go away.

I'll try & scratch up what LSD additive they've used in mine.

[bushido]

try penrite limslip 90.

[evoman]

The motul FF-LSD type 2 is a 75w-90, which I thought was the correct grade for our boxes.

Shane, I have no issues with the motul oil. It hasn't made my gearbox worse. If it's ok for you I would definately keep using it as from all I have read it's meant to be the best.

[Bennoz]

Its not the grade, its the fact that the Motul FF-LSD type 2 is a GL-5 oil, meaning its contains sulpher which can damage yellow metals (ie syncro's) in some gearboxes.

You need a GL-4 rated oil such as Castrol SMX-S 75w-85

[Shane001]

I though GL5 was the same as GL4 only better?

[Bennoz]

Depends on how you look at it. I consider it more of an age thing, the GL5 has a bunch more additives suitable for more modern metalurgy, and seeing as our boxes are 20 years old in design, I tend to stick with the Mitsi spec of GL4.

Quote from Wiki

GL-4 and GL-5 are standards set by the American Petroleum Institute for gear oils. GL-4 are intended for axles with spiral bevel and hypoid gears operating under moderate to severe conditions of speeds and loads. They are also suitable for sychronized manual transmissions when MT-1 gear oils are NOT recommended. GL-4 should be used in limited-slip differentials. The GL-4 generally indicates "Limited Slip" properties in the gear oil; sometimes abbreviated as LS.

GL-5 is indicated for high-speed/shock loads and low-speed/high-torque conditions. GL-5 also has multi-purpose or mild EP (extreme) properties too. GL-5 is often seen with the MT-1 designation too.

MT-1 indicates lubricants intended for NON-sychronized manual transmissions. MT-1 indicates the additional additives necessary to protect against thermal degradation, component wear and oil-seal deterioration which are not requirements by GL-4 or GL-5 approval.

GL-5 is not the latest and greatest improvement over GL-4; unlike oil classifications where higher classification numbers mean tougher standards and backward compatiblity. It is important to know what type of gears you are lubricating, their applications and follow the manufacturer's recommendations

Quote from Caltex

"API GL-5 gear oil designates service of hypoid and other types of gears
commonly found in rear axles. A GL-4 oil may be employed in certain manual
transmissions.

These differences are mainly distinguished by the level of active additives
employed in the product. Different applications require different additive
levels and different component materials can be affected by the levels of
additives present in the lubricant.

Having said that GL-4 and GL-5 gear oils are not compatible and
manufacturer's recommendations should be adhered to. They cannot meet the
same specifications and the product performance and tests are different.

Typically, a GL-5 gear oil will have about 2 times the active additive level
of a GL-4 product. This additional additive can cause problems with yellow
metals like brass or bronze."

[evoman]

Hmm, so maybe the Redline MT90 might be a better option?

http://www.redlineoil.com/product.aspx?pid=46&pcid=7

Either way, does anyone still have any experience with friction modifiers to adjust these oils for the LSD box? How much do you put in and when do you know when to stop?

[Shane001]

Redline actually recommended an equal mix of MT90 & MTL.

God I hate oils lol!

[Shane001]

After a bit more reading and research I've decided to stick with the Motul FF-LSD.

The workshop manual does say "GL4 or above", suggesting a GL5 should be OK. Also word from Motul is this oil was designed specifically for this type of gearbox, and they know of quite a few EVO's (both competition and street) that run this and never had a problem. Also I'm never real keen on mixing additives with synthetic oils, unless it's recommended by the oil manufacturer. There oils are already loaded with all sorts of additives, and you just don't know what affect putting something else in their might have.

Anyway I'll let you all know how I get on after my next track day

[evoman]

Just wanted to bump this one up again. Does anyone have any new info to add here.
Any suggestions on oil for the LSD box that will stop the cold grinding/notchiness?..but be good enough for all round use.
Any input on how you use friction modifier and when you know you have put enough in?

I hate oils.

[Shane001]

I hate oils.

I've used the Motul for several race events now and love it. I drained it after the last run of EC and clean, no sign of synchro wear, unlike the Penrite I originally had in.

So with the Penrite SIN 75 I had gear crunching and it was destroying my synchros, the Redline LWSP was very smooth on gear changes (synchros) but too noisy with the LSD, the Motul is great all round.

But then my box doesn't stay cold for long

[Bennoz]

Im currently using a combo of Castol Syntrax & Nulon G70. Works a treat! Was very noisy (diff) before adding the G70 thou..
Used a hair over 2 litres of box oil, then a full 125ml tube of G70.

[evoman]

Hmm, interesting info, thanks.

I've already got the Motul FF-LSD Type 2 and I can't fault it when warm so maybe I might take Shanes advice and stick with it.
However I might take Ben's suggestion and try this Nulon G70 a go as it sure sounds like a godlike additive if it does half the stuff the website claims.

My only concern is that if I use it with an oil already designed for the LSD box might it push it too far and mess the friction levels up? Meh, the site says suitable for use with all oils so it might be time to stop worrying and start trying.

[Bennoz]

How'd you end up going Evoman? Tried the G70 in there?

[evoman]

I'll let you know next Thursday ....unless you want to jack the car up and put it in for me on the weekend

I hope it helps because I sure as hell am sick of changing straight from 1st to 3rd in the mornings and dicking around rev matching when I just need to get into work.

[Bennoz]

Be happy to, but I've just changed mine again & found an even better oil!

The Syntrax I was using degraded badly and very quickly. Just swapped it out for the Valvoline LSD 90W and its 10 times better than it was before. No clunking from the diff & on a cold start this morning, no issue going 1st to 2nd.

And for the grand price of 30 bucks for 4 litres

Looks like Im doing some work for FTO-BOY this Sunday if you want to drop in, I can do you a box oil change.