Shimming oil pressure relief spring

[haggisbasher]

Evening all

The threads on my oil drain plug stripped at the weekend so I have dropped the pan to get a proper repair done. I have read some of the historical threads here that suggest shimming the oil pressure spring to improve oil pressure on this engine.

Since i have the pan off aanyway I would like to do this but info on the mod is fairly slim. Has anyone here done it and if so what did you use? The best thread I found quotes a NZ tech bulletin stating 2 x 6mm spring washers are the fix. What would you understand a spring washer to be?

Google says it could be this

or this

I'm leaning toward the second but looking for some guidance.

Thanks
Tom

 

[1980GS1000E]

My thinking is that they are talking about a washer that will hold against a spring. In other words, a properly fitting flat washer. That's what I would use.

 

[Steve]

Yep, simply a flat washer to add a litle bit of preload to the spring.

Sorry, but I don't have any dimensions available.

.

 

[GregT]

In NZ a spring washer is the second pic. I'd assume they were used because they were on hand and about the right thickness - and Suzuki NZ put out the bulletin because it worked.....

 

[rapidray]

In the USA, the first is a "wave" or spring washer, & the second is a LOCK washer. Ray.

 

[haggisbasher]

Thanks all

Greg It was your post I found glad your still around. I think I'll take some pics and put together a little how to for this mod to help my fellow mechanical illiterates.

Thanks again guys

Tom

 

[GregT]

In the USA, the first is a "wave" or spring washer, & the second is a LOCK washer. Ray.

Terminology differs Ray, your GS is my GSX....

 

[Guest]

Haggisbasher...can't wait to see your post with pics. This is one of the last few mods left to do on my '82 GS750EZ. Pretty much done everything else suggested here but like you, wanted to see some pics. Also be sure to add what size washer you use. Thanks

 

[subid]

Thanks all

Greg It was your post I found glad your still around. I think I'll take some pics and put together a little how to for this mod to help my fellow mechanical illiterates.

Thanks again guys

Tom

I would be interested in knowing how much this mod increases the oil pressure.

If possible, would you measure and let us know?

Stock should be above 43psi and below 78psi at 3000 rpm with a warm engine.

 

[haggisbasher]

I would be interested in knowing how much this mod increases the oil pressure.

If possible, would you measure and let us know?

I guess thats really the only way to determine the merit of this mod. The pan is already off awaiting me putting in an insert for the stripped drain plug. I dont have an oil pressure gauge but i will trawl around and see what i can find. If I can setup a suitable gauge in teh next couple of days i will button it up and do a before before stripping it down again and doing the mod and doing an after.

Anyone know the thread size on the oil pressure switch?

Tom

 

[Guest]

Any progress on thism mod? Anxiuosly waiting on pics as this is going to be a winter project for my '82 GS750EZ.

 

[Buffalo Bill]

I guess thats really the only way to determine the merit of this mod. The pan is already off awaiting me putting in an insert for the stripped drain plug. I dont have an oil pressure gauge but i will trawl around and see what i can find. If I can setup a suitable gauge in teh next couple of days i will button it up and do a before before stripping it down again and doing the mod and doing an after.

Anyone know the thread size on the oil pressure switch?

Tom

I would like to put an oil pressure gage on my GSX750F, but the gage I bought in the auto store uses ASE thread sizes, not metric. :-\\\
I suppose the solution would be: IF the plug is wide enough, drill and tap a hole through it, to fit the oil gage fitting.

 

[Steve]

As I read these threads about shimming the oil pressure springs, I have to wonder: doesn't the spring just control the relief valve?

It is my impression (and I could be wrong here) that the oil pump will pump whatever it can, and it is constantly pumping against a spring-loaded relief system. If the pressure ever gets too high, it overcomes the spring and the pressure is reduced to acceptable levels. OK, shimming the spring will increase the pressure at which it will open, but I thought that the root desire for this mod was to increase the operating oil pressure, not the upper limit. Am I wrong?

From what I have read, to increase the operating pressure, you need to use a different set of gears (I don't remember specifics here) that have a different ratio, therefore they spin faster, or something like that.

I don't have one of the bikes that had this problem, nor have I had to work on one, so I don't have any first-hand experience, just trying to keep my facts straight so I don't go spreading any mis-information.

.

 

[haggisbasher]

I got the insert fitted in the drain plug and reinstalled the pan and exhaust on Sunday but the bike wont start. I also have to figure out a way to connect a pressure gauge in place of the pressure switch.

I put it back together stock so i can do the baseline as I dont think the info is very useful without a before pressure reading. Hopefully I can get it running and the gauge hooked up in the next week or so.

Tom

 

[Guest]

It was my understanding that Suzuki put out a supplemental memo to it's mechanics that this was an update solution to the problem of weak oiling for the top end of certain bikes. I forget which bikes and which years. Anybody have access to this memo and can share?

 

[Buffalo Bill]

You're right?

You're right?

It is my impression (and I could be wrong here) that the oil pump will pump whatever it can, and it is constantly pumping against a spring-loaded relief system. If the pressure ever gets too high, it overcomes the spring and the pressure is reduced to acceptable levels. OK, shimming the spring will increase the pressure at which it will open, but I thought that the root desire for this mod was to increase the operating oil pressure, not the upper limit. Am I wrong?

An intelligent observation.
The Haynes GSX750F manual agrees: ?If the pressure is lower than the standard, than either the relief valve or regulator is stuck open, the oil pump is faulty, or there's other engine damage.?, (bearing oil clearances).

 

[haggisbasher]

The oil pressure spec for my bike is 43-78 psi. If the relief valve is undersprung and releasing pressure at say 50psi then surely no matter what the pump can do the operating pressure will never exceed 50psi. Based on the top end issues experienced in this engine design maybe it needs closer to the 78psi end of the range.

Hopefully by measuring the operating pressure stock and after shimming I can shed some light on the merits of this mod for everyone. I am expecting the pressure stock to be in the lower end of the range and the post shim pressure to be nearer the top of the range leading to better top end oiling. Equally I will not be too surprised to find that nothing changes.

On a good note I got the motor running last night so just have to figure out a pressure gauge attachment and teh experiment can begin.

Tom

 

[gearhead13]

If you run heavy oil like 20w50 then the shimming would be more beneficial IMO. Thin oil would never allow the pressure high enough for the relief valve to open. Also worn bearings or a worn out pump wouldnt allow the pump to build pressure. Starting and revving it cold would have the relief open, but wouldnt come into play on a hot engine with thin oil, when you actually would need the extra oil pressure.

 

[Steve]

The oil pressure spec for my bike is 43-78 psi. If the relief valve is undersprung and releasing pressure at say 50psi then surely no matter what the pump can do the operating pressure will never exceed 50psi. Based on the top end issues experienced in this engine design maybe it needs closer to the 78psi end of the range.

This is very possible, but nobody has ever led me to believe that is what is happening.

Hopefully by measuring the operating pressure stock and after shimming I can shed some light on the merits of this mod for everyone. I am expecting the pressure stock to be in the lower end of the range and the post shim pressure to be nearer the top of the range leading to better top end oiling. Equally I will not be too surprised to find that nothing changes.

Yes, measurements would be a very good thing. If you have the time, please note the pressures at a cold startup, then again at full operating temperature for stock and shimmed setups. Pressure readings at idle, mid-RPM and somewhere near max-RPM would be interesting to note.

Good to see that you are approaching this with an open mind, realizing that you might not see any change, let alone improvement.

If you run heavy oil like 20w50 then the shimming would be more beneficial IMO. Thin oil would never allow the pressure high enough for the relief valve to open.

I do not agree with the overall concept of using thicker oil to raise the oil pressure. True, pressure will go up, but that is not necessarily good for the engine. The reason pressure goes up is because there is more resistance to flow. The thicker oil has a harder time going through the small bearing clearances and other small passages, so pressure is higher at the pump.

Also worn bearings or a worn out pump wouldnt allow the pump to build pressure.

True, but it's not only pressure, but FLOW through the bearings that keeps them happy.

Starting and revving it cold would have the relief open, but wouldnt come into play on a hot engine with thin oil, when you actually would need the extra oil pressure.

Starting and revving a cold engine makes me cringe anyway, but that's a topic for another thread. I prefer to maintain the lowest possible engine speed to allow the engine to run smoothly while warming up.


Regarding the "need" for high oil pressures: I have found it interesting that the only bike that has this oiling problem is a high oil pressure bike. I have not noted any such failures on the bikes with roller bearing cranks, where pressures are typically in the single digits after warm-up. What keeps those cams lubricated with 6 psi oil pressure? Certainly not pressure, must just be a lot of oil flow.

.

 

[haggisbasher]

Good to see that you are approaching this with an open mind, realizing that you might not see any change, let alone improvement.

This seems to be a commonly accepted problem with a less commonly accepted cure. I dont know how big a problem it is or how good the cure is. I obviously can't answer whether it prevents a premature engine failure but if I can show the pressure figures before and after maybe people with these motors can have a better idea whether this is a mod worth doing for peace of mind. I have received untold knowledge and wisdom on this site so if I can contribute a little to the collective knowledge thats awesome.

Tom