looking into a new custom part for the 7m. Having a custom oil pump drive sprocket made up. I had a stock one fail some time back and dont trust it anymore. This is a must for a 7m with a higher than stock lift cam (contact motor). It will be aluminum and hard anodized interested?
custom oil drive sprocket for 7m
1 - 20 of 27 Posts
Joined
·
2,105 Posts
what?
nope it was still tight sprocket blew up
http://www.supramania.com/forums/attachment.php?attachmentid=42253&d=1272066658
here is a pic was still tight this was about 3k miles or so ripped the gates belt too
here is a pic was still tight this was about 3k miles or so ripped the gates belt too
Joined
·
2,105 Posts
wow i have never ever ever seen a 7m do that i have owned and built prolly 100+ why would u need to make a special one just for an interferance engine? how tight was your oil drive pump shaft? did u check that?. seems to me that ur oil driveshaft seized and it did that. did u check ur clearances? does it spin easly by hand now?.
lol i build too and all was perfect. As for need one if you run aggressive cams and you snap a t belt=game over. This is not for all however it will add reliability to the engine sprocket is cheaper than a new motor. I ask alot of my engines i expect them to live with no problems at 30+ psi daily or 20k miles of abuse before i feel like tearing down.
Joined
·
2,105 Posts
how agressive of a cam are u running ive run the 272 with out this ever happening at 30+ psi
Joined
·
4,693 Posts
^ I was wondering the same. The only way something like that would happen is either harmonics or, more likely, a bolt or something else got caught in it.
Joined
·
1,534 Posts
How can this pulley be subjected to harmonics? It's only connection to the crank is a rubber belt, thus mitigating all possible induced vibration or harmonics.
Typically, the oil pump pulley fails when the timing belt is too stiff from over adjusting the tensioner, or fatigue from a lifetime of use, or simply odds from normal production failure percentage.
Would be interested to see what the final product is. Depending on cost and / or part complexity, I may be interested.
Joined
·
14,237 Posts
I have witnessed the same thing happen to oil pump drive gears on two different occasions. One was an MHG+ARP bolt but otherwise stock unknown mileage JDM 7M-GTE longblock on a CT upgrade, and another was a semi-built engine (OG HKS 264's w/1SZ-FE shimless buckets, valvesprings & retainers, ARP head studs, HKS stopper, coated J&E pistons w/ ARP rod bolts & new Toyota rod & main bearings & new Toyota oil pump)
The spokes just came apart on both. The bolt was properly torqued and the outer ring itself was fine. The spokes all broke in different places, too.
Might be a worthwhile thing to make, but you'd have few if any buyers for it.
Stock crank pullies on both engines, and I know the timing belt tension was set correctly on the semi-built engine and it was checked again less than two days before it failed. Never saw over 7000rpm.
The spokes just came apart on both. The bolt was properly torqued and the outer ring itself was fine. The spokes all broke in different places, too.
Might be a worthwhile thing to make, but you'd have few if any buyers for it.
Stock crank pullies on both engines, and I know the timing belt tension was set correctly on the semi-built engine and it was checked again less than two days before it failed. Never saw over 7000rpm.
not really looking for buyers was just making a new part availble if a select few wanted one for reliability. I have seen this before im not the first or last hurt the front cover a bit and left me stuck on the way to work one morning. For me 200.00 is not worth waiting for a tow truck during a morning commute. I also had a dis-4 die on me once now i have a spare sitting under my pass seat lol. Plan for me is to pick up titan cam gears and replace the sprocket too.
Joined
·
1,534 Posts
Here's a picture of a version I prototyped in CAD ~10yrs back. Weren't too delighted with the cost per part for a anticipated small run, so never pursued the idea through to production.
Let me know how things develop with progress, cost, etc..
Let me know how things develop with progress, cost, etc..
Attachments
Joined
·
5,622 Posts
Aluminum may not be the best choice for longevity unless you're doing to do some kind of plating or hard anodizing. Ever seen the original aluminum HKS cam gears? The best way to do that in my opinion would be to machine a billet aluminum center section and just bolt it to the very outer ring. It appears the spokes are the weak point, so just replace them with a solid aluminum disk, You should cut down machining cost and design time substantially without having to worry about the outer gear wearing down over time if it's aluminum.
good point but i mentioned hard anodizing in my first post. I want nothing to do with the stock gear this will be setup like aftermarket cam gears
Joined
·
3,614 Posts
If you make it a 40t unit so that the pump puts out 15% more flow, I will send people your way.
I don't have time to make the conversion pieces any longer.
A 40t will give you 30 psi hot idle pressure.
![]()
![]()
![]()
![]()
Requires a sleeve to be pressed onto the idler to rake up the slack in the timing belt due to the smaller pump pulley.
And yes, an aluminum pulley will require hard anodizing.
I was using KG 'Gun Kote', and that seems to be working now.
The first one that I put on my car was bare aluminum, and within a year was showing a lot of wear.
I don't have time to make the conversion pieces any longer.
A 40t will give you 30 psi hot idle pressure.
Requires a sleeve to be pressed onto the idler to rake up the slack in the timing belt due to the smaller pump pulley.
And yes, an aluminum pulley will require hard anodizing.
I was using KG 'Gun Kote', and that seems to be working now.
The first one that I put on my car was bare aluminum, and within a year was showing a lot of wear.
Joined
·
750 Posts
Nice work sixpack, had to do the same thing with the malta dragster years ago. Gear would break from the RPM and load from the 13mm cams. Of course, dry sump fixed all that.
Quake - You can always make an aluminum center and turn the steel gear section off of an old gear or cam gear to resemble a sleeve. Then press that onto the aluminum hub and drill in some set screws. I can think of a few people who might need one, the gear tends to break above 8500 rpm with bigger lift cams.
Quake - You can always make an aluminum center and turn the steel gear section off of an old gear or cam gear to resemble a sleeve. Then press that onto the aluminum hub and drill in some set screws. I can think of a few people who might need one, the gear tends to break above 8500 rpm with bigger lift cams.
1 - 20 of 27 Posts
