MTFCA Forum

I am just now getting to the water pump on my 08 model SR. The water pumps were built into the radiator similar to the first 2500 T's, but ran off a gear mounted on the flywheel which is on the front of the engine. Mesh was adjusted through rubber pads/shims on the radiator mounting. I found that the gear on the water pump shaft is Fiber. The gear that drives it on the flywheel is bronze. The who knows how old fiber gear on the pump shaft looks to be in good shape, but was just wondering if there was a way to treat the gear to help give it some strength. It runs out in the open is 15 tooth and the drive gear on the flywheel is 20 tooth, so will run above engine speed. I am definitely going to make a pattern of the gear before running it, but am trying to get the original radiator/water pump up and at least functioning, so I can get the car started. It is a work in progress.

Thanks Jim

If it were mine and I did not have a drawing of that exact part, I would remove it and get it to an expert to determine the pitch, pressure angle and pitch diameter while it is intact. Being fiber, it would be a great idea to replicate it while it is intact.

I'd suggest contacting Dan McEachern and talk directly to him before you do ANYTHING to that gear.

If you know the outside diameter and the number of teeth you've pretty much got the design of the gear. From the formula: O.D.= (N+2)/P, with P being Pitch and O.D. being the outside diameter and N being the number of teeth, you can calculate the pitch. Manipulating the formula: P=(N+2)/O.D.

As for the pressure angle, almost all gears of that era were a 14-1/2 degree pressure angle.

So, knowing Pitch, Pressure angle & number of teeth, as well as the gear width, is all you need to spec out a replacement gear.

I agree with Scott about consulting Dan. Maybe he can make a bronze or aluminum replica. I've had bad experiences with both fiber and nylon timing gears. Having a new gear made might be expensive, but aren't most things on a car of that vintage?

Thanks guys, will do on seeing about having replacement made and just setting the original aside for future reference if needed.

thanks again Jim

Glen Rand makes reproductions. He’s not on line. But a member of the EFR. I,m running one of his gears on my S roadster. It works great.

Thanks Paul, I'll give him a call and see if he has any

Jim

Definitely the way to go.

Thanks all. If you can't get one, contact me thru the forum and we can proceed accordingly. Dan

Thanks Dan, will do as I may need to have a shaft as it appears the gear and shaft are integral, I haven't had a chance to call Glen yet, been mowing all day and most likely tomorrow. To all who responded, many thanks for the help, this car is getting close, but these early ones are a challenge and as I do have the original radiator, thought I'd at least give it a try while getting the engine running, and of course I do need to have the water pump up and going no matter what.

Jim

This is the type of gear that can easily be made with a bandsaw and a good file. Here is an original. I may have enough red fiber if you want to do it yourself, otherwise Glen may have them on the shelf.

And, the vital stats are 15 tooth, 5 D.P., 14 1/2degree pressure angle

Tim- the OD looks large- most likely a long addendum gear as there is no undercut. Can you confirm OD?

Possibly some kind of penetrating epoxy that will fill it with plastic, I would rather get it 3d scanned and replicated with a cnc router.

Dan, a close guess to overall outside diameter would be 3 3/8”. The split would give me a bit of pause, but it’s measured across the good part of the gear. Other than the tip wear, the profile shows 5DP. Be glad to hear your thoughts. Jonah, It’s easy to overthink some of this. It was pretty crude originally and worked well, sometimes for well over 100 years.

Gently clamp and soak it in quick poly. If you can find it.

Thanks Tim, Dan : I talked to Glen and he has the gears and the hubs. I'll try to get a picture of my gear and post it. I am getting things cleaned up so I can have measurements, etc. and a list ready for Glen next time I talk to him.

Jim

Tim- thanks for the measurement- appears to be just a vanilla 15 tooth 5 DP gear.