JK D3 Motor Bracket

[HomeRacingWorld]

[waaytoomuchintothis]

Ever since Dave, and others before him, posted the home made bracket made from square tubing, I have used the method for motor/axle mounting. Its pretty much all I do these days. To make the axle/motor shaft/ body height equation come out right, I use the method Harry did to level and set chassis clearance to the desired setting. A benefit of this method is that the brass bracket sets a nice a weight above the rear axle for traction.

[dreinecke]

Thanks Boss!

[bill from nh]

JK also makes 3/4" & 1" wide motor brackets with hypoid offset. The narrow bracket was originally made for building F1 cars, but it's been used in other applications too.

[HomeRacingWorld]

Yes sir, used that one as well.

[munter]

Lovely work there Harry. I do admit to not understanding why the need for the bearing tube instead of just fitting the bearings to the bracket. In 1/24 use some width would help but in (Gods given) 1/32 scale is it really necessary?

Another bracket I have used is the 3/4" hypoid RGeo item.

[HomeRacingWorld]

Because most brackets do not have the spacing to allow the motor shaft to rest inside the crown flange.

Therefore I do this to set my width accurately and it does the obvious of preventing side to side freeplay.

It also reduces the stress and wear on brackets that do have the length allowance for the motor shaft. Using some aluminum crowns can show wear after many hours of hard racing.

Finally it adds strength. I know you don't crash hard, but we sure do here. The support near the outer porting behind the wheel can help reduce that rare axle bend. Some feel it also helps reduce runout.

You can measure and create bushings/shafts as you have done here, but cutting and measuring time is about the same to me.

One could also use axle stops such as SCC and others produce. I am just lazy I suppose and just use a design that does not require them.

[gascarnut]

I alerted Rick Bennardo of R-Geo to this thread this morning, hopefully he will join up and provide details on how to get his brackets, as his eBay store does not list them at the moment. He makes brackets in two widths, 3/4" and 1", with or without a hypoid offset, and either for axle tubes or for direct bushing mountings. They are made from .050 brass so they are strong, although perhaps a little heavy for a 1/32 car. Their prime usage is in 1/24 scale retro cars.

Munter, there are IMO two reasons for using axle tubes:

1: Many home made brackets are not perfectly square or straight, soi the Axle tube set up the way Harry describes provides guaranteed alignment of the bushings.
2: The closer the bushings are to the wheels, the less chatter develops in the car as the bushings wear. This is not as critical with Oilites as it is with ball bearings, but still a consideration.

Finally, remember that the JK F1 bracket has about .055" of hypoid offset, which is more than is molded into the offset Slot.it gears. They have about .040" of offset (1 mm). In 1/24 scale, we run straight-cut Parma 48DP crown gears and an angled steel pinion and it all works fine, but those gears are bigger and heavier than the Slot.it or other 1/32 scale gears. Not that they cannot be used of course, but often the big offset will mean that the rear tires have to be much bigger than necessary in 1/32 to get a desired clearance.

Dennis

[HomeRacingWorld]

Thank you Dennis, it's great having a veteran of the art help out.

I will add if I may?

1. YES, very few brackets I have used are perfectly aligned. Using the tube method allows you to accomplish what you described. I simply forgot that reason :)

2. On this bracket, the openings are larger (7/32) than my 3/16 bushings (Parmas that I have a ton of). This would allow you to balance and align them easily enough using your axle and setup block, but I just preferred the tubing.

3. Correct on the offset for the "INDY" bracket. But so far the Slot.it crown gear has held up very well and I have not had a failure.

But I did stop using it. I stick with this D3 bracket now as it works well for our full bodied Sportsman models.

[munter]

A good discussion this.

Thanks for the explanations Dennis and Harry.

The beauty of scratchbuilding is that there is more than one way to skin a cat.

My Bentley chassis using the offset RGeo bracket worked well with a slotit white(offset) gear but I did have large diameter vintage rims.
I think there was still about an eighth inch ground clearance once built.

[gascarnut]

Thanks for the compliments, guys!

I have been building some of my 1/24 cars again with zero-offset brackets. This means that the motor lays at an angle in the frame, back end up in the air, front end at the bottom level of the frame. The reasoning has been to get the best possible gear mesh and reduce friction for use on the high-speed banked tracks. I'm not convinced it really made much difference, but since one of the latest cars is the fastest I have built so far, perhaps it did.

I also made the brackets to take the bearing directly in the bracket, which means i had to be very careful making the brackets to get the bearing alignment spot on. This was for weight saving, as some plastic spacers weigh a lot less than axle tubes. Here's a shot of a 1/24 F1 frame with one of these brackets:



Dennis

[munter]

That chassis is pure art...I love your signature statement and have quoted it here and there.

On a recent visit to the UK I met up with some 1/24 Retro guys at the North London club.
George Kimber was one of them...he can produce a tidy chassis. In fact it seemed he produced about two thirds of the chassis' running.

[Rick]

The 3/4" hypoid bracket does not require a tube because it is made out of .050 thick brass. The bracket are quite robust! But I can make them with the regular 3/16" hole for direct bearing/bushing fit or on special order, make the axle hole accept a tube. Parts can be ordered via e-mail: scrgeo@comcast.net or on my FB page: Richard Bennardo

I also make brackets 1" width and in a non hypoid 2 degree format, in both 3/4" and 1" With the Z-poid the brackets still build flat on the jig but are tilted 2 degrees, ( face of the bracket) for pinion shaft and axle to align straight.

I am now also making custom pans with pin tube holders integral.

As soon as I figure out how to post a pic here, I will list some other items that may be useful and easier for more 32nd scale building.....

[HomeRacingWorld]

Thank you sir. You can email me photos with description and I can host and publish for you.

harry@homeracingworld.com

[ccobra]

Wow Dennis, that chassis is a real work of art. Sure do wish I could do something that nice.