Monza Jr. Fork rebuild

[ducridersantafe]

Hi all, I'm in the process of rebuilding my junior forks. On reassembly there's a lot of play between the thin Aluminum sleeves at the bottom of the stanchions and the inside of the fork legs. Is this normal, or should I look at having new ones made up? They were pretty scored up when I took them apart. I know they'll get more rigid once the whole assembly is tightened up, but I feel this much play will put too much pressure on the oil seals.
As an alternative, has anyone replaced these forks with n/c 31.5mm forks?
Thanks, Terry

[Rick]

I'm not familiar with those forks, but I've read that the Monza Jr headstock tube was shorter than the 175/200/250/350 tube, so mounting a set of 31.5 forks might require modifying the triple clamp stem. The headstock tube on the other frames is 175mm.
Rick

[ducridersantafe]

Thanks Rick. Either way I'm in for more work...

[Rick]

There are cup adapters available to convert the loose ball headstock bearings to taper roller bearings- the problem is the adapters move the bearings further apart so the bearing journals on the stem are in the wrong place. Maybe you could get lucky, and the shorter headstock on the 160 frame would compensate for the difference, and you could get better forks and easier to service headstock bearings- might be worth measuring, especially if you have the 31.5 forks/clamps available.
Rick

[ducridersantafe]

Thanks Rick, I do as well as a set of tapered bearings. BUT, I just picked up a 130mm headlight! I think I'll ask my machinist what a set of thicker bushings will cost, might just be easier than a conversion. Cheers, Terry

[DesmoDog]

I put a 31.5 fork on a 160 frame (Whole assy with triple clamps, etc) and all I used was a simple spacer on the steering stem.

Keep in mind if you go the tapered roller route you can't use a top triple clamp with bar mounts, you'll need to use clip ons. The bar clamps will interfere with the top bearing race. (The lower bearing will work)

stem_9094.jpg

[ducridersantafe]

Thanks Craig, good info. If I recall, you also went with bigger wheels on yours, correct? Just where did the spacer go, under the cup, or on top? I have two frames here, the 160 tube measures 133mm and the 250 measures 145mm so that's a 12mm spacer, or maybe two 6mm, one at each end.
Did it change the frame geometry much? My 160 forks are still in pieces so I can't compare lengths.
Cheers, Terry

[DesmoDog]

I did put bigger wheels (17") on a 160, but that bike used the stock forks.

The spacer went below the top triple clamp and above the bearing cone, only one spacer. I never checked the geometry, the bike I'm doing it to will have issues much greater than the fork swap... it's going to be a hardtail...