Fitting new HT bearings to your GT 750

[Suzsmokeyallan]

Some things to consider when performing this update.
The "All Balls" kits use bigger diameter rollers and less of them than the Pyramid kits. Buying the kit with the slightly smaller rollers means you have more of them to spread the load across the bearing race so its a better design.
Most steering tubes seem to be cut down to some degree after 1973, but its still not enough, you need to nearly double the cut distance for the top race to fit down far enough.
The lower inner race on both brands of bearing is too tall, this pushes the seal almost outside the lower cup of the frame allowing water to enter easily.
You need to have at least 2-3mm ground off squarely from the lower facing portion of the race where it sits down onto the lower tree.
If you do not do this two things become apparent, water gets in and destroys the lower bearing eventually, and two, the distance between the top and bottom of each fork ear is too tall, so they never get tight on their cushion rubbers when you draw down the top tree stem nut.
The top bearing set up is fine with both brands of these kits, why they do not address this 'stack height' issue on the lower bearings is puzzling.

[Coyote]

I installed 'All Balls' on my 550. I noticed the gap at the lower neck. I went to the hardware store and found a nice fat o-ring. I placed it at the bottom of the lower bearing. Not under it, just around it. When cinching it up, It forced the o-ring down to fill the void. Easy fix.

[two-stroke-brit]

Some things to consider when performing this update.
The "All Balls" kits use bigger diameter rollers and less of them than the Pyramid kits. Buying the kit with the slightly smaller rollers means you have more of them to spread the load across the bearing race so its a better design.
Most steering tubes seem to be cut down to some degree after 1973, but its still not enough, you need to nearly double the cut distance for the top race to fit down far enough.
The lower inner race on both brands of bearing is too tall, this pushes the seal almost outside the lower cup of the frame allowing water to enter easily.
You need to have at least 2-3mm ground off squarely from the lower facing portion of the race where it sits down onto the lower tree.
If you do not do this two things become apparent, water gets in and destroys the lower bearing eventually, and two, the distance between the top and bottom of each fork ear is too tall, so they never get tight on their cushion rubbers when you draw down the top tree stem nut.
The top bearing set up is fine with both brands of these kits, why they do not address this 'stack height' issue on the lower bearings is puzzling.

so allan do recomend i fit them and see how much its out by then uninstall the bottom race then do the cut back or do you think if just take say 2.5 mm of the lower face on the tripple tree it should be ok ( i am fairly sure it has not been apart before).
cheers mark.

[Suzsmokeyallan]

Mark to do what you suggest you will have to press the lower race on the lower tree then remove it with a chisel driven between it and the tree. This is what Suzuki recommend so its not back yard mechanics, its just that NORMALLY when you are doing this the bearing is bad.
I really do not like the idea of beating onto a bearing you are going to be re-using, so its best to make it a one time thing.
If you get the Pyramid kit which I prefer due to the roller size and count, you can safely have the 2.5mm ground off the lower bearings face before you actually do the retrofitting.

[two-stroke-brit]

Thanks Allan , I already had a set waiting to fit. I will do themachining and should. Be good to go . Thanks mark

[Suzsmokeyallan]

Before you actually press the modified lower bearings inner race onto the tree, once you have installed the tapered outer race into the lower head tube cup, offer up the lower inner race with the seal held up against the bottom of it. With the ground bearing face you should now see approximately a bit more than 2/3 of the seal go into the with a very small portion just protuding. Once you see this the fit will be correct for the distance between the upper and lower ears and give you a better seal as well.
Here's how it should look at the base of the tree when its been altered.

[two-stroke-brit]

thanks allan ,"a picture and a thousand words and all that".
more fun at the weekend.
cheers mark

[Coyote]

I found a pic of my easy fix. The purchased o-ring nearly fit over the bottom inner race. In assembly (pulling it all together), it forcrd the o-ring out over the lower outer race and filled the gap. A $0.35 item.

[tz375]

Coyote, I like that fix. Works for me..

Allan, thanks for the info. The number of rollers does effect teh load capacity, but in this case it doesn't make much difference.

BTW, anyone else noticed that modern bikes still come with balls and not tapered rollers. We were always told that tapered rollers were better, but GSXR100, R1 etc all seem to use balls and are none the worse for it. I stopped fitting tapered rollers to race bikes because I couldn't tell the difference, but if that's all that's available, that's fine.

[Suzsmokeyallan]

Coyote somethings amiss here as your lower races were obviously different than the ones I worked on. Just look at how much distance you have between the upper tree and the headtube compared to mine, they look almost identical in appearance yet I ground a lot off of my lower inner races lower face to carry the tree closer to the headtube.
This tells me you need to check your lower inner races before pressing them onto the tree to confirm whats happening with that particular bearing.
Richard the tapered rollers are far superior to any ball races in a headtube, its all scales of economy on how to cheapen running costs.
Dirtbikes have used rollers for what seems like forever as did the early 80s GSX models and the first gen Bandit 1200 uses them too, yet strangely a lot of modern road bikes have alternated between the two designs.
I'll stick with the better design of tapered rollers.

[tz375]

As I understand it, taper rollers carry the load over a greater area and therefore will have a longer service life, but are no better in the real world for the loads imposed on them. They can carry higher loads, but higher than is needed doesn't add anything except a larger margin of safety.

I would not tell anyone NOT to fit taper rollers, but the improvement in steering or handling is really small in the real world.

[tgrogan]

Depends on what the 'real world' is. Wear in ball bearings is going to occur a lot quicker and with a lot more consequences for steering. Maybe on a race bike where you clean and adjust more than regularly and don't see potholes, you will see no issues. But in 'real life' tapered bearings will always work better.