Steering head bearings and nut

General discussion about Street two-stroke Suzuki motorcycles.

Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan

dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: Steering head bearings and nut

Post by dude99 »

Sorry, I'm a little confused. Which surface on the bearing are you grinding away?
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
User avatar
Suzsmokeyallan
Moto GP
Posts: 4326
Joined: Fri Oct 24, 2008 9:11 am
Location: Mostly Barbados, sometimes Florida and western Canada
Contact:

Re: Steering head bearings and nut

Post by Suzsmokeyallan »

The lower part of the inner race where it presses down onto the lower tree. When you have a stock lower bearing and compare it to the one in the photo you will see the differences.
The inner race has a lower section thats close to 5mms thick below where the rollers sit, I reduce it to 2.5mms.

Image
Here you can see the bearing apart and inverted after the modifications.
Two strokes, its just that simple.

69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: Steering head bearings and nut

Post by dude99 »

I must be having an off day here…. any chance you could draw in an arrow to the part you machine down. I can't see any machining marks on the picture. What did you use to grind it down with? My machining budget is pretty much topped out at this point in the game….
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
User avatar
Suzsmokeyallan
Moto GP
Posts: 4326
Joined: Fri Oct 24, 2008 9:11 am
Location: Mostly Barbados, sometimes Florida and western Canada
Contact:

Re: Steering head bearings and nut

Post by Suzsmokeyallan »

I must have done it too good if you cant see any marks from my work. Grinding and machining on any hardened surface of a bearing requires a lot of patience, a steady hand with tools and a digital vernier to make sure the thickness is retained so it sits squarely. For this I simply used the top part of the inner race as a reference for maintaining correct thickness when thinning it from the base side.

The part I worked on is the flat surface on the bearing in the centre thats facing upwards. After I ground down the height by 2.5mm and refinished the surface I had to put back the radius where the inner diameter hole and the base surfaces meet. I also removed a slight portion of the race holding the rollers so the dust seal that was now closer to it did not drag on it. See the captions for the colours below.

Image

Remember the bearing is upside down so you are looking at the lower facing sides that go against the lower tree.
Red is the surface area that was ground down by 2.5mms and refinished back to a stock look.
Blue is the area of race cage that was trimmed just enough to allow the dust seal to pass without scraping against it. The seal got closer to the race after grinding and refinishing the red section down by the 2.5mms.
Yellow is the section that was radiused back to stock since it disappeared when I ground the red part down by 2.5mms
Two strokes, its just that simple.

69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
dude99
Around the block
Posts: 94
Joined: Wed Mar 23, 2016 12:53 pm
Country: Canada
Suzuki 2-Strokes: GT750
Location: Just outside of Vancouver BC

Re: Steering head bearings and nut

Post by dude99 »

Awesome, thanks. Much clearer now... So you used files to do this? I can't imagine how long that must have taken you. I had to drill through a bearing race once and it took FOREVER.....
Bikes:
1975? GT750 project -the reason I'm here :)
1978 GS750 -my current ride
1982 GS(X)400 -sold
1981 RD350LC -sold and missed
1979 Honda CB400 hawk -sold and not missed, horrible bike
User avatar
Suzsmokeyallan
Moto GP
Posts: 4326
Joined: Fri Oct 24, 2008 9:11 am
Location: Mostly Barbados, sometimes Florida and western Canada
Contact:

Re: Steering head bearings and nut

Post by Suzsmokeyallan »

Nope you cant file hardened steel, it has to be ground and then the surface refinished. The race surface has to remain 100% parallel to the top one so it sits square like the original when its installed. Thats why you need to use a digital vernier to check progress to make sure you are grinding perfectly level as you reduce the thickness.
Two strokes, its just that simple.

69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: Steering head bearings and nut

Post by jabcb »

Am confused by this old topic that doesn’t have any working pics. (Thanks to Photobucket!)

Am working on the GT550 cafe build. Got the All-Balls bearing kit.
Have the dust seal & lower inner bearing installed on the lower triple tree.
Also have the steering column ground back ~ 6mm per the instructions.

If I install the outer races and assemble the triple tree, then how will this affect the dimension between the upper & lower triple tree?
Will the fork ears be held in place tightly?
Do I need to use an additional bracket cushion to hold the ears in place? (The cushions are still available and are only a few $.)
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
User avatar
Alan H
Moto GP
Posts: 3160
Joined: Thu Feb 16, 2012 11:50 am
Country: England
Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
Location: The Republic of South Yorkshire

Re: Steering head bearings and nut

Post by Alan H »

Image

I've done 2 so far and just used emery tape wrapped around the centre upright, pulling each end sequentially - and measure carefully. You can't put filings back...........
Think of how stupid the average person is, then realise that half of them are more stupid than that.
sportston
Expert racer
Posts: 1119
Joined: Wed Jul 10, 2013 12:04 pm
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S

Re: Steering head bearings and nut

Post by sportston »

Suzsmokeyallan wrote:Every bearing set I've bought to retrofit onto a GT750 or RE5 has had the same issue. Basically the lower inner race is a bit too tall and so the dust seal rides outside the frame head tube and besides that the trees are to far apart so the head light ears fit slack.
I had the same problem on my gt380. I bought a new set of bearings from Pyramid parts instead of All Balls. I will see if they have managed to get the correct size lower bearing. Yet to attempt fitting them.
Alan H wrote:Image
I've done 2 so far and just used emery tape wrapped around the centre upright, pulling each end sequentially - and measure carefully. You can't put filings back...........
That part is the easy bit Alan. The problem is the lower bearing being too tall for the lower yoke to sit high enough.
jabcb wrote: If I install the outer races and assemble the triple tree, then how will this affect the dimension between the upper & lower triple tree?
Will the fork ears be held in place tightly?
Do I need to use an additional bracket cushion to hold the ears in place? (The cushions are still available and are only a few $.)
No the fork ears will not be held tightly. Maybe a second set of cushions would work, but the ultimate solution would be to alter the bearing seat height as smokey has done.
On my GT380 the problem caused by the bearing height difference is that the lugs for the steering lock do not line up. How no-one has figured this out at the bearing manufacturer's development stage is scandalous! What sort of engineer thinks that a 3mm difference is acceptable?
User avatar
Suzsmokeyallan
Moto GP
Posts: 4326
Joined: Fri Oct 24, 2008 9:11 am
Location: Mostly Barbados, sometimes Florida and western Canada
Contact:

Re: Steering head bearings and nut

Post by Suzsmokeyallan »

Your luck may have run out on Pyramid. I got a set from them as well thinking they were aware of the lower bearing stack height issue but it was the same thing, approx 2.5mm too tall. What I also did not like about their bearings were the lack of rollers in the races of the bearings they used compared to the ones used by All balls.
Things may have changed so kindly update me on the issue. I've got one more lower race to do soon, so I'll be grinding another one again.
Two strokes, its just that simple.

69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: Steering head bearings and nut

Post by jabcb »

It hadn’t occurred to me that the steering lock might not line up properly.

Some PO of my GT550 cafe build had trashed the frame bracket for the steering lock. So I had a replacement welded on. Could have easily accommodated the height differential at that time. Just did some quick measurements & looks like it might have worked out ok.

The T500 cafe build will have a GT500 triple tree. The T500 & GT500 have different steering lock designs. Will have to weld on another bracket. This time I’ll sort the issue out before getting the frame powder coated.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
sportston
Expert racer
Posts: 1119
Joined: Wed Jul 10, 2013 12:04 pm
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S

Re: Steering head bearings and nut

Post by sportston »

Suzsmokeyallan wrote:Your luck may have run out on Pyramid. I got a set from them as well thinking they were aware of the lower bearing stack height issue but it was the same thing, approx 2.5mm too tall. What I also did not like about their bearings were the lack of rollers in the races of the bearings they used compared to the ones used by All balls.
Things may have changed so kindly update me on the issue. I've got one more lower race to do soon, so I'll be grinding another one again.
I'll let you know. I have a few days off soon and hope to catch up on sorting the bike out.
sportston
Expert racer
Posts: 1119
Joined: Wed Jul 10, 2013 12:04 pm
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S

Re: Steering head bearings and nut

Post by sportston »

Ok. So I finally got it sorted kinda. I did what smokey allan did.
For those that wish to do the same. I suggest you get a set of Pyramid bearings and a set of All Balls.
I butchered two sets. Took the bottom bearing of the Pyramid kit and the top bearing of the All Balls. I had to machine down the butt of both top and bottom bearing races considerably to make everything fit. It still wasn't as compact as the Suzuki unit but as good as I could get under the circumstances. If you do this, don't forget to chamfer the ground edges so that no sharp edges cut into the bearing rollers.
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: Steering head bearings and nut

Post by jabcb »

Working on the 1972 GT550 cafe build.

The bearing grinding is way beyond my skill set, so I did a bit of research.
The All-Balls kit is 22-1005. It has lower bearing 99-3508 (27x48x14mm) & upper bearing 99-3505 (25x48x15mm).

The available All-Balls taper roller bearings are listed here:
https://www.allballsracing.com/media/pr ... eChart.pdf

Bearing 99-3508 is the only listed 27x48 bearing. I did some research & didn’t find another bearing that is thinner.
Bearing 99-3509 is 25x48x13mm. That’s 2mm thinner than the kit bearing.

My steering stem was modified per All-Balls instructions. I ordered the thinner top bearing & just installed the lower triple tree.
The All-Balls dust seal for the top bearing touches the steering tube. Both dust-seal sealing bumps look to be in contact with the tube.
There is a bigger gap at the bottom bearing but the steering stop is functional. (My steering stop was repaired so I don’t know if this applies to the stock stop.) Looks like the first dust-seal sealing bump might be in contact with the steering tube.

Am going to use the stock fork ears but they are at the painter’s. So the final results are TBD.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: Steering head bearings and nut

Post by jabcb »

Noticed something interesting. All-Balls bearing 99-3515 is 30x48x12mm.
So a sleeve for the lower bearing between the 27mm OD stem & 30mm ID bearing would solve the problem. Don’t know how doable that is.
A custom bearing with a 27mm ID & everything else per the 99-3515 specs would work, but it would be shockingly expensive.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
Post Reply