TAPERED BEARING CONVERSION ?s TO MY 78 T140E

scottholl

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1978 T140E Bonneville 750
Requesting help in determining 1978 T140E bonny steering head dimensions with respect to 2 areas,

1.) Converting to tapered roller bearing up grade kit. See this:

TRIUMPH & BSA 650 750 OIL IN FRAME STEERING HEAD BEARING SET 1971-83 PN# 97-4031

There are no markings on these bearing packages, I am attempting to try and learn these bearing dimensions, i.e., O.D., I.D. & height. Additionally, there is no distinction between which set goes where, i.e., upper & lower TRB

2.) The other reason for knowing the dimensions [above] is to give me a base line because I intend to do a HONDA LOWER TRIPLE TREE / steering stem swap AND I WILL ALSO BE USING THE HONDA upper TRIPLE TREE whereby I;m going to install an '83 Honda CX 650 Turbo front end. Sorry purists.

I know what the bearing dimensions are the the upper & lower steering stem bearings for the Honda front end, so I need to understand the size difference between the TRB's and the steering stems.

My 78 parts book show 2 bearing sets each with the same part # 97-4031 DESCRIBED as tapered roller bearings!!! I would never expected the factory to install TRB as opposed to simple loose ball bearings.

I look forward to any and all help Sorry purists.

Regards

Scott

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brooke

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My 84 CX e model went just 13,000 km before I changed to the tapered bearings . If I recall correctly the turbo model had tapered from the factory . I don’t know if any triumphs use them , pretty sure both mine are needles .
 

scottholl

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from what I am interpreting from my 83 CX 650 Euro workshop manual - the parts illustration looks like it's trying to depict a CAGED ball bearing assembly. I'll know shortly because I am doing a fork rebuild. I think this design is shared among my CX's 500 & 650 and my GL's 500 and GL 650 and possibly early GL 1000's & 1100's??

AND I am attempting to understand my 78 Triumph the parts illustration looks like it's trying to depict a SEALED bearing assembly. My 78 parts book show 2 bearing sets each with the same part # 97-4031 DESCRIBED as tapered roller bearings!!! There is no parts discriminator such as "upper" or "lower". I would never expected the english factory to install TRB as opposed to simple loose ball bearings.

Thanks
 

brooke

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Yes , think you’re
correct . I had in my mind that the CX used needles but that was the 250 Can Am GP which had the adjustable cones set up at the top and bottom allowing the rake to be moved from about 25 to 32 degrees . Don’t believe many people ever changed it but if you were racing on some backyard style tracks or ice racing pulling it back a few degrees made a huge difference.
The balls seemed very sensitive to over tightening and by the 10 k km mark had settled in to a place they liked but was developing into a head shake . The taper set up was stellar , felt tight but loosey goosey moving the bars and am sure they would outlast any motorcycle. Am thinking the little needles would be an improvement over the balls ?
 

scottholl

Member
Riding for 47 Years
Local time
Today, 11:46
Joined
Jan 9, 2018
Messages
37
Points
7
Age
67
Location
Las Cruces New Mexico
First Name
scott
My Ride
1978 T140E Bonneville 750
Yes , think you’re
correct . I had in my mind that the CX used needles but that was the 250 Can Am GP which had the adjustable cones set up at the top and bottom allowing the rake to be moved from about 25 to 32 degrees . Don’t believe many people ever changed it but if you were racing on some backyard style tracks or ice racing pulling it back a few degrees made a huge difference.
The balls seemed very sensitive to over tightening and by the 10 k km mark had settled in to a place they liked but was developing into a head shake . The taper set up was stellar , felt tight but loosey goosey moving the bars and am sure they would outlast any motorcycle. Am thinking the little needles would be an improvement over the balls ?
I'll let you know what I find out. Will by one set of TRB from all balls set # 22-1011 for the CX 650 E and another set from the bonneville shop for the 78 Triumph - i wouldn't think that the triumph TRB would be using the same size for both upper and lower triple tree positions. Regards
 
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