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Author Topic: Subframe alignment check  (Read 82 times)

Offline dogshome

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Subframe alignment check
« on: November 15, 2021, 06:25:08 PM »
I bought a spare subframe with the intention of bracing and powder coating. My friend said to check it by putting on a sheet of glass. Standing on end it has a few mm play. I will measure. Any thoughts or insights?
肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline Tony Smith

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Re: Subframe alignment check
« Reply #1 on: November 16, 2021, 01:15:06 AM »
Just a quick question.  What difference do you think some misalignment in the rear subframe might make?

To answer my own question, I am going with none at all.
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline Barry

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Re: Subframe alignment check
« Reply #2 on: November 16, 2021, 03:05:30 AM »
The thing that has puzzled me about the rear sub frame is the low torque specified for the sub frame bolts which I think it's 11ftlbs. That just seems low for 8mm 8.8 bolts  If there is any movement possible in the mounting holes I doubt the clamping force from 11ftlbs would keep it in alignment.
Barry Cheshire, England 79 R45

Offline dogshome

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Re: Subframe alignment check
« Reply #3 on: November 16, 2021, 01:02:05 PM »
Standing it on a sheet of FLAT glass now the missus is out reveals no play. Ancient, slightly crinkly glass in the shed, not so flat.  :mad:  :)

What difference? I just look at this subframe and think about what's loaded on it (me mainly, then ~50% the weight of the bike through the shocks). It has the look of one of those fold up chairs you buy with a cup holder in the arm. Adequate for occasional use. It is also mounted to a potentially wibbly part of the main frame but I don't plan on removing that any time soon.

I don't feel the frame moving like it did on other bikes, but then I don't go hooning around at a million miles an hour anymore. The RD used to bend like a cat under really heavy braking. Back wheel closing in on front one. DT175 would flex by standing on one peg and not the other.

Hoping to improve on "none at all". Fully expecting a "told you so" though  :tekst-toppie:


RE Low bolt torques: the 81 onwards have countersunk heads = less steel. Maybe that is the reason? Flanged nuts and form G washers may find their way in here if they don't protrude.
« Last Edit: November 16, 2021, 01:04:21 PM by dogshome »
肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O