SU carbs HS6 1.3/4 Throttle spindle re-bushing

[Martin Gerrard Hill]

Has any person re-bushed a pair of HS6 carbs? If so I would appreciate any advice as to the best way to go about getting the old bushes out and the new ones in without getting them out of line .

[RobH]

The original bushes are cast into the body so are not removable.  The usual fix for light wear is to ream with a special reamer and fit an oversized shaft either +.010"  or +.015".  The special in-line reamer has a guide portion which keeps the alignment correct.  It is expensive. 

To fit new bushes they have to be reamed out entirely, again using a special reamer.  There is a bush fitting tool available from Burlen.  If you haven't a lathe or pillar drill it might be best to find a machine shop who can do it for you.

https://sucarb.co.uk/technical-h-type-carburetter-replacement-spindle-and-brushes

 

Edited July 29, 2023 by RobH
extra info

[stuart]

1 hour ago, RobH said:

The original bushes are cast into the body so are not removable.  The usual fix for light wear is to ream with a special reamer and fit an oversized shaft either +.010"  or +.015".  The special in-line reamer has a guide portion which keeps the alignment correct.  It is expensive. 

To fit new bushes they have to be reamed out entirely, again using a special reamer.  There is a bush fitting tool available from Burlen.  If you haven't a lathe or pillar drill it might be best to find a machine shop who can do it for you.

https://sucarb.co.uk/technical-h-type-carburetter-replacement-spindle-and-brushes

 

+1 and make sure that whoever you get to do it understands they need to be line bored accurately, Ive seen several scrap bodies due to DIY  efforts.

Stuart.

[RogerH]

Hi Martin

before you drill/ream/break anything check to see if the bushes in the body actually need reaming/replacing.

When I went to redo the bushes etc I found they were still within tolerance and the brass spindle had worn away very badly.

This was a blessing.  The jb became easy.

 

Roger

[BlueTR3A-5EKT]

1 minute ago, RogerH said:

Hi Martin

before you drill/ream/break anything check to see if the bushes in the body actually need reaming/replacing.

When I went to redo the bushes etc I found they were still within tolerance and the brass spindle had worn away very badly.

This was a blessing.  The jb became easy.

 

Roger

+1

[Chris Hubball]

Hi Martin

Its 21 years since my 32 years employment at SU Carburetters came to an end with its closure, but if my memory service me right HS 6 Carbs had a pressed in Glacier DU Throttle Spindle Bush part number AUD 3080 and was not reamed, it was the H Type Carbs that had the brass cast in bush that needed reaming I think the part number was AUD 2717.

Cheers Chris

[RobH]

Interesting Chris but the Burlen site says reaming of the body is necessary as does this old thread, and implies that AUD 3080 (which appears to be a plain brass bush) needs reaming to suit the spindle too - confused now ! :

 

[Chris Hubball]

Interesting Rob, I was Purchase Manager there and remember purchasing AUD 3080 Bushes from Glacier Metal company in Kilmarnoch  I have an original pair of HS 6 Carburetters  AUD 209 from a TR4A in the garage I will dismantle the tomorrow and check the bushes 

Cheers Chris

[Drewmotty]

I’ve rebuilt a dozen or so pairs of SUs and I’ve yet to find a set with bushes worn enough to need replacing. As Roger has already pointed out the shafts tend to wear rather than the bearing so a new spindle is normally all that is required. 

[Martin Gerrard Hill]

Thanks for the advice everybody. I think that I will purchase a rebuild kit and hope the bushes are OK. If not is there someone providing a bush replacement service as I seem to remember coming across such a person on e-bay but can't find it again.

[BlueTR3A-5EKT]

Andrew Turner may be able to assist.

http://www.su-carbs.co.uk/phdi/p1.nsf/supppages/turner?opendocument&part=2

 

Edited July 30, 2023 by BlueTR3A-5EKT

[Chris Hubball]

Dismantled one of the carbs this morning, it seems my memory is disappearing with my hair. They are indeed brass bushes , on further investigation the pressed in DU Steel bushes were fitted to the later HIF Carbs. Burlen are correct if you drill out the old bushes and fit replacements they will need to be bored and reamed accurately otherwise the rotation of the spindle will become compromised.

Cheers Chris

 

 

[Nigel Triumph]

When Andrew Turner overhauled the twin Dolomite Sprint HS6s for my 2.5 litre GT6, he mentioned that new throttle spindles seem to be 1-2 thou oversize, and are often a good fit without rebushing.

This proved to be the case with my carbs. I would suggest you try new spindles for size and only think of rebushing if absolutely necessary.

Nigel

[jerrytr5]

12 hours ago, Martin Gerrard Hill said:

Thanks for the advice everybody. I think that I will purchase a rebuild kit and hope the bushes are OK. If not is there someone providing a bush replacement service as I seem to remember coming across such a person on e-bay but can't find it again.

This might be the gentleman you are looking for. He did a pair for me not so long ago.

https://www.ebay.co.uk/itm/393085743719?hash=item5b85bc7267:g:eWgAAOSw8OtdpfwZ

Jerry

[BlueTR3A-5EKT]

40 minutes ago, jerrytr5 said:

This might be the gentleman you are looking for. He did a pair for me not so long ago.

https://www.ebay.co.uk/itm/393085743719?hash=item5b85bc7267:g:eWgAAOSw8OtdpfwZ

Jerry

Ahh good old Ron.   Glad to see he is still in business.

[Martin Gerrard Hill]

This is the man I was trying to remember thanks.