Salutations:
Mr. Massey very kindly forwarded an excellent transcript from GMC Motorhome News from Mr. Aulgur (Yes, I'll be subscribing as soon as I clear the credit card up again).. Thank you very much, this really may be one of the best listserver groups on the net!
He makes a very sound argument against wheel replacement using simple outward movement of tire contact patch to match rear wheel footprint.. Basically, it will further cantilever the wheel bearing face by moving the contact patch outward from the bearing - which in our case would, I agree, present a serious safety concern.. This was related to using a light truck rim in place of the half dual rim that would normally be picked up from our good friends at Alcoa..
I wholly agree with engineer Aulgur's proposition, in that when I sported up my second SAAB (a 900) - I extended my wheels out for a little local racing work with almost exactly the same results as described.. Hit a course marker (a cinder block) with the brakes on and snapped the knuckle and associated wheel, rotor,- basically everything attached on the outside of the bearing - right off the car.. Interestingly, the brake line kept the whole mess from bouncing away - flinging it around and crushing the rear of the front quarter panel and driver side door - then rolling away into the infield.. I think I finally released the brake when the wheel tried to join me in the front seat as I kept the caliper when the wheel and supporting entourage visited the weeds.. But I digress..
The modification I am suggesting at this point is to find a half dual rim (I say Alcoa and aluminum as they are known factor - there is a world of rim manufactory and materials) that would maintain the correct contact patch under the bearing face by extending inwards as well as outwards.. And I think I have the room behind the wheel to do this.. no pesky springs.. Perhaps I could even find a rim that moved the weight further out on bearing surface and thus lessen the strain if I shopped a bit..
Certainly, it would provide some latitude for negative toe adjustment if it (right rim) could be found.. Indeed, while a perfect outside match would be nice, I expect that the best I will do is find some mid-point solution that is wider, but not a perfect square to the rear footprint (which might actually be the right answer as increased traction would compensate for what triangulation would be left)
What I am trying to understand is why they choose to triangulate the wheel base in the first place.. I am pondering the somewhat unchristian view that GMC was not above saying 'you have the Toronado drivetrain and powerplant - you are on your own from here boys' and the good guys in Pontiac didn't extend the footprint as it would comprise the 'combined build' approach they needed to take in light of warranty and service promises made by marketing group.. However, there may well have been some serious engineering I am not understanding that went 'that Toro drive train is absolutely terrific - what a great fluke we won't have to fire up a new steering and suspension component manufacturing plant in Canada this time round after all.. ' ..
..
I also traced a link to http://www.california.com/~eagle/ site which was (is) always extremely interesting and that outlines several views and options tried regarding this.. I was surprised to read that most attempts resulted in more steering sensitivity (a general twist of front wheel drive vehicles at the best of times).. I would have thought exactly the opposite would be true if one were set the toe in a bit on wider wheels..
Anyway, do Vic Marks or Chuck Aulgur subscribe to this list? Boy, would I like to chat with you guys off-list sometime really soon..
Well, thanks for feedback thusfar.. Congratulations on the 200+ year run with that republic thang' of yours.. We kicked yer' butts in 1812, but we're all good pals now.. Please forward any experience this list communtiy thinks germane.
J Dexter
Mr. Massey very kindly forwarded an excellent transcript from GMC Motorhome News from Mr. Aulgur (Yes, I'll be subscribing as soon as I clear the credit card up again).. Thank you very much, this really may be one of the best listserver groups on the net!
He makes a very sound argument against wheel replacement using simple outward movement of tire contact patch to match rear wheel footprint.. Basically, it will further cantilever the wheel bearing face by moving the contact patch outward from the bearing - which in our case would, I agree, present a serious safety concern.. This was related to using a light truck rim in place of the half dual rim that would normally be picked up from our good friends at Alcoa..
I wholly agree with engineer Aulgur's proposition, in that when I sported up my second SAAB (a 900) - I extended my wheels out for a little local racing work with almost exactly the same results as described.. Hit a course marker (a cinder block) with the brakes on and snapped the knuckle and associated wheel, rotor,- basically everything attached on the outside of the bearing - right off the car.. Interestingly, the brake line kept the whole mess from bouncing away - flinging it around and crushing the rear of the front quarter panel and driver side door - then rolling away into the infield.. I think I finally released the brake when the wheel tried to join me in the front seat as I kept the caliper when the wheel and supporting entourage visited the weeds.. But I digress..
The modification I am suggesting at this point is to find a half dual rim (I say Alcoa and aluminum as they are known factor - there is a world of rim manufactory and materials) that would maintain the correct contact patch under the bearing face by extending inwards as well as outwards.. And I think I have the room behind the wheel to do this.. no pesky springs.. Perhaps I could even find a rim that moved the weight further out on bearing surface and thus lessen the strain if I shopped a bit..
Certainly, it would provide some latitude for negative toe adjustment if it (right rim) could be found.. Indeed, while a perfect outside match would be nice, I expect that the best I will do is find some mid-point solution that is wider, but not a perfect square to the rear footprint (which might actually be the right answer as increased traction would compensate for what triangulation would be left)
What I am trying to understand is why they choose to triangulate the wheel base in the first place.. I am pondering the somewhat unchristian view that GMC was not above saying 'you have the Toronado drivetrain and powerplant - you are on your own from here boys' and the good guys in Pontiac didn't extend the footprint as it would comprise the 'combined build' approach they needed to take in light of warranty and service promises made by marketing group.. However, there may well have been some serious engineering I am not understanding that went 'that Toro drive train is absolutely terrific - what a great fluke we won't have to fire up a new steering and suspension component manufacturing plant in Canada this time round after all.. ' ..
..I also traced a link to http://www.california.com/~eagle/ site which was (is) always extremely interesting and that outlines several views and options tried regarding this.. I was surprised to read that most attempts resulted in more steering sensitivity (a general twist of front wheel drive vehicles at the best of times).. I would have thought exactly the opposite would be true if one were set the toe in a bit on wider wheels..
Anyway, do Vic Marks or Chuck Aulgur subscribe to this list? Boy, would I like to chat with you guys off-list sometime really soon..
Well, thanks for feedback thusfar.. Congratulations on the 200+ year run with that republic thang' of yours.. We kicked yer' butts in 1812, but we're all good pals now.. Please forward any experience this list communtiy thinks germane.
J Dexter
