| [GMCnet] JUST WONDERING [message #60242] |
Thu, 15 October 2009 20:57  |
Charles Aulgur
Messages: 78
Registered: March 2006
Karma: 0
|
Member |
|
|
KEN POSTED:
Charles, et al,
After spending a little time thinking & drawing, I've finally seen the
light: You're right about the down-force shift from the rear wheels to
the center wheels with just the rear swing arm. Big surprise! :-)
With your suspension mods on the center and rear wheels, someone with a
HydroBoost driving 6-wheel disc brakes should have truly phenomenal
brakes.
A. Ken,you do not need HydroBoost to have great brakes. When we did
all the brake testing on the reaction bar system the first of this
year we tested various combinations of calipers sizes and different
brake pads. With 80 mm calipers and yellow brake pads on all six
wheels, we could slide all six wheels with the pressure from a stock
P-3 MM. That is more brakes then anyone needs as you loose control
of the vehicle with all six wheels sliding.
Without the benefit of a more powerful booster, I'm still not convinced
that the 4-link will be necessary on the rear wheels. Smaller calipers
could prevent sliding there at much lower cost than the 4-link.
A. I have to disagree with you on this statement. Having the reaction
bars on the rear two wheels improves your braking capability more
then having them on the mid-axle during high pressure stops. The
reaction bars on the mid-axles increases there capability by
utilizing approximately 1/2 of the braking energy that is normally
wasted lifting the rear of the coach. Thus, most of the braking
energy on the mid-axle is used to slow the coach. However, the mid-
axle tires are more likely to slide because they are now only
carrying 1/2 of the weight of the rear of the coach. The rear tires
are not taking weight off themselves so you gain all of the braking
energy on the rear wheels that was previously ZERO with them being
lifted off the ground during hard braking. With the reaction bars on
all four rear wheels, both sets of wheels should provide similar
braking capability under all braking conditions..
Chuck Aulgur
La Mesa, CA
Congratulations, Chuck. Terrific mod!
Ken H.
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
| Re: [GMCnet] JUST WONDERING [message #60245 is a reply to message #60242] |
Thu, 15 October 2009 21:16  |
 |
ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
|
Senior Member |
|
|
Time to start working on a 6 channel anti-lock system!
These coaches may never fill up with money.
Ljdavick at comcast.net
On Oct 15, 2009, at 6:57 PM, Charles Aulgur <cwasdc@sbcglobal.net>
wrote:
> KEN POSTED:
>
> Charles, et al,
>
> After spending a little time thinking & drawing, I've finally seen the
> light: You're right about the down-force shift from the rear wheels
> to
> the center wheels with just the rear swing arm. Big surprise! :-)
>
> With your suspension mods on the center and rear wheels, someone
> with a
> HydroBoost driving 6-wheel disc brakes should have truly phenomenal
> brakes.
>
> A. Ken,you do not need HydroBoost to have great brakes. When we did
> all the brake testing on the reaction bar system the first of this
> year we tested various combinations of calipers sizes and different
> brake pads. With 80 mm calipers and yellow brake pads on all six
> wheels, we could slide all six wheels with the pressure from a stock
> P-3 MM. That is more brakes then anyone needs as you loose control
> of the vehicle with all six wheels sliding.
>
>
> Without the benefit of a more powerful booster, I'm still not
> convinced
> that the 4-link will be necessary on the rear wheels. Smaller
> calipers
> could prevent sliding there at much lower cost than the 4-link.
>
> A. I have to disagree with you on this statement. Having the reaction
> bars on the rear two wheels improves your braking capability more
> then having them on the mid-axle during high pressure stops. The
> reaction bars on the mid-axles increases there capability by
> utilizing approximately 1/2 of the braking energy that is normally
> wasted lifting the rear of the coach. Thus, most of the braking
> energy on the mid-axle is used to slow the coach. However, the mid-
> axle tires are more likely to slide because they are now only
> carrying 1/2 of the weight of the rear of the coach. The rear tires
> are not taking weight off themselves so you gain all of the braking
> energy on the rear wheels that was previously ZERO with them being
> lifted off the ground during hard braking. With the reaction bars on
> all four rear wheels, both sets of wheels should provide similar
> braking capability under all braking conditions..
>
> Chuck Aulgur
> La Mesa, CA
>
>
> Congratulations, Chuck. Terrific mod!
>
> Ken H.
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
|
|
|
|
| Re: [GMCnet] JUST WONDERING [message #60270 is a reply to message #60242] |
Thu, 15 October 2009 22:43 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
|
Senior Member |
|
|
Charles,
A. It may be that my 10+ year old booster is not as effective as I
think it is, so maybe I'll try a new one before going to the
Hydroboost. But the numbers I've seen and developed myself indicate
that the line pressure with ANY vacuum booster will not be above
1100-1200 psi; that's not enough. I'm very anxious to SEE anyone slide
all the wheels on a GMC.
B. Something don't compute here: You say the center wheels will slide
because they're only carrying 1/2 of the weight of the rear of the coach
-- but the reason they're only carrying that, instead of maybe 3/4, is
because you've put the 4-link on the rear, eliminating the weight
sharing I was ignoring earlier. So eliminating the rear 4-link should
put the center brakes back to working harder than the rears (where I'd
put smaller calipers). Thanks to the 4-link preventing pole-vaulting,
the rears will still carry about 1/2 of their normal load -- NOT lift
off the ground as in the past. What am I missing here?
I don't deny that 4-link on all 4 rear wheels would be optimal. But I
still think the marginal utility of the rears is not economically
justified. Maybe I can test myself into submission. :-)
Ken H.
Charles Aulgur wrote:
> KEN POSTED:
>
> Charles, et al,
>
> After spending a little time thinking & drawing, I've finally seen the
> light: You're right about the down-force shift from the rear wheels to
> the center wheels with just the rear swing arm. Big surprise! :-)
>
> With your suspension mods on the center and rear wheels, someone with a
> HydroBoost driving 6-wheel disc brakes should have truly phenomenal
> brakes.
>
> A. Ken,you do not need HydroBoost to have great brakes. When we did
> all the brake testing on the reaction bar system the first of this
> year we tested various combinations of calipers sizes and different
> brake pads. With 80 mm calipers and yellow brake pads on all six
> wheels, we could slide all six wheels with the pressure from a stock
> P-3 MM. That is more brakes then anyone needs as you loose control
> of the vehicle with all six wheels sliding.
>
>
> Without the benefit of a more powerful booster, I'm still not convinced
> that the 4-link will be necessary on the rear wheels. Smaller calipers
> could prevent sliding there at much lower cost than the 4-link.
>
> A. I have to disagree with you on this statement. Having the reaction
> bars on the rear two wheels improves your braking capability more
> then having them on the mid-axle during high pressure stops. The
> reaction bars on the mid-axles increases there capability by
> utilizing approximately 1/2 of the braking energy that is normally
> wasted lifting the rear of the coach. Thus, most of the braking
> energy on the mid-axle is used to slow the coach. However, the mid-
> axle tires are more likely to slide because they are now only
> carrying 1/2 of the weight of the rear of the coach. The rear tires
> are not taking weight off themselves so you gain all of the braking
> energy on the rear wheels that was previously ZERO with them being
> lifted off the ground during hard braking. With the reaction bars on
> all four rear wheels, both sets of wheels should provide similar
> braking capability under all braking conditions..
>
> Chuck Aulgur
> La Mesa, CA
>
>
> Congratulations, Chuck. Terrific mod!
>
> Ken H.
>
>
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
