Bosch Hydromax brake booster info - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**CarolinaHD** · 08-08-2020, 07:58 PM

Got called off work Friday so used my free day to swap in the 1.75" bore master cylinder. After carefully measuring push rod depths we needed to put a .055" spacer between the master and booster to be flush. I used 4 lock washers that measured .080" leaving me with .025" before the pushrod touches. A gallon of brake fluid later she was ready to for the road...

It felt more or less the same, had slightly better pedal travel and more control over braking force. Not sure if it was worth the hassle of swapping but oh well.

1st pic is 1.75" master
2nd pic is 2" master still installed
3rd pics is hydroboost pushrod
4th pic is pushrod side view
5th pic shows lock washer "spacers" installed circled in red

Campbel45 · 08-10-2020, 07:28 AM

Alex,

Thanks for putting more work into it! I'm glad that it got slightly better for you.

Do you believe the truck is safely driveable? Better braking performance than the original brake system?

**CarolinaHD** · 08-10-2020, 11:53 AM

Considering the old one didnt work at all I'd say it's pretty good

On a real note I dont have anything to compare it to so I'm not really sure.
There was a point coming down a steep hill where I was fully on the brakes and it didnt stop as quickly as I would have liked. Might need to increase the pressure going to the rear line but I cant much more before it locks up.

If I can't get this thing to stop how I want it, then I'll follow Richard's lead and ream out the front axle for the disc brake conversion. The end game is to make it into a dump truck or pull around a 20k lbs dump trailer so the brakes have to be dang near perfect.

Campbel45 · 11-11-2020, 11:15 AM

Alex,

I hope all is well. I wanted to let you know I found a lead on a machinist that is making disc brake kits for these big old trucks. He's actually a member on the stovebolt forum and is Indianapolis (same as me).

He doesn't give out a parts list as its taken him many years to come up with this kit, but if you were to talk to him he will give you more details.

Swapping over to disc brakes may give you a better braking experience!

Randy Domeck
Indianapolis Fabrications
rdomeck@me.com
Indianapolis, In. 46254
317-258-0039

08-08-2020, 07:58 PM	#26
CarolinaHD Moderator Join Date: Aug 2017 Location: Cabarrus Posts: 417	Re: Bosch Hydromax brake booster info Got called off work Friday so used my free day to swap in the 1.75" bore master cylinder. After carefully measuring push rod depths we needed to put a .055" spacer between the master and booster to be flush. I used 4 lock washers that measured .080" leaving me with .025" before the pushrod touches. A gallon of brake fluid later she was ready to for the road... It felt more or less the same, had slightly better pedal travel and more control over braking force. Not sure if it was worth the hassle of swapping but oh well. 1st pic is 1.75" master 2nd pic is 2" master still installed 3rd pics is hydroboost pushrod 4th pic is pushrod side view 5th pic shows lock washer "spacers" installed circled in red Attached Images __________________ Alex 1967 C50 292ci Lumber truck 1967 C50 292ci Dump truck 1967 C60 366ci Fire truck Last edited by CarolinaHD; 08-08-2020 at 08:11 PM.

08-10-2020, 07:28 AM	#27
Campbel45 Registered User Join Date: May 2013 Location: Greenwood, IN Posts: 379	Re: Bosch Hydromax brake booster info Alex, Thanks for putting more work into it! I'm glad that it got slightly better for you. Do you believe the truck is safely driveable? Better braking performance than the original brake system?

08-10-2020, 11:53 AM	#28
CarolinaHD Moderator Join Date: Aug 2017 Location: Cabarrus Posts: 417	Re: Bosch Hydromax brake booster info Considering the old one didnt work at all I'd say it's pretty good On a real note I dont have anything to compare it to so I'm not really sure. There was a point coming down a steep hill where I was fully on the brakes and it didnt stop as quickly as I would have liked. Might need to increase the pressure going to the rear line but I cant much more before it locks up. If I can't get this thing to stop how I want it, then I'll follow Richard's lead and ream out the front axle for the disc brake conversion. The end game is to make it into a dump truck or pull around a 20k lbs dump trailer so the brakes have to be dang near perfect. __________________ Alex 1967 C50 292ci Lumber truck 1967 C50 292ci Dump truck 1967 C60 366ci Fire truck

11-11-2020, 11:15 AM	#29
Campbel45 Registered User Join Date: May 2013 Location: Greenwood, IN Posts: 379	Re: Bosch Hydromax brake booster info Alex, I hope all is well. I wanted to let you know I found a lead on a machinist that is making disc brake kits for these big old trucks. He's actually a member on the stovebolt forum and is Indianapolis (same as me). He doesn't give out a parts list as its taken him many years to come up with this kit, but if you were to talk to him he will give you more details. Swapping over to disc brakes may give you a better braking experience! Randy Domeck Indianapolis Fabrications rdomeck@me.com Indianapolis, In. 46254 317-258-0039



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