Strange vibrations
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Strange vibrations I took a trip down to El Paso today (200 miles round trip) in the '39. It has a stock LM4 with 4L60E and Ford 8.8. Everything went fine and on the way back I stopped at the checkpoint and then back up to speed of 70-75 MPH. Started to notice my rear view mirrors were buzzing but thought it was the road (ongoing road work). Then I noticed the hood ornament shacking and started to slow and the vibes slowed. Worried I was getting a flat, wheel coming loose etc. Had to stop for a light and then went back to speed and the vibration appeared to have gone away. Question is, can the transmission somehow get stuck when upshifting and cause this problem? Also noticed my engine temp when up during the vibration. Came back down after the stop.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Well, think I found the problem. I've been having problems with the front wheels not turning freely. Stuck caliper, collapsed hose, bad residual valve and or bad master cylinder. Found out the front rotors are Ford Granada 11" and not Camaro 10 1/2". The Granada rotors move the wheel out about 1/4". The calipers are GM metric and are used with the Granada rotors BUT require a different bracket to account for that 1/4". What was happening is the brakes would heat up and clamp harder but only on the outside. Long run at highway speeds and hot weather got thing a bit hot and protested with vibrations. Good news is the rotors are not warped just discolored on the outside only where the one pad was dragging. I did NOT know that Granada rotors would fit the MII setup. Lesson learned. Not LS related but may help someone in the future.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
More on the vibration. Several times I've overlooked the only other component in the bake system, a 2# residual valve. Changed it and the rotors turn free, at least for now. Road test and jack it up to see if the wheels turn free.
Pass that nut on the way to a friends shop at least 3 times a week. Did you go to White Sands? Larges gypsum deposit in the world. Home of the high speed test track...just about mach 10. Alternate landing for the old space shuttle. And of course the Trinity Site (birthplace of the Atomic Age).
Pass that nut on the way to a friends shop at least 3 times a week. Did you go to White Sands? Larges gypsum deposit in the world. Home of the high speed test track...just about mach 10. Alternate landing for the old space shuttle. And of course the Trinity Site (birthplace of the Atomic Age).
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Verdad Gallardo you must be at McGinns or Eagle ranch, make sure to fill up on the samples, then head up the road to Ruidoso and do a little gambling (if that’s your thing) at the Mescalero Indian Reservation, very familiar with that area, lived in El Paso for many years, use to do a lot skiing at Ski Apache in Ruidoso, but it just doesn’t snow there like the old days anymore.
Trivia - as a 5 year old, I got lost in White Sands. Dad was stationed at Ft. Bliss and we went for a picnic at little covered picnic tables they had in the middle of all that gypsum - circa 1959. I wandered up over a dune -- got turned around, came back over the hill to what I thought was our picnic table only to find gypsum dunes as far as the eye could see. Remembered dad's coaching 'if you ever get yourself misplaced son, just sit down and stop moving, we'll find you'. So I sat down and cried. Shortly, my hero daddy showed up. Thanks for the memories.
Also remember going to visit Hueco Tanks as a kid.....
Also remember going to visit Hueco Tanks as a kid.....
Trivia - as a 5 year old, I got lost in White Sands. Dad was stationed at Ft. Bliss and we went for a picnic at little covered picnic tables they had in the middle of all that gypsum - circa 1959. I wandered up over a dune -- got turned around, came back over the hill to what I thought was our picnic table only to find gypsum dunes as far as the eye could see. Remembered dad's coaching 'if you ever get yourself misplaced son, just sit down and stop moving, we'll find you'. So I sat down and cried. Shortly, my hero daddy showed up. Thanks for the memories.
Also remember going to visit Hueco Tanks as a kid.....
Also remember going to visit Hueco Tanks as a kid.....
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Strangest problem with the brakes. Ride around the block, jack the car up and front wheels locked up. Loosen the M/C from the booster and wheels turn freely. Tighten M/C and step on the brakes hard then check rotation and they are free. Go for a ride around the block, jack the car up and locked up. Loosed M/C, wheels free. Put a shim (flat washer) between M/C and booster, tighten and wheels turn free. Take for a ride and jack it up...wheels locked. Loosen M/C and wheels turn free. Add a second washer but got the same results. Can't figure what is going on!
Sounds like the booster push rod is still a little bit too long. What booster are you using? Also, do you have a return spring on the pedal? I assume the master is under the floor since you said you have residual valves in it. Under floor boosters usually need a pretty hefty return spring.
Last edited by ls1nova71; Sep 1, 2021 at 10:32 AM.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Yes, the M/C and booster are under the floor. I changed the combo to a new set with a 1" bore vs the 1 1/8" I had before (which had the same problem). Before installing I used that special tool to set the pin between the M/C and booster to .020". I also changed the 2# residual valve. Yes the pedal has a spring which returns the pedal to the top but maybe I should try a stronger spring. Thing is, while jacked up I can relieve the pressure then press the brake and wheels still turn free. Even started the car and tried it with same results. What I mean there is the brakes work and when the pedal is released the wheels turn freely. What would cause the brakes to lock on a trip around the block but can't duplicate on jackstands?
Have a friend that I've helped get his old Ferrari back on the road. We rebuilt the master cylinder and worked hard to get the brakes/system bled and filled with fresh fluid. Brakes worked fine when applied, but would stay locked when he released the pedal. Like a 'hill assist' but on all the time. Turned out that there was an internal failure in the vacuum booster. Had the booster rebuilt - problem solved.
Had a very similar issue on a 69 Chevelle, the rod ended up being like a 1/8" too long. It was a hydro boost swap car. Measured the rod before hand with calipers, seems like it should have been perfect, but put it on the grinder and it was fixed. Couldn't argue with results.
Might try unhooking the vacuum source from the booster to see if that is causing it. Otherwise we will need more info on your set up. Any proportioning valve of any kind? What booster and master cylinder are you using?
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Yes, that's my next move, duplicate the lock up and disconnect the vacuum line and see if the brakes release. I also increased the pedal return spring tension and will also try tapping on the M/C to see if bottom plunger (front brakes) is hanging up. Test should be done later today and I'll give an update. Thanks all.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Well, went around the block, jacked the car up and wheels spun freely. Took a nap! Took the car on a two mile loop and wheels were locked. Unplugged the booster vacuum line (had a vacuum on it) but did not release the brakes. Rotors are hot (190) right now. Will let it cool and see if the brakes release on their own. Tells me that heat build up is expanding the fluid but it can't get back into the M/C. I did set the M/C to booster pin with a special tool to ..020" and on test added a shim to the M/C to move it away from the booster a bit. Can't be that far off can it?
System is on my '39 with a MII style front end, Granada rotors, GM calipers, M/C under floor with #2 residual valve.
System is on my '39 with a MII style front end, Granada rotors, GM calipers, M/C under floor with #2 residual valve.