How long did it take to pull the front sub-frame assembly? It seems like it would be easier to pull the whole deal out to service and reseal the engine and trans.
1975 GMC Palm Beach Restomod
- Thread starter Mike Perez
- Start date
I am thinking about buying an all original 76 palm Peach with 70k on it. I know that I would want to go through all mechanical stuff to make it reliable. I don't I would go as far as your build, which is ballin', but I would want to at least reseal the engine and trans and replace the wearable parts. Pulling the subframe seems like it would be easier than trying to do all of it in the coach.
I think your thinking along the right tracks but short of doing a full resto you would probably better served by only replacing the basics in the coach.
Dont get me wrong but ive seen way to many a projects never get finished because people take it appart and one thing leads to another.....5 years later its still apart and now its not worth anything and it was never enjoyed.
Mike and the others have invested major funds and time. They have a plan and a schedule plus the means to get it done (skills, tools, contacts etc).
Im not trying to discourage you in any way.....just want you to enjoy your coach instead of looking at it in the driveway.
I totally understand and that is why I have been doing a lot of research and asking many questions to the GMC Motorhome community. I do have the talent, tools, and drive to tear it apart and rebuild it mechanically. In the end I would want to go through all known issues like the intake manifold crack, fuel lines, timing chain, gaskets, mail seals. etc..... I have resealed many old engines and it was always easier taking the engine out and doing it on an engine stand. It is good to see some pics showing the subframe out and all apart.
I'd be interested as well. The old v belts are a pain to tighten and getting harder to find.
There are a few parts to the setup. I can't tell you it will absolutely work well since I haven't ran it yet, but I'm about 95% confident. The brackets are from a 88-92 Camaro.
The aluminum brackets pictured above are made by a guy on the Real Olds Power forum. His screen name is extreme supreme. Originally the brackets were designed to adapt to the truck accessory brackets of the same era. After some testing, I was convinced that the truck bracket's alternator would be too tall for the GMC floor. Also, the design was originally designed for a crankshaft pulley from a Ford 5.0 that I felt was not only too small, but also required too much modification. Additionally, this only works because I'm using a balancer that comes out of the box with both Oldsmobile and Chevy bolt pattern for the pulley. This allowed me to use a big block Chevy pulley, although I still had to use a paper thin shim for the pulley. That particular balancer required removing the counterweight because it hit the engine mount bracket before the balancer was all the way in. For me, it forced me to get the crankshaft internally balanced when I had the engine built.
I had to make some modifications to the intended design because of the left adapter bracket interfered with the mount bracket for the final drive. Additionally, I had to build a custom bracket for the lower passenger side and two other support brackets. With a serpentine, there can be zero room for bracket movement so the belt doesn't jump off.
Also, this era brackets for both car and truck use an R4 A/C compressor which is notoriously bad. I was planning on using a Sanden compressor, and luckily adapters are available for that.
The Camaro had a smog pump that has to be removed to the Olds radiator hose clears.
This system could be duplicated, but it is not easy or cheap. I think a universal serpentine bracket could be developed for modern accessories with a stock water pump. I have a few ideas, but it will have to be put on hold for a few years.
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Thanks,
It looked involved, like the rest of the build, but was hoping it was more of a bolt on affair.
I know there have been serpentine conversions for the GMC, but i never paid attention. That was before I had changed the belts half a dozen times - I'm ready for serpentine...
It looked involved, like the rest of the build, but was hoping it was more of a bolt on affair.
I know there have been serpentine conversions for the GMC, but i never paid attention. That was before I had changed the belts half a dozen times - I'm ready for serpentine...
Don't forget about those wheel wells, unless you move them out 
, i gave alot of thought to the best floor plan due to them and I'll be doing a rear bathroom / twin beds royal style floor-plan.
, i gave alot of thought to the best floor plan due to them and I'll be doing a rear bathroom / twin beds royal style floor-plan.
Don't forget about those wheel wells, unless you move them out
Bathroom over left wheel well, and storage/fridge over right.
did you get a photo of the crank mods? be interesting to see just how/where they went about it. 455 has a massive crankshaft.
No. My engine shop built the engine. I'm sure they just drilled out or added weight in the counterweights which is typical. The original plan was not going to internally balance it, but my hand was forced since I designed the crank trigger wheel around a specific balancer. That specific balancer also had the correct pulley bolt holes for the big block chevy that I needed. That balancer was just never designed for the Toronado front bracket, so I had to call an audible.
I rolled the dice on some seats. These are second row seats from a Toyota Sienna van. They matched what I want to do with the inside, so that was a plus. They already have adapters on them for solid floor mounting. I may or may not keep those because to mount these in the GMC is going to require a completely new engineered base that is designed to take the loads on the seats with an occupant belted in. Also, I have some 1/2" aluminum plate being sent to me as well to start the modification/strengthening of the floor area.
They recline with foot rests too. The weather has been terrible so I can't do too much, but I took some measurements yesterday. The passenger seat should recline nicely and have room to extend the foot rest fully. The drivers seat is going to come down to how I design and mount the dinette area seating. The backrest reclining will still be limited by the steering wheel, but I could always put a quick release hub like I had on my track car. Good for security too. Hard to drive with no wheel.
Nice seats.
I would think bolting the seats to a suitable thickness plate which is the footprint of the original seats, plus the OE seatbelt mounting point, and using the stock seat mount, and belt, holes would do it. The shoulder belt is is just holding you to the seat, which the stock belts were doing.
Carpet over the plate, and Bobs your uncle.
But, I am not an automotive safety engineer and do not play one on TV...
I would think bolting the seats to a suitable thickness plate which is the footprint of the original seats, plus the OE seatbelt mounting point, and using the stock seat mount, and belt, holes would do it. The shoulder belt is is just holding you to the seat, which the stock belts were doing.
Carpet over the plate, and Bobs your uncle.
But, I am not an automotive safety engineer and do not play one on TV...
It is a bit more complicated than that. The original belts were not holding you to the seat. The original belts are holding you to the coach. Unfortunately, since it is only a lap belt, you lower body would be restrained, but your upper would not be. In an accident, the upper part of the seat back doesn't have any load on it other than the forces from the accident on the lightweight clamshell seat. The original seat base was not designed to take any load at all other than the weight of the seat. In the track car I built, the sanctioning bodies wanted the seat secure, but it didn't have to to secure the driver because the belts were mounted to the chassis roll cage.
When you add a seat belt integrated into the seat, now the base/mount has to carry the load of the seat AND my 200 lb body. Additionally, the moment arm is much longer with a shoulder harness seat. Think of it this way. What is the required force to open the front door to your house by pushing on the door near the doorknob? Not too much, right? Now open it again except push it open 1 inch from the edge on the hinge side. Considerably more. On the shoulder harness seat, a lot of the force in an accident is now 3-4 feet away from the base plate so the forces on the base are magnified tremendously.
I'm basically doing what you suggest, but the "plate" will be mounted under the plywood floor so there will basically be a 20"x21" area where a seat could be anchored. The wood will cover the structure, but it won't be required to take any of the load. If I do it like I want, the final base will be smaller than the footprint of the seat so the flooring material can be completely flat. I'm trying to avoid carpet.
I saw a set that came out something new that swivelled as well.....figured they'd be cool but im betting they were mucho heavy.
Interesting. I've never seen seats that have all three things....swivel, recliner function, and slides. I've seen combinations of those three, but never all three in a single seat.
In the "stupid ways to mount a seat department.....check out the drivers seat from my coach when I bought it. That is a air ride trucker seat. It was seriously heavy. You can imagine my surprise when I found that it was attached to the floor with nothing but a few bolts through the plywood. ?
Some of this stuff is crazy scary.....Interesting. I've never seen seats that have all three things....swivel, recliner function, and slides. I've seen combinations of those three, but never all three in a single seat.
In the "stupid ways to mount a seat department.....check out the drivers seat from my coach when I bought it. That is a air ride trucker seat. It was seriously heavy. You can imagine my surprise when I found that it was attached to the floor with nothing but a few bolts through the plywood. ?
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