removable rear upper crossmembers
Discussion
I thought of making the two rear upper crossmembers removable by cutting them and reconnecting them with two steel plates and bolts.
To make life easier i wanted to assemble engine and gearbox prior to lifting them in or out.
Also thought of adding an additional, removable crossmember (yellow line) to add strength to the upper wishbone mounting.
I'm not sure, if i will loose torsional rigidity by bolting them in place, rather than welding.
Any concerns about doing that?
cheers
Cornel
To make life easier i wanted to assemble engine and gearbox prior to lifting them in or out.
Also thought of adding an additional, removable crossmember (yellow line) to add strength to the upper wishbone mounting.
I'm not sure, if i will loose torsional rigidity by bolting them in place, rather than welding.
Any concerns about doing that?
cheers
Cornel
I usually agree with most of Steve D,s posts, but I think he has this one wrong. The comments above that say this can be done without sacrificing torsional strenght are correct. Furthermore the change that you envision can make life a lot simpler because you can move the engine-gerabox out as a single unit avoiding manhandling the gearbox in from the back. This will save wear and tear on the cross tubes that the gear box has to be moved over to get in posistion to mate to the engine and actualy mating the box and engine outside the car could be a little easier if you are able to support the engine from the front and hoist the gearbox inplace. Just my thoughts. I didn't do this on mine and I wish I would have. Lee
I have removed both of the rear upper cross-members on mine.
I fabricated a top brace that bolts in and has forward triangulation too.
The rear brace is replaced with a tube bolted in to support the exhaust system.
I can use the engine crane to either lift out the engine and transmission all in one or just the trans on it's own (I can do this with the car on my car lift giving easy access underneath too).
No damage to chassis tubes by the box and easy to do.
My car was already 12 years old, but not sure I would do it to a nice new chassis. It did not feel so bad to do as I had other chassis parts to replace due to poor modifications before I purchased it.
If you do do it - only do one at a time so that you avoid chassis twisting.
Paul
I fabricated a top brace that bolts in and has forward triangulation too.
The rear brace is replaced with a tube bolted in to support the exhaust system.
I can use the engine crane to either lift out the engine and transmission all in one or just the trans on it's own (I can do this with the car on my car lift giving easy access underneath too).
No damage to chassis tubes by the box and easy to do.
My car was already 12 years old, but not sure I would do it to a nice new chassis. It did not feel so bad to do as I had other chassis parts to replace due to poor modifications before I purchased it.
If you do do it - only do one at a time so that you avoid chassis twisting.
Paul
The chassis has to be weaker...two bolted flanges cannot be as strong as a fully welded box section unless you increase the size of the sections and material thickness.
So back to my question...how many times are you planning to take the 'box out and does that justify the extra work and reduced chassis strength.
My 'box has only been out once since I built the car in 2004.
Steve
So back to my question...how many times are you planning to take the 'box out and does that justify the extra work and reduced chassis strength.
My 'box has only been out once since I built the car in 2004.
Steve
Steve_D said:
The chassis has to be weaker...two bolted flanges cannot be as strong as a fully welded box section unless you increase the size of the sections and material thickness.
So back to my question...how many times are you planning to take the 'box out and does that justify the extra work and reduced chassis strength.
My 'box has only been out once since I built the car in 2004.
Steve
Hi SteveSo back to my question...how many times are you planning to take the 'box out and does that justify the extra work and reduced chassis strength.
My 'box has only been out once since I built the car in 2004.
Steve
That box section is very thin and I have used a thicker material and used sleeved staggered bolts and then triangulated to just forward of the roll bar brace.
My trans has had to be removed once already to replace the clutch with a Factory uprated clutch. Working alone it took me 3.5 leisurely hours to complete.
Paul
Storer said:
Hi Steve
That box section is very thin and I have used a thicker material and used sleeved staggered bolts and then triangulated to just forward of the roll bar brace.
My trans has had to be removed once already to replace the clutch with a Factory uprated clutch. Working alone it took me 3.5 leisurely hours to complete.
Paul
Got to be worth a couple of pics, I have a view to box removal in the next month or so for a thorough check up before power hike.That box section is very thin and I have used a thicker material and used sleeved staggered bolts and then triangulated to just forward of the roll bar brace.
My trans has had to be removed once already to replace the clutch with a Factory uprated clutch. Working alone it took me 3.5 leisurely hours to complete.
Paul
As Steve will testify. I have had the gearbox out of mine at least 4 times this year due to various issues with clutch old and new! I would not even consider cutting the chassis to assist with this. It probably takes longer to undo the chassis tube bolts than it does to lift the gearbox out through the back of the chassis. We all know what the hardest part of the job is (unless you have a hydraulic release bearing) and that becomes very easy once you have the hang of it.
macgtech said:
Agreed.
Adding the additional crossmember won't make too much difference (obviously it will make some), you would be better off adding in some diagonals to stiffen things up.
Yes, additional diagonals are already on the list. The little extra weight might be worth it.Adding the additional crossmember won't make too much difference (obviously it will make some), you would be better off adding in some diagonals to stiffen things up.
Have to lift the whole unit in and out several times to fabricate engine mounts, diagonals under the engine, for the rollbar and a few from the lower rear wishbone mounts to the rear of the chassis.
The reason will be quite clear, if i have had the non cropped version of the pic. attached! ---voila---
356Speedster said:
I agree with this. I wouldn't cut these pieces out and then find a way to re-bolt them as they'll just crush... instead, you'd be better to build a set of new braces to replace them. Just my 2p worth.
Unless you weld sleeves into the holes as I did for the gbox mounts.OK. Pictures below.
Don't be fooled by the small tube. It is a much thicker wall than the old chassis box. The arrangement of the fixings is designed to avoid twist and movement and seems to work well.
I know there are bound to be many out there sucking their teeth and shaking their heads but it works for me!
Paul
Don't be fooled by the small tube. It is a much thicker wall than the old chassis box. The arrangement of the fixings is designed to avoid twist and movement and seems to work well.
I know there are bound to be many out there sucking their teeth and shaking their heads but it works for me!
Paul
Here are my removable crossmembers. Not as neat as Paul's, but should do the job. I will eventually connect the two with a tubular cross.
I welded a bar across the chassis before cutting out the first crossmember, making it, and then making the second one. When I had made the crossmembers, but had taken them out, I only had to put a little weight from my foot onto the bottom crossmember to see the chassis moving considerably.
I don't plan to remove the engine often, but I like to tinker, so for me it was worth doing. Chassis strength is not compromised. The only problem would be if there was play in the bolted joints which would allow the chassis to twist.
Incidentally, related to the rusty chassis thread, you can see clean steel inside one of the sawn-off tubes.
I welded a bar across the chassis before cutting out the first crossmember, making it, and then making the second one. When I had made the crossmembers, but had taken them out, I only had to put a little weight from my foot onto the bottom crossmember to see the chassis moving considerably.
I don't plan to remove the engine often, but I like to tinker, so for me it was worth doing. Chassis strength is not compromised. The only problem would be if there was play in the bolted joints which would allow the chassis to twist.
Incidentally, related to the rusty chassis thread, you can see clean steel inside one of the sawn-off tubes.
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