Straightening a 914, no one around here has a cellette Options

[FourBlades]

I am thinking of putting my IMSA car on a frame jig and having it pulled totally straight. It was pretty hard getting the front suspension to line up when I installed it and the rear needs about an inch of spacers to get the camber right.

I have not found anyone nearby that has a cellette bench to do the work.

Will shops with other systems be able to get this done?

This car has a 10 point roll cage in it, I hope to leave it as it and not cut any, but I guess I can replace some tubes if I have to.

Can the experts give me some advice here about how to go about this or if this is a good idea. If you have been through this and don't mind sharing your experiences and costs it would be great.

Thanks,

John

[brant]

I certainly am not a body shop or expert by any means

but my limited roll cage experience and one experience of trying to straighten a caged car....


I think you will have to cut the cage to change anything at all

[McMark]

The cage will make it nearly impossible to pull, if the damage is tied into the cage. IF the cage was put in when the car was straight, it may actually help it pull back straight more easily. Not gonna know until you try, but be prepared to cut it out.

I've never worked with or seen anyone work with a 914 on a different bench. Of course it's possible, but it's the age old question of finding a shop that can be trusted with such an endeavor. At the very least I would print out a lot of the measurement diagrams from the factory manuals, and preferably, be there when they pull it to double check their measurements.

Go to Celette.com and call the company. See if they have a listing of any shops in your area that have the bench. I bet you find someone within towing range.

[rick 918-S]

All bets are off when a cage comes into play. Sometimes it requires some of the cage to be cut loose first before trying to pull the chassis.

Here's why:

The cage install may have caused some of the issues. Even simple chassis repairs using reproduction parts gives some guys fits when the welding on the chassis causes the car to settle or twist. Imagine the possibility of distortion that could be caused while welding in a cage.

Then there is the issue with off course excursions and bumping.

Then imagine trying to pull sheet metal that is being held in place with a 4130 safety cage designed not to move or collapse during impact or a rollover with huge impact forces and the weight of the entire car driving that force.

There are many shops out there that could get the car close with conventional pulling systems. But it is less likely without fixtures on an open top car with the added complication of a cage.

[URY914]

John,

Have you string lined the car to see what is off?

[FourBlades]

Thanks for all the advice!

Mark: I will contact cellette and see where there is a shop, good idea.

I get the idea that the cage makes it hard to change. I am hoping the car was straight when they installed the cage. It has seen some front impacts and one side impact since then. If I had to cut the rear pick up tubes or those in the front trunk that would not be too hard to replace.

When I had the car upside down I measured a lot of side to side and diagonal measurements between suspension mounting holes that all looked good. I also leveled the car and did not see any lengthwise twist in it. I did not measure any of the vertical distances and I think this is what is off. I need to try to measure that while the car is on the wheels.

Maybe I should take the car in for an alignment and see what the shop says about that? It would be about $400 for Porsche to do it and maybe I would learn how far off it is?

I'd like to get this right before moving on and painting the car only to find out the handling is tweaked. Am I being overly cautious?

John

[SirAndy]

I am hoping the car was straight when they installed the cage.

Don't bet on it.
I made the same mistake, no one else to blame here. I had the cage installed without checking the car for previous damage first.

When i finally found out that the chassis was tweaked we had to cut the cage to be able to pull the car back. The cage was just too strong.
After the pulling we then had to bend the cage to match the now straight car. It all worked out OK in the end but it was a lot of work to get there ...
(IMG:style_emoticons/default/smash.gif)

[BKLA]

Check your swing arms first - I found a significant difference in two left side arms when set on a simple jig I made.

I talked with Rothsport about the "zonk" and straightening my chassis. (left rear corner is about an inch high and the outer swignarm attachment is about 1/2" high as well.) I was told that the two rear strut ties would need to be cut from the cage and replaced in order to straighten/square the rear portion of the tub.

Depending on the rest of your chassis, it might only be a few tubes that need to be cut/replaced.

[FourBlades]

I am hoping the car was straight when they installed the cage.

Don't bet on it.
I made the same mistake, no one else to blame here. I had the cage installed without checking the car for previous damage first.

When i finally found out that the chassis was tweaked we had to cut the cage to be able to pull the car back. The cage was just too strong.
After the pulling we then had to bend the cage to match the now straight car. It all worked out OK in the end but it was a lot of work to get there ...
(IMG:style_emoticons/default/smash.gif)

I remember reading your celette story.

How many tubes had to be cut?

Where did you cut them?

John

[SirAndy]

How many tubes had to be cut?
Where did you cut them?

We cut the horizontal top hoop where it meets the vertical back hoop and we cut the side bars where they meet the vertical front hoop.

4 cuts, which effectively disconnected the cage completely front to back and allowed for the bench to take out the twist along the center axis of the car.
(IMG:style_emoticons/default/shades.gif)

[doug_b_928]

I don't mean to hijack. I'm just learning about all of this via this forum. My question concerns the timing of straightening a twisted chassis that also needs extensive rustoration. I'd assume that it's best to get a chassis straightened before doing the repairs. But, on the other hand, there might be some logic to doing extensive rust repairs before putting the chassis on a celette so that any twisting from the welding can be straightened out. Which is the best option?

[FourBlades]

Good question Doug. I think it depends on the condition of the car you are starting with.

If I had tried to straighten this car before replacing the floors and front of the car it would have just fallen apart.

You could put your fingers through a lot of the metal.

I tried to do all the repairs as straight and aligned as I could while I went.

I don't think the car is twisted or is far out of whack, but if I am ever going to fix it, now is the time, compared to after it is painted.

John

[FourBlades]

Hey George, shouldn't you be working?

(IMG:style_emoticons/default/biggrin.gif)

[doug_b_928]

Good question Doug. I think it depends on the condition of the car you are starting with.

If I had tried to straighten this car before replacing the floors and front of the car it would have just fallen apart.

You could put your fingers through a lot of the metal.

I tried to do all the repairs as straight and aligned as I could while I went.

I don't think the car is twisted or is far out of whack, but if I am ever going to fix it, now is the time, compared to after it is painted.

John

Thanks, John. Good to know that sometimes it's better to actually do the structural rust repairs before getting the chassis straightened. I suspect that's the boat I'm in.

[brant]

Doug,

you may want to consider adding temporary bracing while doing structural repairs...

for example you need to use door bars at a minimum
most people add bars for the job.

[ThePaintedMan]

Doh, I guess I left this on in the background John, that's why it looked like I've been reading it all day.

I am, however interested to see what all needs to be done to get the car where it needs to be. If you need help once you've identified where you're going to take it, I'll be happy to come over and help! Be really careful when cutting cage tubes though - I've been told that they can store a ton of potential energy like a spring!

[jd74914]

Just adding to the above, I think you are also going to have to cut the cage. I'm helping remake a Caterham frame now that was wrecked then attempted to be straightened on a bench. The end result was doubling the number of buckled tubes and cracked welds (as compared to the original accident). The weld cracking was a bit scarier as not all was easy to see (unlike the painfully obvious tubes) and wouldn't have been found without a cafeful inspection. For reference, Caterhams are TIG welded, fillet brazed, and them most likely stress relieved, so their joints are significantly more ductile than the MIG welds on most cages.

[rick 918-S]

Just adding to the above, I think you are also going to have to cut the cage. I'm helping remake a Caterham frame now that was wrecked then attempted to be straightened on a bench. The end result was doubling the number of buckled tubes and cracked welds (as compared to the original accident). The weld cracking was a bit scarier as not all was easy to see (unlike the painfully obvious tubes) and wouldn't have been found without a cafeful inspection. For reference, Caterhams are TIG welded, fillet brazed, and them most likely stress relieved, so their joints are significantly more ductile than the MIG welds on most cages.

I believe that Caterham was more likely gas welded like an air frame. Specially if it's 4130. The best process for 4130 is gas welding. Tig works if properly stress relieved. The heat concentration with tig is too small causing the welds to cool fast rather than naturalize with the tubes. Lots of guys tig tube I know but I'm referring to the likely method back in the day. The best method is still old school.

[jd74914]

Just adding to the above, I think you are also going to have to cut the cage. I'm helping remake a Caterham frame now that was wrecked then attempted to be straightened on a bench. The end result was doubling the number of buckled tubes and cracked welds (as compared to the original accident). The weld cracking was a bit scarier as not all was easy to see (unlike the painfully obvious tubes) and wouldn't have been found without a cafeful inspection. For reference, Caterhams are TIG welded, fillet brazed, and them most likely stress relieved, so their joints are significantly more ductile than the MIG welds on most cages.

I believe that Caterham was more likely gas welded like an air frame. Specially if it's 4130. The best process for 4130 is gas welding. Tig works if properly stress relieved. The heat concentration with tig is too small causing the welds to cool fast rather than naturalize with the tubes. Lots of guys tig tube I know but I'm referring to the likely method back in the day. The best method is still old school.

You're correct. The frame is a 2001 which per google looks to have mostly been bronze welded. The interesting part is that most of the welding appears to have "steel" filler. I agree that gas welding on 4130 is better since you don't need to stress relieve. We've built a few tube chassis and the stress relieving after TIGing takes forever; it seems like it would be quicker to have a good torch guy gas weld the whole thing and skip the relieving step. (IMG:style_emoticons/default/smile.gif)

Is there a way to tell if something is TIG or gas welded
Sorry for hijacking John...

[FourBlades]

This is all good information.

Thanks for the offer George I may need your help.

What ever I do I plan to be there to watch and supervise.

John