Re:Re:Is the front cross-member really needed?

A somewhat contentious subject but that's what forums are for.

I am going to fit a 50mm suspension lift so I did a bit of a perusal under Tonka and the front cross-member evoked the thought "why is it there". It's not particularly strong, the RHS is relatively thin and the bolts are not up to much and the bends at each end will reduce the effectiveness of the member if it's use is purely to stiffen the chassis. Now those where my first thoughts but then you have the prop-shaft that obviously needs the kinks or it would foul the cross-member plus the catalytic converter gets a degree of protection.

As a chassis stiffener it would do a poor job. The prop-shaft, if it could talk would cry " I don't want you there", which leaves the cat as the only reason for it's existence. I know that a 50mm lift should not foul the member but by how much and are there any comments to cutting a half moon slot out of the member and welding in a suitable stiffener.This at least would provide the same level of protection to the cat. as it had previously.

Or are there any other options?

Roger

I have also wondered about how much extra stiffness it really provides, it does look rather flimsy.
On my 50mm lift the propshaft touches the crossmember at full droop.

Some suspension suppliers have gone with a drop bracket. Others appear to have just ditched it. A local (South Africa) manufacturer is busy developing one like you have suggested with the half moon cut-out.

I'm not a chassis engineer. But I'd have thought chassis stiffening is a compound result, something small and potentially weak on its own, may well contribute to an entire design.

It must serve a purpose, else Suzuki wouldn't have gone to the cost and effort of fitting it. Personally I'd not advise removing it.

Dropping it seems an easy solution and I suspect with very few downsides. Notching it is obviously another option and one that should work and is done on other vehicles. But will clearly be more effort.

As for it not being an issue with a 50mm kit. It really depends on the kit in question. It isn't really about the lift exactly, unless it is extreme. It is more about if the new suspension offers more suspension droop or not. At full droop with the stock suspension it is not an issue, if you extend the droop, then the crossmember gets in the way.

I'm not a chassis designer either but I am a practical engineer with 40 years working in the automotive industry. Looking at the chassis in question I see braces in front and behind that are in proportion to the main rails and are fully welded both sides. this is how it should be. The cross member in question is cheap and cheerful and as I pointed out apparently only there to give some (but not a lot) of protection to the cat. Notching it serves two purposes, it retains the cross member and safeguards the prop-shaft and protects the cat. According to the people who supply kits, a 50mm lift will not foul the cross member but a 75mm will, so it's a close run thing and getting airborne with the 50mm may well see contact and possible damage. After the lift kit is fitted I would suspend the front axle with suitable props and look at the clearance. It is more than likely that I would notch the member and the droop test would tell me by how much.

Roger

Those of you who remember the original marketing of the new Jimny will recall this picture and the description that the chassis had been stiffened to improve "torsional" strength. In the same text it also mentions the body and how the overall stiffness has been improved by 50%

Roger Fairclough wrote: I'm not a chassis designer either but I am a practical engineer with 40 years working in the automotive industry. Looking at the chassis in question I see braces in front and behind that are in proportion to the main rails and are fully welded both sides. this is how it should be. The cross member in question is cheap and cheerful and as I pointed out apparently only there to give some (but not a lot) of protection to the cat. Notching it serves two purposes, it retains the cross member and safeguards the prop-shaft and protects the cat. According to the people who supply kits, a 50mm lift will not foul the cross member but a 75mm will, so it's a close run thing and getting airborne with the 50mm may well see contact and possible damage. After the lift kit is fitted I would suspend the front axle with suitable props and look at the clearance. It is more than likely that I would notch the member and the droop test would tell me by how much.

Roger

I believe it still depends on the kit to how much droop you get. As said, the lift to some extent is not part of the equation unless you are lifting it to the point of fully extended the shocks. What kit are you looking at?

Pretty sure some of the 50mm/2” kits will hit the cross member. At least based on the info I’ve found.