MG Sports Cars

Hi guys, this is my first post.

Does anybody have any first hand experience with the differences/benefits of modding the "B" with a 3 link rear vs a 4 link rear? Also, has anyone ever done a deDion semi-independent or even a full independent on an MGB?
I use to see ads for a pretty expensive IRS in British mags years ago for the B but I would love to know if anyone has dabbled in converting some existing modern car's IRS to the B.

A lot of questions for a first post, I know. Sorry.

Thanks

[www.britishv8.org]

Russell, first welcome. The link that David posted will take you to all sorts of information about suspensions, but two that I'd like to comment on are the 4 link system from Bill Guzman at Classic Conversion Engineering [www.britishv8.org] and the Jag IRS conversion designed by Jim Blackwood and used in both his car and the Project Roadmaster. [forum.britishv8.org]
There have been several IRS units used in MGBs, Jag is the most common but the custom made units from both Hoyle as used by Larry Shimp [www.britishv8.org] and Todd Budde [www.britishv8.org] are also good designs.

Hi Russell,
You may want to check out my B with Jag rear. ( the Grey one ) It's a low buck install and works pretty darn good. The one in build state has a late model holden ( GTO ) rear with Torsen limited slip. [www.cardomain.com]
If you need some more pictures let me know on the site.
Regards,
Bill

Welcome to the forum Russell!

Martyn Harvey has a custom (Larry Ellis) 4-link plus Panhard rod in his MGB, and he let me drive it at Nelson Ledges. I really like it! The design is rather elaborate, but very neatly engineered.

several photos here: [www.britishv8.org]

Dax DeDion photos:

I haven't heard from him in awhile, but one of our BritishV8 readers (from Sweden) was putting a DeDion under his MGB. It's his second DeDion. He already built a Super 7 knock-off with one. Seems to me, if you're going to do a DeDion you might as well do inboard brakes at the same time to minimize unsprung weight.

Here's what the Lotus Eleven LeMans DeDion looks like:




(photos from an upcoming BritishRaceCar.com article)

Here's my Classic Conversions (Bill Guzman) 4-link:


Graham Creswick also has this suspension on his MGB Ford 302

Wow! Thanks everyone for your input. I had no idea there was so much innovation going on around here.

I guess nobody has actually evaluated a 3-link to compare it to a 4-link.

Great to see you guys are continually pushing the envelope. Keep up the good work.

-Russell

I've often considered the "3-link" a misnomer as the 3-link systems I've seen also employ a panhard rod thus rendering them as a 4-link system.
In Bill Guzman's design, he has angled the 2 upper links (eliminating the need for a panhard) so they control body to axle relationship and yet do not bind under full axle articulation.
An ill-conceived panhard used with a 3 -link design may exhibit bump steer at the extreme axle bump or rebound conditions - so design is critical and adds some complexity to the system. The British V8 (as Bill Young points out) has some excellent reviews on both the 3 & 4 link setups.

Quote:

I guess nobody has actually evaluated a 3-link to compare it to a 4-link.

I'm not sure what you're looking to hear. Were you hoping for a seat-of-the-pants comparison between the one and only commercially available MGB 3-link (that's made by Ted Lathrop) and the one and only commercially available MGB 4-link (that's made by Bill Guzman), or were you hoping for a comparison between 3-links and 4-links generically? There can be a world of differences between two different 3-link designs, or between two different 4-link designs.

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Quote:

In Bill Guzman's design, he has angled the 2 upper links (eliminating the need for a panhard) so they control body to axle relationship and yet do not bind under full axle articulation.
An ill-conceived panhard used with a 3 -link design may exhibit bump steer at the extreme axle bump or rebound conditions - so design is critical and adds some complexity to the system.

You're right, Graham... but there are of course two sides to every coin. By definition, a Panhard will cause bump/roll steer. (Whether the effect is significant or negligible depends mainly on length. Longer is better. If someone wants more explanation of this point, they can go to this article and scroll down to the section that's titled: "Why Are Longer Suspension Links Better than Short Ones") However, the two angled links of Bill's 4-link system are essentially functioning as a pair of Panhard rods - they certainly will cause bump steer too! In fact, they're shorter than most Panhard rods, so whether they bind or not, they will typically cause more bump steer for a bump of a given height. (As I interpreted our conversation, Bill has explained that he sees this as a worthwhile trade-off because the related roll steer effect is something he has harnessed for good.)

I wonder if anyone noticed the Panhard rod in the first photo above of the Lotus XI DeDion rear suspension? It's short, and mounted at a funny angle, but it's a Panhard rod! (The chassis mounting point is very near the righthand brake caliper.)

One of the reasons some racers like Panhard rods is that they can have the effect of lowering a rear suspension's roll center, assuming that they're mounted lower than axle height. One of the reasons some roadracers don't like Panhard rods is that they behave differently on right hand turns than they do on left hand turns (depending on which end of the bar is mounted to the axle and which end to the body...) In lieu of a Panhard rod, you might consider following one of these paths:

Thanks, Curtis, for pointing-out the complexities of this topic. I see now that it is always going to be difficult to compare apples to apples with these different setups and their somewhat different approaches.

What I guess I really am trying to figure out is out in the real world, filled with bumpy corners and potholes, can a live axle set-up be maximized to truly make someone not miss IRS? Forgetting for a moment the significant differences in unsprung weight, can a truly well-suspended live axle articulate a one-wheel bump without sending the car off its given line?

The added expense and complexity of a "good "IRS is usually considered the ultimate as far as the ride/handling compromise is concerned. I'm simply trying to figure out if I will ever be satisfied without it.

My first car was a '74 Glacier White MGBGT with orangish-tan fabric interior and OD and I will always wax poetic about it ( I was in college when I got it brand new). But now that I've experienced modern IRS in a number of late model cars, I'm trying to decide which way to go with my current "B" project.

For the record, probably like most of you, I have a really hard time getting excited about cars made today. They simply lack soul.

The Jag IRS is a really good fit if it's done right, and once I get my engine done I may make up some more parts to offer. I'm thinking along the lines of a fabricated aluminum lower control arm, tubular half-shafts and a light weight mounting cross member and front brace. In terms of ride the solid axle is never going to compare, and it's yet to be seen if it has any real advantage in putting the power to the ground. The IRS on the MGB-Roadmaster seems to hook up really well, but to be fair we aren't far enough along to do any real power testing yet. But the ride is on par with anything new being built today, and a very major improvement on the old solid axle.

Anyway, with those 6 major components, a few lesser ones, and a pair of coil-over units you could source the Jag IRS of your choice and be ready to do the swap, which is a one day job once the unit is assembled, with no modifications to the car itself. I still haven't worked out pricing and really won't be able to until after a run of 2nd generation parts have been made, perhaps in late spring or early summer. It will be more expensive to do than a solid axle of course. For instance, there are $400 worth of bearings and seals just in the uprights, and nearly that much more in the pumpkin. So a great deal can be saved by finding a used unit with the correct gears and posi that is in good enough condition that it doesn't need to be torn down. That might cost a bit more than the entry level $250 junkyard special but it would be a worthwhile investment. At this point I'm thinking that the kit that would be needed to complete the package would run around $2000-$2500 but a lot would depend on what had to be included and on material costs so it's really too early to project prices.

Jim