Steering, Suspension, & Brakes

I'm thinking about having a spring shop modify a set of rear springs. I've done this before, on my '71. In that case I had the shop de-arch the spring pack 1-5/8" and add a full length leaf to increase stiffness. This ended up lowering the rear 1" and matched the spring rates to the -1" Huffaker competition springs I was running on the front.

On the Chump car we need the rear to come down about 3 or 3-1/2 inches ('74-1/2) so I'm thinking about reversing one or both spring eyes on the main leaf, probably both. The early shackle is also a bit shorter. The disadvantage is that the 2nd leaf would then have to be shorter, so it might make sense to increase the thickness of the primary leaf by 1/16" to compensate and add back in some strength and stiffness. Then maybe another long leaf, It's hard to say if it would be needed or not, but it could be added and taken out later if it ends up too stiff. I suspect it'd be OK, and there is a balance between spring and shock rates that can be shifted a bit either way to compensate some.

There are spring shops all over the country and making up leafs is a basic part of the business. The cost is not high if they do the work locally and you can get the spring pack customized to your own requirements. I avoid riser blocks whenever possible as they give the axle additional leverage against the springs and when you add torque and better brakes and tires that is going in exactly the opposite direction from what you need and encourages wheel hop. An MGB spring pack with an extra leaf does a really good job of controlling that.

Jim


(Moderator has split this message out of fender flare thread...)



Edited 1 time(s). Last edit at 08/18/2014 11:42AM by Moderator.

Keith, On rubber bumper cars you can drill the mounting holes 1" higher and cut off the excess. I'm not a fan of blocks either but 1" or under don't seem to be a problem. Look up homemade Cal-Trac traction bars. There was a video of a guy reversing the arch of the main leaf with a hydrauilic press.

Jim, have you ever done that hole drilling trick? It looks pretty difficult to me, I don't quite see how you can get a drill in there to do it, though in this case I might be willing to try. Seems like getting the holes lined up might be tricky too.

Springs can be cold bent though it's a sort of risky proposition since they can also break and the ends could take flight (beware rusty and pitted leafs). But I often wondered if the spring shops anneal/bend/heat treat or just cold bend to re-arch. Good bit of trial and error if it's your first time I'd think.

[www.mobiloil.com]
[www.youtube.com]
[www.youtube.com]

Here is the basic setup and proceedure. Be sure to scroll down to see the stop he added.
[grassrootsmotorsports.com]


Jim

Jim B, I haven't done the hole trick. My B is 73 chrome bumper. I read Lloyd's thread on Mgexperience on proper way to lower a rubber bumper car. It does look pretty tight up there and would not be easy. Those links are what I remember.



Edited 1 time(s). Last edit at 08/17/2014 02:53PM by mgb260.

I think we'll try it next time we work on the car. Pull the main leaf and see if we can reverse the arch. Might not even need to add a leaf.

Jim

I think you'll find most competitive MGB racers, including the ones with cars on BritishRacecar.com, run significantly SOFTER springs than stock at the rear. They typically remove two of the six original leafs. Traction bars are typically fitted, but IMHO they're more for roll steer effect than for wheel hop. (Look for a photo that shows what angle those bars sit at.) Meanwhile, the racers tighten-up the front suspension. From memory, typical front spring rates for MGB racecars are between 650 and 850 #/inch. You'll probably want a rear anti-sway bar, especially after you soften up the rear springs. Typically, the rear sway bar is used more for fine tuning during a race weekend because it's easier to get to than the front bar.

Curtis beat me to it.

Pleas don't cut that rear sway bar in half. We will need it with the 7/8" bar up front. Softer springs in the rear is better. Plus, this car will be lighter than stock. Lose a leaf or two & de-arch as needed.

Lowering to CB specs.

[www.mgexp.com]

Great stuff by Dave Headley.

[www.fast-mg.com]

Well, first off the '74-1/2 has no swaybars anywhere. Go figure. So whatever it gets will have to be added.

Good info on the links. I'd forgotten about the shackle mount. On the spring rates, it makes sense as most race tracks are mostly level so bottoming the suspension isn't much of a problem. That makes it even easier in fact, as just flipping over the main leaf will both lower the car and soften the spring rate. We might want to try that first.

Jim

I forgot the bean counters left the sway bars off the '74.5-'76 rubber bumper cars. I don't think that the factory rear bar is an easy retro-fit, either.

Actually, I think only the '77-'80 B had a factory rear bar. I like mine. I believe it helps balance out the oversized front bar.



Edited 1 time(s). Last edit at 08/18/2014 08:15PM by MGBV8.

I expect it does. So initially we may have to go with a lighter front bar. I think I have a GT bar here somewhere, that worked really well on my '71 when it was lowered about 2".

This works. I've beaten spring into shape like this a number of times.

[www.jalopyjournal.com]

We ended up putting a 1" bar on the front since we had that and the brackets for it.. Probably will make it plow but we'll see. We didn't have the brackets for the smaller bars, though I'm sure they are around hers somewhere.

I've been considering the option of de-arching the springs here. Not all that hard to do and I have a press, so we might go that route. It'd save some money too and that's important.

Jim