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MG MGB Technical - Results of rebuilt shocks and lighter oil

I'm posting this in hopes of getting some advice on fine tuning the suspension and sharing what I think I've noticed with a few subtle changes. I just started driving the car last year (only MG I've ever driven, so I have nothing relevant to compare it to). It's a 66 MGB w/o front sway bar.

Phase 1 (last spring)
New Energy Suspension bushings throughout.
New Sumitomo 185/70R14 tires; 30 psi rear, 28 psi front (wire wheels with inner tubes)
Shocks - drained, pumped/filled all with 40W fork oil in hopes of low buck performance (shocks were stiff, fronts leaked).
Shocks passed the bounce test on all four corners.
The ride was harsh, but the car seemed to hold the road very well. I liked it.

Phase 2 (a week or so ago)
After searching archives and reading that the 40W was bad for the shocks the 40W was changed to 20W mineral based fork oil in the rear shocks only. Fronts were left alone (planned on getting replacements).
Everything else was the same.
The ride was softer, but the rear end seemed to want to let go in corners. This may have been due to driving faster because of the softer ride - don't really know for sure because speeds weren't recorded.

Phase 3 (yesterday)
Replaced front shocks with rebuilt ones from World Wide Parts.
While replacing I noticed a couple of things about the old front shocks: the lever arm on one was extremely limp as if it has no oil (it did pass the bounce test prior to removal); the arm on the other was very stiff, maybe it didn't leak as much (still had 40W). Of course it's possible I can't judge the bounce test, but I think I can.
The arms on the new rebuilt shocks were fairly easy to move (I think I've read they use 20W), but they didn't go down by their own weight - stayed raised a bit during installation.
The ride...I don't know, seems like the rear was less sticky as in Phase 2, but also seemed like the front held a little tighter - really hard to say.

I'm not satisfied - I think it can be much better, but I'm not sure where to begin. I am sure I'll leave the front shocks alone.
Should I:
1) play around with tire pressures - any suggestions
2) try 30W or 40W in the rear shocks
3) add little washers to shim the rear shock valves and use 20W
4) all or none of the above?

Thanks.
Glenn

Glenn,
I'm by no means an expert, but I think your tire pressures are too high. Here's a little treatise on how to derive the proper pressures for your particular car and driving style:
http://mgaguru.com/mgtech/tires/tire1.htm

The info was written by and MGA guy, but the same priciples and procedures apply....

Good luck!
Rob Edwards

Get an anti-sway bar for the front, but don't over do it size wise. 5/8" would probably be about right unless you intend to do further suspension mods. Don't stiffen up the rear at all.

~Jerry
Jerry Causey

I would suggest you go to a 3/4 inch bar on the front and drop tyre pressures to 21 front and 24 rear, the rear suspension should be left soft and compliant - I think the original Armstrong shock absorber fluid is only 5 weight.
Chris at Octarine Services

Thanks for the link and the suggestions.

I've been thinking about adding a front sway bar since before I started driving it, but the car has needed other things more.

I will try lighter tire pressures next time out.
Glenn

I just tried it with 21 and 24 psi front and rear. The ride seemed about the same, maybe a little softer, and the car held the corners just fine.

Thanks again.
Glenn

I've always had good luck with higher pressures. Softer gives a better ride but is less precise in corners. Now with 195/60-15 tires I run 28-30 psi and it sticks like glue.
Steve Simmons

This thread was discussed between 20/04/2004 and 22/04/2004

MG MGB Technical index

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