Checking For Bump Steer On An MGB Or Any Car

Checking For Bump Steer On An MGB Or Any Car
I was given some great advice by Alastair Cox at AJ Barnard Engineering ajbengineering... for an easy way to check for bump steer on a car. You will need a set of wheel alignment gauges and be able to remove the springs from the car whilst keeping the suspension intact to check for bump steer at home.
The whole process is fairly simple, the front springs are removed and then the car raised and lowered on the jack whilst checking for any change in front wheel alignment.
On my car I found I had around 70 minutes (approx 5mm) of toe out during bump, I misspoke at the start of the video saying 30 degrees of toe out; it should be 30 minutes.
From speaking to Alastair at AJ Barnard he would usually take measurements 1”/25mm either side of ride height. He recommended that if you can get it within 10-20 minutes that would be fine for an MGB. Also in my car it’s toeing out on bump which is ideal for stability. It will toe in on rebound.
What is bump steer? Bump steer is the term for the tendency of the wheel of a car to steer itself as it moves through the suspension stroke. Bump steer causes a vehicle to turn itself when one wheel hits a bump or falls down into a hole or rut.
I can’t say that I have experienced it in my car, but I am keen to re-locate the steering rack in my car without detriment to the handling.
I will add some pillow blocks in order to move the steering rack forward slightly to clear the front pulley on my engine and then take some more measurements.

[@lanceneuman9528]

Well done David. I believe Brown and Gammons have shims for under the steering rack to address this. When I installed my crossmember camber kit, they were included. Thanks for the content.

[@davidrussellwilks]

I think you are totally correct Lance, I've seen a few MGB race cars with pillow blocks under the steering rack (it's quite hard to spot unless you look underneath). Hopefully I can raise the rack and move it forwards slightly.

[@MGB-learning]

Always an outstanding video and presentation.

[@davidrussellwilks]

Many thanks!

[@BrailsfordsRides]

Good video, I did alot of reading about bump steer while I was contemplating lowering my Foxbody mustang

[@davidrussellwilks]

Many thanks Matt

[@samuelwahls8315]

Could you do a video on the SU carburetors?

[@user-ee5hf6nj7e]

Hi David, not seen any videos for a while. Have you been out racing this season?

[@davidrussellwilks]

Unfortunately no racing this year, we started what should have been a 3 month house renovation in February and it's still going! Should be back again for 2024 though. I hope to make some videos over winter too, there's pltn to do.

[@johnedbish]

Heya David, loving these useful MGB videos, I was just wandering if you could possibly tell me what brand or make those alignment guages are? I've been on the hunt for some good ones!

[@davidrussellwilks]

Thanks for your message John, the gauges I am using are Dunlop AGO40's I think they are still made but do come up on eBay now and again.

[@toyotatim2521]

I was getting a bit worried when you said you had 30 degrees toe out but it's nice to see someone using the old Dunlop tracking device, I have the same one which must be 60 or more years old and still as accurate as ever and easy to calibrate. Can you re-adjust the bump steer when you've moved the rack?

[@davidrussellwilks]

Yes, my mistake with degrees and minutes! I will try moving the race and see what changes, I do think raising the rack slightly may mean less bump steer looking at the angle of the steering arms, will try it and see.

[@mgbroadsterJ]

How do you get the orrect springs ?

[@davidrussellwilks]

It's a little bit of trial and error, you'll need to know the height and weight of the springs currently fitted and then make changes to achieve the ride you want.