TC front axle bump stop clearance

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John Crellin
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TC front axle bump stop clearance

Post by John Crellin » Mon May 04, 2020 9:36 am

When I bought TC8767 both front rubber bump stops were missing.On fitting replacements the axle/stop clearance on each side is about 3/4" (18mm) when the car is on the ground. I have checked the spring camber against the Blower manual and they appear correct. I gather from TC's Forever More that adjustment is by cutting back the rubber stop.

3/4" seems very little for the bump clearance and I am unable to find any source of guidance. I would welcome some advice ?

John Crellin

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Steve Simmons
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Re: TC front axle bump stop clearance

Post by Steve Simmons » Mon May 04, 2020 10:12 am

Hi John, welcome! TC8975 was missing its bump stops when I bought it as well. It also still has its original springs, so they may or may not be sagging a little. But my clearance is about the same as yours. It's been so long since I installed the bumpers that I don't recall for sure what effect they had, but I can say that they do play a part in the ride (and therefore handling) of the car. Look at the photo below and you will see the clean spot on the axle plates. What is notable is the size of the mark. It's much larger than the tip of the stop, so it gives an idea of how much the stop is compressed in normal driving. Both sides are identical, and I haven't hit any larger than normal road anomalies in the past several drives. The design makes sense to me because the springs are really stiff, so without the stop, a large enough bump would compress the springs really far and then the rebound back to normal would be very strong. I'm guessing you might notice the car being less bouncy on big bumps with the stops installed.
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MG TC Bump Stop
MG TC Bump Stop
bump-stop.jpg (60.65 KiB) Viewed 2882 times
1949 TC8975 / XPAG 9609
1948 TC6011 / XPEG1182 (XPAG6472)
http://www.mgnuts.com

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Duncan M
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Re: TC front axle bump stop clearance

Post by Duncan M » Mon May 04, 2020 10:54 am

bump.jpg
Rubber stops are known original on TC9866, but they did need to be re-glued (gorilla glue) when I did mechanical resto a few years back. Springs are original low miles, and have been taken apart and cleaned etc and re-greased. No teflon strips. Gap I measure is .4 inch, and dead even on each side. Pic shows a foam ear plug. Have you two used teflon, which could account for the gap difference?
I have close to a thousand miles with this configuration, and have never noticed anything unusual on rough roads.

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Ray White
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Re: TC front axle bump stop clearance

Post by Ray White » Mon May 04, 2020 1:06 pm

The bump stops had long since disappeared from my TC and I have just replaced them as part of the rebuild. This thread has been a help to me and I can check out the gap tomorrow.

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SteveT
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Re: TC front axle bump stop clearance

Post by SteveT » Tue May 05, 2020 6:39 am

Hi just had a quick check of mine and without getting serious I'd say I have 3/4 inch on both sides.
TC 6927

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John Crellin
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Re: TC front axle bump stop clearance

Post by John Crellin » Tue May 05, 2020 9:18 am

Many thanks for those replies, it would seem that mine are about right after all. I can confirm my springs were dismantled, cleaned and greased without teflon strips as for TC 9866. This seems to lead to a conclusion that these components have an active role in the front suspension as variable rate springs as well as being just a stop.

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Duncan M
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Re: TC front axle bump stop clearance

Post by Duncan M » Tue May 05, 2020 9:59 am

Original rubber piece on my stops now measures around 1.9 inches (not including plate). Curious what the replacement ones are measuring?

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Steve Simmons
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Re: TC front axle bump stop clearance

Post by Steve Simmons » Tue May 05, 2020 10:22 am

I just measured two stops. One is new and unused, purchased from ASL probably around 1980. Including the plate it's a tad over 2". Then I measured as best I could with a small tape measurer, the Moss parts on TC8975. They've been on there for probably 30K miles and they appear to be about the same size as the others, maybe a touch taller.
1949 TC8975 / XPAG 9609
1948 TC6011 / XPEG1182 (XPAG6472)
http://www.mgnuts.com

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jddevel
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Re: TC front axle bump stop clearance

Post by jddevel » Thu May 07, 2020 4:39 am

I`m sure I`ll be corrected but I was taught that you shouldn`t "grease" springs as indicated in Duncan M. comment. Was I mis-informed?

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Ray White
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Re: TC front axle bump stop clearance

Post by Ray White » Thu May 07, 2020 8:39 am

jddevel wrote:
Thu May 07, 2020 4:39 am
I`m sure I`ll be corrected but I was taught that you shouldn`t "grease" springs as indicated in Duncan M. comment. Was I mis-informed?
Leaf springs have been greased by diligent owners since Adam was a lad. Any lubrication is better than none at all - if only to extend the spring's lifespan.

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Steve Simmons
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Re: TC front axle bump stop clearance

Post by Steve Simmons » Thu May 07, 2020 8:41 am

There are those who say dry is best, and that grease only attracts dirt which wears the metal. But there are also those who say that grease is the only way for the spring to slide as smoothly as possible. And then there are the old spring oiling machines. And modern slippery adhesive tape, liners, etc. So who knows what's truly best? Not me.
1949 TC8975 / XPAG 9609
1948 TC6011 / XPEG1182 (XPAG6472)
http://www.mgnuts.com

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Duncan M
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Re: TC front axle bump stop clearance

Post by Duncan M » Thu May 07, 2020 11:48 am

Well lubed leaf springs keep moisture and dirt and rust from getting in between. As Ray points out, it will extend life. The old argument about grease/oil attracting dirt and sand falls flat when you know about gaiters or tape or twine wraps. The gaiters and wraps keep the oil in the springs, and keep the elements out. The TC had no giaters or wraps originally, because it was an inexpensive car. Hot rodders in the 50's found a great alternative to fancy aftermarket gaiters in Denso brand Densyl tape. Used to wrap metal pipes before burial, it is a "petroleum" impregnated heavy cloth tape. Comes in 2 inch wide rolls and is not cheap, but seems to work quite well. I used silicone grease mixed with graphite powder, and then wrapped.
densyl.jpg

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John Crellin
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Re: TC front axle bump stop clearance

Post by John Crellin » Thu May 07, 2020 9:40 pm

Returning for the moment to the orignal topic of this thread i.e. what should the at rest clearnce between the rubber bump stop and the axle pad be, a local contact has drawn my attention to Jim Buell's very comprehensive 24 page booklet-"The MGTC Front End" which is freely available to download on line. This deals in considerable detail with all aspects of setting up the steering gear and front suspension and is well worth a read from cover to cover.

On page 12 under the heading "Front Springs" Jim writes:
"The front springs and their mounts are another cause for concern.After all these years springs tend to sag or they may be broken.
As a quick check, there should be approximately 2" between the conical shaped rubber buffer and the buffer pad when the car is on the ground(loaded clearance should be at least 3/4")"

Early posts on this thread all seem to be close to or on this minimum figure and as my TC seems to ride and handle just fine I intend to leave as is.

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Duncan M
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Re: TC front axle bump stop clearance

Post by Duncan M » Thu May 07, 2020 11:32 pm

John, the Buell article is in the "resources" section on this site, and most of us have used it as a reference. http://www.mg-tabc.org/library/Buell-TC ... 3rd-ed.pdf When I was doing my front end about 5 years ago I used it from this site and was confused about the then 2nd edition which stated the wheel bearing nut should be tightened to 10 pounds torque. That 2nd edition had been out for a quite a number of years and nobody had noticed that error before, on page 17. The 3rd edition (now) says the correct 80 lbs. Some editing troubles? Not sure what the 2 inches refers to, or what the "loaded" refers to. -- I do not think it means there is a range between 2" and 3/4".-- Maybe the 2 inches should be with the car jacked up off the ground? And the 3/4" back down on the ground under its own weight? 3/4" seems like a reasonable number for a TC.

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Steve Simmons
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Re: TC front axle bump stop clearance

Post by Steve Simmons » Thu May 07, 2020 11:57 pm

I hadn't thought to check Jim's article. I wonder if that 2" is another typo. That he meant to say at least 2" when OFF the ground. Clearance on the unloaded chassis in my garage looks to be around 2.5".

If you want to check the condition of your springs, here is a chart that shows specs when new:
http://www.tcmotoringguild.org/techinfo ... g-data.jpg
1949 TC8975 / XPAG 9609
1948 TC6011 / XPEG1182 (XPAG6472)
http://www.mgnuts.com

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Duncan M
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Re: TC front axle bump stop clearance

Post by Duncan M » Sat May 09, 2020 12:47 pm

To add info to the apparent spec's supplied in the Buell article, I lifted at frame to get a front wheel off the ground and got 2 3/8 distance. When I dropped the car back down, the gap was then 3/4 inch. The earlier mentioned figure was obtained as the car sat after a drive, or "settled."
justdropped.jpg

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John Cockrem
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Re: TC front axle bump stop clearance

Post by John Cockrem » Sat May 09, 2020 10:41 pm

I recon every member has probably been in his or her garage checking the bump stop gap. For the record mine is pretty close to Duncans` 2 2/8 inch on the left side and 2 1/8 on the right side with the springs hanging. Ground measurement was 1/2 inch both sides. My springs have been greased if that makes a difference as I measured 1/2 before and after the hanging loose measurement.
BTW check page 17 of the "Brown Book", spring lubrication was recomended by the factory I would say.
John Cockrem TC2268

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