I had no intention to spend big bucks on a set of rubber bump stops for the Jimny. What's the point its just rubber something else should fit?
So with that ideology and with a limited search for one in the market found the Alto's rear bump stops could be a suitable alternative. It was and along with the spring change this was put in. Its about half an inch longer than the stock, give or take.
I was not really happy with it because the first segment was hollow. Well, that is kind of good makes it sort of dual stage bump stops but may be a bit too soft in the running and are not pointy like the rear. I like pointy. Said a great man in 2012.
Against my wishes i decided to import a set of bump stops with a plan in my mind. Jimnybits 25mm bump stops were chosen and they come with cone type (progressive) rubber buffer. The plan was simple I wouldn't use the supplied bump rubbers but intended to use the Jimny's original rear bump stops in the front.
It wasn't a straight swap, never thought it would be as it isn't advertised like that. The threading on the aluminium bushing is M10x1.5. The threading on the OE Jimny rear bump stops are M10x1.25. The long stud supplied with the Jimnybits aluminium bump stop bush is an M10x1.5, this is required to mount the aluminium bushing on to the vehicle.
What now needs to be done is to make the lower part (about 1.5cm) of the thread on the bushing M10x1.25 and leave the rest as is. So the lower part of the bushing can take the OEM Jimny rear bump stop and the top the M10x1.5 stud supplied for installation.
Sensible thing to do is to drill out the section of the thread that needs to be re done and do a helicoil insert. This is how it should be done, can't tap a coarse thread to fine. But that isn't how I done. I took the M10x1.25 tap and ran it through the coarse thread till required length to cut new fine threads within that coarse thread.
This seemed to work, the bump stop screws in smooth and fits tight all right. Its a bump stop, all it needs to do is hold on and don't fall off. Guess this is good enough for that. If and when the rubber engages with the axle the shock is transmitted through the metal base to the aluminium bushing and not the threads. Think I will a add a drop of blue Loctite to prevent it from any accidental loosening.
The stock Jimny bump stop seems to be approximately 60mm length. Not pictured but the Alto rear bump stop is about 10-15mm longer give or take couple of mm's. The Jimnybits 25mm extended bump stop (rubber and aluminium bush combined) is 80mm which seems about right. My hybrid bump stop (Jimnybits aluminium bush with Jimny OE rear bump stop) is about 100mm. It doesn't mean that suspension travel sees a hard stop at the new length, being conical these are progressive bump stops there is more give than a block type bump stop.
So now I have nice pointy bump stop with means to go longer (wouldn't be necessary) and easily replaceable, both OEM and both locally, if I need to in future. Being Maruti it is a lot easier and cheaper to buy the OEM bump stops than to try and source any universal type bump stop rubbers which has these M10x1.5 threads.
There is no need to import the bush either if one can do the legwork and follow up. Any lathe workshop would be able to machine a set for you easily with the correct thread. I would have done so in the past.
Why?
The compressed length of Dobinson IMS at the front is ~395mm and the compressed length of stock shock absorber is ~380mm (as given on TGR, who is a friend). I haven't measured at what compression length of stock shocks the axle engages the stock bump stops. But I assume the stock bump stop length is kept as is by Suzuki to work with stock shocks to engage the axle before OE shock bottoms out.
The Dobinson IMS bottoms out in compression 15mm before the stock shocks does. This could mean the stock bump stop may or may not engage the axle before the IMS bottoms out internally in compression. If it bottoms out internally before hitting the external bump stops it could damage the shocks over time. I don't think the internal bump stops (if there is any) will be up take the pounding. In my opinion it is wise to extend the front bump stop by 15 mm to save the IMS from bottoming out internally.